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Dworetsky A, Seitzman BA, Adeyemo B, Nielsen AN, Hatoum AS, Smith DM, Nichols TE, Neta M, Petersen SE, Gratton C. Two common and distinct forms of variation in human functional brain networks. Nat Neurosci 2024; 27:1187-1198. [PMID: 38689142 DOI: 10.1038/s41593-024-01618-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 03/07/2024] [Indexed: 05/02/2024]
Abstract
The cortex has a characteristic layout with specialized functional areas forming distributed large-scale networks. However, substantial work shows striking variation in this organization across people, which relates to differences in behavior. While most previous work treats individual differences as linked to boundary shifts between the borders of regions, here we show that cortical 'variants' also occur at a distance from their typical position, forming ectopic intrusions. Both 'border' and 'ectopic' variants are common across individuals, but differ in their location, network associations, properties of subgroups of individuals, activations during tasks, and prediction of behavioral phenotypes. Border variants also track significantly more with shared genetics than ectopic variants, suggesting a closer link between ectopic variants and environmental influences. This work argues that these two dissociable forms of variation-border shifts and ectopic intrusions-must be separately accounted for in the analysis of individual differences in cortical systems across people.
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Affiliation(s)
- Ally Dworetsky
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, USA
- Department of Psychology, Florida State University, Tallahassee, FL, USA
- Department of Psychology, Northwestern University, Evanston, IL, USA
| | - Benjamin A Seitzman
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA
| | - Babatunde Adeyemo
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
| | - Ashley N Nielsen
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
| | - Alexander S Hatoum
- Department of Psychological and Brain Sciences, Washington University School of Medicine, St. Louis, MO, USA
| | - Derek M Smith
- Department of Psychology, Northwestern University, Evanston, IL, USA
- Department of Neurology, Division of Cognitive Neurology/Neuropsychology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Thomas E Nichols
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Population Health, University of Oxford, Oxford, United Kingdom
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Maital Neta
- Department of Psychology, University of Nebraska-Lincoln, Lincoln, NE, USA
- Center for Brain, Biology, and Behavior, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Steven E Petersen
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, USA
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
- Department of Psychological and Brain Sciences, Washington University School of Medicine, St. Louis, MO, USA
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO, USA
- Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, MO, USA
| | - Caterina Gratton
- Department of Psychology, Florida State University, Tallahassee, FL, USA.
- Department of Psychology, Northwestern University, Evanston, IL, USA.
- Neuroscience Program, Florida State University, Tallahassee, FL, USA.
- Department of Neurology, Northwestern University, Evanston, IL, USA.
- Interdepartmental Neuroscience Program, Northwestern University, Evanston, IL, USA.
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2
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Brewer AA, Barton B. Cortical field maps across human sensory cortex. Front Comput Neurosci 2023; 17:1232005. [PMID: 38164408 PMCID: PMC10758003 DOI: 10.3389/fncom.2023.1232005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Accepted: 11/07/2023] [Indexed: 01/03/2024] Open
Abstract
Cortical processing pathways for sensory information in the mammalian brain tend to be organized into topographical representations that encode various fundamental sensory dimensions. Numerous laboratories have now shown how these representations are organized into numerous cortical field maps (CMFs) across visual and auditory cortex, with each CFM supporting a specialized computation or set of computations that underlie the associated perceptual behaviors. An individual CFM is defined by two orthogonal topographical gradients that reflect two essential aspects of feature space for that sense. Multiple adjacent CFMs are then organized across visual and auditory cortex into macrostructural patterns termed cloverleaf clusters. CFMs within cloverleaf clusters are thought to share properties such as receptive field distribution, cortical magnification, and processing specialization. Recent measurements point to the likely existence of CFMs in the other senses, as well, with topographical representations of at least one sensory dimension demonstrated in somatosensory, gustatory, and possibly olfactory cortical pathways. Here we discuss the evidence for CFM and cloverleaf cluster organization across human sensory cortex as well as approaches used to identify such organizational patterns. Knowledge of how these topographical representations are organized across cortex provides us with insight into how our conscious perceptions are created from our basic sensory inputs. In addition, studying how these representations change during development, trauma, and disease serves as an important tool for developing improvements in clinical therapies and rehabilitation for sensory deficits.
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Affiliation(s)
- Alyssa A. Brewer
- mindSPACE Laboratory, Departments of Cognitive Sciences and Language Science (by Courtesy), Center for Hearing Research, University of California, Irvine, Irvine, CA, United States
| | - Brian Barton
- mindSPACE Laboratory, Department of Cognitive Sciences, University of California, Irvine, Irvine, CA, United States
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3
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Lynch CJ, Elbau I, Ng T, Ayaz A, Zhu S, Manfredi N, Johnson M, Wolk D, Power JD, Gordon EM, Kay K, Aloysi A, Moia S, Caballero-Gaudes C, Victoria LW, Solomonov N, Goldwaser E, Zebley B, Grosenick L, Downar J, Vila-Rodriguez F, Daskalakis ZJ, Blumberger DM, Williams N, Gunning FM, Liston C. Expansion of a frontostriatal salience network in individuals with depression. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.09.551651. [PMID: 37645792 PMCID: PMC10461904 DOI: 10.1101/2023.08.09.551651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Hundreds of neuroimaging studies spanning two decades have revealed differences in brain structure and functional connectivity in depression, but with modest effect sizes, complicating efforts to derive mechanistic pathophysiologic insights or develop biomarkers. 1 Furthermore, although depression is a fundamentally episodic condition, few neuroimaging studies have taken a longitudinal approach, which is critical for understanding cause and effect and delineating mechanisms that drive mood state transitions over time. The emerging field of precision functional mapping using densely-sampled longitudinal neuroimaging data has revealed unexpected, functionally meaningful individual differences in brain network topology in healthy individuals, 2-5 but these approaches have never been applied to individuals with depression. Here, using precision functional mapping techniques and 11 datasets comprising n=187 repeatedly sampled individuals and >21,000 minutes of fMRI data, we show that the frontostriatal salience network is expanded two-fold in most individuals with depression. This effect was replicable in multiple samples, including large-scale, group-average data (N=1,231 subjects), and caused primarily by network border shifts affecting specific functional systems, with three distinct modes of encroachment occurring in different individuals. Salience network expansion was unexpectedly stable over time, unaffected by changes in mood state, and detectable in children before the subsequent onset of depressive symptoms in adolescence. Longitudinal analyses of individuals scanned up to 62 times over 1.5 years identified connectivity changes in specific frontostriatal circuits that tracked fluctuations in specific symptom domains and predicted future anhedonia symptoms before they emerged. Together, these findings identify a stable trait-like brain network topology that may confer risk for depression and mood-state dependent connectivity changes in frontostriatal circuits that predict the emergence and remission of depressive symptoms over time.
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Hovde K, Rautio IV, Hegstad AM, Witter MP, Whitlock JR. Visuomotor interactions in the mouse forebrain mediated by extrastriate cortico-cortical pathways. Front Neuroanat 2023; 17:1188808. [PMID: 37228422 PMCID: PMC10203190 DOI: 10.3389/fnana.2023.1188808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 04/14/2023] [Indexed: 05/27/2023] Open
Abstract
Introduction The mammalian visual system can be broadly divided into two functional processing pathways: a dorsal stream supporting visually and spatially guided actions, and a ventral stream enabling object recognition. In rodents, the majority of visual signaling in the dorsal stream is transmitted to frontal motor cortices via extrastriate visual areas surrounding V1, but exactly where and to what extent V1 feeds into motor-projecting visual regions is not well known. Methods We employed a dual labeling strategy in male and female mice in which efferent projections from V1 were labeled anterogradely, and motor-projecting neurons in higher visual areas were labeled with retrogradely traveling adeno-associated virus (rAAV-retro) injected in M2. We characterized the labeling in both flattened and coronal sections of dorsal cortex and made high-resolution 3D reconstructions to count putative synaptic contacts in different extrastriate areas. Results The most pronounced colocalization V1 output and M2 input occurred in extrastriate areas AM, PM, RL and AL. Neurons in both superficial and deep layers in each project to M2, but high resolution volumetric reconstructions indicated that the majority of putative synaptic contacts from V1 onto M2-projecting neurons occurred in layer 2/3. Discussion These findings support the existence of a dorsal processing stream in the mouse visual system, where visual signals reach motor cortex largely via feedforward projections in anteriorly and medially located extrastriate areas.
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Affiliation(s)
- Karoline Hovde
- Kavli Institute for Systems Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway
- Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ida V. Rautio
- Kavli Institute for Systems Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway
| | - Andrea M. Hegstad
- Kavli Institute for Systems Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway
| | - Menno P. Witter
- Kavli Institute for Systems Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway
| | - Jonathan R. Whitlock
- Kavli Institute for Systems Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway
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5
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Wu X, Sarpong GA, Zhang J, Sugihara I. Divergent topographic projection of cerebral cortical areas to overlapping cerebellar lobules through distinct regions of the pontine nuclei. Heliyon 2023; 9:e14352. [PMID: 37025843 PMCID: PMC10070096 DOI: 10.1016/j.heliyon.2023.e14352] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 02/09/2023] [Accepted: 03/01/2023] [Indexed: 03/11/2023] Open
Abstract
The massive axonal projection from the cerebrum to the cerebellum through the pontine nuclei supports the cerebrocerebellar coordination of motor and nonmotor functions. However, the cerebrum and cerebellum have distinct patterns of functional localization in their cortices. We addressed this issue by bidirectional neuronal tracing from 22 various locations of the pontine nuclei in the mouse in a comprehensive manner. Cluster analyses of the distribution patterns of labeled cortical pyramidal cells and cerebellar mossy fiber terminals classified all cases into six groups located in six different subareas of the pontine nuclei. The lateral (insular), mediorostral (cingulate and prefrontal), and caudal (visual and auditory) cortical areas of the cerebrum projected to the medial, rostral, and lateral subareas of the pontine nuclei, respectively. These pontine subareas then projected mainly to the crus I, central vermis, and paraflocculus divergently. The central (motor and somatosensory) cortical areas projected to the centrorostral, centrocaudal and caudal subareas of the pontine nuclei, which then projected mainly to the rostral and caudal lobules with a somatotopic arrangement. The results indicate a new pontine nuclei-centric view of the corticopontocerebellar projection: the generally parallel corticopontine projection to pontine nuclei subareas is relayed to the highly divergent pontocerebellar projection terminating in overlapping specific lobules of the cerebellum. Consequently, the mode of the pontine nuclei relay underlies the cerebellar functional organization.
