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Neural basis of unfamiliar conspecific recognition in domestic chicks (Gallus Gallus domesticus). Behav Brain Res 2020; 397:112927. [PMID: 32980353 DOI: 10.1016/j.bbr.2020.112927] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 09/14/2020] [Accepted: 09/20/2020] [Indexed: 12/27/2022]
Abstract
Domestic chickens are able to distinguish familiar from unfamiliar conspecifics, however the neuronal mechanisms mediating this behaviour are almost unknown. Moreover, the lateralisation of chicks' social recognition has only been investigated at the behavioural level, but not at the neural level. The aim of the present study was to test the hypothesis that exposure to unfamiliar conspecifics will selectively activate septum, hippocampus or nucleus taeniae of the amygdala of young domestic chicks. Moreover we also wanted to test the lateralisation of this response. For this purpose, we used the immediate early gene product c-Fos to map neural activity. Chicks were housed in pairs for one week. At test, either one of the two chicks was exchanged by an unfamiliar individual (experimental 'unfamiliar' group) or the familiar individual was briefly removed and then placed back in its original cage (control 'familiar' group). Analyses of chicks' interactions with the familiar/unfamiliar social companion revealed a higher number of social pecks directed towards unfamiliar individuals, compared to familiar controls. Moreover, in the group exposed to the unfamiliar individual a significantly higher activation was present in the dorsal and ventral septum of the left hemisphere and in the ventral hippocampus of the right hemisphere, compared to the control condition. These effects were neither present in other subareas of hippocampus or septum, nor in the nucleus taeniae of the amygdala. Our study thus indicates selective lateralised involvement of domestic chicks' septal and hippocampal subregions in responses to unfamiliar conspecific.
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52
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Burmeister SS, Liu Y. Integrative Comparative Cognition: Can Neurobiology and Neurogenomics Inform Comparative Analyses of Cognitive Phenotype? Integr Comp Biol 2020; 60:925-928. [PMID: 33141899 DOI: 10.1093/icb/icaa113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A long-standing question in animal behavior is what are the patterns and processes that shape the evolution of cognition? One effective way to address this question is to study cognitive abilities in a broad spectrum of animals. While comparative psychologists have traditionally focused on a narrow range of organisms, today they may work with any number of species, from frogs to birds or bees. This broader range of study species has greatly enriched our understanding of the diversity of cognitive processes among animals. Yet, this diversity has highlighted the fundamental challenge of comparing cognitive processes across animals. An analysis of the neural and molecular mechanisms of cognition may be necessary to solve this problem. The goal of our symposium was to bring together speakers studying a range of species to gain a broadly integrative perspective on cognition while at the same time considering the potentially important role of neurobiology and genomics in addressing the difficult problem of comparing cognition across species. For example, work by MaBouDi et al. indicates that neural constraints on computing power may impact the cognitive processes underlying numerical discrimination in bees. A presentation by Lara LaDage demonstrated how neurobiology can be used to better understand cognition and its evolution in reptiles while Edwards et al. identify the cerebellum as potentially important in the performance of the complex process of nest building. We see that molecular approaches highlight the contributions of the prefrontal cortex and hippocampus to cognitive phenotype across vertebrates while, at the same time, identifying the genes and cellular processes that may contribute to evolution of cognition. The potentially important role of neurogenesis and synaptic plasticity emerge clearly from such studies. Still unanswered is the question of whether molecular tools will contribute to our ability to discriminate convergent/parallel evolution from homology in the evolution of cognitive phenotype.
