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Navigation expertise and the human hippocampus: A structural brain imaging analysis
Abstract
Grey matter volume in the posterior hippocampus of London taxi drivers is greater than in age-matched controls, and the size of this increase correlates positively with time spent taxi driving (E.A. Maguire et al., 2000. Proc Natl Acad Sci USA 97: 4398-4403). This change suggests that increased posterior hippocampal grey matter volume is acquired in response to increased taxi driving experience, perhaps reflecting their detailed representation of the city. However, an alternate hypothesis is that the difference in hippocampal volume is instead associated with innate navigational expertise, leading to an increased likelihood of becoming a taxi driver. To investigate this possibility, we used structural brain imaging and voxel-based morphometry (VBM) to examine a group of subjects who were not taxi drivers. Despite this group showing a wide range of navigational expertise, there was no association between expertise and posterior hippocampal grey matter volume (or, indeed, grey matter volume throughout the brain). This failure to find an association between hippocampal volume and navigational expertise thus suggests that structural differences in the human hippocampus reflect the detail and/or duration of use of the spatial representation acquired, and not innate navigational expertise per se.
... For study one, we expect modulation of BOLD fMRI activity in regions of hippocampus, anterior cingulate cortex, and frontopolar regions / BA10. The hippocampus has been heavily implicated in spatial navigation with evidence suggesting the region is critical for flexible route-taking and periods of active navigation Hartley et al., 2003). In contrast, the anterior cingulate cortex (ACC) has been implicated in decision-making paradigms with choice value (Kennerley et al., 2006;Rushworth & Behrens, 2008). ...
... The first region of interest in this study is the hippocampus as this task requires integration of spatial information and flexible route-taking during active navigation, roles for which the hippocampus has been implicated Hartley et al., 2003). The second regions of interest is the anterior cingulate cortex, inspired by the recent work in macaques with multi-agent tracking (Yoo, Hayden, & Pearson, 2021;Yoo, Sleezer, & Hayden, 2018;Yoo, Tu, & Hayden, 2021). ...
... The correlation of activity in parietal regions, dorsolateral prefrontal cortex, and frontopolar prefrontal regions (BA10) with the contrast of active navigation compared to a passive control (the Follow phase in this task) is consistent with prior fMRI findings with a similar design structure Hartley et al., 2003). This result supports the argument that hippocampal and frontal regions support route planning and active navigation (Aguirre et al., 1996;Ekstrom et al., 2003;Iaria et al., 2003). ...
This thesis focused on a primary aim: investigate behavioral and neural correlates of flexible spatial navigation using a variety of methods. To do so, we combined immersive virtual reality, real-world navigation, and neuroimaging to better understand the nuances in flexible behavior. Across all five studies discussed in this thesis, we utilized Sea Hero Quest as a baseline measure of spatial ability and prospective predictor for both behavioral and neural measures. Importantly, the work presented in this thesis aimed for novelty in methods. First, this thesis presents the first fMRI results from a dynamic navigation task with a continuously moving goal position – to our knowledge. Second, we found no evidence for a relationship between performance in Sea Hero Quest and either real-world wayfinding / spatial memory measures or related neural measures (hippocampal volume ratio) – in contrast to some recent findings. Last, a new task design looking at spatial performance in an urban version of Sea Hero Quest highlighted the importance of realism in task design. Overall, the work presented in this thesis adds to an understanding of flexible navigation and, importantly, highlights areas in which the field might advance.
... Intact hippocampal function is necessary for place learning in a cross-maze task as well (Packard & McGaugh, 1996). Evidence from neuroimaging studies of humans and patients with hippocampal damage further implicates the hippocampus' role for both place learning and flexible navigation of novel routes and environments (Spiers et al. 2001a,b;Hartley et al., 2003;Bohbot et al., 2007;Iaria et al., 2004;Xu et al., 2010;Howard et al., 2014;Javadi et al., 2019a;Javadi et al., 2019b;Patai et al., 2019). ...
... Differences in acquisition time of place and response learning, with the latter taking longer to form, also suggest that these behavioural strategies instantiate in the brain as dissociable neural mechanisms (Packard & McGaugh, 1996). Subsequently, human neuroimaging research has provided convergent evidence for the involvement of the dorsal striatum in such response strategy navigation (Iaria et al. 2004;Voermans et al., 2004;Hartley et al., 2003). Response learning is not traditionally considered flexible because it is tied to the specific features of the environment (e.g. ...
... They found activity in the caudate nucleus to be parametrically modulated by the influence of intramaze landmarks on goal locations, while the right posterior hippocampus correlated with boundary-related influence on goal locations (Doeller et al., 2008). In another study in which participants navigated a virtual town, caudate activity was preferentially active during route following trials, while anterior hippocampus was preferentially active during wayfinding trials (Hartley et al., 2003). ...
Animals and humans are remarkable in their ability to flexibly adapt to changes in their surroundings. Navigational flexibility may take many forms and in this thesis we investigate its neural and behavioral underpinnings using a variety of methods and tasks tailored to each specific research aim. These methods include functional resonance magnetic imaging (fMRI), freely moving virtual reality, desktop virtual reality, large-scale online testing, and computational modelling. First, we reanalysed previously collected rodent data in the lab to better under- stand behavioural bias that may occur during goal-directed navigation tasks. Based on finding some biases we designed a new approach of simulating results on maze configurations prior to data collection to select the ideal mazes for our task. In a parallel line of methods development, we designed a freely moving navigation task using large-scale wireless virtual reality in a 10x10 space. We compared human behaviour to that of a select number of reinforcement learning agents to investigate the feasibility of computational modelling approaches to freely moving behaviour. Second, we further developed our new approach of simulating results on maze configuration to design a novel spatial navigation task used in a parallel experiment in both rats and humans. We report the human findings using desktop virtual reality and fMRI. We identified a network of regions including hippocampal, caudate nu- cleus, and lateral orbitofrontal cortex involvement in learning hidden goal locations. We also identified a positive correlation between Euclidean goal distance and brain activity in the caudate nucleus during ongoing navigation. Third, we developed a large online testing paradigm to investigate the role of home environment on wayfinding ability. We extended previous reports that street network complexity is beneficial in improving wayfinding ability as measured using a previously reported virtual navigation game, Sea Hero Quest, as well as in a novel virtual navigation game, City Hero Quest. We also report results of a navigational strategies questionnaire that highlights differences of growing up inside and outside cities in the United States and how this relates to wayfinding ability. Fourth, we investigate route planning in a group of expert navigators, licensed London taxi drivers. We designed a novel mental route planning task, probing 120 different routes throughout the extensive street network of London. We find hip- pocampal and retrosplenial involvement in route planning. We also identify the frontopolar cortex as one of several brain regions parametrically modulated by plan- ning demand. Lastly, I summarize the findings from these studies and how they all come to provide different insights into our remarkable ability to flexibly adapt to naviga- tional challenges in our environment.
... The connection strength from OPA to PPA was especially high in the left hemisphere, with the signal between these regions showing positive correlations with vivid mental imagery ability ( Figure 4). Several different studies confirm that a network of brain areas support VMI, spatial cognition and navigation, including the right hippocampus and right caudate nucleus that are associated with knowing where places are and navigating accurately to and between them [54]. There appears to be in-built redundancy in the VMI network, as evidenced by the reported ability to experience vivid VMI in the absence of significant amounts of cortical tissue (depending, of course, on the amount and location of the missing or damaged tissue). ...
... Perception and mental imagery of objects requires a network of structures at different Several different studies confirm that a network of brain areas support VMI, spatial cognition and navigation, including the right hippocampus and right caudate nucleus that are associated with knowing where places are and navigating accurately to and between them [54]. There appears to be in-built redundancy in the VMI network, as evidenced by the reported ability to experience vivid VMI in the absence of significant amounts of cortical tissue (depending, of course, on the amount and location of the missing or damaged tissue). ...
The Action Cycle Theory (ACT) is an enactive theory of the perception and a mental imagery system that is comprised of six modules: Schemata, Objects, Actions, Affect, Goals and Others’ Behavior. The evidence supporting these six connected modules is reviewed in light of research on mental imagery vividness. The six modules and their interconnections receive empirical support from a wide range of studies. All six modules of perception and mental imagery are influenced by individual differences in vividness. Real-world applications of ACT show interesting potential to improve human wellbeing in both healthy people and patients. Mental imagery can be applied in creative ways to make new collective goals and actions for change that are necessary to maximize the future prospects of the planet.
... Hippocampal volume tracking with structural MRI has proven clinical utility in a variety of diseases, including Alzheimer's disease [19,20], temporal lobe epilepsy [21], and traumatic brain injury [22]. Interestingly, Maguire et al. showed that taxi drivers' hippocampi were larger than those of other people, which was not correlated with innate navigational expertise but with training and their ability to use their spatial knowledge [23,24]. ...
... Interestingly, Ericksonn et al. showed that physical activity training increased hippocampal perfusion, reversing effect of agerelated loss [50]. Memory training can also increase the hippocampi volumes as showed studies in taxi drivers [23,24]. ...
Background
The hippocampus is a critical organ for irradiation. Thus, we explored changes in hippocampal volume according to the dose delivered and the location relative to the glioblastoma.
Methods
All patients were treated for glioblastoma with surgery, concomitant radiotherapy and temozolomide, and adjuvant temozolomide. Hippocampi were retrospectively delineated on three MRIs, performed at baseline, at the time of relapse, and on the last MRI available at the end of follow-up. A total of 98, 96, and 82 hippocampi were measured in the 49 patients included in the study, respectively. The patients were stratified into three subgroups according to the dose delivered to 40% of the hippocampus. In the group 1 (n = 6), the hippocampal D 40% was < 7.4 Gy, in the group 2 (n = 13), only the H contra D 40% was < 7.4 Gy, and in the group 3 (n = 30), the D 40% for both hippocampi was > 7.4 Gy.
Results
Regardless of the time of measurement, homolateral hippocampal volumes were significantly lower than those contralateral to the tumor. Regardless of the side, the volumes at the last MRI were significantly lower than those measured at baseline. There was a significant correlation among the decrease in hippocampal volume regardless of its side, and D max ( p = 0.001), D 98% ( p = 0.028) and D 40% ( p = 0.0002). After adjustment for the time of MRI, these correlations remained significant. According to the D 40% and volume at MRI last , the hippocampi decreased by 4 mm ³ /Gy overall.
Conclusions
There was a significant relationship between the radiotherapy dose and decrease in hippocampal volume. However, at the lowest doses, the hippocampi seem to exhibit an adaptive increase in their volume, which could indicate a plasticity effect. Consequently, shielding at least one hippocampus by delivering the lowest possible dose is recommended so that cognitive function can be preserved.
Trial registration Retrospectively registered.
... The association between hippocampal volume and memory functions was also validated in the opposite direction, as demonstrated by a positive correlation between grey matter volume in the posterior hippocampus of London taxi drivers and their spatial memory, along with their navigational abilities (46). ...
Background
The landscape of brain metastases radiotherapy is evolving, with a shift away from whole-brain radiotherapy (WBRT) toward targeted stereotactic approaches aimed at preserving neurocognitive functions and maintaining overall quality of life. For patients with multiple metastases, especially in cases where targeted radiotherapy is no longer feasible due to widespread dissemination, the concept of hippocampal sparing radiotherapy (HA_WBRT) gains prominence.
