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| Variability of brain size and external topography. Photographs and weights of the brains of different species. Primates: human (Homo sapiens, 1.176 kg), chimpanzee (Pan troglodytes, 273 g), baboon (Papio cynocephalus, 151 g), mandrill (Mandrillus sphinx, 123 g), macaque (Macaca tonkeana, 110 g). Carnivores: bear (Ursus arctos, 289 g), lion (Panthera leo, 165 g), cheetah (Acinonyx jubatus, 119 g), dog (Canis familiaris, 95 g), cat (Felis catus, 32 g). Artiodactyls: giraffe (Giraffa camelopardalis, 700 g), kudu
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The tremendous expansion and the differentiation of the neocortex constitute two major events in the evolution of the mammalian brain. The increase in size and complexity of our brains opened the way to a spectacular development of cognitive and mental skills. This expansion during evolution facilitated the addition of microcircuits with a similar...
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... different conclusions may be reached even when comparative studies are performed using the same volumetric data (Clark et al., 2001;Kaas and Collins, 2001;de Winter and Oxnard, 2001;Barton, 2002;Sultan, 2002). Furthermore, there is remarkable variability in brain size among different mammalian species (Figure 7). This variation ranges from a brain weight of about 0.060 g for the insectivorous white-toothed pygmy shrew (Suncus etruscus, 2-3 g body weight: this mammal, together with the bumblebee bat Craseonycteris thonglongyai with a body weight of 2 g, represents the smallest of mammals that exists on Earth) to up to 9.200 kg for the brain of the sperm whale (Physeter macrocephalus: 50,000 kg body weight). ...
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... Monotremes (prototherians), one of the three main extant mammalian groups, diverged from therians around 166-186 million years ago, while the marsupial (metatherian) and placental (eutherian) lineages are thought to have split around 147-160 million years ago (Bininda-Emonds et al., 2007;Phillips et al., 2009). The brain size of present-day mammals is extremely variable, ranging from <0.1 g in the Etruscan pygmy shrew to more than 9 kg in some large cetaceans (DeFelipe, 2011). In placentals, evolutionary processes have led to the emergence of large brains in several groups of species sometimes separated by a long independent phylogenetic history (Manger et al., 2013). ...
... The mammalian neocortex is typically subdivided into six layers defined by vertical differences in the size, shape, or density of neurons (Brodmann, 1909). There are, however, variations in the number, thickness or overall cytoarchitectonic organisation of the layers across the cortical mantle (Kaas, 1987;DeFelipe, 2011), which have formed the basis of its subdivision into distinct regions. ...
... These variations are believed to be pivotal for the functional specialization of cortical areas (e.g. Elston and Rosa 1997;Jacobs et al. 2001;Bianchi et al. 2011;DeFelipe 2011;Elston et al. 2011;Elston and Manger 2014;Eyal et al. 2016;Mohan et al. 2015;Jacobs et al. 2015;Benavides-Piccione et al. 2020, 2021Galakhova et al. 2022;Kanari et al. 2023). Indeed, the dendritic tree structure inf luences the biophysical and computational properties of neurons, and these differences are crucial factors contributing to the variations in the functional organization of the cerebral cortex (reviewed in Segev and London 2000;Stuart and Spruston 2015;Fisek and Häusser 2020;Poirazi and Papoutsi 2020). ...
The basic building block of the cerebral cortex, the pyramidal cell, has been shown to be characterized by a markedly different dendritic structure among layers, cortical areas, and species. Functionally, differences in the structure of their dendrites and axons are critical in determining how neurons integrate information. However, within the human cortex, these neurons have not been quantified in detail. In the present work, we performed intracellular injections of Lucifer Yellow and 3D reconstructed over 200 pyramidal neurons, including apical and basal dendritic and local axonal arbors and dendritic spines, from human occipital primary visual area and associative temporal cortex. We found that human pyramidal neurons from temporal cortex were larger, displayed more complex apical and basal structural organization, and had more spines compared to those in primary sensory cortex. Moreover, these human neocortical neurons displayed specific shared and distinct characteristics in comparison to previously published human hippocampal pyramidal neurons. Additionally, we identified distinct morphological features in human neurons that set them apart from mouse neurons. Lastly, we observed certain consistent organizational patterns shared across species. This study emphasizes the existing diversity within pyramidal cell structures across different cortical areas and species, suggesting substantial species-specific variations in their computational properties.