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Affiliation(s)
- Sabrina S Burmeister
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Yuxiang Liu
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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LaDage LD. Broadening the functional and evolutionary understanding of postnatal neurogenesis using reptilian models. ACTA ACUST UNITED AC 2020; 223:223/15/jeb210542. [PMID: 32788272 DOI: 10.1242/jeb.210542] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The production of new neurons in the brains of adult animals was first identified by Altman and Das in 1965, but it was not until the late 20th century when methods for visualizing new neuron production improved that there was a dramatic increase in research on neurogenesis in the adult brain. We now know that adult neurogenesis is a ubiquitous process that occurs across a wide range of taxonomic groups. This process has largely been studied in mammals; however, there are notable differences between mammals and other taxonomic groups in how, why and where new neuron production occurs. This Review will begin by describing the processes of adult neurogenesis in reptiles and identifying the similarities and differences in these processes between reptiles and model rodent species. Further, this Review underscores the importance of appreciating how wild-caught animals vary in neurogenic properties compared with laboratory-reared animals and how this can be used to broaden the functional and evolutionary understanding of why and how new neurons are produced in the adult brain. Studying variation in neural processes across taxonomic groups provides an evolutionary context to adult neurogenesis while also advancing our overall understanding of neurogenesis and brain plasticity.
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Affiliation(s)
- Lara D LaDage
- Division of Mathematics and Natural Sciences, Penn State Altoona, 3000 Ivyside Dr., Altoona, PA 16601, USA
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Abstract
Cortical interneurons display striking differences in shape, physiology, and other attributes, challenging us to appropriately classify them. We previously suggested that interneuron types should be defined by their role in cortical processing. Here, we revisit the question of how to codify their diversity based upon their division of labor and function as controllers of cortical information flow. We suggest that developmental trajectories provide a guide for appreciating interneuron diversity and argue that subtype identity is generated using a configurational (rather than combinatorial) code of transcription factors that produce attractor states in the underlying gene regulatory network. We present our updated three-stage model for interneuron specification: an initial cardinal step, allocating interneurons into a few major classes, followed by definitive refinement, creating subclasses upon settling within the cortex, and lastly, state determination, reflecting the incorporation of interneurons into functional circuit ensembles. We close by discussing findings indicating that major interneuron classes are both evolutionarily ancient and conserved. We propose that the complexity of cortical circuits is generated by phylogenetically old interneuron types, complemented by an evolutionary increase in principal neuron diversity. This suggests that a natural neurobiological definition of interneuron types might be derived from a match between their developmental origin and computational function.
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Affiliation(s)
- Gord Fishell
- Department of Neurobiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA;
- Stanley Center for Psychiatric Research, Broad Institute, Cambridge, Massachusetts 02142, USA
- Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Adam Kepecs
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
- Department of Neuroscience, Washington University in St. Louis, St. Louis, Missouri 63130, USA;
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55
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Morey RA, Haswell CC, Stjepanović D, Dunsmoor JE, LaBar KS. Neural correlates of conceptual-level fear generalization in posttraumatic stress disorder. Neuropsychopharmacology 2020; 45:1380-1389. [PMID: 32222725 PMCID: PMC7297719 DOI: 10.1038/s41386-020-0661-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 03/09/2020] [Accepted: 03/12/2020] [Indexed: 02/02/2023]
Abstract
Posttraumatic stress disorder (PTSD) may develop when mechanisms for making accurate distinctions about threat relevance have gone awry. Generalization across conceptually related objects has been hypothesized based on clinical observation in PTSD, but the neural mechanisms remain unexplored. Recent trauma-exposed military veterans (n = 46) were grouped into PTSD (n = 23) and non-PTSD (n = 23). Participants learned to generalize fear across conceptual categories (animals or tools) of semantically related items that were partially reinforced by shock during functional magnetic resonance imaging. Conditioned fear learning was quantified by shock expectancy and skin conductance response (SCR). Relative to veteran controls, PTSD subjects exhibited a stronger neural response associated with fear generalization to the reinforced object category in the striatum, anterior cingulate cortex, amygdala, occipitotemporal cortex, and insula (Z > 2.3; p < 0.05; whole-brain corrected). Based on SCR, both groups generalized the shock contingency to the reinforced conceptual category, but learning was not significantly different between groups. We found that PTSD was associated with an enhanced neural response in fronto-limbic, midline, and occipitotemporal regions to a learned representation of threat that is based on previously established conceptual knowledge of the relationship between basic-level exemplars within a semantic category. Behaviorally, veterans with PTSD were somewhat slower to differentiate threat and safety categories as compared with trauma-exposed veteran controls owing in part to an initial overgeneralized behavioral response to the safe category. These results have implications for understanding how fear spreads across semantically related concepts in PTSD.