Methods
In this narrative review we explore the role of the hippocampi in memory formation and the implications of their postradiotherapy lateral damage. We also consider the potential advantages of selectively sparing one hippocampus during whole-brain radiotherapy (WBRT). Additionally, by systematic evaluation of relevant papers published on PubMed database over last 20 years, we provide a comprehensive overview of the various changes that can occur in the left or right hippocampus as a consequence of radiotherapy.
Results
While it is important to note that various neurocognitive functions are interconnected throughout the brain, we can discern certain specialized roles of the hippocampi. The left hippocampus appears to play a predominant role in verbal memory, whereas the right hippocampus is associated more with visuospatial memory. Additionally, the anterior part of the hippocampus is more involved in episodic memory and emotional processing, while the posterior part is primarily responsible for spatial memory and pattern separation. Notably, a substantial body of evidence demonstrates a significant correlation between post-radiotherapy changes in the left hippocampus and subsequent cognitive decline in patients.
Conclusion
In the context of individualized palliative radiotherapy, sparing the unilateral (specifically, the left, which is dominant in most individuals) hippocampus could expand the repertoire of strategies available for adapted WBRT in cases involving multiple brain metastases where stereotactic radiotherapy is not a viable option. Prospective ongoing studies assessing various memory-sparing radiotherapy techniques will define new standard of radiotherapy care of patients with multiple brain metastases.
... To become a healthy citizen, depends more on personal activity history that genome. The brain is a self-regulated and self-controlled organ, which develops and works similarly to the Prigogine's theory of dissipative structures, that is, it has a historical nature (Ardila, 2018;Firth et al., 2019;Maguire et al., 2003;Maguire, Woollett, & Spiers, 2006). Brain will construct itself to respond the activity asked to each one. ...
On human mental activity, the cellular orientation by R. Virchow is no longer so heuristic. The cell (neuron) is not the unit of mental life, but human activity. Plasticity depends not only on genetics, proteins, information in the DNA inside neuron or other cells, but it depends also on the object-oriented activity performed by the individuals in ontogenesis. More and more information from neuroscience and molecular biology and molecular genetics, helps to build our understanding on human mind and behavior. Advances in science pushed us to rethink our clinical practice. Vygotsky’s cultural-historical and activity theory seems consistent in the integration of neurosciences with psychological science, is the fact that is a monistic approach. We illustrate our idea with a clinical case of a man diagnosed by psychiatry with obsessive-compulsive disorder (OCD). The neuropsychological education program includes the methodology of neuropsychological rehabilitation proposed by A. R. Luria and mental human developmental (step-by-step) theory of P. Galperin. The prevalence of OCD is high, and remission rates are extremely low (at 15 years, 60% continue to show the symptoms). The results with the clinical case presented here, as well as in several hundred other clinical cases are encouraging. Vygotsky’s cultural-historical and activity theory seems to be a good proposal for a new clinical practice in clinical psychology and psychiatry. This article is an invitation to other colleagues to experiment the same methodology, in other clinical centers and even in other countries, in the sense that we study the possibility of this being an efficient and effective response that we intend to have available to our clients.
... Conversely, there were only a few clusters exhibiting a positive correlation with age: the right thalamus, the left hippocampus, and the leftparahippocampal gyrus. It is interesting to note that these regions were found to be developing structurally and functionally in association with age, experience, and development (e.g., social skills, memory) (Gauthier et al. 2000;Maguire et al. 2003). Overall, the nonautistic group had more extensive clusters, covering most gray matter tissue, showing a negative correlation with age, while the autistic group had relatively less coverage of a positive correlation of GMV and age. ...
Autism spectrum disorder (ASD) is characterized by difficulties in theory of mind (ToM) and social communication. Studying structural and functional correlates of ToM in the brain, and how autistic and nonautistic groups differ in terms of these correlates can help with diagnosis and understanding biological mechanisms of ASD. In this study, we investigated white matter volume (WMV) and gray matter volume (WMV) differences between matching autistic and nonautistic samples, and how these structural features relate to age and theory of mind (ToM) skills, indexed by the Reading the Mind in the Eyes (RMIE) measure. The results showed widespread GMV and WMV differences between the two groups in regions crucial for social processes. The autistic group did not express the typically observed negative GMV and positive WMV correlations with age at the same level as the nonautistic group, pointing to abnormalities in developmental structural changes. In addition, we found differences between the two groups in how GMV relates to ToM, particularly in left frontal regions, and how WMV relates to ToM, mostly in the cingulate and corpus callosum. Finally, GMV in left insula, a region that is part of the salience network, was found to be crucial in distinguishing ToM performance between the two groups.
... Such mental constructions can vary among different people and depend on factors such as viewpoint, scale or spatial complexity of the environment. Previous experiences can also affect this process [4,5]. ...
The architectural experience of visiting a virtual building and exploring its contents requires tools to provide visitors with accessible and pleasurable ways to conduct their stroll and facilitate the contemplation and enjoyment of the contents displayed. Natural user interfaces (NUI) are effective and engaging tools for interacting with digital content. In this paper, the authors combine their previous work in the research lines of natural user interfaces and assisted navigation, putting them together on a UX test scenario and studying their combined effect. The testbed consisted of an installation controlled using a depth camera for NUI interaction and applying an attractor-based approach of assisted navigation. The UX experiment consisted of five stages, with three test sets of increasing complexity. The system monitored and recorded the users’ movements on each test during the experiment to extract quantitative data. After each task, users filled out specific questionnaires that provided qualitative information. The study also evaluates the influence of users’ previous expertise on 3D video games in their performance taking the test. The results indicate the benefits of combining both technologies and how they enhance the virtual visit experience. Furthermore, the combined use of natural interaction and assisted navigation facilitates universal access to installations of this kind, frequently found in museums and exhibits, independently of previous user expertise in interactive 3D environments, such as video games.
... Conversely, there were only a few clusters exhibiting a positive correlation with age: the right thalamus, the left hippocampus, and the leftparahippocampal gyrus. It is interesting to note that these regions were found to be developing structurally and functionally in association with age, experience, and development (e.g., social skills, memory) (Gauthier et al. 2000;Maguire et al. 2003). Overall, the nonautistic group had more extensive clusters, covering most gray matter tissue, showing a negative correlation with age, while the autistic group had relatively less coverage of a positive correlation of GMV and age. ...
Autism spectrum disorder (ASD) is characterized by difficulties in theory of mind (ToM) and social communication. Studying structural and functional correlates of ToM in the brain and how autistic and nonautistic groups differ in terms of these correlates can help with diagnosis and understanding the biological mechanisms of ASD. In this study, we investigated white matter volume (WMV) and gray matter volume (GMV) differences between matching autistic and nonautistic samples, and how these structural features relate to age and ToM skills, indexed by the Reading the Mind in the Eyes (RMIE) measure. The results showed widespread GMV and WMV differences between the two groups in regions crucial for social processes. The autistic group did not express the typically observed negative GMV and positive WMV correlations with age at the same level as the nonautistic group, pointing to abnormalities in developmental structural changes. In addition, we found differences between the two groups in how GMV relates to ToM, particularly in the left frontal regions, and how WMV relates to ToM, mostly in the cingulate and corpus callosum. Finally, GMV in the left insula, a region that is part of the salience network, was found to be crucial in distinguishing ToM performance between the two groups.
... Nos falantes de Inglês, há uma ativação de uma dada área visual, tendo em vista que a grafia das palavras não corresponde a um padrão fonético uniforme. Nos falantes do Chinês, por força da escrita ideográfica, áreas do lobo parietal destinadas à percepção espacial são ativadas(KOCHUNOV et al., 2003).Maguire e sua equipe observaram que as dimensões da massa cinzenta do hipocampo posterior, em motoristas de taxi londrinos, é maior do que em outros condutores não profissionais, com idades compatíveis, evidenciando uma modificação induzida pela frequência com que os taxistas lidam com o mapa mental da cidade(MAGUIRE et al., 2000).Estas são evidências de modificações na circuitaria neuronal e na densidade do córtex em resposta à interação social, ou seja, ao aprendizado. Evidentemente, o equilíbrio entre estrutura e função se modifica ao longo da vida. ...
Este artigo, partindo da teoria psicogenética de Piaget e da teoria histórico-cultural de Vygotsky, investiga a relação entre a estrutura do sistema nervoso central e as funções psicológicas superiores, visando observar a existência de eventos críticos que justifiquem saltos qualitativos na capacidade cognitiva da criança, bem como a rigidez de etapas de desenvolvimento. Diante da inexistência dos referidos eventos críticos, concluimos que a interação social, através da apreensão da cultura historicamente construída, representa um fator relevante no desenvolvimento do pensamento abstrato, atuando fisicamente sobre a citoarquitetura do sistema nervoso central e plasmando a evolução cognitiva imprescindível ao raciocínio abstrato, o qual não pode ser alcançado exclusivamente pelo desenvolvimento biológico.
... Possible mechanisms for this improvement in cognitive functions with PA have been speculated, such as PA causes an increase in cerebral blood flow (CBF) 37 and volume 38 to meet the increased demands for glucose and oxygen in active neurons 39 , and PA can modify the brain structure by causing neuronal modification and creation of new neurons by various mechanism [40][41][42] . PA also stimulates the production of various important growth factors; these factors have a big impact on brain morphology 43,44 . ...
Unlabelled:
Increased depressive severity has been linked to neurocognitive impairment. Aerobic exercise (AE) is an efficient technique for improving cognitive function. However, studies indicating the importance of AE to neurophysiological and neuropsychological functions in the depressed elderly using event-related potentials (ERPs) are scarce.
Objectives:
This study aimed to identify the potential benefits of AE on neurophysiological and neuropsychological functions.
Methods:
A total of 30 depressed older adults (AE group: n=15; control group (CG): n=14) were recruited based on the inclusion and exclusion criteria. The AE group was subjected to an 8-week-period AE program (3 times/week for 30 min per session) at moderate intensity, determined using heart rate maximum (HRmax). The training intensity was set at 50% HRmax and increased by 5% in subsequent weeks. Pre- and post-training measures for neurophysiological function were tested using ERP-P300 (amplitude-μV and latency-ms) and also for neuropsychological functions using the trail making test (TMT), mini mental status examination (MMSE), and everyday cognition questionnaire (ECog).
Results:
In the experimental group, statistically significant improvements were observed when analyzed for all 3 (group-by-time interaction effect, main effect of time, and main effect of group), in both neurophysiological functions (*p<0.001) and neuropsychological functions (*p<0.001), except for ECog scores, where the results were insignificant for the main effect of a group. Correlation analysis demonstrated no association between neurophysiological and neuropsychological functions (*p>0.05).
Conclusion:
Findings showed that 8 weeks of AE training may be a promising approach to improve cognitive functions in depressed older adults. However, considering relatively small number of patients, the question arises for effectiveness in other populations.