... Yet how cells and circuits generate these incredible phenomena remains unknown. In particular, we do not know whether the human brain is simply a scaled version of the extensively studied rodent brain (DeFelipe, 2011;Herculano-Houzel et al., 2015), or whether its uniqueness is produced by the specific properties of cells (Eyal et al., 2016), dendrites (Gidon et al., 2020;Mertens et al., 2024), or synapses (Campagnola et al., 2022;Molnár et al., 2016Molnár et al., , 2008Testa-Silva et al., 2014). Distinguishing between these possibilities requires structural and functional analysis of living human brain tissue. ...
The human brain has remarkable computational power. It generates sophisticated behavioral sequences, stores engrams over an individual’s lifetime, and produces higher cognitive functions up to the level of consciousness. However, so little of our neuroscience knowledge covers the human brain, and it remains unknown whether this organ is truly unique, or is a scaled version of the extensively studied rodent brain. To address this fundamental question, we determined the cellular, synaptic, and connectivity rules of the hippocampal CA3 recurrent circuit using multicellular patch clamp-recording. This circuit is the largest autoassociative network in the brain, and plays a key role in memory and higher-order computations such as pattern separation and pattern completion. We demonstrate that human hippocampal CA3 employs sparse connectivity, in stark contrast to neocortical recurrent networks. Connectivity sparsifies from rodents to humans, providing a circuit architecture that maximizes associational power. Unitary synaptic events at human CA3–CA3 synapses showed both distinct species-specific and circuit-dependent properties, with high reliability, unique amplitude precision, and long integration times. We also identify differential scaling rules between hippocampal pathways from rodents to humans, with a moderate increase in the convergence of CA3 inputs per cell, but a marked increase in human mossy fiber innervation. Anatomically guided full-scale modeling suggests that the human brain’s sparse connectivity, expanded neuronal number, and reliable synaptic signaling combine to enhance the associative memory storage capacity of CA3. Together, our results reveal unique rules of connectivity and synaptic signaling in the human hippocampus, demonstrating the absolute necessity of human brain research and beginning to unravel the remarkable performance of our autoassociative memory circuits.
... However, the difference in scale between rodent models and humans [27] requires adapting multiples aspects of the ultrasound imaging and processing techniques, notably imaging at greater depth while maintaining an adequate volume acquisition rate. For non-invasive application, transcranial 3D ULM of the human brain will require using transducers with lower frequencies to image through the skull. ...
... There is increasing empirical evidence, however, suggesting the early use of relatively complex communicative strategies by Homo erectus in the LP/ESA, perhaps some 1.8 mya. Some general indications include (tentative) evidence for dramatic cognitive expansion occurred during the LP/ESA, with brains rapidly doubling in size (see DeFelipe, 2011;Potts, 2011), for increased technological and niche intensification (Van Arsdale, 2013), cooking and other food processing innovations (Joordens et al., 2009;Wrangham, 2009), long-distance hunting (Henrich, 2017), as well as social adaptations such as cooperative breeding and secondary altriciality (Cofran & Desilva, 2015;Isler & Van Schaik, 2012), all of which suggest the need for new communicative strategies. Further research may indicate changes in body composition (Leonard et al., 2003;Henrich, 2017), brain lateralization, hyoid bone adaptations for increased speech capacities (Capasso et al., 2008), cortical growth required for language (Hillert, 2021), and expansion of Broca's area (with Homo habilis) associated with gestures, increased vocalization (Corballis, 2003), and procedural know-how (Henrich, 2017). ...
Concepts such as “symbolism” and “symbolic cognition” often remain unspecified in discussions the symbolic capacities of earlier hominins. In this paper, I use conceptual tools from phenomenology to reflect on the origins of early symbolic cognition. In particular, I discuss the possible early use of pointing gestures around the time of the earliest known stone tool industries. I argue that unlike more basic social acts such as expression, gaze following, and attention-getters, which are used by extant non-human great apes, communicative pointing involves key elements that are characteristic of symbolic cognition. In particular, it involves “third order intentionality” as well as “shared practice horizons”: shared frameworks of understanding which are required for the interpretation of communicative acts whose meaning is not codified indexically or iconically in the signaling behavior. In the final part, I briefly review some indications for the use of pointing gestures around the time of the Lomekwian and Oldowan industries, as a way to sustain cooperation and possibly learning by instruction. It is suggested that pointing is more complex than is standardly acknowledged, and that it may have been an important communicative act for Early Stone Age hominins in transitioning to more fully symbolic speech capacities.