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Affiliation(s)
- Rajendra A. Morey
- 0000 0004 0419 3073grid.281208.1Mid-Atlantic Mental Illness Research Education and Clinical Center, Durham, NC USA ,0000000122483208grid.10698.36Duke-UNC Brain Imaging and Analysis Center, Durham, NC USA ,0000000100241216grid.189509.cDepartment of Psychiatry, Duke University Medical Center, Durham, NC USA ,0000 0004 1936 7961grid.26009.3dCenter for Cognitive Neuroscience, Duke University, Durham, NC USA
| | - Courtney C. Haswell
- 0000 0004 0419 3073grid.281208.1Mid-Atlantic Mental Illness Research Education and Clinical Center, Durham, NC USA ,0000000122483208grid.10698.36Duke-UNC Brain Imaging and Analysis Center, Durham, NC USA
| | - Daniel Stjepanović
- 0000000122483208grid.10698.36Duke-UNC Brain Imaging and Analysis Center, Durham, NC USA
| | | | - Joseph E. Dunsmoor
- 0000 0004 1936 9924grid.89336.37Department of Psychiatry, University of Texas at Austin, Austin, TX USA
| | - Kevin S. LaBar
- 0000000100241216grid.189509.cDepartment of Psychiatry, Duke University Medical Center, Durham, NC USA ,0000 0004 1936 7961grid.26009.3dCenter for Cognitive Neuroscience, Duke University, Durham, NC USA
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56
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Liu Y, Jones CD, Day LB, Summers K, Burmeister SS. Cognitive Phenotype and Differential Gene Expression in a Hippocampal Homologue in Two Species of Frog. Integr Comp Biol 2020; 60:1007-1023. [DOI: 10.1093/icb/icaa032] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
SynopsisThe complexity of an animal’s interaction with its physical and/or social environment is thought to be associated with behavioral flexibility and cognitive phenotype, though we know little about this relationship in amphibians. We examined differences in cognitive phenotype in two species of frog with divergent natural histories. The green-and-black poison frog (Dendrobates auratus) is diurnal, displays enduring social interactions, and uses spatially distributed resources during parental care. Túngara frogs (Physalaemus=Engystomops pustulosus) are nocturnal, express only fleeting social interactions, and use ephemeral puddles to breed in a lek-type mating system. Comparing performance in identical discrimination tasks, we find that D. auratus made fewer errors when learning and displayed greater behavioral flexibility in reversal learning tasks than túngara frogs. Further, túngara frogs preferred to learn beacons that can be used in direct guidance whereas D. auratus preferred position cues that could be used to spatially orient relative to the goal. Behavioral flexibility and spatial cognition are associated with hippocampal function in mammals. Accordingly, we examined differential gene expression in the medial pallium, the amphibian homolog of the hippocampus. Our preliminary data indicate that genes related to learning and memory, synaptic plasticity, and neurogenesis were upregulated in D. auratus, while genes related to apoptosis were upregulated in túngara frogs, suggesting that these cellular processes could contribute to the differences in behavioral flexibility and spatial learning we observed between poison frogs and túngara frogs.
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Affiliation(s)
- Yuxiang Liu
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Corbin D Jones
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Department of Genetics, Integrative Program for Biological & Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Lainy B Day
- Department of Biology, University of Mississippi, Oxford, MS 38677, USA
| | - Kyle Summers
- Biology Department, East Carolina University, Greenville, NC 27858, USA
| | - Sabrina S Burmeister
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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57
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Morandi-Raikova A, Mayer U. The effect of monocular occlusion on hippocampal c-Fos expression in domestic chicks (Gallus gallus). Sci Rep 2020; 10:7205. [PMID: 32350337 PMCID: PMC7190859 DOI: 10.1038/s41598-020-64224-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 04/09/2020] [Indexed: 01/07/2023] Open
Abstract
In birds, like in mammals, the hippocampus is particularly sensitive to exposure to novel environments, a function that is based on visual input. Chicks' eyes are placed laterally and their optic fibers project mainly to the contralateral brain hemispheres, with only little direct interhemispheric coupling. Thus, monocular occlusion has been frequently used in chicks to document functional specialization of the two hemispheres. However, we do not know whether monocular occlusion influences hippocampal activation. The aim of the present work was to fill this gap by directly testing this hypothesis. To induce hippocampal activation, chicks were exposed to a novel environment with their left or right eye occluded, or in conditions of binocular vision. Their hippocampal expression of c-Fos (neural activity marker) was compared to a baseline group that remained in a familiar environment. Interestingly, while the hippocampal activation in the two monocular groups was not different from the baseline, it was significantly higher in the binocular group exposed to the novel environment. This suggest that the representation of environmental novelty in the hippocampus of domestic chicks involves strong binocular integration.
