Figure 2 - available from: The Cerebellum
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Course of ipsilateral dentate nucleus-mammillary connections. Ten axial T2-weighted images show the course of the connections between the dentate nucleus and mammillary bodies. On the right side, fibers are red colored and, on the left side, blue colored. The first three images depict tracts leaving the dentate nuclei, and then fibers pass through the superior cerebellar peduncles, surround red nuclei, passing medially to the substantia nigra, and finally reach the mammillary bodies
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According to the classical view, the cerebellum has long been confined to motor control physiology; however, it has now become evident that it exerts several non-somatic features other than the coordination of movement and is engaged also in the regulation of cognition and emotion. In a previous diffusion-weighted imaging-constrained spherical deco...
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Background:
Prelemniscal radiations (Rapl) lesions and deep brain stimulation (DBS) effectively control motor symptoms of Parkinson's disease (PD), but individual variations in the stereotactic location of its fiber components constitute a significant concern.
Objective:
To determine individual variations in the stereotactic location of fiber tr...
Citations
... The role of the hippocampus (HPC) in eyeblink conditioning in mammals, based on[132][133][134][135][136]. HPC cells show firing patterns, triggered by conditional (CS) but not unconditional (US) stimuli, that arise in training, progress during conditioning, and often model the conditioned eyeblink response (CR). ...
The construction of complex engrams requires hippocampal–cortical interactions. These include both direct interactions and ones via often-overlooked subcortical loops. Here, we review the anatomical organization of a hierarchy of parallel ‘Papez’ loops through the hypothalamus that are homologous in mammals from rats to humans. These hypothalamic loops supplement direct hippocampal–cortical connections with iterative reprocessing paced by theta rhythmicity. We couple existing anatomy and lesion data with theory to propose that recirculation in these loops progressively enhances desired connections, while reducing interference from competing external goals and internal associations. This increases the signal-to-noise ratio in the distributed engrams (neocortical and cerebellar) necessary for complex learning and memory. The hypothalamic nodes provide key motivational input for engram enhancement during consolidation.
... Fifteen studies reported sensorimotor connectivity [2, 7, 10, 15, 19, 21, 24, 28, 33, 35-37, 39, 43, 44]. Cognitive, associative, and limbic connectivities were described in 14 studies [3,7,8,17,20,21,31,34,35,37,39,40,43,44]. ...
The cerebellum is historically implicated in motor coordination, but accumulating modern evidence indicates involvement in non-motor domains, including cognition, emotion, and language. This correlates with the symptoms observed in postoperative cerebellar mutism syndrome (CMS). Profound knowledge of cerebellar functional topography and tractography is important when approaching cerebellar tumors, as surgical trauma to relevant structures of cerebellar pathways plays a role in the pathogenesis of CMS. The aim of this systematic review is to provide a concise overview of relevant modern neuroimaging data and cerebellar functional tracts with regard to neurosurgical procedures.
... There is increasing evidence that the cerebellum may be particularly involved in the coordination of emotional processes, particularly negative ones (Utz et al. 2015). The cerebellum connects with the limbic structures both ipsilaterally and contralaterally (Cacciola et al. 2017). It has also been found that the vermis may be particularly connected to the limbic structures (Blatt et al. 2013). ...
Background: Many individuals participate in spiritual retreats to enhance their sense of spirituality or to improve their overall mental and spiritual well-being. We are not aware of any studies specifically evaluating changes in functional connectivity using functional magnetic resonance imaging (fMRI) in individuals undergoing an intense spiritual retreat program. The goal of this study was to determine whether such changes occur as a result of participating in the Spiritual Exercises of St. Ignatius. Methods: We conducted psychological and spiritual measures in conjunction with functional connectivity analysis of fMRI in 14 individuals prior to and following shortly after their participation in a one-week spiritual retreat. Results: Significant changes in functional connectivity were observed after the retreat program, compared to baseline evaluation, particularly in the posterior cingulate cortex, pallidum, superior frontal lobe, superior parietal lobe, superior and inferior temporal lobe, and the cerebellum. Significant changes in a variety of psychological and spiritual measures were identified as result of participation in the retreat. Conclusion: Overall, these preliminary findings suggest that this intensive spiritual retreat resulted in significant changes in brain functional connectivity, and warrants further investigation to evaluate the physiological, psychological, and spiritual impact of these changes.