... Therefore, the results correlate the spatial elaboration and navigation (derived from the taxi driver profession) to an increment in the ability of allocentric spatial elaboration. Therefore, an implicit result suggested by such studies is the ability to elaborate space allocentrically (and as a consequence PT ability) can be trained through specific tasks such as driving in big cities and changing the destination constantly (Chase, 1983;Maguire, 2000Maguire, , 2003Dünser, 2006). ...
... It has been well established that prior learning experiences alter the canvas against which new learning occurs. Learning results in numerous structural changes in the brain ranging from cellular and synaptic changes (Lendvai et al., 2000;Nyberg et al., 2003;Holtmaat et al., 2005;De Paola et al., 2006;Epp et al., 2013) to altered macroscale measurements of regional size and shape (Maguire et al., 2003;Draganski et al., 2004;Bermudez et al., 2008;Hyde et al., 2009;Scholz et al., 2009). A classic example of learning-induced structural changes is the change in hippocampal volume that occurs as a result of intense practice with spatial navigation in London taxi drivers (Maguire et al., 2000). ...
Memory storage and retrieval are shaped by past experiences. Prior learning and memory episodes have numerous impacts on brain structure from micro to macroscale. Previous experience with specific forms of learning increases the efficiency of future learning. It is less clear whether such practice effects on one type of memory might also have transferable effects to other forms of memory. Different forms of learning and memory rely on different brain-wide networks but there are many points of overlap in these networks. Enhanced structural or functional connectivity caused by one type of learning may be transferable to another type of learning due to overlap in underlying memory networks. Here, we investigated the impact of prior chronic spatial training on the task-specific functional connectivity related to subsequent contextual fear memory recall in mice. Our results show that mice exposed to prior spatial training exhibited decreased brain-wide activation compared to control mice during the retrieval of a context fear memory. With respect to functional connectivity, we observed changes in several network measures, notably an increase in global efficiency. Interestingly, we also observed an increase in network resilience based on simulated targeted node deletion. Overall, this study suggests that chronic learning has transferable effects on the functional connectivity networks of other types of learning and memory. The generalized enhancements in network efficiency and resilience suggest that learning itself may protect brain networks against deterioration.
... Spatial cognition is very variable from one individual to another in a healthy population (Juan-Espinosa et al., 2000;Just and Carpenter, 1985;Maguire et al., 2003) and is influenced by several factors (Prestopnik and Roskos-Ewoldsen, 2000) such as gender (Iachini et al., 2009;Postma et al., 2004), anxiety (Lawton, 1994;Malinowski and Gillespie, 2001), cognitive style and strategies (Chen et al., 2009;Piccardi et al., 2011aPiccardi et al., , 2011b, and age (Allen et al., 2004). ...
We report the clinical case of AB, a right-handed 19-year-old woman who presents severe developmental topographical disorientation, a relatively rare syndrome, leading to difficulties in navigating in familiar (and novel) environments. This symptomatology appears without acquired cerebral damage (MRI described as normal) nor more global cognitive disability (high degree of education achieved).
An extensive assessment of spatial cognition with different aspects of underlying cognitive processes is first presented. Second, the patient's preserved cognitive abilities and her major difficulties in calculation, as well as her attention deficit, as seen in a detailed neuropsychological assessment, are reported.
For the first time to our knowledge, we show that developmental topographical disorientation can be associated with other developmental cognitive disorders affecting number processing (dyscalculia) and attention (Attention Deficit-Hyperactivity Disorder (ADHD)). We discuss the links between these different cognitive processes in relation to visuo-spatial working memory and magnitude representation, which could represent common denominators for all these syndromes.
This case report highlights the importance of thoroughly assessing potentially associated neurocognitive disorders in developmental topographical disorientation. In addition, it highlights the necessity to keep in mind the prevalence of spatial difficulties in the assessment of children and adolescents with other neurodevelopmental syndromes. Finally, this case study raises a new question about the nosology of developmental disorders affecting the visuo-spatial and spatial domains.
... Wayfinding implies developing mental constructions to classify, order and relate spaces and places, creating complex cognitive models of the environment used to plan the route to follow. Previous experiences can also affect this process [8,9]. ...
This paper describes the results of a case study about how Assisted Navigation and Natural User Interfaces can facilitate user control in virtual architectural walkthroughs and improve the overall experience. This study combines the authors’ previous research in these lines, studying the summed effect of both on a UX test scenario. The installation uses a depth camera for NUI interaction and applies an attractor based approach to assisted navigation. The analysis uses the data collected in an experiment with two test groups of participants considering their previous experience and gaming abilities. The experiment was composed of five stages, with three different test sets of increasing complexity. During the test, the system monitored and recorded the user movements to extract relevant data about time to complete the task, number of collisions and time spent in a collision condition. In addition, the users completed specifically questionnaires immediately after completion of tasks. The results indicate the benefits of combining both technologies enhancing the virtual visit experience. It also evaluates the effects of users’ previous expertise on 3D video games in the results.
... The hippocampus has been proposed to process complex catenations of spatial features 84 and the posterior hippocampus in particular is responsible for the processing of allocentric memory 85 . In line with this, experienced taxi drivers that had acquired a complete and detailed allocentric memory of the layout of the city of London were reported to have greater gray matter density in their posterior hippocampus and less gray matter density in their anterior hippocampus compared to control subjects 86,87 . Opposite changes in hippocampal size were identified in blind individuals: the posterior hippocampus was smaller and the anterior hippocampus was larger than in sighted individuals 88 . ...
In the weeks immediately after onset of sensory loss, extensive reorganization of both the cortex and hippocampus occurs. Two fundamental characteristics comprise widespread changes in the relative expression of GABA and glutamate receptors and debilitation of hippocampal synaptic plasticity. Here, we explored whether recovery from adaptive changes in the expression of plasticity-related neurotransmitter receptors and hippocampal synaptic plasticity occurs in the time-period of up to 12 months after onset of sensory loss. We compared receptor expression in CBA/J mice that develop hereditary blindness, with CBA/CaOlaHsd mice that have intact vision and no deficits in other sensory modalities throughout adulthood. GluN1-subunit expression was reduced and the GluN2A:GluN2B ratio was persistently altered in cortex and hippocampus. GABA-receptor expression was decreased and metabotropic glutamate receptor expression was altered. Hippocampal synaptic plasticity was persistently compromised in vivo. But although LTP in blind mice was chronically impaired throughout adulthood, a recovery of the early phase of LTP became apparent when the animals reached 12 months of age. These data show that cortical and hippocampal adaptation to early postnatal blindness progresses into advanced adulthood and is a process that compromises hippocampal function. A partial recovery of hippocampal synaptic plasticity emerges in advanced adulthood, however.
... Previous studies have found that more frequency and duration of PA predict higher gray matter in healthy elderly adults (Erickson et al., 2010) and could decrease the probability of a dementia diagnosis in elderly participants (Larson et al., 2006). Moreover, previous research has found links between other types of activities during work time, such as the spatial navigation task in the London taxi drivers, and hippocampal volume (Maguire et al., 2003;Suo et al., 2012;Burzynska et al., 2020). We believe that the frequency and duration of the activities performed at work might have had an important role in these studies. ...
Previous research on Physical Activity (PA) has been highly valuable in elucidating how PA affects the structure and function of the hippocampus in elderly populations that take part in structured interventions. However, how PA affects the hippocampus in younger populations that perform PA during daily-life activities remains poorly understood. In addition, this research has not examined the impact of PA on the internal structure of the hippocampus. Here, we performed a cross-sectional exploration of the way structural and functional aspects of the hippocampus are associated with habitual PA performed during work, leisure time, and sports in the daily lives of healthy young adults (n = 30; 14 female; mean age = 23.9 y.o.; SD = 7.8 y.o.). We assessed PA in these three different contexts through a validated questionnaire. The results show that PA performed during work time correlated with higher subicular volumes. In addition, we found that PA changed functional connectivity (FC) between a location in the middle/posterior hippocampus and regions of the default mode network, and between a location in the anterior hippocampus and regions of the somatomotor network. No statistical effects of PA performed during leisure time and sports were found. The results generalize the impact of PA on younger populations and show how PA performed in daily-life situations correlates with the precise internal structure and functional connectivity of the hippocampus.
... These documented correlations between creativity levels and differences in the configuration of semantic networks, and their apparent domain-specificity, raise the question of whether changes in the networks of so-called "low creative" individuals might be possible as a result of engagement in creative tasks and, as I conjecture, practice with diverse constraints. Just as other experience has been shown to strengthen various aspects of human cognition, for example, better visual selective attention in video game players (Green & Bavelier, 2003) and larger hippocampal regions in London taxi drivers (Maguire et al., 2003), so might willing experimentation with diverse constraints for the goal of creativity not only improve creativity, but also alter semantic networks and enhance executive functions. The latter possibility is suggested by other research that proposes what sets more highly creative people apart from less creative ones is the deployment of better executive functions to access semantic content rather than the structure of their associative hierarchies (Benedek & Neubauer, 2014). ...
Despite their negative connotation, and the pervasiveness of blue-sky, outside-the-box thinking metaphors, constraints are at the heart of creativity. Using a multidisciplinary approach, as part of the Integrated Constraints in Creativity (IConIC) model, I propose that creative outcomes emerge from the successful leveraging of different types of constraints. I introduce a new, constraint-based definition of creativity, grounded in categorization theory, and parsimonious taxonomies of constraints based on which I outline testable predictions and corroborating evidence. I argue that constraints differ in terms of their flexibility (fixed, faux-fixed, or flexible) and functions (exclusionary or focusing), and in terms of whether they apply to the problem search time or the problem search space. Within the search space, constraints can refer to specific concepts or categories. I also advance a distinction between creativity maximizers and satisficers as a function of creativity goals, semantic networks, expertise, and the new constructs of constraint leveraging power and constraint leveraging mindset, that help to explain differences in successful integration of constraints for creativity and creative achievement.
... Moreover, considering the implementation level, individual variation in the volume and functioning of the neural structures underlying navigation may affect strategy availability and selection. Gray matter volume of the hippocampus has been linked to navigation ability (Bohbot et al., 2007;Maguire et al., 2000Maguire et al., , 2003Schinazi et al., 2013;Sherrill et al., 2018), although a recent study with a large sample found no evidence for this relationship in healthy young adults (Weisberg, Newcombe, & Chatterjee, 2019). We have also seen that the neural circuits underlying navigation are affected by physiological changes, such as levels of circulating hormones that vary with the menstrual cycle and menopause in humans, with the estrous cycle in animals, and with stress levels. ...
Navigating to goal locations in a known environment (wayfinding) can be accomplished by different strategies, notably by taking habitual, well-learned routes (response strategy) or by inferring novel paths, such as shortcuts, from spatial knowledge of the environment's layout (place strategy). Human and animal neuroscience studies reveal that these strategies reflect different brain systems, with response strategies relying more on activation of the striatum and place strategies associated with activation of the hippocampus. In addition to individual differences in strategy, recent behavioral studies show sex differences such that men use place strategies more than women, and age differences such that older adults use more response strategies than younger adults. This paper takes a comprehensive multilevel approach to understanding these differences, characterizing wayfinding as a complex information processing task. This analysis reveals factors that affect navigation strategy, including availability of the relevant type of environmental knowledge, momentary access to this knowledge, trade-offs between physical and mental effort in different navigation contexts, and risk taking. We consider how strategies are influenced by the computational demands of a navigation task and by factors that affect the neural circuits underlying navigation. We also discuss limitations of laboratory studies to date and outline priorities for future research, including relating wayfinding strategies to independent measures of spatial knowledge, and studying wayfinding strategies in naturalistic environments.