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6
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Perez DC, Dworetsky A, Braga RM, Beeman M, Gratton C. Hemispheric Asymmetries of Individual Differences in Functional Connectivity. J Cogn Neurosci 2023; 35:200-225. [PMID: 36378901 PMCID: PMC10029817 DOI: 10.1162/jocn_a_01945] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Resting-state fMRI studies have revealed that individuals exhibit stable, functionally meaningful divergences in large-scale network organization. The locations with strongest deviations (called network "variants") have a characteristic spatial distribution, with qualitative evidence from prior reports suggesting that this distribution differs across hemispheres. Hemispheric asymmetries can inform us on constraints guiding the development of these idiosyncratic regions. Here, we used data from the Human Connectome Project to systematically investigate hemispheric differences in network variants. Variants were significantly larger in the right hemisphere, particularly along the frontal operculum and medial frontal cortex. Variants in the left hemisphere appeared most commonly around the TPJ. We investigated how variant asymmetries vary by functional network and how they compare with typical network distributions. For some networks, variants seemingly increase group-average network asymmetries (e.g., the group-average language network is slightly bigger in the left hemisphere and variants also appeared more frequently in that hemisphere). For other networks, variants counter the group-average network asymmetries (e.g., the default mode network is slightly bigger in the left hemisphere, but variants were more frequent in the right hemisphere). Intriguingly, left- and right-handers differed in their network variant asymmetries for the cingulo-opercular and frontoparietal networks, suggesting that variant asymmetries are connected to lateralized traits. These findings demonstrate that idiosyncratic aspects of brain organization differ systematically across the hemispheres. We discuss how these asymmetries in brain organization may inform us on developmental constraints of network variants and how they may relate to functions differentially linked to the two hemispheres.
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Affiliation(s)
| | | | | | | | - Caterina Gratton
- Northwestern University, Evanston, IL
- Florida State University, Tallahassee
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7
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Bauer GB, Reep RL. Manatee cognition in the wild: an exploration of the manatee mind and behavior through neuroanatomy, psychophysics, and field observations. Anim Cogn 2022; 25:1161-1182. [PMID: 36071307 DOI: 10.1007/s10071-022-01686-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 08/16/2022] [Accepted: 08/25/2022] [Indexed: 11/28/2022]
Abstract
Cognition refers to the mechanisms for acquiring, processing, storing, and acting on information, all of which are critical to understanding the behavior of animals. These mechanisms are poorly known in manatees, especially how they are expressed in the wild. To expand our understanding of manatee cognition, we gathered information from behavioral experimentation in the laboratory, neuroanatomical research, controlled field studies, integrated laboratory and field measurement, and natural history observations (published reports, written surveys, and interviews with knowledgeable observers). Laboratory research, both neuroanatomical and behavioral, provided the most empirical data, primarily on sensory/perceptual capacities. Inferences from these data and narratives from surveys and interviews illuminated possibilities for higher order cognition. Evidence from field measurements was sparse, although substantial amounts of information have been collected from tracking data and to a lesser extent vessel impact studies, which can be used to infer cognitive attributes. Manatees are tactile-auditory specialists with complementary visual and chemosensory abilities. They demonstrate learning characteristics typical of vertebrates. Movement tracking data plus direct observations suggest that they have good spatial cognition, indicated by their ability to traverse complicated water networks and memory for foraging and warm water sites. They engage in a wide range of play-like, object manipulation, and mimetic behaviors, which suggests cognitive capacities beyond basic associative learning. Understanding manatee cognition beyond the laboratory will be necessary for conservation of manatees as they face challenges such as habitat degradation and threats from water-borne vessel traffic. There is a clear need for more direct research in natural settings.
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Affiliation(s)
- Gordon B Bauer
- Division of Social Sciences, New College of Florida, Sarasota, FL, 34243, USA.
| | - Roger L Reep
- Department of Physiological Sciences, University of Florida College of Veterinary Medicine, Gainesville, FL, 32603, USA
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8
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García-Cabezas MÁ, Hacker JL, Zikopoulos B. Homology of neocortical areas in rats and primates based on cortical type analysis: an update of the Hypothesis on the Dual Origin of the Neocortex. Brain Struct Funct 2022:10.1007/s00429-022-02548-0. [PMID: 35962240 PMCID: PMC9922339 DOI: 10.1007/s00429-022-02548-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 07/27/2022] [Indexed: 11/02/2022]
Abstract
Sixty years ago, Friedrich Sanides traced the origin of the tangential expansion of the primate neocortex to two ancestral anlagen in the allocortex of reptiles and mammals, and proposed the Hypothesis on the Dual Origin of the Neocortex. According to Sanides, paraolfactory and parahippocampal gradients of laminar elaboration expanded in evolution by addition of successive concentric rings of gradually different cortical types inside the allocortical ring. Rodents had fewer rings and primates had more rings in the inner part of the cortex. In the present article, we perform cortical type analysis of the neocortex of adult rats, Rhesus macaques, and humans to propose hypotheses on homology of cortical areas applying the principles of the Hypothesis on the Dual Origin of the Neocortex. We show that areas in the outer rings of the neocortex have comparable laminar elaboration in rats and primates, while most 6-layer eulaminate areas in the innermost rings of primate neocortex lack homologous counterparts in rats. We also represent the topological distribution of cortical types in simplified flat maps of the cerebral cortex of monotremes, rats, and primates. Finally, we propose an elaboration of the Hypothesis on the Dual Origin of the Neocortex in the context of modern studies of pallial patterning that integrates the specification of pallial sectors in development of vertebrate embryos. The updated version of the hypothesis of Sanides provides explanation for the emergence of cortical hierarchies in mammals and will guide future research in the phylogenetic origin of neocortical areas.
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Affiliation(s)
- Miguel Ángel García-Cabezas
- Department of Anatomy, Histology and Neuroscience, School of Medicine, Universidad Autónoma de Madrid, Madrid, Spain,Neural Systems Laboratory, Department of Health Sciences, Boston University, Boston, MA, USA
| | - Julia Liao Hacker
- Human Systems Neuroscience Laboratory, Department of Health Sciences, Boston University, 635 Commonwealth Ave., Room 401D, Boston, MA 02215, USA,Present Address: Department of Neurology, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Basilis Zikopoulos
- Human Systems Neuroscience Laboratory, Department of Health Sciences, Boston University, 635 Commonwealth Ave., Room 401D, Boston, MA, 02215, USA. .,Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MA, USA. .,Graduate Program in Neuroscience, Boston University, Boston, MA, USA.
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9
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Avidor-Reiss T, Achinger L, Uzbekov R. The Centriole's Role in Miscarriages. Front Cell Dev Biol 2022; 10:864692. [PMID: 35300410 PMCID: PMC8922021 DOI: 10.3389/fcell.2022.864692] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 02/14/2022] [Indexed: 12/17/2022] Open
Abstract
Centrioles are subcellular organelles essential for normal cell function and development; they form the cell’s centrosome (a major cytoplasmic microtubule organization center) and cilium (a sensory and motile hair-like cellular extension). Centrioles with evolutionarily conserved characteristics are found in most animal cell types but are absent in egg cells and exhibit unexpectedly high structural, compositional, and functional diversity in sperm cells. As a result, the centriole’s precise role in fertility and early embryo development is unclear. The centrioles are found in the spermatozoan neck, a strategic location connecting two central functional units: the tail, which propels the sperm to the egg and the head, which holds the paternal genetic material. The spermatozoan neck is an ideal site for evolutionary innovation as it can control tail movement pre-fertilization and the male pronucleus’ behavior post-fertilization. We propose that human, bovine, and most other mammals–which exhibit ancestral centriole-dependent reproduction and two spermatozoan centrioles, where one canonical centriole is maintained, and one atypical centriole is formed–adapted extensive species-specific centriolar features. As a result, these centrioles have a high post-fertilization malfunction rate, resulting in aneuploidy, and miscarriages. In contrast, house mice evolved centriole-independent reproduction, losing the spermatozoan centrioles and overcoming a mechanism that causes miscarriages.
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Affiliation(s)
- Tomer Avidor-Reiss
- Department of Biological Sciences, University of Toledo, Toledo, OH, United States.,Department of Urology, College of Medicine and Life Sciences, University of Toledo, Toledo, OH, United States
| | - Luke Achinger
- Department of Biological Sciences, University of Toledo, Toledo, OH, United States
| | - Rustem Uzbekov
- Faculté de Médecine, Université de Tours, Tours, France.,Faculty of Bioengineering and Bioinformatics, Moscow State University, Moscow, Russia
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10
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MacIver MA, Finlay BL. The neuroecology of the water-to-land transition and the evolution of the vertebrate brain. Philos Trans R Soc Lond B Biol Sci 2022; 377:20200523. [PMID: 34957852 PMCID: PMC8710882 DOI: 10.1098/rstb.2020.0523] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The water-to-land transition in vertebrate evolution offers an unusual opportunity to consider computational affordances of a new ecology for the brain. All sensory modalities are changed, particularly a greatly enlarged visual sensorium owing to air versus water as a medium, and expanded by mobile eyes and neck. The multiplication of limbs, as evolved to exploit aspects of life on land, is a comparable computational challenge. As the total mass of living organisms on land is a hundredfold larger than the mass underwater, computational improvements promise great rewards. In water, the midbrain tectum coordinates approach/avoid decisions, contextualized by water flow and by the animal's body state and learning. On land, the relative motions of sensory surfaces and effectors must be resolved, adding on computational architectures from the dorsal pallium, such as the parietal cortex. For the large-brained and long-living denizens of land, making the right decision when the wrong one means death may be the basis of planning, which allows animals to learn from hypothetical experience before enactment. Integration of value-weighted, memorized panoramas in basal ganglia/frontal cortex circuitry, with allocentric cognitive maps of the hippocampus and its associated cortices becomes a cognitive habit-to-plan transition as substantial as the change in ecology. This article is part of the theme issue 'Systems neuroscience through the lens of evolutionary theory'.
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Affiliation(s)
- Malcolm A. MacIver
- Center for Robotics and Biosystems, Northwestern University, Evanston, IL 60208, USA
| | - Barbara L. Finlay
- Department of Psychology, Behavioral and Evolutionary Neuroscience Group, Cornell University, Ithaca, NY 14850, USA
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11
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Preuss TM, Wise SP. Evolution of prefrontal cortex. Neuropsychopharmacology 2022; 47:3-19. [PMID: 34363014 PMCID: PMC8617185 DOI: 10.1038/s41386-021-01076-5] [Citation(s) in RCA: 63] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 06/01/2021] [Accepted: 06/15/2021] [Indexed: 02/07/2023]
Abstract
Subdivisions of the prefrontal cortex (PFC) evolved at different times. Agranular parts of the PFC emerged in early mammals, and rodents, primates, and other modern mammals share them by inheritance. These are limbic areas and include the agranular orbital cortex and agranular medial frontal cortex (areas 24, 32, and 25). Rodent research provides valuable insights into the structure, functions, and development of these shared areas, but it contributes less to parts of the PFC that are specific to primates, namely, the granular, isocortical PFC that dominates the frontal lobe in humans. The first granular PFC areas evolved either in early primates or in the last common ancestor of primates and tree shrews. Additional granular PFC areas emerged in the primate stem lineage, as represented by modern strepsirrhines. Other granular PFC areas evolved in simians, the group that includes apes, humans, and monkeys. In general, PFC accreted new areas along a roughly posterior to anterior trajectory during primate evolution. A major expansion of the granular PFC occurred in humans in concert with other association areas, with modifications of corticocortical connectivity and gene expression, although current evidence does not support the addition of a large number of new, human-specific PFC areas.