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Affiliation(s)
| | - Uwe Mayer
- Center for Mind/Brain Sciences, University of Trento, Trento, Italy.
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58
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Ultrastructural Alterations in Granular Neurons of the Dentate Fascia Caused by Intrahippocampal Injection of Beta-Amyloid 1-42. Bull Exp Biol Med 2020; 168:802-806. [PMID: 32350713 DOI: 10.1007/s10517-020-04806-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Indexed: 10/24/2022]
Abstract
The deposition of beta-amyloid (Aβ) in the brain is detected in Alzheimer's disease and during ageing. Until now, ultrastructural studies of changes caused by Aβ in the dentate gyrus are very scarce. The effects of Aβ 1-42 injection into the CA1 field of rat hippocampus were studied by electron microscopy. In 2 weeks after injection of aggregated Aβ in low concentrations, destructive changes were seen in the structure of dentate gyrus cells, which consisted in a decrease in the number of dentate gyrus neurons and axo-dendritic synapses. These changes were accompanied by enlargement of the endoplasmic reticulum cisterns and widening of the active zones of synapses. Thus, injection of aggregated Aβ 1-42 into the hippocampus led to irreversible (a decrease in the number of neurons and axo-dendritic synapses, agglutination of synthetic vesicles) and adaptive changes (an increase in the sizes of endoplasmic reticulum cisterns and active zones of synapses) in dentate gyrus neurons aimed at the maintenance of functional activity of the nervous system.
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59
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Armstrong EA, Rufener C, Toscano MJ, Eastham JE, Guy JH, Sandilands V, Boswell T, Smulders TV. Keel bone fractures induce a depressive-like state in laying hens. Sci Rep 2020; 10:3007. [PMID: 32080271 PMCID: PMC7033198 DOI: 10.1038/s41598-020-59940-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 02/03/2020] [Indexed: 02/06/2023] Open
Abstract
In commercial flocks of laying hens, keel bone fractures (KBFs) are prevalent and associated with behavioural indicators of pain. However, whether their impact is severe enough to induce a depressive-like state of chronic stress is unknown. As chronic stress downregulates adult hippocampal neurogenesis (AHN) in mammals and birds, we employ this measure as a neural biomarker of subjective welfare state. Radiographs obtained longitudinally from Lohmann Brown laying hens housed in a commercial multi-tier aviary were used to score the severity of naturally-occurring KBFs between the ages of 21-62 weeks. Individual birds' transitions between aviary zones were also recorded. Focal hens with severe KBFs at 3-4 weeks prior to sampling (n = 15) had lower densities of immature doublecortin-positive (DCX+) multipolar and bipolar neurons in the hippocampal formation than focal hens with minimal fractures (n = 9). KBF severity scores at this time also negatively predicted DCX+ cell numbers on an individual level, while hens that acquired fractures earlier in their lives had fewer DCX+ neurons in the caudal hippocampal formation. Activity levels 3-4 weeks prior to sampling were not associated with AHN. KBFs thus lead to a negative affective state lasting at least 3-4 weeks, and management steps to reduce their occurrence are likely to have significant welfare benefits.
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Affiliation(s)
- E A Armstrong
- Centre for Behaviour & Evolution, Newcastle University, Newcastle upon Tyne, UK.