... In humans, diffusion-weighted imaging studies revealed several tracts that connect with the MB, such as the fornix and mammillotegmental tract (Granziera et al., 2011;Kwon et al., 2011;Mori and Aggarwal, 2014;Christiansen et al., 2016;Cacciola et al., 2017;Wei et al., 2017;Kamali et al., 2018;Choi et al., 2019;Maller et al., 2019). Clinical studies also revealed that memory-impaired patients with Korsakoff syndrome exhibit atrophy of the MB (Squire et al., 1990;Harding et al., 2000;Tsivilis et al., 2008;Fama et al., 2012;Kril and Harper, 2012;Aggleton, 2014;Kopelman, 2015;Isenberg-Grzeda et al., 2016;Arts et al., 2017;Johnson and Fox, 2018). ...
The mammillary body (MB) has been thought to implement mnemonic functions. Although recent animal studies have revealed dissociable roles of the lateral and medial parts of the MB, the dissociable roles of the lateral/medial MB in the human brain is still unclear. Functional connectivity using resting-state functional magnetic resonance imaging (fMRI) provides a unique opportunity to noninvasively inspect the intricate functional organization of the human MB with a high degree of spatial resolution. The present study divided the human MB into lateral and medial parts and examined their functional connectivity with the hippocampal formation, tegmental nuclei, and anterior thalamus. The subiculum of the hippocampal formation was more strongly connected with the medial part than with the lateral part of the MB, whereas the pre/parasubiculum was more strongly connected with the lateral part than with the medial part of the MB. The dorsal tegmental nucleus was connected more strongly with the lateral part of the MB, whereas the ventral tegmental nucleus showed an opposite pattern. The anterior thalamus was connected more strongly with the medial part of the MB. These results confirm the extant animal literature on the lateral/medial MB and provide evidence on the parallel but dissociable systems involving the MB that ascribe mnemonic and spatial-navigation functions to the medial and lateral MBs, respectively.
... The large wing of the sphenoid, the ethmoid, the crista galli, and a section of the frontal bone can be observed. The arrows show different anatomical structures as they are clearly represented and distinguished by means of the volume rendering: vascular structures arteries of the circle of Willis (white arrow), muscular structures, ocular recti muscles lateral rectus (green arrow), medial rectus (gray arrow), optic nerves (cyan arrow), eyeballs (yellow arrow), brain parenchyma (blue arrow) and skull (magenta).International Archives of Otorhinolaryngology Vol.24 No. 1/2020 ...
... The image shows: the internal carotid arteries (blue arrows), the ophthalmic arteries (green arrow), left anterior ethmoidal artery (AEA) (white arrow), right AEA (yellow arrow). As clearly demonstrated by the image, in this patient, the left AEA was extracanal, while the right AEA is intracanal, within the AEC.International Archives of Otorhinolaryngology Vol.24 No. Summary of the studies of the last decade on the assessment of the anterior ethmoidal artery scans, excluding patients with nasal polyposis, sinus anomalies, previous sinus surgery.CT scans Positive correlation between the AEC, the superior-inferior depth of the lateral lamella of the cribriform plate LLCP, and the anterior-posterior length. ...
Introduction The clinical relevance of the anatomy and variations of the anterior ethmoidal artery (AEA) is outstanding, considering its role as a landmark in endoscopic surgery, its importance in the therapy of epistaxis, and the high risks related to iatrogenic injuries.
Objective To provide an anatomical description of the course and relationships of the AEA, based on direct computed-tomography (CT)-based 3D volume rendering.
Methods Direct volume rendering was performed on 18 subjects who underwent (CT) with contrast medium for suspected cerebral aneurism.
Results The topographical location of 36 AEAs was assessed as shown: 10 dehiscent (27.8%), 20 intracanal (55.5%), 6 incomplete canals (16.7%). Distances from important topographic landmarks are reported.
Conclusion This work demonstrates that direct 3D volume rendering is a valid imaging technique for a detailed description of the anterior ethmoidal artery thus representing a useful tool for head pre-operatory assessments.
... Along with its inability to detect signal directionality and presence of synapses 81,82 , and a recent paper underlined that tractographic reconstruction is prone to high rates of false positive tracts, when compared to ground truth tracts obtained from a simulated human brain dataset 83 . Despite its intrinsic limitations, tractography remains the only way to study structural connectivity in humans in vivo [84][85][86][87][88][89][90][91][92][93][94][95][96][97] . Moreover, it should be considered that the present study is based on a consolidated anatomical foundation and globally replicates what has already been found out in other species. ...