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Affiliation(s)
- Todd M Preuss
- Yerkes National Primate Research Center, Emory University, Atlanta, GA, 30329, USA.
| | - Steven P Wise
- Olschefskie Institute for the Neurobiology of Knowledge, Bethesda, MD, 20814, USA
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12
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Belyk M, Eichert N, McGettigan C. A dual larynx motor networks hypothesis. Philos Trans R Soc Lond B Biol Sci 2021; 376:20200392. [PMID: 34719252 PMCID: PMC8558777 DOI: 10.1098/rstb.2020.0392] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/05/2021] [Indexed: 01/14/2023] Open
Abstract
Humans are vocal modulators par excellence. This ability is supported in part by the dual representation of the laryngeal muscles in the motor cortex. Movement, however, is not the product of motor cortex alone but of a broader motor network. This network consists of brain regions that contain somatotopic maps that parallel the organization in motor cortex. We therefore present a novel hypothesis that the dual laryngeal representation is repeated throughout the broader motor network. In support of the hypothesis, we review existing literature that demonstrates the existence of network-wide somatotopy and present initial evidence for the hypothesis' plausibility. Understanding how this uniquely human phenotype in motor cortex interacts with broader brain networks is an important step toward understanding how humans evolved the ability to speak. We further suggest that this system may provide a means to study how individual components of the nervous system evolved within the context of neuronal networks. This article is part of the theme issue 'Voice modulation: from origin and mechanism to social impact (Part I)'.
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Affiliation(s)
- Michel Belyk
- Department of Speech Hearing and Phonetic Sciences, University College London, London WC1N 1PJ, UK
- Department of Psychology, Edge Hill University, Ormskirk, L39 4QP, UK
| | - Nicole Eichert
- Wellcome Centre for Integrative Neuroimaging, Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
| | - Carolyn McGettigan
- Department of Speech Hearing and Phonetic Sciences, University College London, London WC1N 1PJ, UK
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13
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Wiring of higher-order cortical areas: Spatiotemporal development of cortical hierarchy. Semin Cell Dev Biol 2021; 118:35-49. [PMID: 34034988 DOI: 10.1016/j.semcdb.2021.05.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 04/27/2021] [Accepted: 05/08/2021] [Indexed: 01/04/2023]
Abstract
A hierarchical development of cortical areas was suggested over a century ago, but the diversity and complexity of cortical hierarchy properties have so far prevented a formal demonstration. The aim of this review is to clarify the similarities and differences in the developmental processes underlying cortical development of primary and higher-order areas. We start by recapitulating the historical and recent advances underlying the biological principle of cortical hierarchy in adults. We then revisit the arguments for a hierarchical maturation of cortical areas, and further integrate the principles of cortical areas specification during embryonic and postnatal development. We highlight how the dramatic expansion in cortical size might have contributed to the increased number of association areas sustaining cognitive complexification in evolution. Finally, we summarize the recent observations of an alteration of cortical hierarchy in neuropsychiatric disorders and discuss their potential developmental origins.
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14
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Changeux JP, Goulas A, Hilgetag CC. A Connectomic Hypothesis for the Hominization of the Brain. Cereb Cortex 2021; 31:2425-2449. [PMID: 33367521 PMCID: PMC8023825 DOI: 10.1093/cercor/bhaa365] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 10/30/2020] [Accepted: 11/02/2020] [Indexed: 02/06/2023] Open
Abstract
Cognitive abilities of the human brain, including language, have expanded dramatically in the course of our recent evolution from nonhuman primates, despite only minor apparent changes at the gene level. The hypothesis we propose for this paradox relies upon fundamental features of human brain connectivity, which contribute to a characteristic anatomical, functional, and computational neural phenotype, offering a parsimonious framework for connectomic changes taking place upon the human-specific evolution of the genome. Many human connectomic features might be accounted for by substantially increased brain size within the global neural architecture of the primate brain, resulting in a larger number of neurons and areas and the sparsification, increased modularity, and laminar differentiation of cortical connections. The combination of these features with the developmental expansion of upper cortical layers, prolonged postnatal brain development, and multiplied nongenetic interactions with the physical, social, and cultural environment gives rise to categorically human-specific cognitive abilities including the recursivity of language. Thus, a small set of genetic regulatory events affecting quantitative gene expression may plausibly account for the origins of human brain connectivity and cognition.
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Affiliation(s)
- Jean-Pierre Changeux
- CNRS UMR 3571, Institut Pasteur, 75724 Paris, France
- Communications Cellulaires, Collège de France, 75005 Paris, France
| | - Alexandros Goulas
- Institute of Computational Neuroscience, University Medical Center Eppendorf, Hamburg University, 20246 Hamburg, Germany
| | - Claus C Hilgetag
- Institute of Computational Neuroscience, University Medical Center Eppendorf, Hamburg University, 20246 Hamburg, Germany
- Department of Health Sciences, Boston University, Boston, MA 02115, USA
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15
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Willoughby WR, Thoenes K, Bolding M. Somatotopic Arrangement of the Human Primary Somatosensory Cortex Derived From Functional Magnetic Resonance Imaging. Front Neurosci 2021; 14:598482. [PMID: 33488347 PMCID: PMC7817621 DOI: 10.3389/fnins.2020.598482] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 12/08/2020] [Indexed: 11/13/2022] Open
Abstract
Functional magnetic resonance imaging (fMRI) was used to estimate neuronal activity in the primary somatosensory cortex of six participants undergoing cutaneous tactile stimulation on skin areas spread across the entire body. Differences between the accepted somatotopic maps derived from Penfield's work and those generated by this fMRI study were sought, including representational transpositions or replications across the cortex. MR-safe pneumatic devices mimicking the action of a Wartenberg wheel supplied touch stimuli in eight areas. Seven were on the left side of the body: foot, lower, and upper leg, trunk beneath ribcage, anterior forearm, middle fingertip, and neck above the collarbone. The eighth area was the glabella. Activation magnitude was estimated as the maximum cross-correlation coefficient at a certain phase shift between ideal time series and measured blood oxygen level dependent (BOLD) time courses on the cortical surface. Maximally correlated clusters associated with each cutaneous area were calculated, and cortical magnification factors were estimated. Activity correlated to lower limb stimulation was observed in the paracentral lobule and superomedial postcentral region. Correlations to upper extremity stimulation were observed in the postcentral area adjacent to the motor hand knob. Activity correlated to trunk, face and neck stimulation was localized in the superomedial one-third of the postcentral region, which differed from Penfield's cortical homunculus.
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Affiliation(s)
- W. R. Willoughby
- Department of Radiology, The University of Alabama at Birmingham, Birmingham, AL, United States
| | - Kristina Thoenes
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, United States
| | - Mark Bolding
- Department of Radiology, The University of Alabama at Birmingham, Birmingham, AL, United States
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16
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Warriner CL, Fageiry SK, Carmona LM, Miri A. Towards Cell and Subtype Resolved Functional Organization: Mouse as a Model for the Cortical Control of Movement. Neuroscience 2020; 450:151-160. [PMID: 32771500 PMCID: PMC10727850 DOI: 10.1016/j.neuroscience.2020.07.054] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 06/06/2020] [Accepted: 07/30/2020] [Indexed: 10/23/2022]
Abstract
Despite a long history of interrogation, the functional organization of motor cortex remains obscure. A major barrier has been the inability to measure and perturb activity with sufficient resolution to reveal clear functional elements within motor cortex and its associated circuits. Increasingly, the mouse has been employed as a model to facilitate application of contemporary approaches with the potential to surmount this barrier. In this brief essay, we consider these approaches and their use in the context of studies aimed at resolving the logic of motor cortical operation.
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Affiliation(s)
- Claire L Warriner
- Department of Neuroscience, The Mortimer B. Zuckerman Mind, Brain, and Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Samaher K Fageiry
- Department of Neuroscience, The Mortimer B. Zuckerman Mind, Brain, and Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Lina M Carmona
- Department of Neuroscience, The Mortimer B. Zuckerman Mind, Brain, and Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Andrew Miri
- Department of Neurobiology, Northwestern University, Evanston, IL 60201, USA.
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17
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Perich MG, Rajan K. Rethinking brain-wide interactions through multi-region 'network of networks' models. Curr Opin Neurobiol 2020; 65:146-151. [PMID: 33254073 DOI: 10.1016/j.conb.2020.11.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 10/17/2020] [Accepted: 11/08/2020] [Indexed: 12/20/2022]
Abstract
The neural control of behavior is distributed across many functionally and anatomically distinct brain regions even in small nervous systems. While classical neuroscience models treated these regions as a set of hierarchically isolated nodes, the brain comprises a recurrently interconnected network in which each region is intimately modulated by many others. Uncovering these interactions is now possible through experimental techniques that access large neural populations from many brain regions simultaneously. Harnessing these large-scale datasets, however, requires new theoretical approaches. Here, we review recent work to understand brain-wide interactions using multi-region 'network of networks' models and discuss how they can guide future experiments. We also emphasize the importance of multi-region recordings, and posit that studying individual components in isolation will be insufficient to understand the neural basis of behavior.
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Affiliation(s)
- Matthew G Perich
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Kanaka Rajan
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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18
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Self-organization of cortical areas in the development and evolution of neocortex. Proc Natl Acad Sci U S A 2020; 117:29212-29220. [PMID: 33139564 DOI: 10.1073/pnas.2011724117] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
While the mechanisms generating the topographic organization of primary sensory areas in the neocortex are well studied, what generates secondary cortical areas is virtually unknown. Using physical parameters representing primary and secondary visual areas as they vary from monkey to mouse, we derived a network growth model to explore if characteristic features of secondary areas could be produced from correlated activity patterns arising from V1 alone. We found that V1 seeded variable numbers of secondary areas based on activity-driven wiring and wiring-density limits within the cortical surface. These secondary areas exhibited the typical mirror-reversal of map topography on cortical area boundaries and progressive reduction of the area and spatial resolution of each new map on the caudorostral axis. Activity-based map formation may be the basic mechanism that establishes the matrix of topographically organized cortical areas available for later computational specialization.