... When a gene is deleted, it can have a dramatic effect on the expression of other genes that interact with it in a functional network [30]. Gene knockout experiments provide direct evidence of modular interactive networks, but are limited to experimental animals that fail to reflect the complexity of the human brain [31,32] or emotional, cognitive, and social features that require self-awareness [31][32][33] (Supplementary Text S1). ...
... When a gene is deleted, it can have a dramatic effect on the expression of other genes that interact with it in a functional network [30]. Gene knockout experiments provide direct evidence of modular interactive networks, but are limited to experimental animals that fail to reflect the complexity of the human brain [31,32] or emotional, cognitive, and social features that require self-awareness [31][32][33] (Supplementary Text S1). ...
Genome-wide association studies of human personality have been carried out, but transcription of the whole genome has not been studied in relation to personality in humans. We collected genome-wide expression profiles of adults to characterize the regulation of expression and function in genes related to human personality. We devised an innovative multi-omic approach to network analysis to identify the key control elements and interactions in multi-modular networks. We identified sets of transcribed genes that were co-expressed in specific brain regions with genes known to be associated with personality. Then we identified the minimum networks for the co-localized genes using bioinformatic resources. Subjects were 459 adults from the Young Finns Study who completed the Temperament and Character Inventory and provided peripheral blood for genomic and transcriptomic analysis. We identified an extrinsic network of 45 regulatory genes from seed genes in brain regions involved in self-regulation of emotional reactivity to extracellular stimuli (e.g., self-regulation of anxiety) and an intrinsic network of 43 regulatory genes from seed genes in brain regions involved in self-regulation of interpretations of meaning (e.g., production of concepts and language). We discovered that interactions between the two networks were coordinated by a control hub of 3 miRNAs and 3 protein-coding genes shared by both. Interactions of the control hub with proteins and ncRNAs identified more than 100 genes that overlap directly with known personality-related genes and more than another 4000 genes that interact indirectly. We conclude that the six-gene hub is the crux of an integrative network that orchestrates information-transfer throughout a multi-modular system of over 4000 genes enriched in liquid-liquid-phase-separation (LLPS)-related RNAs, diverse transcription factors, and hominid-specific miRNAs and lncRNAs. Gene expression networks associated with human personality regulate neuronal plasticity, epigenesis, and adaptive functioning by the interactions of salience and meaning in self-awareness. Molecular Psychiatry; https://doi.
... Neuroscientists face technical and ethical limitations that limit the acquisition of large datasets from the human brain [70][71][72]. However, there are structural and functional properties that are specific to the human brain and its neurons [73][74][75][76][77][78][79][80], which is why animal neurons cannot completely replace human ones [81]. Human neurons are not only larger but also more complex than those of for example macaques and marmosets [11]. ...
Investigating and modelling the functionality of human neurons remains challenging due to the technical limitations, resulting in scarce and incomplete 3D anatomical reconstructions. Here we used a morphological modelling approach based on optimal wiring to repair the parts of a dendritic morphology that were lost due to incomplete tissue samples. In Drosophila , where dendritic regrowth has been studied experimentally using laser ablation, we found that modelling the regrowth reproduced a bimodal distribution between regeneration of cut branches and invasion by neighbouring branches. Interestingly, our repair model followed growth rules similar to those for the generation of a new dendritic tree. To generalise the repair algorithm from Drosophila to mammalian neurons, we artificially sectioned reconstructed dendrites from mouse and human hippocampal pyramidal cell morphologies, and showed that the regrown dendrites were morphologically similar to the original ones. Furthermore, we were able to restore their electrophysiological functionality, as evidenced by the recovery of their firing behaviour. Importantly, we show that such repairs also apply to other neuron types including hippocampal granule cells and cerebellar Purkinje cells. We then extrapolated the repair to incomplete human CA1 pyramidal neurons, where the anatomical boundaries of the particular brain areas innervated by the neurons in question were known. Interestingly, the repair of incomplete human dendrites helped to simulate the recently observed increased synaptic thresholds for dendritic NMDA spikes in human versus mouse dendrites. To make the repair tool available to the neuroscience community, we have developed an intuitive and simple graphical user interface (GUI), which is available in the TREES toolbox ( www.treestoolbox.org ).