... Combining Sea Hero Quest with neuroimaging or neural recording methods will be useful for exploring whether brain structure or function can predict performance metrics from Sea Hero Quest. Current research is divided on whether variation in hippocampal structural measures can be linked to performance; with some studies reporting a correlation (Bohbot et al., 2007;Schinazi, Nardi, Newcombe, Shipley, & Epstein, 2013;Hartley & Harlow, 2014;Q6 Brunec et al., 2019;Hodgetts et al., 2020) and others reporting no correlation (Clark et al., 2020;Maguire et al., 2003;Weisberg, Newcombe, & Chatterjee, 2019). Sea Hero Quest would be beneficial in that the participants can be selected to cover a useful range in the distribution of individual differences. ...
Navigation ability varies widely across humans. Prior studies have reported that being younger and a male has an advantage for navigation ability. However, these studies have generally involved small numbers of participants from a handful of western countries. Here, we review findings from our project Sea Hero Quest, which used a video game for mobile and tablet devices to test 3.9 million people on their navigation ability, sampling across every nation-state and from 18 to 99 years of age. Results revealed that the task has good ecological validity and across all countries sufficiently sampled (N = 63), age is linked to a near-linear decline in navigation ability from the early 20s. All countries showed a male advantage, but this varied considerably and could be partly predicted by gender inequality. We found that those who reported growing up in a city were on average worse at navigating than those who grew up outside cities and that navigation performance helped identify those at greater genetic risk of Alzheimer's disease. We discuss the advantages and challenges of using a mobile app to study cognition and the future avenues for understanding individual differences in navigation ability arising from this research.
... In addition, volume of the posterior HF is positively associated with the time of duration as the taxi drivers, while anterior HF shows negative correlation (Maguire et al., 2000). The posterior HF may expand significantly in response to store plenty of surrounding spatial information (Maguire et al., 2003). Moreover, different hemispheres of the cuneus was found significantly activated in distinct soundmediated pattern-spatial recognition tasks for blind subjects compared to the normal controls (Arno et al., 2001;Voss et al., 2008). ...
The detailed morphometry alterations of the human hippocampal formation (HF) for blind individuals are still understudied. 50 subjects were recruited from Yantai Affiliated Hospital of Binzhou Medical University, including 16 congenital blindness, 14 late blindness, and 20 sighted controls. Volume and shape analysis were conducted between the blind (congenital or late) and sighted groups to observe the (sub)regional alterations of the HF. No significant difference of the hippocampal volume was observed between the blind and sighted subjects. Rightward asymmetry of the hippocampal volume was found for both congenital and late blind individuals, while no significant hemispheric difference was observed for the sighted controls. Shape analysis showed that the superior and inferior parts of both the hippocampal head and tail expanded, while the medial and lateral parts constrained for the blind individuals as compared to the sighted controls. The morphometry alterations for the congenital blind and late blind individuals are nearly the same. Significant expansion of the superior part of the hippocampal tail for both congenital and late blind groups were observed for the left hippocampi after FDR correction. Current results suggest that the cross-model plastic may occur in both hemispheres of the HF to improve the navigation ability without the stimuli of visual cues, and the alteration is more prominent for the left hemisphere.
... Again, the automobile provides a surprising example. Several studies at the beginning of the century revealed that London taxi and bus drivers have enlarged hippocampi, the part of the brain implicated with spatial navigation (Maguire et al. 2000(Maguire et al. , 2003Maguire, Woollett, and Spiers 2006). What this indicates is that the affordances of automobiles and the city of London potentially generated significant structural changes in the human brain. ...
Following Gosden and Malafouris, this article explores why process archaeology provides a beneficial framework for understanding the emergent, self-organising dynamics of human existence. To demonstrate the potential of process archaeology for reframing discourses about humanity's nature, this article examines automotive culture from evolutionary, ecological, developmental , and socio-political perspectives. Automobiles provide a robust example of how forms emerge from and transform flows of energy-matter across multiple dynamic scales. The article concludes with a reflection on symbolism and how American automotive culture can be understood as a form of cult ritual. Archaeology's obsession with ritual stems from a Cartesian assumption that rituals are arbitrary manifestations of symbolic minds. Process archaeology understands ritual as a means of organising energetic flows of persons and things into stable forms that endure over time. This perspective supports exploring the emergence of symbolic relationships and cultural forms as a developmental entwining of cognitive and ecological processes.
... A number of further studies by this group of researchers working with London taxi drivers has shown the HC to be both essential for complex spatial navigation and also adaptive to increased demand on spatial representations of real-world environments (e.g. Maguire et al., 2000Maguire et al., , 2003. Lee et al. (2006) investigated the role of the hippocampus in scene perception. ...
My thesis investigated whether performance on complex scene and object
perceptual and memory tasks would be influenced by possession of different variants of
the APOE gene. A particular focus was on the effect of the APOE-e4 allele on scene
processing. APOE-e4 is known to increase risk for Alzheimer's disease (AD) in later life
and is associated with structural and functional changes in the medial temporal lobe
(MTL) and posteromedial cortex, regions known to be affected early in AD. Previous
studies have shown sensitivity to spatial processing in AD, including difficulties in
differentiating scene, but not object, stimuli (Lee et al., 2006), impairments remembering
scenes over a delay (Bird et al., 2010), and deficits in navigation around spatial
environments (Pengas et al., 2010). These findings suggest that difficulties with complex
spatial processing may be a hallmark of AD, and that investigation of scene processing
in individuals at greater risk of developing AD later in life may be of interest in
understanding the genesis of these later life cognitive impairments.
In Chapter 1, I provide an overview of relevant literature on the APOE gene and
its relationship to AD, and discuss experiments which have demonstrated brain and
behaviour differences between APOE-e4 carriers and non-carriers. I interpret these
findings in the context of recent models of memory which focus on representational
networks, and where distinctions between scene and object processing are a key feature
(Bussey & Saksida, 2007; Graham, Barense, & Lee, 2010; Murray, Wise, & Graham, 2017).
The subsequent chapters describe experiments which aimed to extend the research
described in Chapter 1 by investigating scene perception and memory in carriers of
different APOE alleles in early- and mid-adulthood. In Chapter 2, I describe findings
from applying a novel conjunctive learning task, in which participants were required to
discriminate between objects and scenes. In Chapter 3, I report results from applying a
new visual paired-comparison task in the same group of participants. Chapter 4 extends
the approach outlined in Chapter 3, using the visual paired-comparison task in middle-
aged participants, again focusing on the comparison of performance in groups with
different APOE genotypes. Finally, in Chapter 5, I assess how performance in the tasks
used in Chapters 2-4 are related to the volumes of brain regions (in the MTL and
extrastriate cortex). As these have been strongly linked to object and scene perception
and memory, I was interested in whether volume would be associated with performance
on my new tasks. The final chapter summarises the experimental findings from Chapters
2-5 and explains how these build upon our current body of knowledge about how the
APOE gene affects cognition in both early- and mid-adulthood.
... Previous research has shown the hippocampal volume sensitivity to specific occupational activities. One example is the classical study on the hippocampal volume of the taxi drivers in London (Maguire et al., 2003). Hippocampal volume differences were associated to the spatial cognitive task performed continuously during the working time of the taxi drivers. ...
Research on the impact of physical activity (PA) has shown that PA produces changes in the structure and function of a brain structure called the hippocampus. There are three main limitations in this research. First, the majority of the work has been carried out in elderly populations and as such, there is a paucity of research on the impact of PA on the brains of healthy young individuals. Second, whereas PA is typically assessed through controlled interventions, changes in the brain due to PA as performed during daily-life activities has not been explored. Finally, the hippocampus has a complex internal structure and the impact of PA on this internal structure is unclear. Here we examined how structural and functional aspects of the hip-pocampus are associated with habitual PA performed during work, leisure time and sports in the daily lives of young healthy adults. We found that PA performed during work time correlated with increased subicular volumes and with changed functional connectivity between a location in middle/posterior hippocampus and regions of the default mode network and between a location in anterior hippocampus and regions of the somatomotor network. No effects of PA performed during leisure time and sports were found. The results generalize the impact of PA to younger populations and show how PA performed in daily-life situations correlates with the precise internal structure of the hippocampus.
... Another likely neuroanatomical determinant of problem-solving abilities of raccoons is the neurophysiological processing of the hippocampus (HC), a brain structure known for its role in cognitive and emotional processing (Bird & Burgess, 2008;Hartley et al., 2007;Maguire et al., 2003;Tyng et al., 2017). Activation of the HC in humans, especially in the right hemisphere, has been implicated in insight learning related to unique problem-solving tasks (Luo & Niki, 2003). ...
With rates of psychiatric illnesses such as depression continuing to rise, additional preclinical models are needed to facilitate translational neuroscience research. In the current study, the raccoon (Procyon lotor) was investigated due to its similarities with primate brains, including comparable proportional neuronal densities, cortical magnification of the forepaw area, and cortical gyrification. Specifically, we report on the cytoarchitectural characteristics of raccoons profiled as high, intermediate, or low solvers in a multi-access problem-solving task. Isotropic fractionation indicated that high-solvers had significantly more cells in the hippocampus (HC) than the other solving groups; further, a nonsignificant trend suggested that this increase in cell profile density was due to increased non-neuronal (e.g., glial) cells. Group differences were not observed in the cellular density of the somatosensory cortex. Thionin-based staining confirmed the presence of von Economo neurons (VENs) in the frontoinsular (FI) cortex, although no impact of solving ability on VEN cell profile density levels was observed. Elongated fusiform cells were quantified in the hippocampus dentate gyrus where high-solvers were observed to have higher levels of this cell type than the other solving groups. In sum, the current findings suggest that varying cytoarchitectural phenotypes contribute to cognitive flexibility. Additional research is necessary to determine the translational value of cytoarchitectural distribution patterns on adaptive behavioral outcomes associated with cognitive performance and mental health.
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The midbrain consists of many oddly shaped nuclei-forming curves, crescents, and globes, and specialised conglomerates of networks and pathways. Together these structures play a powerful role in our body sense and wellbeing, our self-based memories and emotions, and our vital chemosensory sense (olfaction—smell), cravings, habits, and self-awareness. These structures are uniquely adapted to operate separately and in concert as specialised drive, emotion, body-talk, and body-state hubs that together form our primordial body brain. Importantly, in this chapter we construct our first sensory organ and its receptor systems vital to our perception of the world around us. Through the magical and invisible transduction of odour molecules floating in the air around us, we will create our sense of smell.
This book was the first handbook where the world's foremost 'experts on expertise' reviewed our scientific knowledge on expertise and expert performance and how experts may differ from non-experts in terms of their development, training, reasoning, knowledge, social support, and innate talent. Methods are described for the study of experts' knowledge and their performance of representative tasks from their domain of expertise. The development of expertise is also studied by retrospective interviews and the daily lives of experts are studied with diaries. In 15 major domains of expertise, the leading researchers summarize our knowledge on the structure and acquisition of expert skill and knowledge and discuss future prospects. General issues that cut across most domains are reviewed in chapters on various aspects of expertise such as general and practical intelligence, differences in brain activity, self-regulated learning, deliberate practice, aging, knowledge management, and creativity.