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19
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Clark EA, Rutlin M, Capano LS, Aviles S, Saadon JR, Taneja P, Zhang Q, Bullis JB, Lauer T, Myers E, Schulmann A, Forrest D, Nelson SB. Cortical RORβ is required for layer 4 transcriptional identity and barrel integrity. eLife 2020; 9:e52370. [PMID: 32851975 PMCID: PMC7492084 DOI: 10.7554/elife.52370] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 08/26/2020] [Indexed: 02/01/2023] Open
Abstract
Retinoic acid-related orphan receptor beta (RORβ) is a transcription factor (TF) and marker of layer 4 (L4) neurons, which are distinctive both in transcriptional identity and the ability to form aggregates such as barrels in rodent somatosensory cortex. However, the relationship between transcriptional identity and L4 cytoarchitecture is largely unknown. We find RORβ is required in the cortex for L4 aggregation into barrels and thalamocortical afferent (TCA) segregation. Interestingly, barrel organization also degrades with age in wildtype mice. Loss of RORβ delays excitatory input and disrupts gene expression and chromatin accessibility, with down-regulation of L4 and up-regulation of L5 genes, suggesting a disruption in cellular specification. Expression and binding site accessibility change for many other TFs, including closure of neurodevelopmental TF binding sites and increased expression and binding capacity of activity-regulated TFs. Lastly, a putative target of RORβ, Thsd7a, is down-regulated without RORβ, and Thsd7a knock-out alone disrupts TCA organization in adult barrels.
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MESH Headings
- Animals
- Antigens, Surface/chemistry
- Antigens, Surface/genetics
- Antigens, Surface/metabolism
- Female
- Male
- Membrane Proteins/chemistry
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Mice
- Mice, Knockout
- Neurons/chemistry
- Neurons/cytology
- Neurons/metabolism
- Nuclear Receptor Subfamily 1, Group F, Member 2/chemistry
- Nuclear Receptor Subfamily 1, Group F, Member 2/genetics
- Nuclear Receptor Subfamily 1, Group F, Member 2/metabolism
- Somatosensory Cortex/chemistry
- Somatosensory Cortex/cytology
- Somatosensory Cortex/metabolism
- Somatosensory Cortex/physiology
- Thalamus/chemistry
- Thalamus/metabolism
- Transcription Factors/chemistry
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Transcriptome/genetics
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Affiliation(s)
- Erin A Clark
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | - Michael Rutlin
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | - Lucia S Capano
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | - Samuel Aviles
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | - Jordan R Saadon
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | - Praveen Taneja
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | - Qiyu Zhang
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | - James B Bullis
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | - Timothy Lauer
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | - Emma Myers
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
| | | | - Douglas Forrest
- Laboratory of Endocrinology and Receptor Biology, National Institutes of Health, NIDDKBethesdaUnited States
| | - Sacha B Nelson
- Department of Biology and Program in Neuroscience, Brandeis UniversityWalthamUnited States
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20
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Latchoumane CFV, Barany DA, Karumbaiah L, Singh T. Neurostimulation and Reach-to-Grasp Function Recovery Following Acquired Brain Injury: Insight From Pre-clinical Rodent Models and Human Applications. Front Neurol 2020; 11:835. [PMID: 32849253 PMCID: PMC7396659 DOI: 10.3389/fneur.2020.00835] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 07/06/2020] [Indexed: 12/26/2022] Open
Abstract
Reach-to-grasp is an evolutionarily conserved motor function that is adversely impacted following stroke and traumatic brain injury (TBI). Non-invasive brain stimulation (NIBS) methods, such as transcranial magnetic stimulation and transcranial direct current stimulation, are promising tools that could enhance functional recovery of reach-to-grasp post-brain injury. Though the rodent literature provides a causal understanding of post-injury recovery mechanisms, it has had a limited impact on NIBS protocols in human research. The high degree of homology in reach-to-grasp circuitry between humans and rodents further implies that the application of NIBS to brain injury could be better informed by findings from pre-clinical rodent models and neurorehabilitation research. Here, we provide an overview of the advantages and limitations of using rodent models to advance our current understanding of human reach-to-grasp function, cortical circuitry, and reorganization. We propose that a cross-species comparison of reach-to-grasp recovery could provide a mechanistic framework for clinically efficacious NIBS treatments that could elicit better functional outcomes for patients.
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Affiliation(s)
- Charles-Francois V. Latchoumane
- Department of Animal and Dairy Science, University of Georgia, Athens, GA, United States
- Regenerative Bioscience Center, University of Georgia, Athens, GA, United States
| | - Deborah A. Barany
- Department of Kinesiology, University of Georgia, Athens, GA, United States
| | - Lohitash Karumbaiah
- Department of Animal and Dairy Science, University of Georgia, Athens, GA, United States
- Regenerative Bioscience Center, University of Georgia, Athens, GA, United States
| | - Tarkeshwar Singh
- Regenerative Bioscience Center, University of Georgia, Athens, GA, United States
- Department of Kinesiology, University of Georgia, Athens, GA, United States
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21
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Assaf Y, Bouznach A, Zomet O, Marom A, Yovel Y. Conservation of brain connectivity and wiring across the mammalian class. Nat Neurosci 2020; 23:805-808. [PMID: 32514137 DOI: 10.1038/s41593-020-0641-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 04/10/2020] [Indexed: 11/09/2022]
Abstract
Over 100 years ago, Ramon y Cajal hypothesized that two forces played a role in the evolution of mammalian brain connectivity: minimizing wiring costs and maximizing conductivity speed. Using diffusion MRI, we reconstructed the brain connectomes of 123 mammalian species. Network analysis revealed that both connectivity and the wiring cost are conserved across mammals. We describe a conservation principle that maintains the overall connectivity: species with fewer interhemispheric connections exhibit better intrahemispheric connectivity.
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Affiliation(s)
- Yaniv Assaf
- School of Neurobiology, Biochemistry and Biophysics, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel. .,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
| | | | - Omri Zomet
- School of Computer Sciences, Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Assaf Marom
- Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
| | - Yossi Yovel
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel. .,School of Zoology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel. .,The Steinhardt Museum of Natural History, National Research Center for Biodiversity Studies, Tel-Aviv University, Tel Aviv, Israel.
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22
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Abstract
The posterior parietal cortex (PPC) and frontal motor areas comprise a cortical network supporting goal-directed behaviour, with functions including sensorimotor transformations and decision making. In primates, this network links performed and observed actions via mirror neurons, which fire both when individuals perform an action and when they observe the same action performed by a conspecific. Mirror neurons are believed to be important for social learning, but it is not known whether mirror-like neurons occur in similar networks in other social species, such as rodents, or if they can be measured in such models using paradigms where observers passively view a demonstrator. Therefore, we imaged Ca2+ responses in PPC and secondary motor cortex (M2) while mice performed and observed pellet-reaching and wheel-running tasks, and found that cell populations in both areas robustly encoded several naturalistic behaviours. However, neural responses to the same set of observed actions were absent, although we verified that observer mice were attentive to performers and that PPC neurons responded reliably to visual cues. Statistical modelling also indicated that executed actions outperformed observed actions in predicting neural responses. These results raise the possibility that sensorimotor action recognition in rodents could take place outside of the parieto-frontal circuit, and underscore that detecting socially-driven neural coding depends critically on the species and behavioural paradigm used.
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23
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Bottom RT, Krubitzer LA, Huffman KJ. Early postnatal gene expression in the developing neocortex of prairie voles (Microtus ochrogaster) is related to parental rearing style. J Comp Neurol 2020; 528:3008-3022. [PMID: 31930725 DOI: 10.1002/cne.24856] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 01/08/2020] [Accepted: 01/09/2020] [Indexed: 11/10/2022]
Abstract
The earliest and most prevalent sensory experience includes tactile, thermal, and olfactory stimulation delivered to the young via contact with the mother, and in some mammals, the father. Prairie voles (Microtus ochrogaster), like humans, are biparental and serve as a model for understanding the impact of parent/offspring interactions on the developing brain. Prairie voles also exhibit natural variation in the level of tactile stimulation delivered by the parents to the offspring, and this has been well documented and quantified. Previous studies revealed that adult prairie vole offspring who received either high (HC) or low (LC) tactile contact from their parents have differences in the size of cortical fields and the connections of somatosensory cortex. In the current investigation, we examined gene expression, intraneocortical connectivity, and cortical thickness in newborn voles to appreciate when differences in HC and LC offspring begin to emerge. We observed differences in developmentally regulated genes, as well as variation in prelimbic and anterior cingulate cortical thickness at postnatal Day 1 (P1) in HC and LC voles. Results from this study suggest that parenting styles, such as those involving high or low physical contact, impact the developing neocortex via very early sensory experience as well as differences in epigenetic modifications that may emerge in HC and LC voles.
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Affiliation(s)
- Riley T Bottom
- Interdepartmental Neuroscience Program, University of California, Riverside, Riverside, California
| | - Leah A Krubitzer
- Center for Neuroscience, University of California, Davis, Davis, California.,Department of Psychology, University of California, Davis, Davis, California
| | - Kelly J Huffman
- Interdepartmental Neuroscience Program, University of California, Riverside, Riverside, California.,Department of Psychology, University of California, Riverside, Riverside, California
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24
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Parra A, Baker CA, Bolton MM. Regional Specialization of Pyramidal Neuron Morphology and Physiology in the Tree Shrew Neocortex. Cereb Cortex 2019; 29:4488-4505. [PMID: 30715235 DOI: 10.1093/cercor/bhy326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Revised: 10/12/2018] [Accepted: 12/07/2018] [Indexed: 01/08/2023] Open
Abstract
The mammalian cerebral cortex is divided into different areas according to their function and pattern of connections. Studies comparing primary visual (V1) and prefrontal cortex (PFC) of primates have demonstrated striking pyramidal neuron (PN) specialization not present in comparable areas of the mouse neocortex. To better understand PFC evolution and regional PN specialization, we studied the tree shrew, a species with a close phylogenetic relationship to primates. We defined the tree shrew PFC based on cytoarchitectonic borders, thalamic connectivity and characterized the morphology and electrophysiology of layer II/III PNs in V1 and PFC. Similar to primates, the PFC PNs in the tree shrew fire with a regular spiking pattern and have larger dendritic tree and spines than those in V1. However, V1 PNs showed strikingly large basal dendritic arbors with high spine density, firing at higher rates and in a more varied pattern than PFC PNs. Yet, unlike in the mouse and unreported in the primate, medial prefrontal PN are more easily recruited than either the dorsolateral or V1 neurons. This specialization of PN morphology and physiology is likely to be a significant factor in the evolution of cortex, contributing to differences in the computational capacities of individual cortical areas.