... Este fenómeno de la evolución del Australopithecus al Homo sapiens ha sido estudiado por muchos autores (DeFelipe, 2011;Gowlett, 2016;Harari, 2014). Sin embargo, no tener en cuenta la evolución del hombre con relación a los elementos que han facilitado su calidad de vida, como es caso del fogón dentro de la arquitectura doméstica, genera vacíos epistemológicos que implican un desconocimiento del quehacer humano en cuanto a sus procesos de alimentación (Quiroz-Carranza & Cantú-Gutiérrez, 2012). ...
La conceptualización de lo que conocemos como arquitectura se origina en el descubrimiento del fuego, que resolvió la necesidad de cocinar e influyó en la evolución de las personas, incluso en su desarrollo intelectual y en el habitar en sociedad. Por tal motivo, esta investigación establece un estudio sobre la importancia del fogón y su transición como componente arquitectónico en comunidades afrodescendientes del Caribe colombiano, para lo cual hace un análisis etnográfico y ergonómico desde la adaptación del hombre a los fogones. Como resultados, se determina que el binde trasciende al fogón de banco como consecuencia de factores económicos y la mejora de posturas ligadas a la ergonomía de las antiguas cocineras, al igual que de la transición del fogón de banco al fogón industrial debido a los riesgos producidos por el uso de madera como biocom-bustible; todo lo cual está soportado en referentes y resultados del análisis etnográfico y entrevis-tas. Sin embargo, se establece que las tipologías de fogones a leña actualmente hacen parte de la tradición gastronómica, pese a los desarrollos tecnológicos ligados a los fogones industriales, presentes en comunidades rurales y urbanas de los municipios de Turbo y Necoclí.. Palabras Clave: arquitectura; ergonomía; etnografía; gastronomía; tipologías de fogón Resumen
... In particular, the cerebral cortex is the most complex structure known in biology. Although base architecture seems to be preserved across mammals [1], different studies have suggested significant differences in the cellular composition of the human nervous system [2]. Specifically, marked variations were observed in the proportions of neuronal and non-neuronal cells and in the transcription of genes associated with neuronal structure and activity [3]. ...
Modeling human neuronal properties in physiological and pathological conditions is essential to identify novel potential drugs and to explore pathological mechanisms of neurological diseases. For this purpose, we generated a three-dimensional (3D) neuronal culture, by employing the readily available human neuroblastoma SH-SY5Y cell line, and a new differentiation protocol. The entire differentiation process occurred in a matrix and lasted 47 days, with 7 days of pre-differentiation phase and 40 days of differentiation, and allowed the development of a 3D culture in conditions consistent with the physiological environment. Neurons in the culture were electrically active, were able to establish functional networks, and showed features of cholinergic neurons. Hence here we provide an easily accessible, reproducible, and suitable culture method that might empower studies on synaptic function, vesicle trafficking, and metabolism, which sustain neuronal activity and cerebral circuits. Moreover, this novel differentiation protocol could represent a promising cellular tool to study physiological cellular processes, such as migration, differentiation, maturation, and to develop novel therapeutic approaches.
... However, the volume and number of neocortical neurons increased rapidly compared to subcortical structures during the evolutionary expansion of the neocortex [4][5][6][7][8]. While the general principles of cortical development and basic architecture are conserved, studies have shown differences in the cellular composition of the human cortex [9]. These differences include the expansion of superficial cortical layers during mammalian evolution, which may involve rare cell types and novel cellular interactions contributing to the complexity of primate brain function [10]. ...
Primates exhibit complex brain structures that augment cognitive function. The neocortex fulfills high-cognitive functions through billions of connected neurons. These neurons have distinct transcriptomic, morphological, and electrophysiological properties, and their connectivity principles vary. These features endow the primate brain atlas with a multimodal nature. The recent integration of next-generation sequencing with modified patch-clamp techniques is revolutionizing the way to census the primate neocortex, enabling a multimodal neuronal atlas to be established in great detail: (1) single-cell/single-nucleus RNA-seq technology establishes high-throughput transcriptomic references, covering all major transcriptomic cell types; (2) patch-seq links the morphological and electrophysiological features to the transcriptomic reference; (3) multicell patch-clamp delineates the principles of local connectivity. Here, we review the applications of these technologies in the primate neocortex and discuss the current advances and tentative gaps for a comprehensive understanding of the primate neocortex.