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK.
| | - C Rufener
- Department of Animal Science, University of California, Davis, USA
- Centre for Proper Housing: Poultry and Rabbits (ZTHZ), University of Bern, Zollikofen, Switzerland
| | - M J Toscano
- Centre for Proper Housing: Poultry and Rabbits (ZTHZ), University of Bern, Zollikofen, Switzerland
| | - J E Eastham
- Centre for Behaviour & Evolution, Newcastle University, Newcastle upon Tyne, UK
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
| | - J H Guy
- Centre for Behaviour & Evolution, Newcastle University, Newcastle upon Tyne, UK
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - V Sandilands
- Department of Agriculture, Horticulture and Engineering Sciences, SRUC, Edinburgh, UK
| | - T Boswell
- Centre for Behaviour & Evolution, Newcastle University, Newcastle upon Tyne, UK
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - T V Smulders
- Centre for Behaviour & Evolution, Newcastle University, Newcastle upon Tyne, UK
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
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60
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Billings BK, Behroozi M, Helluy X, Bhagwandin A, Manger PR, Güntürkün O, Ströckens F. A three-dimensional digital atlas of the Nile crocodile (Crocodylus niloticus) forebrain. Brain Struct Funct 2020; 225:683-703. [PMID: 32009190 DOI: 10.1007/s00429-020-02028-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 01/16/2020] [Indexed: 12/22/2022]
Abstract
The phylogenetic position of crocodilians in relation to birds and mammals makes them an interesting animal model for investigating the evolution of the nervous system in amniote vertebrates. A few neuroanatomical atlases are available for reptiles, but with a growing interest in these animals within the comparative neurosciences, a need for these anatomical reference templates is becoming apparent. With the advent of MRI being used more frequently in comparative neuroscience, the aim of this study was to create a three-dimensional MRI-based atlas of the Nile crocodile (Crocodylus niloticus) brain to provide a common reference template for the interpretation of the crocodilian, and more broadly reptilian, brain. Ex vivo MRI acquisitions in combination with histological data were used to delineate crocodilian brain areas at telencephalic, diencephalic, mesencephalic, and rhombencephalic levels. A total of 50 anatomical structures were successfully identified and outlined to create a 3-D model of the Nile crocodile brain. The majority of structures were more readily discerned within the forebrain of the crocodile with the methods used to produce this atlas. The anatomy outlined herein corresponds with both classical and recent crocodilian anatomical analyses, barring a few areas of contention predominantly related to a lack of functional data and conflicting nomenclature.
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Affiliation(s)
- Brendon K Billings
- Faculty of Health Sciences, School of Anatomical Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, 2193, South Africa
| | - Mehdi Behroozi
- Faculty of Psychology, Institute of Cognitive Neuroscience, Biopsychology, Ruhr-University Bochum, Universitätsstraße 150, 44780, Bochum, Germany
| | - Xavier Helluy
- Faculty of Psychology, Institute of Cognitive Neuroscience, Biopsychology, Ruhr-University Bochum, Universitätsstraße 150, 44780, Bochum, Germany
| | - Adhil Bhagwandin
- Faculty of Health Sciences, School of Anatomical Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, 2193, South Africa.,Faculty of Health Sciences, Department of Human Biology, Division of Clinical Anatomy and Biological Anthropology, University of Cape Town, Cape Town, South Africa
| | - Paul R Manger
- Faculty of Health Sciences, School of Anatomical Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, 2193, South Africa
| | - Onur Güntürkün
- Faculty of Psychology, Institute of Cognitive Neuroscience, Biopsychology, Ruhr-University Bochum, Universitätsstraße 150, 44780, Bochum, Germany
| | - Felix Ströckens
- Faculty of Psychology, Institute of Cognitive Neuroscience, Biopsychology, Ruhr-University Bochum, Universitätsstraße 150, 44780, Bochum, Germany.