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Affiliation(s)
- Andres Parra
- Disorders of Neural Circuit Function, Max Planck Florida Institute for Neuroscience, Jupiter, USA.,Functional Architecture of the Cerebral Cortex, Max Planck Florida Institute for Neuroscience, Jupiter, USA.,Cellular and Systems Neurobiology, Instituto de Neurociencias de Alicante, Alicante, Spain
| | - Christopher A Baker
- Disorders of Neural Circuit Function, Max Planck Florida Institute for Neuroscience, Jupiter, USA
| | - M McLean Bolton
- Disorders of Neural Circuit Function, Max Planck Florida Institute for Neuroscience, Jupiter, USA
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25
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Courellis HS, Nummela SU, Metke M, Diehl GW, Bussell R, Cauwenberghs G, Miller CT. Spatial encoding in primate hippocampus during free navigation. PLoS Biol 2019; 17:e3000546. [PMID: 31815940 PMCID: PMC6922474 DOI: 10.1371/journal.pbio.3000546] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 12/19/2019] [Accepted: 11/15/2019] [Indexed: 12/29/2022] Open
Abstract
The hippocampus comprises two neural signals-place cells and θ oscillations-that contribute to facets of spatial navigation. Although their complementary relationship has been well established in rodents, their respective contributions in the primate brain during free navigation remains unclear. Here, we recorded neural activity in the hippocampus of freely moving marmosets as they naturally explored a spatial environment to more explicitly investigate this issue. We report place cells in marmoset hippocampus during free navigation that exhibit remarkable parallels to analogous neurons in other mammalian species. Although θ oscillations were prevalent in the marmoset hippocampus, the patterns of activity were notably different than in other taxa. This local field potential oscillation occurred in short bouts (approximately .4 s)-rather than continuously-and was neither significantly modulated by locomotion nor consistently coupled to place-cell activity. These findings suggest that the relationship between place-cell activity and θ oscillations in primate hippocampus during free navigation differs substantially from rodents and paint an intriguing comparative picture regarding the neural basis of spatial navigation across mammals.
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Affiliation(s)
- Hristos S. Courellis
- Cortical Systems and Behavior Laboratory, University of California, San Diego, San Diego, California, United States of America
- Department of Bioengineering, University of California, San Diego, San Diego, California, United States of America
| | - Samuel U. Nummela
- Cortical Systems and Behavior Laboratory, University of California, San Diego, San Diego, California, United States of America
| | - Michael Metke
- Cortical Systems and Behavior Laboratory, University of California, San Diego, San Diego, California, United States of America
- Neurosciences Graduate Program, University of California, San Diego, San Diego, United States of America
| | - Geoffrey W. Diehl
- Neurosciences Graduate Program, University of California, San Diego, San Diego, United States of America
| | - Robert Bussell
- Center for Functional MRI, University of California, San Diego, San Diego, United States of America
| | - Gert Cauwenberghs
- Department of Bioengineering, University of California, San Diego, San Diego, California, United States of America
- Neurosciences Graduate Program, University of California, San Diego, San Diego, United States of America
| | - Cory T. Miller
- Cortical Systems and Behavior Laboratory, University of California, San Diego, San Diego, California, United States of America
- Neurosciences Graduate Program, University of California, San Diego, San Diego, United States of America
- * E-mail:
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26
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Magrou L, Barone P, Markov NT, Killackey HP, Giroud P, Berland M, Knoblauch K, Dehay C, Kennedy H. How Areal Specification Shapes the Local and Interareal Circuits in a Macaque Model of Congenital Blindness. Cereb Cortex 2019; 28:3017-3034. [PMID: 29850900 PMCID: PMC6041985 DOI: 10.1093/cercor/bhy125] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Indexed: 01/08/2023] Open
Abstract
There is little understanding of the structural underpinnings of the functional reorganization of the cortex in the congenitally blind human. Taking advantage of the extensive characterization of the macaque visual system, we examine in macaque the influence of congenital blindness resulting from the removal of the retina during in utero development. This effectively removes the normal influence of the thalamus on cortical development leading to an induced hybrid cortex (HC) combining features of primary visual and extrastriate cortex. Retrograde tracers injected in HC reveal a local, intrinsic connectivity characteristic of higher order areas and show that the HC receives a uniquely strong, purely feedforward projection from striate cortex but no ectopic inputs, except from subiculum, and entorhinal cortex. Statistical modeling of quantitative connectivity data shows that HC is relatively high in the cortical hierarchy and receives a reinforced input from ventral stream areas while the overall organization of the functional streams are conserved. The directed and weighted anophthalmic cortical graph from the present study can be used to construct dynamic and structural models. These findings show how the sensory periphery governs cortical phenotype and reveal the importance of developmental arealization for understanding the functional reorganization in congenital blindness.
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Affiliation(s)
- Loïc Magrou
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, Bron, France
| | - Pascal Barone
- Université De Toulouse Paul Sabatier, Toulouse, France.,Centre De Recherche Cerveau & Cognition, CNRS, UMR 5549, Toulouse, France
| | - Nikola T Markov
- Princeton Neuroscience Institute and Department of Psychology, Princeton University, Princeton, USA
| | - Herbert P Killackey
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA, USA
| | - Pascale Giroud
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, Bron, France
| | - Michel Berland
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, Bron, France
| | - Kenneth Knoblauch
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, Bron, France
| | - Colette Dehay
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, Bron, France
| | - Henry Kennedy
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, Bron, France.,Institute of Neuroscience, State Key Laboratory of Neuroscience, Chinese Academy of Sciences (CAS) Key Laboratory of Primate Neurobiology, CAS, Shanghai, China
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27
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The Mouse Cortical Connectome, Characterized by an Ultra-Dense Cortical Graph, Maintains Specificity by Distinct Connectivity Profiles. Neuron 2019; 97:698-715.e10. [PMID: 29420935 DOI: 10.1016/j.neuron.2017.12.037] [Citation(s) in RCA: 112] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 08/30/2017] [Accepted: 12/22/2017] [Indexed: 11/21/2022]
Abstract
The inter-areal wiring pattern of the mouse cerebral cortex was analyzed in relation to a refined parcellation of cortical areas. Twenty-seven retrograde tracer injections were made in 19 areas of a 47-area parcellation of the mouse neocortex. Flat mounts of the cortex and multiple histological markers enabled detailed counts of labeled neurons in individual areas. The observed log-normal distribution of connection weights to each cortical area spans 5 orders of magnitude and reveals a distinct connectivity profile for each area, analogous to that observed in macaques. The cortical network has a density of 97%, considerably higher than the 66% density reported in macaques. A weighted graph analysis reveals a similar global efficiency but weaker spatial clustering compared with that reported in macaques. The consistency, precision of the connectivity profile, density, and weighted graph analysis of the present data differ significantly from those obtained in earlier studies in the mouse.
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28
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Abstract
During the course of evolution the human brain has increased in size and complexity, ultimately these differences are the result of changes at the genetic level. Identifying and characterizing molecular evolution requires an understanding of both the genetic underpinning of the system as well as the comparative genetic tools to identify signatures of selection. This chapter aims to describe our current understanding of the genetics of human brain evolution. Primarily this is the story of the evolution of the human brain since our last common ape ancestor, but where relevant we will also discuss changes that are unique to the primate brain (compared to other mammals) or various other lineages in the evolution of humans more generally. It will focus on genetic changes that both directly affected the development and function of the brain as well as those that have indirectly influenced brain evolution through both prenatal and postnatal environment. This review is not meant to be exhaustive, but rather to begin to construct a general framework for understanding the full array of data being generated.
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Affiliation(s)
- Eric J Vallender
- University of Mississippi Medical Center, Jackson, MS, United States; Tulane National Primate Research Center, Covington, LA, United States.
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Patel GH, Sestieri C, Corbetta M. The evolution of the temporoparietal junction and posterior superior temporal sulcus. Cortex 2019; 118:38-50. [PMID: 30808550 DOI: 10.1016/j.cortex.2019.01.026] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 01/04/2019] [Accepted: 01/14/2019] [Indexed: 12/20/2022]
Abstract
The scale at which humans can handle complex social situations is massively increased compared to other animals. However, the neural substrates of this scaling remain poorly understood. In this review, we discuss how the expansion and rearrangement of the temporoparietal junction and posterior superior temporal sulcus (TPJ-pSTS) may have played a key role in the growth of human social abilities. Comparing the function and anatomy of the TPJ-pSTS in humans and macaques, which are thought to be separated by 25 million years of evolution, we find that the expansion of this region in humans has shifted the architecture of the dorsal and ventral processing streams. The TPJ-pSTS contains areas related to face-emotion processing, attention, theory of mind operations, and memory; its expansion has allowed for the elaboration and rearrangement of the cortical areas contained within, and potentially the introduction of new cortical areas. Based on the arrangement and the function of these areas in the human, we propose that the TPJ-pSTS is the basis of a third frontoparietal processing stream that underlies the increased social abilities in humans. We then describe a model of how the TPJ-pSTS areas interact as a hub that coordinates the activities of multiple brain networks in the exploration of the complex dynamic social scenes typical of the human social experience.
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Affiliation(s)
- Gaurav H Patel
- Columbia University, USA; New York State Psychiatric Institute, USA.
| | | | - Maurizio Corbetta
- University of Padova, Italy; Washington University School of Medicine, USA
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Lin MK, Takahashi YS, Huo BX, Hanada M, Nagashima J, Hata J, Tolpygo AS, Ram K, Lee BC, Miller MI, Rosa MGP, Sasaki E, Iriki A, Okano H, Mitra P. A high-throughput neurohistological pipeline for brain-wide mesoscale connectivity mapping of the common marmoset. eLife 2019; 8:e40042. [PMID: 30720427 PMCID: PMC6384052 DOI: 10.7554/elife.40042] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 02/04/2019] [Indexed: 11/13/2022] Open
Abstract
Understanding the connectivity architecture of entire vertebrate brains is a fundamental but difficult task. Here we present an integrated neuro-histological pipeline as well as a grid-based tracer injection strategy for systematic mesoscale connectivity mapping in the common marmoset (Callithrix jacchus). Individual brains are sectioned into ~1700 20 µm sections using the tape transfer technique, permitting high quality 3D reconstruction of a series of histochemical stains (Nissl, myelin) interleaved with tracer labeled sections. Systematic in-vivo MRI of the individual animals facilitates injection placement into reference-atlas defined anatomical compartments. Further, by combining the resulting 3D volumes, containing informative cytoarchitectonic markers, with in-vivo and ex-vivo MRI, and using an integrated computational pipeline, we are able to accurately map individual brains into a common reference atlas despite the significant individual variation. This approach will facilitate the systematic assembly of a mesoscale connectivity matrix together with unprecedented 3D reconstructions of brain-wide projection patterns in a primate brain.