The Red Nucleus (RN) is a large nucleus located in the ventral midbrain: it is subdivided into a small caudal magnocellular part (mRN) and a large rostral parvocellular part (pRN). These distinct structural regions are part of functionally different networks and show distinctive connectivity features: the mRN is connected to the interposed nucleus, whilst the pRN is mainly connected to dentate nucleus, cortex and inferior olivary complex. Despite functional neuroimaging studies suggest RN involvement in complex motor and higher order functions, the pRN and mRN cannot be distinguished using conventional MRI. Herein, we employ high-quality structural and diffusion MRI data of 100 individuals from the Human Connectome Project repository and constrained spherical deconvolution tractography to perform connectivity-based segmentation of the human RN. In particular, we tracked connections of RN with the inferior olivary complex, the interposed nucleus, the dentate nucleus and the cerebral cortex. We found that the RN can be subdivided according to its connectivity into two clusters: a large ventrolateral one, mainly connected with the cerebral cortex and the inferior olivary complex, and a smaller dorsomedial one, mainly connected with the interposed nucleus. This structural topography strongly reflects the connectivity patterns of pRN and mRN respectively. Structural connectivity-based segmentation could represent a useful tool for the identification of distinct subregions of the human red nucleus on 3T MRI thus allowing a better evaluation of this subcortical structure in healthy and pathological conditions.
... Findings in our study support that cognitive impairment may be mainly attributed to the decreased efficiency of local connections in the brain regions involved in default networks and frontotemporal lobe after cerebellar infarction. Furthermore, previous studies have documented that there are ipsilateral and contralateral fibrous connections between the cerebellum and the brain (9,63). Current studies have also revealed that the changes of network connections in bilateral brain areas after cerebellar infarction may be associated with ipsilateral and contralateral regulation of the cerebellum, which requires to be further explored. ...
Cerebellar lesions can lead to a series of cognitive and emotional disorders by influencing cerebral activity via cerebro-cerebellar loops. To explore changes in cognitive function and structural brain networks in patients with posterior cerebellar infarction, we conducted the current study using diffusion-weighted MRI (32 cerebellar infarction patients, 29 controls). Moreover, a series of neuropsychological tests were used to assess the subject's cognitive performance. We found cognitive impairment following cerebellar infarction involving multiple cognitive domains, including memory, executive functions, visuospatial abilities, processing speed and language functions, and brain topological abnormalities, including changes in clustering coefficients, shortest path lengths, global efficiency, local efficiencies, betweenness centrality and nodal efficiencies. Our results indicated that measures of local efficiency, mainly in the precuneus, cingulate gyrus and frontal-temporal cortex, were significantly reduced with posterior cerebellar infarction. At the same time, The correlation analysis suggested thatthe abnormal alterations in the right PCG, bilateral DCG, right PCUN may play a core role in the cognitive impairment following cerebellar infarctions. The differences in topological features of the structural brain networks within the cerebro-cerebellar circuits may provide a new approach to explore the pathophysiological mechanisms of cognitive impairment following cerebellar infarction.
... 13,14 This scenario has been widely expanded since anatomical studies using retrograde virus tracing demonstrated bidirectional subcortical connections between cerebellum and basal ganglia. 15,16 More recently, we used constrained spherical deconvolution (CSD)-based tractography, a diffusion MRI-based technique allowing in vivo reconstruction of connectivity patterns between nervous structures, [17][18][19][20][21] to study the human analogues of the above-mentioned direct cortico- 22 and dento-pallidal projections. 23 These connections, likely paralleled by analogue cortico- 24 and dento-nigral 23,25 pathways, may exert a converging influence of cerebral and neocerebellar cortex on the basal ganglia output nuclei. ...
Background
Understanding the topographical organization of the cortico‐basal ganglia circuitry is of pivotal importance because of the spreading of techniques such as DBS and, more recently, MR‐guided focused ultrasound for the treatment of movement disorders. A growing body of evidence has described both direct cortico‐ and dento‐pallidal connections, although the topographical organization in vivo of these pathways in the human brain has never been reported.
Objective
To investigate the topographical organization of cortico‐ and dento‐pallidal pathways by means of diffusion MRI tractography and connectivity based parcellation.
Methods
High‐quality data from 100 healthy subjects from the Human Connectome Project repository were utilized. Constrained spherical deconvolution–based tractography was used to reconstruct structural cortico‐ and dento‐pallidal connectivity. Connectivity‐based parcellation was performed with a hypothesis‐driven approach at three different levels: functional regions (limbic, associative, sensorimotor, and other), lobes, and gyral subareas.