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61
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van der Meij J, Rattenborg NC, Beckers GJL. Divergent neuronal activity patterns in the avian hippocampus and nidopallium. Eur J Neurosci 2020; 52:3124-3139. [PMID: 31944434 DOI: 10.1111/ejn.14675] [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] [Received: 06/03/2019] [Accepted: 12/27/2019] [Indexed: 02/05/2023]
Abstract
Sleep-related brain activity occurring during non-rapid eye-movement (NREM) sleep is proposed to play a role in processing information acquired during wakefulness. During mammalian NREM sleep, the transfer of information from the hippocampus to the neocortex is thought to be mediated by neocortical slow-waves and their interaction with thalamocortical spindles and hippocampal sharp-wave ripples (SWRs). In birds, brain regions composed of pallial neurons homologous to neocortical (pallial) neurons also generate slow-waves during NREM sleep, but little is known about sleep-related activity in the hippocampus and its possible relationship to activity in other pallial regions. We recorded local field potentials (LFP) and analogue multiunit activity (AMUA) using a 64-channel silicon multi-electrode probe simultaneously inserted into the hippocampus and medial part of the nidopallium (i.e., caudal medial nidopallium; NCM) or separately into the caudolateral nidopallium (NCL) of adult female zebra finches (Taeniopygia guttata) anesthetized with isoflurane, an anesthetic known to induce NREM sleep-like slow-waves. We show that slow-waves in NCM and NCL propagate as waves of neuronal activity. In contrast, the hippocampus does not show slow-waves, nor sharp-wave ripples, but instead displays localized gamma activity. In conclusion, neuronal activity in the avian hippocampus differs from that described in mammals during NREM sleep, suggesting that hippocampal memories are processed differently during sleep in birds and mammals.
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Affiliation(s)
| | - Niels C Rattenborg
- Avian Sleep Group, Max Planck Institute for Ornithology, Seewiesen, Germany
| | - Gabriël J L Beckers
- Cognitive Neurobiology and Helmholtz Institute, Utrecht University, Utrecht, The Netherlands
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62
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He HK, Yang R, Huang HM, Yang FF, Wu YZ, Shaibo J, Guo X. Multi-gate memristive synapses realized with the lateral heterostructure of 2D WSe 2 and WO 3. NANOSCALE 2020; 12:380-387. [PMID: 31825449 DOI: 10.1039/c9nr07941f] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The development of novel synaptic device architectures with a high order of synaptic plasticity can provide a breakthrough toward neuromorphic computing. Herein, through the thermal oxidation of two-dimensional (2D) WSe2, unique memristive synapses based on the lateral heterostructure of 2D WSe2 and WO3, with multi-gate modulation characteristics, are firstly demonstrated. An intermediate transition layer in the heterostructure is observed through transmission electron microscopy. Raman spectroscopy and detailed electrical measurements provide insights into the mechanism of memristive behavior, revealing that the protons injected into/removed from the intermediate transition layer account for the memristive behavior. This novel memristive synapse can be used to emulate two neuron-based synaptic functions, like post-synaptic current, short-term plasticity and long-term plasticity, with remarkable linearity, symmetry, and an ultralow energy consumption of ∼2.7 pJ per spike. More importantly, the synaptic plasticity between the drain and source electrodes can be effectively modulated by the gate voltage and visible light in a four-terminal configuration. Such multi-gate tuning of the synaptic plasticity cannot be accomplished by any previously reported multi-gate synaptic devices that only mimic two neuron-based synapses. This new synaptic architecture with electrical and optical modulation enables a realistic emulation of biological synapses whose synaptic plasticity can be additionally regulated by the surrounding astrocytes, greatly improving the recognition accuracy and processing capacity of artificial neuristors, and paving a new way for highly efficient neuromorphic computation devices.
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Affiliation(s)
- Hui-Kai He
- State Key Laboratory of Material Processing and Die & Mould Technology, Laboratory of Solid State Ionics, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, P. R. China.
| | - Rui Yang
- State Key Laboratory of Material Processing and Die & Mould Technology, Laboratory of Solid State Ionics, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, P. R. China.
| | - He-Ming Huang
- State Key Laboratory of Material Processing and Die & Mould Technology, Laboratory of Solid State Ionics, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, P. R. China.
| | - Fan-Fan Yang
- State Key Laboratory of Material Processing and Die & Mould Technology, Laboratory of Solid State Ionics, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, P. R. China.
| | - Ya-Zhou Wu
- State Key Laboratory of Material Processing and Die & Mould Technology, Laboratory of Solid State Ionics, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, P. R. China.
| | - Jamal Shaibo
- State Key Laboratory of Material Processing and Die & Mould Technology, Laboratory of Solid State Ionics, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, P. R. China.
| | - Xin Guo
- State Key Laboratory of Material Processing and Die & Mould Technology, Laboratory of Solid State Ionics, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, P. R. China.