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Affiliation(s)
- Meng Kuan Lin
- Laboratory for Marmoset Neural ArchitectureRIKEN Center for Brain ScienceWakoJapan
| | | | - Bing-Xing Huo
- Laboratory for Marmoset Neural ArchitectureRIKEN Center for Brain ScienceWakoJapan
| | - Mitsutoshi Hanada
- Laboratory for Marmoset Neural ArchitectureRIKEN Center for Brain ScienceWakoJapan
| | - Jaimi Nagashima
- Laboratory for Marmoset Neural ArchitectureRIKEN Center for Brain ScienceWakoJapan
| | - Junichi Hata
- Laboratory for Marmoset Neural ArchitectureRIKEN Center for Brain ScienceWakoJapan
| | | | | | - Brian C Lee
- Center for Imaging ScienceJohns Hopkins UniversityMarylandUnited States
| | - Michael I Miller
- Center for Imaging ScienceJohns Hopkins UniversityMarylandUnited States
| | - Marcello GP Rosa
- Department of Physiology and Biomedicine, Discovery InstituteMonash UniversityMelbourneAustralia
- Australian Research Council Centre of Excellence for Integrative Brain FunctionClaytonAustralia
| | - Erika Sasaki
- Central Institute for Experimental AnimalsKawasakiJapan
| | - Atsushi Iriki
- Laboratory for Symbolic Cognitive DevelopmentRIKEN Center for Brain ScienceWakoJapan
| | - Hideyuki Okano
- Laboratory for Marmoset Neural ArchitectureRIKEN Center for Brain ScienceWakoJapan
- Department of PhysiologyKeio University School of MedicineTokyoJapan
| | - Partha Mitra
- Laboratory for Marmoset Neural ArchitectureRIKEN Center for Brain ScienceWakoJapan
- Cold Spring Harbor LaboratoryCold Spring HarborUnited States
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31
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Miller CT, Hale ME, Okano H, Okabe S, Mitra P. Comparative Principles for Next-Generation Neuroscience. Front Behav Neurosci 2019; 13:12. [PMID: 30787871 PMCID: PMC6373779 DOI: 10.3389/fnbeh.2019.00012] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 01/15/2019] [Indexed: 01/10/2023] Open
Abstract
Neuroscience is enjoying a renaissance of discovery due in large part to the implementation of next-generation molecular technologies. The advent of genetically encoded tools has complemented existing methods and provided researchers the opportunity to examine the nervous system with unprecedented precision and to reveal facets of neural function at multiple scales. The weight of these discoveries, however, has been technique-driven from a small number of species amenable to the most advanced gene-editing technologies. To deepen interpretation and build on these breakthroughs, an understanding of nervous system evolution and diversity are critical. Evolutionary change integrates advantageous variants of features into lineages, but is also constrained by pre-existing organization and function. Ultimately, each species’ neural architecture comprises both properties that are species-specific and those that are retained and shared. Understanding the evolutionary history of a nervous system provides interpretive power when examining relationships between brain structure and function. The exceptional diversity of nervous systems and their unique or unusual features can also be leveraged to advance research by providing opportunities to ask new questions and interpret findings that are not accessible in individual species. As new genetic and molecular technologies are added to the experimental toolkits utilized in diverse taxa, the field is at a key juncture to revisit the significance of evolutionary and comparative approaches for next-generation neuroscience as a foundational framework for understanding fundamental principles of neural function.
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Affiliation(s)
- Cory T Miller
- Cortical Systems and Behavior Laboratory, Neurosciences Graduate Program, University of California, San Diego, San Diego, CA, United States
| | - Melina E Hale
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL, United States
| | - Hideyuki Okano
- Department of Physiology, Keio University School of Medicine, Tokyo, Japan.,Laboratory for Marmoset Neural Architecture, RIKEN Center for Brain Science (CBS), Wako, Japan
| | - Shigeo Okabe
- Department of Cellular Neurobiology, Graduate School of Medicine and Faculty of Medicine, University of Tokyo, Tokyo, Japan
| | - Partha Mitra
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States
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32
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Krubitzer LA, Prescott TJ. The Combinatorial Creature: Cortical Phenotypes within and across Lifetimes. Trends Neurosci 2018; 41:744-762. [PMID: 30274608 DOI: 10.1016/j.tins.2018.08.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 07/31/2018] [Accepted: 08/02/2018] [Indexed: 12/15/2022]
Abstract
The neocortex is one of the most distinctive structures of the mammalian brain, yet also one of the most varied in terms of both size and organization. Multiple processes have contributed to this variability, including evolutionary mechanisms (i.e., alterations in gene sequence) that alter the size, organization, and connections of neocortex, and activity dependent mechanisms that can also modify these same features. Thus, changes to the neocortex can occur over different time-scales, including within a single generation. This combination of genetic and activity dependent mechanisms that create a given cortical phenotype allows the mammalian neocortex to rapidly and flexibly adjust to different body and environmental contexts, and in humans permits culture to impact brain construction.
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Affiliation(s)
- Leah A Krubitzer
- Center for Neuroscience and Department of Psychology, University of California, Davis, Davis, CA 95616, USA.
| | - Tony J Prescott
- Sheffield Robotics and Department of Computer Science, University of Sheffield, Sheffield, UK
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33
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Gaspar P, Renier N. Constraints on somatosensory map development: mutants lead the way. Curr Opin Neurobiol 2018; 53:43-49. [PMID: 29753205 DOI: 10.1016/j.conb.2018.04.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 04/23/2018] [Accepted: 04/24/2018] [Indexed: 12/31/2022]
Abstract
In the rodent somatosensory system, the disproportionally large whisker representation and their specialization into barrel-shaped units in the different sensory relays has offered experimentalists with an ideal tool to identify mechanisms involved in brain map formation. These combine three intertwined constraints: Firstly, fasciculation of the incoming axons; secondly, early neural activity; finally, molecular patterning. Sophisticated genetic manipulations in mice have now allowed dissecting these mechanisms with greater accuracy. Here we discuss some recent papers that provided novel insights into how these different mapping rules and constraints interact to shape the barrel map.
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Affiliation(s)
- Patricia Gaspar
- Inserm, U839, Institut du Fer à Moulin, Paris, France; Sorbonne Universités, Paris, France.
| | - Nicolas Renier
- Sorbonne Universités, Paris, France; Institut du Cerveau et de la Moelle Epinière (ICM) - Hôpital Pitié-Salpêtrière, Inserm, CNRS, Paris, France
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34
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Foubet O, Trejo M, Toro R. Mechanical morphogenesis and the development of neocortical organisation. Cortex 2018; 118:315-326. [PMID: 30503630 DOI: 10.1016/j.cortex.2018.03.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 02/07/2018] [Accepted: 03/07/2018] [Indexed: 12/27/2022]
Abstract
The development of complex neocortical organisations is thought to result from the interaction of genetic and activity-dependent processes. We propose that a third type of process - mechanical morphogenesis - may also play an important role. We review theoretical and experimental results in physics showing how even homogeneous growth can produce a variety of forms, in particular neocortical folding. The mechanical instabilities that produce these forms induce heterogeneous patterns of stress at the scale of the organ. We review the evidence showing how these stresses can influence cell proliferation, migration and apoptosis, cell differentiation and shape, migration and axonal guidance, and could thus be able to influence regional neocortical identity and connectivity.
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Affiliation(s)
- Ophélie Foubet
- Human Genetics and Cognitive Functions Unit, Institut Pasteur, Paris, France; CNRS UMR 3571: Genes, Synapses and Cognition, Institut Pasteur, Paris, France; Université Paris Diderot, Sorbonne Paris Cité, Human Genetics and Cognitive Functions, Paris, France
| | - Miguel Trejo
- Laboratoire de Physique et Mécanique des Milieux Hétérogènes (PMMH), CNRS UMR 7636, ESPCI-ParisTech, Paris Cedex 05, France
| | - Roberto Toro
- Human Genetics and Cognitive Functions Unit, Institut Pasteur, Paris, France; CNRS UMR 3571: Genes, Synapses and Cognition, Institut Pasteur, Paris, France; Université Paris Diderot, Sorbonne Paris Cité, Human Genetics and Cognitive Functions, Paris, France.
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35
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Alzu'bi A, Lindsay SJ, Harkin LF, McIntyre J, Lisgo SN, Clowry GJ. The Transcription Factors COUP-TFI and COUP-TFII have Distinct Roles in Arealisation and GABAergic Interneuron Specification in the Early Human Fetal Telencephalon. Cereb Cortex 2017; 27:4971-4987. [PMID: 28922831 PMCID: PMC5903418 DOI: 10.1093/cercor/bhx185] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 06/12/2017] [Accepted: 07/03/2017] [Indexed: 12/13/2022] Open
Abstract
In human telencephalon at 8-12 postconceptional weeks, ribonucleic acid quantitative sequencing and immunohistochemistry revealed cortical chicken ovalbumin upstream promotor-transcription factor 1 (COUP-TFI) expression in a high ventro-posterior to low anterior gradient except for raised immunoreactivity in the anterior ventral pallium. Unlike in mouse, COUP-TFI and SP8 were extensively co-expressed in dorsal sensory neocortex and dorsal hippocampus whereas COUPTFI/COUPTFII co-expression defined ventral temporal cortex and ventral hippocampus. In the ganglionic eminences (GEs) COUP-TFI immunoreactivity demarcated the proliferative zones of caudal GE (CGE), dorsal medial GE (MGE), MGE/lateral GE (LGE) boundary, and ventral LGE whereas COUP-TFII was limited to ventral CGE and the MGE/LGE boundary. Co-labeling with gamma amino butyric acidergic interneuron markers revealed that COUP-TFI was expressed in subpopulations of either MGE-derived (SOX6+) or CGE-derived (calretinin+/SP8+) interneurons. COUP-TFII was mainly confined to CGE-derived interneurons. Twice as many GAD67+ cortical cells co-labeled for COUP-TFI than for COUP-TFII. A fifth of COUP-TFI cells also co-expressed COUP-TFII, and cells expressing either transcription factor followed posterior or anterio-lateral pathways into the cortex, therefore, a segregation of migration pathways according to COUP-TF expression as proposed in mouse was not observed. In cultures differentiated from isolated human cortical progenitors, many cells expressed either COUP-TF and 30% also co-expressed GABA, however no cells expressed NKX2.1. This suggests interneurons could be generated intracortically from progenitors expressing either COUP-TF.
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Affiliation(s)
- Ayman Alzu'bi
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Susan J Lindsay
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Lauren F Harkin
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
- Present address: School of Healthcare Science, Manchester Metropolitan University, UK
| | - Jack McIntyre
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Steven N Lisgo
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Gavin J Clowry
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
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36
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Abstract
Cortical circuits are known to be plastic and adaptable, as shown by an impressive body of evidence demonstrating the ability of cortical circuits to adapt to changes in environmental stimuli, development, learning, and insults. In this review, we will discuss some of the features of cortical circuits that are thought to facilitate cortical circuit versatility and flexibility. Throughout life, cortical circuits can be extensively shaped and refined by experience while preserving their overall organization, suggesting that mechanisms are in place to favor change but also to stabilize some aspects of the circuit. First, we will describe the basic organization and some of the common features of cortical circuits. We will then discuss how this underlying cortical structure provides a substrate for the experience- and learning-dependent processes that contribute to cortical flexibility.