Results
External globus pallidus segregated into a ventral associative cluster, a dorsal sensorimotor cluster, and a caudal “other” cluster on the base of its cortical connectivity. Dento‐pallidal connections clustered only in the internal globus pallidus, where also associative and sensorimotor clusters were identified. Lobar parcellation revealed the presence in the external globus pallidus of dissociable clusters for each cortical lobe (frontal, parietal, temporal, and occipital), whereas in internal globus pallidus only frontal and parietal clusters were found out.
Conclusion
We mapped the topographical organization of both internal and external globus pallidus according to cortical and cerebellar connections. These anatomical data could be useful in DBS, radiosurgery and MR‐guided focused ultrasound targeting for treating motor and nonmotor symptoms in movement disorders. © 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.
... DTI and tractography has been extensively used as an in-vivo non-invasive and quantitative method to evaluate cerebral white matter organization in healthy and pathological conditions. [17][18][19][20][21][22][23] The application of these techniques in musculoskeletal imaging is currently spreading 24 and several studies have shown their reliability and feasibility for probing the in-vivo architecture of skeletal muscles both in humans 12,25-29 and animals. 30 Furthermore, DTI-derived parameters such as Fractional Anisotropy (FA), Mean Diffusivity (MD) and eigenvalues allow for the evaluation of muscular tissue microstructure. ...
Background:
Diffusion tensor imaging (DTI) is a non-invasive MR technique widely employed to study muscle anatomy. DTI parameters have been use to investigate changes in microstructures dependent on demographic factors or transient condition such as exercise. The present study is aimed at investigating the diffusion parameters changes of the human calf muscles after a 3-months strength training protocol.
Methods:
Ten young men were trained for improving size and strength of the medial (GCM), lateral gastrocnemius (GCL) and soleus (SL) three times a week, with at least 24 hours between training sessions, for a period of three months. Diffusion weighted magnetic resonance images were acquired at the beginning of the training period (TPRE) and at three months (TPOST) using a 3T scanner. The fractional anisotropy (FA), mean diffusivity (MD) and tensor eigenvalues (λ1, λ2, λ3) were derived from the diffusion weighted imaging data.
Results:
We found a significant increase in λ1, λ2, λ3 and MD values and muscle volumes between TPRE and TPOST in all the examined muscles both for the left and right side. No significant differences were highlighted for FA.
Conclusions:
DTI enables the investigation of muscle microstructure, allowing for the assessment of diffusion parameters variation of the muscle tissue in response to training thus being a useful tool to investigate physiological and pathological changes in skeletal muscle microstructure which could be employed to test the outcomes and the effectiveness of a given training protocol.
... DTI and tractography has been extensively used as an in-vivo non-invasive and quantitative method to evaluate cerebral white matter organization in healthy and pathological conditions. [17][18][19][20][21][22][23] The application of these techniques in musculoskeletal imaging is currently spreading 24 and several studies have shown their reliability and feasibility for probing the in-vivo architecture of skeletal muscles both in humans 12,25-29 and animals. 30 Furthermore, DTI-derived parameters such as Fractional Anisotropy (FA), Mean Diffusivity (MD) and eigenvalues allow for the evaluation of muscular tissue microstructure. ...
BACKGROUND:
Diffusion tensor imaging (DTI) is a non-invasive MR technique widely employed to study muscle anatomy. DTI parameters have been use to investigate changes in microstructures dependent on demographic factors or transient condition such as exercise. The present study is aimed at investigating the diffusion parameters changes of the human calf muscles after a 3-months strength training protocol.
METHODS:
Ten young men were trained for improving size and strength of the medial (GCM), lateral gastrocnemius (GCL) and soleus (SL) three times a week, with at least 24 hours between training sessions, for a period of three months. Diffusion weighted magnetic resonance images were acquired at the beginning of the training period (TPRE) and at three months (TPOST) using a 3T scanner. The fractional anisotropy (FA), mean diffusivity (MD) and tensor eigenvalues (λ1, λ2, λ3) were derived from the diffusion weighted imaging data.
RESULTS:
We found a significant increase in λ1, λ2, λ3 and MD values and muscle volumes between TPRE and TPOST in all the examined muscles both for the left and right side. No significant differences were highlighted for FA.
CONCLUSIONS:
DTI enables the investigation of muscle microstructure, allowing for the assessment of diffusion parameters variation of the muscle tissue in response to training thus being a useful tool to investigate physiological and pathological changes in skeletal muscle microstructure which could be employed to test the outcomes and the effectiveness of a given training protocol.