The Cambridge Handbook of Consciousness is the first of its kind in the field, and its appearance marks a unique time in the history of intellectual inquiry on the topic. After decades during which consciousness was considered beyond the scope of legitimate scientific investigation, consciousness re-emerged as a popular focus of research towards the end of the last century, and it has remained so for nearly 20 years. There are now so many different lines of investigation on consciousness that the time has come when the field may finally benefit from a book that pulls them together and, by juxtaposing them, provides a comprehensive survey of this exciting field. An authoritative desk reference, which will also be suitable as an advanced textbook.
The Cambridge Handbook of Consciousness is the first of its kind in the field, and its appearance marks a unique time in the history of intellectual inquiry on the topic. After decades during which consciousness was considered beyond the scope of legitimate scientific investigation, consciousness re-emerged as a popular focus of research towards the end of the last century, and it has remained so for nearly 20 years. There are now so many different lines of investigation on consciousness that the time has come when the field may finally benefit from a book that pulls them together and, by juxtaposing them, provides a comprehensive survey of this exciting field. An authoritative desk reference, which will also be suitable as an advanced textbook.
The Cambridge Handbook of Consciousness is the first of its kind in the field, and its appearance marks a unique time in the history of intellectual inquiry on the topic. After decades during which consciousness was considered beyond the scope of legitimate scientific investigation, consciousness re-emerged as a popular focus of research towards the end of the last century, and it has remained so for nearly 20 years. There are now so many different lines of investigation on consciousness that the time has come when the field may finally benefit from a book that pulls them together and, by juxtaposing them, provides a comprehensive survey of this exciting field. An authoritative desk reference, which will also be suitable as an advanced textbook.
The Cambridge Handbook of Consciousness is the first of its kind in the field, and its appearance marks a unique time in the history of intellectual inquiry on the topic. After decades during which consciousness was considered beyond the scope of legitimate scientific investigation, consciousness re-emerged as a popular focus of research towards the end of the last century, and it has remained so for nearly 20 years. There are now so many different lines of investigation on consciousness that the time has come when the field may finally benefit from a book that pulls them together and, by juxtaposing them, provides a comprehensive survey of this exciting field. An authoritative desk reference, which will also be suitable as an advanced textbook.
The Cambridge Handbook of Consciousness is the first of its kind in the field, and its appearance marks a unique time in the history of intellectual inquiry on the topic. After decades during which consciousness was considered beyond the scope of legitimate scientific investigation, consciousness re-emerged as a popular focus of research towards the end of the last century, and it has remained so for nearly 20 years. There are now so many different lines of investigation on consciousness that the time has come when the field may finally benefit from a book that pulls them together and, by juxtaposing them, provides a comprehensive survey of this exciting field. An authoritative desk reference, which will also be suitable as an advanced textbook.
Immersive virtual reality (VR) carries important potential, both for the creation of scientific knowledge and also for its communication. This is particularly important for studies of human spatial cognition, where psychologists now possess the power to combine the scale and fidelity of the real world with the malleability and control of the laboratory. Accordingly, the application of immersive and motile VR tasks to the study of spatial navigation appears to be the ideal means to bring the real world into the laboratory, and an accessible solution for acquiring more ecologically valid data with which to build our theories. Reports of VR-based studies, however, provide an equivocal picture, and there are circumstances under which our findings might be entirely unaffected by whether participants are freely exploring an immersive virtual world or sat before a computer monitor and navigating using a joystick. This ambiguity has ramifications for the knowledge that we build, as well as the means by which we communicate that knowledge. This paper discusses some of these issues in the context of psychological research, exploring pros and cons in the adoption of immersive VR as an empirical tool, and what it means for the theories we build. An important lesson for scientists and students alike is to reflect upon the utility of a method and to know when it is appropriate for it to be deployed. The study of human navigation can, therefore, provide a useful platform for consideration of how one might critically evaluate the added value of adopting particular digital solutions.
The Cambridge Handbook of Consciousness is the first of its kind in the field, and its appearance marks a unique time in the history of intellectual inquiry on the topic. After decades during which consciousness was considered beyond the scope of legitimate scientific investigation, consciousness re-emerged as a popular focus of research towards the end of the last century, and it has remained so for nearly 20 years. There are now so many different lines of investigation on consciousness that the time has come when the field may finally benefit from a book that pulls them together and, by juxtaposing them, provides a comprehensive survey of this exciting field. An authoritative desk reference, which will also be suitable as an advanced textbook.
This book was the first handbook where the world's foremost 'experts on expertise' reviewed our scientific knowledge on expertise and expert performance and how experts may differ from non-experts in terms of their development, training, reasoning, knowledge, social support, and innate talent. Methods are described for the study of experts' knowledge and their performance of representative tasks from their domain of expertise. The development of expertise is also studied by retrospective interviews and the daily lives of experts are studied with diaries. In 15 major domains of expertise, the leading researchers summarize our knowledge on the structure and acquisition of expert skill and knowledge and discuss future prospects. General issues that cut across most domains are reviewed in chapters on various aspects of expertise such as general and practical intelligence, differences in brain activity, self-regulated learning, deliberate practice, aging, knowledge management, and creativity.
The Cambridge Handbook of Consciousness is the first of its kind in the field, and its appearance marks a unique time in the history of intellectual inquiry on the topic. After decades during which consciousness was considered beyond the scope of legitimate scientific investigation, consciousness re-emerged as a popular focus of research towards the end of the last century, and it has remained so for nearly 20 years. There are now so many different lines of investigation on consciousness that the time has come when the field may finally benefit from a book that pulls them together and, by juxtaposing them, provides a comprehensive survey of this exciting field. An authoritative desk reference, which will also be suitable as an advanced textbook.
Elebidun izateak baditu ondorioak, hizkuntza baten baino gehiagotan komunikatzeko gaitasuna izateaz gain. Hori horrela, elebidunen eta elebakarren arteko alderaketek zientzialari askoren interesa piztu dute aspalditik. Artikulu honetan, ondorio linguistikoei eta kognitiboei erreparatuko diegu, ondorio positiboei zein negatiboei, eta horretarako hainbat ikerketaren emaitzetan oinarrituko gara. Halaber, “abantaila elebidunaren” hipotesia aurkeztuko dugu.
Identification of the initial alterations of brain function in Alzheimer’s disease (AD) is critically important for early disease detection and future use of disease-modifying drugs to delay progression to dementia. Given that AD-related neurodegeneration is first observed in the entorhinal cortex (EC), and that EC neurons contribute to path integration-based navigation, this thesis aimed to test the hypothesis that path integration would be impaired in people at risk of AD, prior to symptom onset. In Experiment 1, path integration was assessed using an immersive virtual reality assessment in 100 cognitively asymptomatic individuals from the PREVENT Dementia Programme with pre-existing clinical and cognitive profiles. They were aged between 43-66 years and stratified by AD risk status on the basis of three risk factors (family history, APOEe4 allele, lifestyle dementia risk score). In addition, a subset of 55 individuals further underwent Experiment 2, a 7 tesla MRI scan to explore structural and functional correlates of path integration function. Results showed that path integration in individuals at higher risk of AD was impaired only when supportive environment boundary information was removed, with this effect observed to differing extents across all AD risk factors. Effects tentatively associated with altered grid cell fMRI representations and, in family history only, altered CA1 subfield volume. In cognitive data collected as part of the PREVENT Programme, a family history of dementia and higher lifestyle risk score were also associated with impaired allocentric spatial memory. Importantly, performance on non-navigation related cognitive assessments was unrelated to risk of AD. These data support the future use of navigation tests to detect the earliest stages of AD, and the basis of path integration testing on knowledge of EC single cell activity aids translational research aiming to understand how the effect of AD molecular pathology on cellular function results in clinical manifestations of disease.
Stone-tool making is an ancient human skill thought to have played a key role in the bio-cultural co-evolutionary feedback that produced modern brains, culture, and cognition. To test the proposed evolutionary mechanisms underpinning this hypothesis we studied stone-tool making skill learning in modern participants and examined interactions between individual neurostructural differences, plastic accommodation, and culturally transmitted behavior. We found that prior experience with other culturally transmitted craft skills increased both initial stone tool-making performance and subsequent neuroplastic training effects in a frontoparietal white matter pathway associated with action control. These effects were mediated by the effect of experience on pre-training variation in a frontotemporal pathway supporting action semantic representation. Our results show that the acquisition of one technical skill can produce structural brain changes conducive to the discovery and acquisition of additional skills, providing empirical evidence for bio-cultural feedback loops long hypothesized to link learning and adaptive change.
The article presents a review of modern studies of the hippocampus’s functions in the implementation of cognitive phenomena, a review which covers a wide range of experimental areas, including high-precision brain morphometry, functional neuroimaging, electroencephalography, deep navigational electrode implantation, and dosed radiation effects on the brain. Literary sources demonstrate the involvement of the hippocampus in almost all spheres and aspects of human mental activity, from memory to eye movements, from circadian rhythms to spatial navigation. The literature review allows us to generalize the results of many works and to speak about the basic characteristic of the hippocampus’s functional activity in information processing: that the hippocampus is a comparator which continuously marks impressions of the current experience according to the degree of novelty. The authors see such a functional analysis as much more productive than attempts to correspond brain structures with mental processes (perception, memory, attention) and, accordingly, than the customary discussion in the scientific literature of the hippocampus functioning mainly as a brain substrate of memory
The subjective experiences and satisfaction of using technology to collaborate remotely may differ due to the individual differences of personal characteristics. The present study aims to investigate the influence of empathy tendency on user experience. Twelve groups of three participants completed a decision-making task in the virtual environment. The results revealed a significant correlation between personal traits (i.e., empathy and the big five personalities), user experience (i.e., social presence), and satisfaction. The level of cognitive empathy has a positive effect on the feeling of social presence, social immersion, and outcome satisfaction in the virtual environment, while is not associated with media satisfaction. The findings of this study suggest that the cognitive ability of empathy, namely the ability to identify with and understand the views of others may increase one’s experience and satisfaction in remote collaboration. This study provides an empirical exploration of team interactions in virtual environments and advances user research by identifying the relationship between user’s traits (empathy), user experience, and satisfaction.
Licensed London taxi drivers have been found to show changes in the gray matter density of their hippocampus over the course of training and decades of navigation in London (UK). This has been linked to their learning and using of the “Knowledge of London,” the names and layout of over 26,000 streets and thousands of points of interest in London. Here we review past behavioral and neuroimaging studies of London taxi drivers, covering the structural differences in hippocampal gray matter density and brain dynamics associated with navigating London. We examine the process by which they learn the layout of London, detailing the key learning steps: systematic study of maps, travel on selected overlapping routes, the mental visualization of places and the optimal use of subgoals. Our analysis provides the first map of the street network covered by the routes used to learn the network, allowing insight into where there are gaps in this network. The methods described could be widely applied to aid spatial learning in the general population and may provide insights for artificial intelligence systems to efficiently learn new environments.