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Affiliation(s)
- Melissa S. Haley
- Department of Neurobiology and Behavior, SUNY–Stony Brook, Stony Brook, NY, USA
| | - Arianna Maffei
- Department of Neurobiology and Behavior, SUNY–Stony Brook, Stony Brook, NY, USA
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37
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Charting the protomap of the human telencephalon. Semin Cell Dev Biol 2017; 76:3-14. [PMID: 28834762 DOI: 10.1016/j.semcdb.2017.08.033] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 08/15/2017] [Indexed: 12/16/2022]
Abstract
The cerebral cortex is divided stereotypically into a number of functionally distinct areas. According to the protomap hypothesis formulated by Rakic neural progenitors in the ventricular zone form a mosaic of proliferative units that provide a primordial species-specific cortical map. Positional information of newborn neurons is maintained during their migration to the overlying cortical plate. Much evidence has been found to support this hypothesis from studies of primary cortical areas in mouse models in particular. Differential expansion of cortical areas and the introduction of new functional modules during evolution might be the result of changes in the progenitor cells. The human cerebral cortex shows a wide divergence from the mouse containing a much higher proportion of association cortex and a more complicated regionalised repertoire of neuron sub-types. To what extent does the protomap hypothesis hold true for the primate brain? This review summarises a growing number of studies exploring arealised gene expression in the early developing human telencephalon. The evidence so far is that the human and mouse brain do share fundamental mechanisms of areal specification, however there are subtle differences which could lead us to a better understanding of cortical evolution and the origins of neurodevelopmental diseases.
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38
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Walker J, MacLean J, Hatsopoulos NG. The marmoset as a model system for studying voluntary motor control. Dev Neurobiol 2016; 77:273-285. [DOI: 10.1002/dneu.22461] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 10/06/2016] [Accepted: 10/07/2016] [Indexed: 11/07/2022]
Affiliation(s)
- Jeff Walker
- Committee on Computational Neuroscience, University of Chicago; Chicago Illinois 60637
| | - Jason MacLean
- Committee on Computational Neuroscience, University of Chicago; Chicago Illinois 60637
- Department of Neurobiology; University of Chicago; Chicago Illinois 60637
| | - Nicholas G. Hatsopoulos
- Committee on Computational Neuroscience, University of Chicago; Chicago Illinois 60637
- Department of Organismal Biology and Anatomy; University of Chicago; Chicago Illinois 60637
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39
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Seelke A, Yuan SM, Perkeybile A, Krubitzer L, Bales K. Early experiences can alter the size of cortical fields in prairie voles ( Microtus ochrogaster). ENVIRONMENTAL EPIGENETICS 2016; 2:dvw019. [PMID: 27818789 PMCID: PMC5094187 DOI: 10.1093/eep/dvw019] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 07/29/2016] [Accepted: 08/05/2016] [Indexed: 06/06/2023]
Abstract
The neocortex of the prairie vole is composed of three well-defined sensory areas and one motor area: primary somatosensory, visual, auditory areas and the primary motor area respectively. The boundaries of these cortical areas are identifiable very early in development, and have been thought to resist alteration by all but the most extreme physical or genetic manipulations. Here we assessed the extent to which the boundaries of sensory/motor cortical areas can be altered by exposing young prairie voles (Microtus ochrogaster) to a chronic stimulus, high or low levels of parental contact, or an acute stimulus, a single dose of saline, oxytocin (OT), or oxytocin antagonist on the day of birth. When animals reached adulthood, their brains were removed, the cortex was flattened, cut parallel to the pial surface, and stained for myelin to identify the architectonic boundaries of sensory and motor areas. We measured the overall proportion of cortex that was myelinated, as well as the proportion of cortex devoted to the sensory and motor areas. Both the chronic and acute manipulations were linked to significant alterations in areal boundaries of cortical fields, but the areas affected differed with different conditions. Thus, differences in parental care and early exposure to OT can both change cortical organization, but their effects are not identical. Furthermore, the effects of both manipulations were sexually dimorphic, with a greater number of statistically significant differences in females than in males. These results indicate that early environmental experience, both through exposure to exogenous neuropeptides and parental contact, can alter the size of cortical fields.
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Affiliation(s)
- A.M.H. Seelke
- Psychology Department, University of California - Davis, Davis, CA, USA
| | - S.-M. Yuan
- Psychology Department, University of California - Davis, Davis, CA, USA
| | | | - L.A. Krubitzer
- Psychology Department, University of California - Davis, Davis, CA, USA
- Center for Neuroscience, University of California - Davis, Davis, CA, USA
| | - K.L. Bales
- Psychology Department, University of California - Davis, Davis, CA, USA
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40
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Abstract
One of the fundamental properties of the mammalian brain is that sensory regions of cortex are formed of multiple, functionally specialized cortical field maps (CFMs). Each CFM comprises two orthogonal topographical representations, reflecting two essential aspects of sensory space. In auditory cortex, auditory field maps (AFMs) are defined by the combination of tonotopic gradients, representing the spectral aspects of sound (i.e., tones), with orthogonal periodotopic gradients, representing the temporal aspects of sound (i.e., period or temporal envelope). Converging evidence from cytoarchitectural and neuroimaging measurements underlies the definition of 11 AFMs across core and belt regions of human auditory cortex, with likely homology to those of macaque. On a macrostructural level, AFMs are grouped into cloverleaf clusters, an organizational structure also seen in visual cortex. Future research can now use these AFMs to investigate specific stages of auditory processing, key for understanding behaviors such as speech perception and multimodal sensory integration.
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Affiliation(s)
- Alyssa A Brewer
- Department of Cognitive Sciences and Center for Hearing Research, University of California, Irvine, California 92697; ,
| | - Brian Barton
- Department of Cognitive Sciences and Center for Hearing Research, University of California, Irvine, California 92697; ,
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41
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Comparative Connectomics. Trends Cogn Sci 2016; 20:345-361. [PMID: 27026480 DOI: 10.1016/j.tics.2016.03.001] [Citation(s) in RCA: 196] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 02/23/2016] [Accepted: 03/01/2016] [Indexed: 12/30/2022]
Abstract
We introduce comparative connectomics, the quantitative study of cross-species commonalities and variations in brain network topology that aims to discover general principles of network architecture of nervous systems and the identification of species-specific features of brain connectivity. By comparing connectomes derived from simple to more advanced species, we identify two conserved themes of wiring: the tendency to organize network topology into communities that serve specialized functionality and the general drive to enable high topological integration by means of investment of neural resources in short communication paths, hubs, and rich clubs. Within the space of wiring possibilities that conform to these common principles, we argue that differences in connectome organization between closely related species support adaptations in cognition and behavior.
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Seelke AMH, Perkeybile AM, Grunewald R, Bales KL, Krubitzer LA. Individual differences in cortical connections of somatosensory cortex are associated with parental rearing style in prairie voles (Microtus ochrogaster). J Comp Neurol 2016; 524:564-77. [PMID: 26101098 PMCID: PMC4689663 DOI: 10.1002/cne.23837] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 06/09/2015] [Accepted: 06/11/2015] [Indexed: 01/05/2023]
Abstract
Early-life sensory experiences have a profound effect on brain organization, connectivity, and subsequent behavior. In most mammals, the earliest sensory inputs are delivered to the developing brain through tactile contact with the parents, especially the mother. Prairie voles (Microtus ochrogaster) are monogamous and, like humans, are biparental. Within the normal prairie vole population, both the type and the amount of interactions, particularly tactile contact, that parents have with their offspring vary. The question is whether these early and pervasive differences in tactile stimulation and social experience between parent and offspring are manifest in differences in cortical organization and connectivity. To address this question, we examined the cortical and callosal connections of the primary somatosensory area (S1) in high-contact (HC) and low-contact (LC) offspring using neuroanatomical tracing techniques. Injection sites within S1 were matched so that direct comparisons between these two groups could be made. We observed several important differences between these groups. The first was that HC offspring had a greater density of intrinsic connections within S1 compared with LC offspring. Additionally, HC offspring had a more restricted pattern of ipsilateral connections, whereas LC offspring had dense connections with areas of parietal and frontal cortex that were more widespread. Finally, LC offspring had a broader distribution of callosal connections than HC offspring and a significantly higher percentage of labeled callosal neurons. This study is the first to examine individual differences in cortical connections and suggests that individual differences in cortical connections may be related to natural differences in parental rearing styles associated with tactile contact.
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Affiliation(s)
- Adele M. H. Seelke
- Center for Neuroscience, University of California - Davis, Davis, CA, 95618 USA
| | - Allison M. Perkeybile
- Department of Psychology, University of California - Davis, Davis, CA, 95616 USA
- Department of Psychology, Northeastern University, Boston, MA, 02115 USA
| | - Rebecca Grunewald
- Center for Neuroscience, University of California - Davis, Davis, CA, 95618 USA
| | - Karen L. Bales
- Department of Psychology, University of California - Davis, Davis, CA, 95616 USA
| | - Leah A. Krubitzer
- Center for Neuroscience, University of California - Davis, Davis, CA, 95618 USA
- Department of Psychology, University of California - Davis, Davis, CA, 95616 USA
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43
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Charvet CJ, Reep RL, Finlay BL. Evolution of cytoarchitectural landscapes in the mammalian isocortex: Sirenians (Trichechus manatus) in comparison with other mammals. J Comp Neurol 2015. [PMID: 26223206 DOI: 10.1002/cne.23864] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The isocortex of several primates and rodents shows a systematic increase in the number of neurons per unit of cortical surface area from its rostrolateral to caudomedial border. The steepness of the gradient in neuronal number and density is positively correlated with cortical volume. The relative duration of neurogenesis along the same rostrocaudal gradient predicts a substantial fraction of this variation in neuron number and laminar position, which is produced principally from layers II-IV neurons. However, virtually all of our quantitative knowledge about total and laminar variation in cortical neuron numbers and neurogenesis comes from rodents and primates, leaving whole taxonomic groups and many intermediate-sized brains unexplored. Thus, the ubiquity in mammals of the covariation of longer cortical neurogenesis and increased cortical neuron number deriving from cortical layers II-IV is undetermined. To begin to address this gap, we examined the isocortex of the manatee using the optical disector method in sectioned tissue, and also assembled partial data from published reports of the domestic cat brain. The manatee isocortex has relatively fewer neurons per total volume, and fewer II-IV neurons than primates with equivalently sized brains. The gradient in number of neurons from the rostral to the caudal pole is intermediate between primates and rodents, and, like those species, is observed only in the upper cortical layers. The cat isocortex (Felis domesticus) shows a similar structure. Key species for further tests of the origin, ubiquity, and significance of this organizational feature are discussed.
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Affiliation(s)
- Christine J Charvet
- Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, DC, 20052
| | - Roger L Reep
- Department of Physiological Sciences, University of Florida, Gainesville, Florida, 32610
| | - Barbara L Finlay
- Behavioral and Evolutionary Neuroscience Group, Department of Psychology, Cornell University, Ithaca, NY, 14853
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Matsunaga E, Nambu S, Oka M, Iriki A. Complex and dynamic expression of cadherins in the embryonic marmoset cerebral cortex. Dev Growth Differ 2015; 57:474-483. [PMID: 26081465 PMCID: PMC4744772 DOI: 10.1111/dgd.12228] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2015] [Revised: 05/05/2015] [Accepted: 05/09/2015] [Indexed: 01/14/2023]
Abstract
Cadherin is a cell adhesion molecule widely expressed in the nervous system. Previously, we analyzed the expression of nine classic cadherins (Cdh4, Cdh6, Cdh7, Cdh8, Cdh9, Cdh10, Cdh11, Cdh12, and Cdh20) and T-cadherin (Cdh13) in the developing postnatal common marmoset (Callithrix jacchus) brain, and found differential expressions between mice and marmosets. In this study, to explore primate-specific cadherin expression at the embryonic stage, we extensively analyzed the expression of these cadherins in the developing embryonic marmoset brain. Each cadherin showed differential spatial and temporal expression and exhibited temporally complicated expression. Furthermore, the expression of some cadherins differed from that in rodent brains, even at the embryonic stage. These results suggest the possibility that the differential expressions of diverse cadherins are involved in primate specific cortical development, from the prenatal to postnatal period.