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63
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He HK, Yang FF, Yang R. Flexible full two-dimensional memristive synapses of graphene/WSe2−xOy/graphene. Phys Chem Chem Phys 2020; 22:20658-20664. [DOI: 10.1039/d0cp03822a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
van der Waals heterostructures realized by stacking different two-dimensional materials offer the possibility to design new devices with atomic-level precision.
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Affiliation(s)
- Hui-Kai He
- State Key Laboratory of Material Processing and Die & Mould Technology
- School of Materials Science and Engineering
- Huazhong University of Science and Technology
- Wuhan 430074
- P. R. China
| | - Fan-Fan Yang
- State Key Laboratory of Material Processing and Die & Mould Technology
- School of Materials Science and Engineering
- Huazhong University of Science and Technology
- Wuhan 430074
- P. R. China
| | - Rui Yang
- State Key Laboratory of Material Processing and Die & Mould Technology
- School of Materials Science and Engineering
- Huazhong University of Science and Technology
- Wuhan 430074
- P. R. China
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64
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Iyer A, Tole S. Neuronal diversity and reciprocal connectivity between the vertebrate hippocampus and septum. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2019; 9:e370. [PMID: 31850675 DOI: 10.1002/wdev.370] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Revised: 11/13/2019] [Accepted: 11/13/2019] [Indexed: 02/02/2023]
Abstract
A hallmark of the nervous system is the precision with which myriad cell types are integrated into functional networks that control complex behaviors. The limbic system governs evolutionarily conserved processes essential for survival. The septum and the hippocampus are central to the limbic system, and control not only emotion-related behaviors but also learning and memory. Here, we provide a developmental and evolutionary perspective of the hippocampus and septum and highlight the neuronal diversity and circuitry that connects these two central components of the limbic system. This article is categorized under: Nervous System Development > Vertebrates: Regional Development Nervous System Development > Vertebrates: General Principles Comparative Development and Evolution > Regulation of Organ Diversity.
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Affiliation(s)
- Archana Iyer
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Shubha Tole
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
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65
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Patterns of c-Fos expression in telencephalic areas of Tropidurus hygomi (Iguania: Tropiduridae) exposed to different social contexts. J Chem Neuroanat 2019; 102:101703. [PMID: 31644950 DOI: 10.1016/j.jchemneu.2019.101703] [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: 10/02/2018] [Revised: 10/06/2019] [Accepted: 10/06/2019] [Indexed: 11/22/2022]
Abstract
Social behavior in lizards contributes to understanding biological standards and provides models for structuring research about neural mechanisms. Studies have confirmed the effectiveness of comparative models and evidence has contributed to clarifying adult brain plasticity phenomenon when exposed to different stimuli. The expression of c-Fos has been widely used to identify brain areas involved in different behavioral stimuli. The purpose of the present study was to map the expression of c-Fos protein in different telencephalic areas of the lizard Tropidurus hygomi after they were exposed to visual stimuli with another individual of the same species in different social contexts. Lizards were allocated to one of four groups: 1) control group (CTL) - males not exposed to any other animal; 2) exposure to juvenile (EJU) - males exposed to a juvenile; 3) exposure to male (EMA) - males exposed to another adult male; and 4) exposure to females (EFE) -males exposed to female. The EFE group exhibited a greater number of c-Fos + cells in cortical areas (medial cortex - MC and dorsomedial cortex - DMC) and in amygdala (AMY), showing a possible relationship between these structures and behavioral components. Studies like this can contribute significantly to a better understanding of neurophysiological, behavioral, and evolutive aspects.