A growing body of theory and research in the last four decades support the crucial role of active environmental stimuli, especially parental, siblings’, teachers’, and peers’ mediation in enhancing children’s cognitive development and cognitive plasticity.
Virtual reality (VR) and event-related functional magnetic resonance imaging were used to study memory for the spatial context of controlled but lifelike events. Subjects received a set of objects from two different people in two different places within a VR environment. Memory for the objects, and for where and from whom they were received was tested by putting the subject back into a place in the company of a person and giving a paired forced choice of objects. In four conditions objects had to be chosen according to different criteria: which was received in that place, which was received from that person, which object was recognized, and which object was widest. Event-related functional magnetic resonance imaging was performed during testing to identify areas involved in retrieval of the spatial context of an event. A network of areas was identified consisting of a temporoparietal pathway running between the precuneus and parahippocampi via retrosplenial cortex and the parieto-occipital sulcus, left hippocampus, bilateral posterior parietal, dorsolateral, ventrolateral and anterior prefrontal cortices, and the anterior cingulate. Of these areas the parahippocampal, right posterior parietal, and posteriodorsal medial parietal areas were specifically involved in retrieval of spatial context compared to retrieval of nonspatial context. The posterior activations are consistent with a model of long-term storage of allocentric representations in medial temporal regions with translation to body-centered and head-centered representations computed in right posterior parietal cortex and buffered in the temporoparietal pathway so as to provide an imageable representation in the precuneus. Prefrontal activations are consistent with strategic retrieval processes, including those required to overcome the interference between the highly similar events.
The neural basis of navigation by humans was investigated with functional neuroimaging of brain activity during navigation
in a familiar, yet complex virtual reality town. Activation of the right hippocampus was strongly associated with knowing
accurately where places were located and navigating accurately between them. Getting to those places quickly was strongly
associated with activation of the right caudate nucleus. These two right-side brain structures function in the context of
associated activity in right inferior parietal and bilateral medial parietal regions that support egocentric movement through
the virtual town, and activity in other left-side regions (hippocampus, frontal cortex) probably involved in nonspatial aspects
of navigation. These findings outline a network of brain areas that support navigation in humans and link the functions of
these regions to physiological observations in other mammals.
A large-scale virtual reality town was used to test the topographical and episodic memory of patients with unilateral temporal lobe damage. Seventeen right and 13 left temporal lobectomy patients were compared with 16 healthy matched control subjects. After they had explored the town, subjects' topographical memory was tested by requiring them to navigate to specific locations in the town. The ability to recognize scenes from and draw maps of the virtual town was also assessed. Following the topographical memory tests, subjects followed a route around the same town but now collected objects from two different characters in two different locations. Episodic memory for various aspects of these events was then assessed by paired forced-choice recognition tests. The results showed an interaction between laterality and test type such that the right temporal lobectomy (RTL) patients were worse on tests of topographical memory, and the left temporal lobectomy (LTL) patients worse on tests of context-dependent episodic memory. Specifically, the RTL group was impaired on navigation, scene recognition and map drawing relative to control subjects. They were also impaired on recognition of objects in the episodic memory task. The LTL group was impaired relative to control subjects on their memory for contextual aspects of the events, such as who gave them the objects, the order in which objects were received and the locations in which they received them. They were also mildly impaired on topographical memory, but less so than the RTL group. These results suggest that topographical memory is predominately mediated by structures in the right medial temporal lobe, whereas the context-dependent aspects of episodic memory in this non-verbal test are more dependent on the left medial temporal lobe.
Disoriented rats and non-human primates reorient themselves using geometrical features of the environment. In rats tested in environments with distinctive geometry, this ability is impervious to non-geometric information (such as colours and odours) marking important locations and used in other spatial tasks. Here we show that adults use both geometric and non-geometric information to reorient themselves, whereas young children, like mature rats, use only geometric information. These findings provide evidence that: (1) humans reorient in accord with the shape of the environment; (2) the young child's reorientation system is impervious to all but geometric information, even when non-geometric information is available and is re-presented by the child--such information should improve performance and is used in similar tasks by the oriented child; and (3) the limits of this process are overcome during human development.
A 60 year old patient, SE, who presented with a severe difficulty in finding his way around previously familiar environments and a mild prosopagnosia is described. SE had herpes simplex encephalitis resulting in selective right temporal lobe damage. He showed normal spatial learning, but was severely imparied in his ability to recognise pictures of buildings and landmarks. The disorder was not confined to the visual modality, but rather involved a loss of knowledge about famous buildings and landmarks when tested from their spoken name. SE was contrasted with a more severely prosopagnosic patient, PHD, who showed normal ability to recognise buildings and landmarks, indicating that recognition of people dissociates from recognition of buildings/landmarks. It is concluded that SE's failure of place knowledge represents a category specific supramodal semantic memory impairment.
Neurogenesis occurs in the dentate gyrus of the hippocampus throughout the life of a rodent, but the function of these new neurons and the mechanisms that regulate their birth are unknown. Here we show that significantly more new neurons exist in the dentate gyrus of mice exposed to an enriched environment compared with littermates housed in standard cages. We also show, using unbiased stereology, that the enriched mice have a larger hippocampal granule cell layer and 15 per cent more granule cell neurons in the dentate gyrus.
Positron emission tomography was used to investigate the functional anatomy of mental simulation of routes (MSR) in five normal volunteers. Normalized regional cerebral blood flow was measured while subjects mentally navigated between landmarks of a route which had been previously learned by actual navigation. This task was contrasted with both static visual imagery of landmarks (VIL) and silent Rest. MSR appears to be subserved by two distinct networks: a non-specific memory network including the posterior and middle parts of the hippocampal regions, the dorsolateral prefrontal cortex and the posterior cingulum, and a specific mental navigation network, comprising the left precuneus, insula and medial part of the hippocampal regions.
Global anterograde amnesia is described in three patients with brain injuries that occurred in one case at birth, in another
by age 4, and in the third at age 9. Magnetic resonance techniques revealed bilateral hippocampal pathology in all three cases.
Remarkably, despite their pronounced amnesia for the episodes of everyday life, all three patients attended mainstream schools
and attained levels of speech and language competence, literacy, and factual knowledge that are within the low average to
average range. The findings provide support for the view that the episodic and semantic components of cognitive memory are
partly dissociable, with only the episodic component being fully dependent on the hippocampus.
Functional imaging to date has examined the neural basis of knowledge of spatial layouts of large-scale environments typically in the context of episodic memory with specific spatiotemporal references. Much human behavior, however, takes place in very familiar environments in which knowledge of spatial layouts has entered the domain of general facts often referred to as semantic memory. In this study, positron emission tomography (PET) was used to examine the neural substrates of topographical memory retrieval in licensed London taxi drivers of many years experience while they recalled complex routes around the city. Compared with baseline and other nontopographical memory tasks, this resulted in activation of a network of brain regions, including the right hippocampus. Recall of famous landmarks for which subjects had no knowledge of their location within a spatial framework activated similar regions, except for the right hippocampus. This suggests that the hippocampus is involved in the processing of spatial layouts established over long time courses. The involvement of similar brain areas in routes and landmarks memory indicates that the topographical memory system may be primed to respond to any relevant topographical stimulation; however, the right hippocampus is recruited specifically for navigation in large-scale spatial environments. In contrast, nontopographical semantic memory retrieval involved the left inferior frontal gyrus, with no change in activity in medial temporal regions.
The genesis of new cells, including neurons, in the adult human brain has not yet been demonstrated. This study was undertaken to investigate whether neurogenesis occurs in the adult human brain, in regions previously identified as neurogenic in adult rodents and monkeys. Human brain tissue was obtained postmortem from patients who had been treated with the thymidine analog, bromodeoxyuridine (BrdU), that labels DNA during the S phase. Using immunofluorescent labeling for BrdU and for one of the neuronal markers, NeuN, calbindin or neuron specific enolase (NSE), we demonstrate that new neurons, as defined by these markers, are generated from dividing progenitor cells in the dentate gyrus of adult humans. Our results further indicate that the human hippocampus retains its ability to generate neurons throughout life.
Running increases neurogenesis in the dentate gyrus of the hippocampus, a brain structure that is important for memory function. Consequently, spatial learning and long-term potentiation (LTP) were tested in groups of mice housed either with a running wheel (runners) or under standard conditions (controls). Mice were injected with bromodeoxyuridine to label dividing cells and trained in the Morris water maze. LTP was studied in the dentate gyrus and area CA1 in hippocampal slices from these mice. Running improved water maze performance, increased bromodeoxyuridine-positive cell numbers, and selectively enhanced dentate gyrus LTP. Our results indicate that physical activity can regulate hippocampal neurogenesis, synaptic plasticity, and learning.
Structural MRIs of the brains of humans with extensive navigation experience, licensed London taxi drivers, were analyzed and compared with those of control subjects who did not drive taxis. The posterior hippocampi of taxi drivers were significantly larger relative to those of control subjects. A more anterior hippocampal region was larger in control subjects than in taxi drivers. Hippocampal volume correlated with the amount of time spent as a taxi driver (positively in the posterior and negatively in the anterior hippocampus). These data are in accordance with the idea that the posterior hippocampus stores a spatial representation of the environment and can expand regionally to accommodate elaboration of this representation in people with a high dependence on navigational skills. It seems that there is a capacity for local plastic change in the structure of the healthy adult human brain in response to environmental demands.
Visuospatial navigation in animals and human subjects is generally studied using maze exploration. We used functional MRI to observe brain activation in male and female subjects as they searched for the way out of a complex, three-dimensional, virtual-reality maze. Navigation activated the medial occipital gyri, lateral and medial parietal regions, posterior cingulate and parahippocampal gyri as well as the right hippocampus proper. Gender-specific group analysis revealed distinct activation of the left hippocampus in males, whereas females consistently recruited right parietal and right prefrontal cortex. Thus we demonstrate a neural substrate of well established human gender differences in spatial-cognition performance.
For over 100 years a central assumption in the field of neuroscience has been that new neurons are not added to the adult mammalian brain. This perspective examines the origins of this dogma, its perseverance in the face of contradictory evidence, and its final collapse. The acceptance of adult neurogenesis may be part of a contemporary paradigm shift in our view of the plasticity and stability of the adult brain.
The vertebrate brain continues to produce new neurons throughout life. In the rat hippocampus, several thousand are produced each day, many of which die within weeks. Associative learning can enhance their survival; however, until now it was unknown whether new neurons are involved in memory formation. Here we show that a substantial reduction in the number of newly generated neurons in the adult rat impairs hippocampal-dependent trace conditioning, a task in which an animal must associate stimuli that are separated in time. A similar reduction did not affect learning when the same stimuli are not separated in time, a task that is hippocampal-independent. The reduction in neurogenesis did not induce death of mature hippocampal neurons or permanently alter neurophysiological properties of the CA1 region, such as long-term potentiation. Moreover, recovery of cell production was associated with the ability to acquire trace memories. These results indicate that newly generated neurons in the adult are not only affected by the formation of a hippocampal-dependent memory, but also participate in it.
Neurons are born throughout adulthood in specific regions of mammalian brains. It now turns out that - in rats at least - these new neurons are essential for the formation of one type of memory.