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Affiliation(s)
- Eiji Matsunaga
- Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Hirosawa 2-1, Wako, 351-0198, Japan
| | - Sanae Nambu
- Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Hirosawa 2-1, Wako, 351-0198, Japan
| | - Mariko Oka
- Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Hirosawa 2-1, Wako, 351-0198, Japan
| | - Atsushi Iriki
- Laboratory for Symbolic Cognitive Development, RIKEN Brain Science Institute, Hirosawa 2-1, Wako, 351-0198, Japan
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Ghazanfar AA, Takahashi DY. The evolution of speech: vision, rhythm, cooperation. Trends Cogn Sci 2014; 18:543-53. [PMID: 25048821 PMCID: PMC4177957 DOI: 10.1016/j.tics.2014.06.004] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 06/11/2014] [Accepted: 06/16/2014] [Indexed: 10/25/2022]
Abstract
A full account of human speech evolution must consider its multisensory, rhythmic, and cooperative characteristics. Humans, apes, and monkeys recognize the correspondence between vocalizations and their associated facial postures, and gain behavioral benefits from them. Some monkey vocalizations even have a speech-like acoustic rhythmicity but lack the concomitant rhythmic facial motion that speech exhibits. We review data showing that rhythmic facial expressions such as lip-smacking may have been linked to vocal output to produce an ancestral form of rhythmic audiovisual speech. Finally, we argue that human vocal cooperation (turn-taking) may have arisen through a combination of volubility and prosociality, and provide comparative evidence from one species to support this hypothesis.
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Affiliation(s)
- Asif A Ghazanfar
- Princeton Neuroscience Institute, Departments of Psychology and Ecology & Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA.
| | - Daniel Y Takahashi
- Princeton Neuroscience Institute, Department of Psychology, Princeton University, Princeton, NJ 08544, USA
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46
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Berbel P, Navarro D, Román GC. An evo-devo approach to thyroid hormones in cerebral and cerebellar cortical development: etiological implications for autism. Front Endocrinol (Lausanne) 2014; 5:146. [PMID: 25250016 PMCID: PMC4158880 DOI: 10.3389/fendo.2014.00146] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2014] [Accepted: 08/25/2014] [Indexed: 12/11/2022] Open
Abstract
The morphological alterations of cortical lamination observed in mouse models of developmental hypothyroidism prompted the recognition that these experimental changes resembled the brain lesions of children with autism; this led to recent studies showing that maternal thyroid hormone deficiency increases fourfold the risk of autism spectrum disorders (ASD), offering for the first time the possibility of prevention of some forms of ASD. For ethical reasons, the role of thyroid hormones on brain development is currently studied using animal models, usually mice and rats. Although mammals have in common many basic developmental principles regulating brain development, as well as fundamental basic mechanisms that are controlled by similar metabolic pathway activated genes, there are also important differences. For instance, the rodent cerebral cortex is basically a primary cortex, whereas the primary sensory areas in humans account for a very small surface in the cerebral cortex when compared to the associative and frontal areas that are more extensive. Associative and frontal areas in humans are involved in many neurological disorders, including ASD, attention deficit-hyperactive disorder, and dyslexia, among others. Therefore, an evo-devo approach to neocortical evolution among species is fundamental to understand not only the role of thyroid hormones and environmental thyroid disruptors on evolution, development, and organization of the cerebral cortex in mammals but also their role in neurological diseases associated to thyroid dysfunction.
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Affiliation(s)
- Pere Berbel
- Departamento de Histología y Anatomía, Facultad de Medicina, Universidad Miguel Hernández, Alicante, Spain
| | - Daniela Navarro
- Departamento de Histología y Anatomía, Facultad de Medicina, Universidad Miguel Hernández, Alicante, Spain
| | - Gustavo C. Román
- Department of Neurology, Weill Cornell Medical College, Cornell University, New York, NY, USA
- Methodist Neurological Institute, Houston, TX, USA
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Arai Y, Pierani A. Development and evolution of cortical fields. Neurosci Res 2014; 86:66-76. [PMID: 24983875 DOI: 10.1016/j.neures.2014.06.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Revised: 06/05/2014] [Accepted: 06/10/2014] [Indexed: 11/17/2022]
Abstract
The neocortex is the brain structure that has been subjected to a major size expansion, in its relative size, during mammalian evolution. It arises from the cortical primordium through coordinated growth of neural progenitor cells along both the tangential and radial axes and their patterning providing spatial coordinates. Functional neocortical areas are ultimately consolidated by environmental influences such as peripheral sensory inputs. Throughout neocortical evolution, cortical areas have become more sophisticated and numerous. This increase in number is possibly involved in the complexification of neocortical function in primates. Whereas extensive divergence of functional cortical fields is observed during evolution, the fundamental mechanisms supporting the allocation of cortical areas and their wiring are conserved, suggesting the presence of core genetic mechanisms operating in different species. We will discuss some of the basic molecular mechanisms including morphogen-dependent ones involved in the precise orchestration of neurogenesis in different cortical areas, elucidated from studies in rodents. Attention will be paid to the role of Cajal-Retzius neurons, which were recently proposed to be migrating signaling units also involved in arealization, will be addressed. We will further review recent works on molecular mechanisms of cortical patterning resulting from comparative analyses between different species during evolution.
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Affiliation(s)
- Yoko Arai
- Institut Jacques Monod, CNRS UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 75205 Paris Cedex, France.
| | - Alessandra Pierani
- Institut Jacques Monod, CNRS UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, 75205 Paris Cedex, France
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de Sousa AA, Proulx MJ. What can volumes reveal about human brain evolution? A framework for bridging behavioral, histometric, and volumetric perspectives. Front Neuroanat 2014; 8:51. [PMID: 25009469 PMCID: PMC4069365 DOI: 10.3389/fnana.2014.00051] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Accepted: 06/03/2014] [Indexed: 11/25/2022] Open
Abstract
An overall relationship between brain size and cognitive ability exists across primates. Can more specific information about neural function be gleaned from cortical area volumes? Numerous studies have found significant relationships between brain structures and behaviors. However, few studies have speculated about brain structure-function relationships from the microanatomical to the macroanatomical level. Here we address this problem in comparative neuroanatomy, where the functional relevance of overall brain size and the sizes of cortical regions have been poorly understood, by considering comparative psychology, with measures of visual acuity and the perception of visual illusions. We outline a model where the macroscopic size (volume or surface area) of a cortical region (such as the primary visual cortex, V1) is related to the microstructure of discrete brain regions. The hypothesis developed here is that an absolutely larger V1 can process more information with greater fidelity due to having more neurons to represent a field of space. This is the first time that the necessary comparative neuroanatomical research at the microstructural level has been brought to bear on the issue. The evidence suggests that as the size of V1 increases: the number of neurons increases, the neuron density decreases, and the density of neuronal connections increases. Thus, we describe how information about gross neuromorphology, using V1 as a model for the study of other cortical areas, may permit interpretations of cortical function.
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Affiliation(s)
| | - Michael J Proulx
- Crossmodal Cognition Lab, Department of Psychology, University of Bath Bath, UK
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Varela C. Thalamic neuromodulation and its implications for executive networks. Front Neural Circuits 2014; 8:69. [PMID: 25009467 PMCID: PMC4068295 DOI: 10.3389/fncir.2014.00069] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2014] [Accepted: 06/07/2014] [Indexed: 01/25/2023] Open
Abstract
The thalamus is a key structure that controls the routing of information in the brain. Understanding modulation at the thalamic level is critical to understanding the flow of information to brain regions involved in cognitive functions, such as the neocortex, the hippocampus, and the basal ganglia. Modulators contribute the majority of synapses that thalamic cells receive, and the highest fraction of modulator synapses is found in thalamic nuclei interconnected with higher order cortical regions. In addition, disruption of modulators often translates into disabling disorders of executive behavior. However, modulation in thalamic nuclei such as the midline and intralaminar groups, which are interconnected with forebrain executive regions, has received little attention compared to sensory nuclei. Thalamic modulators are heterogeneous in regards to their origin, the neurotransmitter they use, and the effect on thalamic cells. Modulators also share some features, such as having small terminal boutons and activating metabotropic receptors on the cells they contact. I will review anatomical and physiological data on thalamic modulators with these goals: first, determine to what extent the evidence supports similar modulator functions across thalamic nuclei; and second, discuss the current evidence on modulation in the midline and intralaminar nuclei in relation to their role in executive function.
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Affiliation(s)
- Carmen Varela
- Picower Institute for Learning and Memory, Massachusetts Institute of Technology Cambridge, MA, USA
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Dooley JC, Franca JG, Seelke AMH, Cooke DF, Krubitzer LA. A connection to the past: Monodelphis domestica provides insight into the organization and connectivity of the brains of early mammals. J Comp Neurol 2014; 521:3877-97. [PMID: 23784751 DOI: 10.1002/cne.23383] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 05/07/2013] [Accepted: 06/07/2013] [Indexed: 11/09/2022]
Abstract
The current experiment is one of a series of comparative studies in our laboratory designed to determine the network of somatosensory areas that are present in the neocortex of the mammalian common ancestor. Such knowledge is critical for appreciating the basic functional circuitry that all mammals possess and how this circuitry was modified to generate species-specific, sensory-mediated behavior. Our animal model, the gray short-tailed opossum (Monodelphis domestica), is a marsupial that is proposed to represent this ancestral state more closely than most other marsupials and, to some extent, even monotremes. We injected neuroanatomical tracers into the primary somatosensory area (S1), rostral and caudal somatosensory fields (SR and SC, respectively), and multimodal cortex (MM) and determined their connections with other architectonically defined cortical fields. Our results show that S1 has dense intrinsic connections, dense projections from the frontal myelinated area (FM), and moderate projections from S2 and SC. SR has strong projections from several areas, including S1, SR, FM, and piriform cortex. SC has dense projections from S1, moderate to strong projections from other somatosensory areas, FM, along with connectivity from the primary (V1) and second visual areas. Finally, MM had dense intrinsic connections, dense projections from SC and V1, and moderate projections from S1. These data support the proposition that ancestral mammals likely had at least four specifically interconnected somatosensory areas, along with at least one multimodal area. We discuss the possibility that these additional somatosensory areas (SC and SR) are homologous to somatosensory areas in eutherian mammals.
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Affiliation(s)
- James C Dooley
- Center for Neuroscience, University of California, Davis, Davis, California, 95618, USA
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