There is extensive evidence indicating that new neurons are generated in the dentate gyrus of the adult mammalian hippocampus, a region of the brain that is important for learning and memory. However, it is not known whether these new neurons become functional, as the methods used to study adult neurogenesis are limited to fixed tissue. We use here a retroviral vector expressing green fluorescent protein that only labels dividing cells, and that can be visualized in live hippocampal slices. We report that newly generated cells in the adult mouse hippocampus have neuronal morphology and can display passive membrane properties, action potentials and functional synaptic inputs similar to those found in mature dentate granule cells. Our findings demonstrate that newly generated cells mature into functional neurons in the adult mammalian brain.
We recently reported on three young patients with severe impairments of episodic memory resulting from brain injury sustained early in life. These findings have led us to hypothesize that such impairments might be a previously unrecognized consequence of perinatal hypoxic–ischaemic injury. Neuropsychological and quantitative magnetic resonance investigations were carried out on five young patients, all of whom had suffered hypoxic–ischaemic episodes at or shortly after birth. All five patients showed severe impairments of episodic memory (memory for events), with relative preservation of semantic memory (memory for facts). However, none had any of the major neurological deficits that are typically associated with hypoxic–ischaemic injury, and all attended mainstream schools. Quantitative magnetic resonance investigations revealed severe bilateral hippocampal atrophy in all cases. As a group, the patients also showed bilateral reductions in grey matter in the regions of the putamen and the ventral part of the thalamus. On the basis of their clinical histories and the pattern of magnetic resonance findings, we attribute the patients' pathology and associated memory impairments primarily to hypoxic–ischaemic episodes sustained very early in life. We suggest that the degree of hypoxia–ischaemia was sufficient to produce selective damage to particularly vulnerable regions of the brain, notably the hippocampi, but was not sufficient to result in the more severe neurological and cognitive deficits that can follow hypoxic–ischaemic injury. The impairments in episodic memory may be difficult to recognize, particularly in early childhood, but this developmental amnesia can have debilitating consequences, both at home and at school, and may preclude independent life in adulthood.
We present evidence for continuous generation of neurons, oligodendrocytes, and astrocytes in the hippocampal dentate gyrus of adult macaque monkeys, using immunohistochemical double labeling for bromodeoxyuridine and cell-type-specific markers. We estimate that the relative rate of neurogenesis is approximately 10 times less than that reported in the adult rodent dentate gyrus. Nevertheless, the generation of these three cell types in a discreet brain region suggests that a multipotent neural stem cell may be retained in the adult primate hippocampus. This demonstration of adult neurogenesis in nonhuman Old World primates-with their phylogenetic proximity to humans, long life spans, and elaborate cognitive abilities-establishes the macaque as an unexcelled animal model to experimentally investigate issues of neurogenesis in humans and offers new insights into its significance in the adult brain.
Why does the adult brain go through the considerable effort to maintain the machinery necessary for neurogenesis? Why does neurogenesis persist in two brain regions and not in others? Whereas early reflections on this topic tended to regard adult hippocampal neurogenesis a mere atavism with little or no functional consequences, this evaluation has begun to change in the last few years. We now hypothesize that adult neurogenesis is necessary for hippocampal function. In the hippocampus, information is processed in order to consolidate memory, hence the emblematic description of the hippocampus as ‘the gateway to memory’. In our view, new neurons are added to the hippocampal dentate gyrus not to increase memory per se, but to optimize the network by strategic insertion of ‘new gatekeepers at the gateway to memory’. Optimization means the smallest (and fastest) possible network that is able to cope with the degree of novelty and complexity an individual experiences. Data on the experience- and activity-dependent regulation of adult hippocampal neurogenesis support this view. Adult hippocampal neurogenesis is a long-term adjustment of the hippocampus to functional needs, not means for acute changes in the sense of ‘putting in more memory, while the computer is running’. What lies ahead is to find out, which molecular rules govern this long-term plasticity. To consider functional implications of adult hippocampal neurogenesis also begins to influence concepts of hippocampal disease, for example certain aspects of epilepsia and major depression.
WE show that the pro-apoptotic proteins Bax and Bak trigger apoptosis when over-expressed in sympathetic neurons cultured in the presence of NGF. This effect can be blocked with z-VAD-fmk, a peptide inhibitor of caspases, but not with anti-apoptotic chemical compounds such as antioxidants or proteasome inhibitors. These results demonstrate that in sympathetic neurons Bax and Bak are sufficient to induce apoptosis in the absence of any other apparent cell death stimulus and that their effect is mediated by caspases but does not require reactive oxygen species nor activity of the proteasome.
In a route-learning task in a computer-simulated environment, subjects repeatedly negotiated a series of rooms each containing two exit doors, and were required to learn which of the doors lead to the next room. In the landmark condition each room contained distinctive objects, while in the non-landmark condition all rooms were identical. The results of experiment 1 revealed that the route-learning performance of both groups was comparable. It was hypothesized that the landmark group relied primarily on paired associate learning in which the landmark objects were associated with the correct door while the non-landmark group learnt a list of correct left/right decisions. In an attempt to suppress the latter strategy, in experiment 2 two groups of subjects were asked to perform the same tasks as the groups in experiment 1, but were required to do a backcounting task while learning the route. This manipulation resulted in superior performance on the part of the landmark group. It is argued that landmarks are only one of many successful strategies that people have at their disposal for learning routes, and that in order to show that landmarks can facilitate route-learning it is necessary to suppress other strategies.
A virtual reality environment was used to test memory performance for simulated “real-world” spatial and episodic information in a 22-year-old male, Jon, who has selective bilateral hippocampal pathology caused by perinatal anoxia. He was allowed to explore a large-scale virtual reality town and was then tested on his memory for spatial layout and for episodes experienced. Topographical memory was tested by assessing his ability to navigate, recognize previously visited locations, and draw maps of the town. Episodic memory was assessed by testing the retrieval of simulated events which consisted of collecting objects from characters while following a route through the virtual town. Memory for the identity of objects, as well as for where they were collected, from whom, and in what order, was also tested. While the first task tapped simple recognition memory, the latter three tested memory for context. Jon was impaired on all topographical tasks and on his recall of the context-dependent questions. However, his recognition of objects from the virtual town, and of “topographical” scenes (as evaluated by standard neuropsychological tests), was not impaired. These findings are consistent with the view that the hippocampus is involved in navigation, recall of long term allocentric spatial information and context-dependent episodic memory, but not visual pattern matching. Hippocampus 2001;11:715–725. © 2001 Wiley-Liss, Inc.
The production of neurons in the mammalian brain is typically restricted to a discrete developmental period ending, for the most part, prior to parturition. However, in certain regions of the brain, including the dentate gyrus, new neurons continue to be produced well into adulthood. In the adult brain, new cells arise from progenitors located within the hilus and subgranular zone of the dentate gyrus, and then migrate into the dentate granule cell layer. Morphological, biochemical, and ultrastructural evidence indicate that many of these new cells become granule neurons, the principal projection neuron of the dentate gyrus. Anatomic studies have demonstrated that adult-generated granule neurons contribute axonal projections to area CA3 of Ammon's horn, while electron microscopy studies have revealed that these cells possess dendritic processes that extend into the dentate molecular layer to form synapses. Collectively, these data indicate that adult-generated granule neurons become functionally incorporated into the pre-existing neural circuitry of the dentate gyrus. The production and survival of adult-generated granule neurons are significantly influenced by experiential and neuroendocrine factors, suggesting that adult neurogenesis represents a substrate by which the environment may affect the structure and function of the adult brain. Although the precise function of adult-generated granule neurons is unknown, the formation of entirely novel neural circuits, and the regulation of this process by neuroendocrine and experiential factors, is likely to represent an important mode of neural plasticity. Moreover, the persistence of neural progenitors within the adult brain provides hope that an understanding of the process of adult neurogenesis may ultimately be of therapeutic relevance.
We used voxel-based morphometry (VBM) to examine human brain asymmetry and the effects of sex and handedness on brain structure in 465 normal adults. We observed significant asymmetry of cerebral grey and white matter in the occipital, frontal, and temporal lobes (petalia), including Heschl's gyrus, planum temporale (PT) and the hippocampal formation. Males demonstrated increased leftward asymmetry within Heschl's gyrus and PT compared to females. There was no significant interaction between asymmetry and handedness and no main effect of handedness. There was a significant main effect of sex on brain morphology, even after accounting for the larger global volumes of grey and white matter in males. Females had increased grey matter volume adjacent to the depths of both central sulci and the left superior temporal sulcus, in right Heschl's gyrus and PT, in right inferior frontal and frontomarginal gyri and in the cingulate gyrus. Females had significantly increased grey matter concentration extensively and relatively symmetrically in the cortical mantle, parahippocampal gyri, and in the banks of the cingulate and calcarine sulci. Males had increased grey matter volume bilaterally in the mesial temporal lobes, entorhinal and perirhinal cortex, and in the anterior lobes of the cerebellum, but no regions of increased grey matter concentration.
While numerous studies have investigated the relationship between environmental familiarity and spatial cognition, no research has systematically examined the effects of familiarity on wayfinding performance. This experiment used a 5 × 5 factorial design to investigate the effects of floor plan complexity and degree of familiarity on spatial cognition and wayfinding. Subjects received five trials within one of five computer-simulated environments representing a range of plan complexity. Wayfinding performance data was collected during each trial. After all trials were completed, environmental knowledge was assessed through a sketchmap task. MANOVAs showed that wayfinding performance significantly decreased as a function of plan complexity. Plan complexity also significantly influenced sketchmap accuracy. Trend analysis showed a significant linear trend for wayfinding errors, which decreased with experience. This analysis also revealed a signficant interaction between plan complexity and experience on wayfinding. The findings suggest that environmental complexity has less of an impact on wayfinding as familiarity increases.
Wayfinding ability was studied in reference to sense of direction (SOD), familiarity with the environment, reported wayfinding strategy use, and sex. A questionnaire, administered to 196 psychology undergraduates, included a SOD scale, a wayfinding strategy scale that measures use of survey and route navigation strategies, and questions regarding familiarity with the environment. Of these students, 94 also completed a mental wayfinding task in which directions for a route from one location on the campus to another were read and mentally followed. At the final location of the route, participants identified the direction of origin of the route. Regression analyses revealed that response latency was predicted by SOD and accuracy was predicted by sex and familiarity.
At its simplest, voxel-based morphometry (VBM) involves a voxel-wise comparison of the local concentration of gray matter between two groups of subjects. The procedure is relatively straightforward and involves spatially normalizing high-resolution images from all the subjects in the study into the same stereotactic space. This is followed by segmenting the gray matter from the spatially normalized images and smoothing the gray-matter segments. Voxel-wise parametric statistical tests which compare the smoothed gray-matter images from the two groups are performed. Corrections for multiple comparisons are made using the theory of Gaussian random fields. This paper describes the steps involved in VBM, with particular emphasis on segmenting gray matter from MR images with nonuniformity artifact. We provide evaluations of the assumptions that underpin the method, including the accuracy of the segmentation and the assumptions made about the statistical distribution of the data.
Voxel-based-morphometry (VBM) is a whole-brain, unbiased technique for characterizing regional cerebral volume and tissue concentration differences in structural magnetic resonance images. We describe an optimized method of VBM to examine the effects of age on grey and white matter and CSF in 465 normal adults. Global grey matter volume decreased linearly with age, with a significantly steeper decline in males. Local areas of accelerated loss were observed bilaterally in the insula, superior parietal gyri, central sulci, and cingulate sulci. Areas exhibiting little or no age effect (relative preservation) were noted in the amygdala, hippocampi, and entorhinal cortex. Global white matter did not decline with age, but local areas of relative accelerated loss and preservation were seen. There was no interaction of age with sex for regionally specific effects. These results corroborate previous reports and indicate that VBM is a useful technique for studying structural brain correlates of ageing through life in humans.
Thirteen normal control subjects and 62 patients who had undergone either a unilateral temporal or a unilateral frontal lobectomy learned the content of a short prose passage to a strict criterion. Compared to other subject, patients with left temporal-lobe excision took longer to learn the story content and, within this group, the slowest rate noted was for patients with extensive removal from the hippocampal region. When retention of the material was tested after a 20 min delay, only the group with large excisions from the left hippocampus and/or parahippocampal gyrus was impaired. This finding of abnormally rapid forgetting of material learned to criterion highlights the role of the left hippocampal region in the long-term maintenance of verbal information presented in a context.
Virtual reality (VR) has become increasingly well-known over the last few years. However, little is known about the side-effects of prolonged immersion in VR. This study set out to investigate the frequency of occurrence and severity of side-effects of using an immersion VR system. Out of 146 subjects, 61% reported symptoms of malaise at some point during a 20-min immersion and 10-min post-immersion period. These ranged from symptoms such as dizziness, stomach awareness, headaches, eyestrain and lightheadedness to severe nausea. These symptoms caused 5% of the subjects to withdraw from the experiment before completing their 20-min immersion period. Further research needs to be conducted that attempts to identify those factors that play a causative role in the side-effects of the VR system, and that looks for methods of reducing these side-effects.
One hundred patients with intractable temporal lobe epilepsy and 22 control subjects were scanned on a 1.5-T Siemens SP63 Magnetom scanner. A combination of hippocampal T2 mapping, hippocampal volume measurement corrected for intracranial volume, and inspection of hippocampal morphology on a hippocampal volume distribution graph compared with a control graph revealed previously undetected forms of bilateral hippocampal sclerosis and four false-positive diagnoses of hippocampal sclerosis made on visual inspection of the scans. A physiological asymmetry in the position of the hippocampi in 41% of control subjects and focal hippocampal atrophies in patients made measurement of the whole length of the hippocampus mandatory. The extent of hippocampal damage in patients with hippocampal sclerosis correlated with the number of secondary generalized seizures during a patient's lifetime. In contrast to patients with unilateral hippocampal sclerosis, patients with severe bilateral hippocampal sclerosis had no history of febrile convulsions. Twenty-six patients with intractable temporal lobe epilepsy had normal hippocampal magnetic resonance imaging measures and as a group were significantly older at the onset of habitual epilepsy than were patients with hippocampal sclerosis. In conclusion, a combination of quantitative magnetic resonance imaging techniques revealed a spectrum of hippocampal sclerosis and optimally defined boundaries of hippocampal normality. The spectrum of hippocampal sclerosis is related to the etiology, the number of secondary generalized seizures, and the age at onset of habitual epilepsy.
The study of navigational ability in humans is often limited by the restricted availability and inconvenience of using large novel environments. In the present study we use a computer-generated virtual environment to study sex differences in human spatial navigation. Adult male and female participants navigated through a virtual water maze where both landmarks and room geometry were available as distal cues. Manipulation of environmental characteristics revealed that females rely predominantly on landmark information, while males more readily use both landmark and geometric information. We discuss these results as a possible link between recent human research reporting hippocampal activation in spatial tasks and animal work showing sex differences in both spatial ability and hippocampal development.
Thousands of hippocampal neurons are born in adulthood, suggesting that new cells could be important for hippocampal function. To determine whether hippocampus-dependent learning affects adult-generated neurons, we examined the fate of new cells labeled with the thymidine analog bromodeoxyuridine following specific behavioral tasks. Here we report that the number of adult-generated neurons doubles in the rat dentate gyrus in response to training on associative learning tasks that require the hippocampus. In contrast, training on associative learning tasks that do not require the hippocampus did not alter the number of new cells. These findings indicate that adult-generated hippocampal neurons are specifically affected by, and potentially involved in, associative memory formation.
We present evidence for continuous generation of neurons, oligodendrocytes, and astrocytes in the hippocampal dentate gyrus of adult macaque monkeys, using immunohistochemical double labeling for bromodeoxyuridine and cell-type-specific markers. We estimate that the relative rate of neurogenesis is approximately 10 times less than that reported in the adult rodent dentate gyrus. Nevertheless, the generation of these three cell types in a discreet brain region suggests that a multipotent neural stem cell may be retained in the adult primate hippocampus. This demonstration of adult neurogenesis in nonhuman Old World primates-with their phylogenetic proximity to humans, long life spans, and elaborate cognitive abilities-establishes the macaque as an unexcelled animal model to experimentally investigate issues of neurogenesis in humans and offers new insights into its significance in the adult brain.
Recent research on navigation has been particularly notable for the increased understanding of the factors affecting human navigation and the neural networks supporting it. The use of virtual reality environments has made it possible to explore the effect of environment layout and content on way-finding performance, and it has shown that these effects may interact with the sex and age of subjects. Functional brain imaging, combined with the use of virtual environments, has revealed strong parallels between humans and other animals in the neural basis of navigation.
We recently reported on three young patients with severe impairments of episodic memory resulting from brain injury sustained early in life. These findings have led us to hypothesize that such impairments might be a previously unrecognized consequence of perinatal hypoxic-ischaemic injury. Neuropsychological and quantitative magnetic resonance investigations were carried out on five young patients, all of whom had suffered hypoxic-ischaemic episodes at or shortly after birth. All five patients showed severe impairments of episodic memory (memory for events), with relative preservation of semantic memory (memory for facts). However, none had any of the major neurological deficits that are typically associated with hypoxic-ischaemic injury, and all attended mainstream schools. Quantitative magnetic resonance investigations revealed severe bilateral hippocampal atrophy in all cases. As a group, the patients also showed bilateral reductions in grey matter in the regions of the putamen and the ventral part of the thalamus. On the basis of their clinical histories and the pattern of magnetic resonance findings, we attribute the patients' pathology and associated memory impairments primarily to hypoxic-ischaemic episodes sustained very early in life. We suggest that the degree of hypoxia-ischaemia was sufficient to produce selective damage to particularly vulnerable regions of the brain, notably the hippocampi, but was not sufficient to result in the more severe neurological and cognitive deficits that can follow hypoxic-ischaemic injury. The impairments in episodic memory may be difficult to recognize, particularly in early childhood, but this developmental amnesia can have debilitating consequences, both at home and at school, and may preclude independent life in adulthood.
Does the human brain actually grow or shrink to reflect the cognitive demands of the environment? The paper by Maguire et al. (1) claims exactly this. Using structural magnetic resonance imaging and sophisticated image analysis techniques, the investigators demonstrated enlarged posterior hippocampal gray matter volume in London taxi drivers, a group required to undergo extensive navigational training to maintain their licenses. At first blush, it might seem that their approach is simply a high-tech reincarnation of the failed methods used by the phrenologists (Fig. 1) of the late 18th century. Although this chapter in the history of scientific thought often is ridiculed, the basic approach of correlating behavioral skills (or deficits) with the size of different brain areas still is very much used today. An extreme case is the recent attribution of Albert Einstein's genius to his relatively large parietal cortex (2).
An optimized MR sequence for structural three-dimensional brain scans is presented, giving good T(1) contrast and excellent white matter/gray matter segmentation. Modification of the usual linear phase encoding order to centric phase encoding restores the contrast loss, which usually occurs after magnetization preparation during the acquisition process when large volumes are imaged. The deleterious effects on the point-spread function are compensated by means of an appropriate k-space filter. RF coil inhomogeneities are corrected by means of shaped excitation pulses. High contrast-to-noise images of the entire brain with 1 mm isotropic resolution can be obtained in 12 min. The contrast-to-noise-ratio is about 100% higher than for sequences based on linear phase encoding.
There are two major sources of information to build a topographic representation of an environment, namely actual navigation within the environment (route perspective) and map learning (survey perspective). The aim of the present work was to use positron emission tomography (PET) to compare the neural substrate of the topographic representation built from these two modes. One group of subjects performed a mental exploration task in an environment learned from actual navigation (mental navigation task). Another group of subjects performed exploration in the same environment learned from a map (mental map task). A right hippocampal activation common to both mental navigation and mental map tasks was evidenced and may correspond the neural substrate of a "dual-perspective" representation. The parahippocampal gyrus was additionally activated bilaterally during mental navigation only. These results suggest that the right hippocampus involvement would be sufficient when the representation incorporates essentially survey information while the bilateral parahippocampal gyrus would be involved when the environment incorporates route information and includes "object" landmarks. The activation of a parietofrontal network composed of the intraparietal sulcus, the superior frontal sulcus, the middle frontal gyrus, and the pre-SMA was observed in common for both mental navigation and mental map and is likely to reflect the spatial mental imagery components of the tasks.
Neuronal plasticity is a central theme of modern neurobiology, from
cellular and molecular mechanisms of synapse formation in Drosophila
to behavioural recovery from strokes in elderly humans. Although the methods
used to measure plastic responses differ, the stimuli required to elicit plasticity
are thought to be activity-dependent. In this article, we focus on the neuronal
changes that occur in response to complex stimulation by an enriched environment.
We emphasize the behavioural and neurobiological consequences of specific
elements of enrichment, especially exercise and learning
The dentate gyrus of the adult hippocampal formation generates neurons throughout life. To date, it remains unclear why. What are the new neurons used for? How can an existing functional neural network integrate and even actively recruit new neurons? The prevailing theories of cognition are based on the assumption that the adult brain is a stable network with regard to the number of neurons. In the current view, structural neural plasticity occurs only at the level of synapses, dendrites, and neurites. The clear demonstration of adult hippocampal neurogenesis, the generation of new granule cell neurons from resident neuronal stem or progenitor cells and their integration in the trisynaptic circuit of the hippocampus, has called this assumption into question. In the light of data on the activity-dependent regulation of adult hip- pocampal neurogenesis, some conclusions can be drawn, why and how new neurons might contribute to hippocampal function. Our hypothesis is that new neurons do not add memory, but insert strategically "new gatekeepers" at the "gateway to memory". In hindsight, there is a clear line from the groundbreaking work by Nottebohm (1981), Goldman and Nottebohm (1983), and Barnea and Nottebohm (1996) on functionally regulated neuro- genesis in the vocal nucleus and the hippocampus of songbirds to the analogous findings in mammals. However, for the researchers studying neurogenesis in the adult mammalian hippocampus, structural questions came before functional considerations. Only after several studies had confirmed the early reports by Altman and Das (1965) and Kaplan and Hinds (1977) that adult hip- pocampal neurogenesis indeed occurs, and after improved meth-