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66
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Rapid learning of a spatial memory task in a lacertid lizard (Podarcis liolepis). Behav Processes 2019; 169:103963. [PMID: 31545992 DOI: 10.1016/j.beproc.2019.103963] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 07/19/2019] [Accepted: 09/19/2019] [Indexed: 12/30/2022]
Abstract
Mammals and birds are capable of navigating to a goal using learned map-like representations of space (i.e. place learning), but research assessing this navigational strategy in reptiles has produced inconclusive results, in part due to the use of procedures that do not take account of the peculiarities of reptilian behavior and physiology. Here I present a procedure suitable for testing spatial cognition that exploits a naturally evolved, ethologically relevant ability common to many lizards (i.e. refuge seeking behavior). The procedure requires lizards to learn the location of an open refuge inside a rectangular arena containing artificial refuges in every corner, using distal extramaze visual cues and with no local cues marking the location of the open refuge. The procedure probes the lizards' place learning ability and effectively rules out the use of egocentric and response-based strategies. The described procedure was successfully used to demonstrate place learning in a lacertid lizard (Podarcis liolepis). Over the course of two weeks of training both the latency to entering the open refuge and the number of corners visited in each trial decreased gradually, indicating that learning had taken place in over 60% of the lizards tested. These results confirm that, under certain circumstances, lizards are capable of navigating to a goal using a place learning strategy.
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67
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Herold C, Schlömer P, Mafoppa-Fomat I, Mehlhorn J, Amunts K, Axer M. The hippocampus of birds in a view of evolutionary connectomics. Cortex 2019; 118:165-187. [DOI: 10.1016/j.cortex.2018.09.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 09/26/2018] [Accepted: 09/26/2018] [Indexed: 12/12/2022]
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Roth TC, Krochmal AR, LaDage LD. Reptilian Cognition: A More Complex Picture via Integration of Neurological Mechanisms, Behavioral Constraints, and Evolutionary Context. Bioessays 2019; 41:e1900033. [PMID: 31210380 DOI: 10.1002/bies.201900033] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/10/2019] [Indexed: 12/16/2022]
Abstract
Unlike birds and mammals, reptiles are commonly thought to possess only the most rudimentary means of interacting with their environments, reflexively responding to sensory information to the near exclusion of higher cognitive function. However, reptilian brains, though structurally somewhat different from those of mammals and birds, use many of the same cellular and molecular processes to support complex behaviors in homologous brain regions. Here, the neurological mechanisms supporting reptilian cognition are reviewed, focusing specifically on spatial cognition and the hippocampus. These processes are compared to those seen in mammals and birds within an ecologically and evolutionarily relevant context. By viewing reptilian cognition through an integrative framework, a more robust understanding of reptile cognition is gleaned. Doing so yields a broader view of the evolutionarily conserved molecular and cellular mechanisms that underlie cognitive function and a better understanding of the factors that led to the evolution of complex cognition.
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Affiliation(s)
- Timothy C Roth
- Department of Psychology, Franklin and Marshall College, P.O. Box 3003, Lancaster, PA, 17603, USA
| | - Aaron R Krochmal
- Department of Biology, Washington College, 300 Washington Avenue, Chestertown, MD, 21620, USA
| | - Lara D LaDage
- Division of Mathematics and Natural Sciences, Penn State University Altoona, Altoona, PA, 16601, USA
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Gualtieri F, Armstrong EA, Longmoor GK, D'Eath RB, Sandilands V, Boswell T, Smulders TV. Unpredictable Chronic Mild Stress Suppresses the Incorporation of New Neurons at the Caudal Pole of the Chicken Hippocampal Formation. Sci Rep 2019; 9:7129. [PMID: 31073135 PMCID: PMC6509118 DOI: 10.1038/s41598-019-43584-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 04/25/2019] [Indexed: 02/08/2023] Open
Abstract
In the mammalian brain, adult hippocampal neurogenesis (AHN) is suppressed by chronic stress, primarily at the ventral pole of the hippocampus. Based upon anatomy, we hypothesise that the caudal pole of the avian Hippocampal Formation (HF) presents a homologous subregion. We thus investigated whether AHN is preferentially suppressed in the caudal chicken HF by unpredictable chronic mild stress (UCMS). Adult hens were kept in control conditions or exposed to UCMS for 8 weeks. Hens experiencing UCMS had significantly fewer doublecortin-positive multipolar neurons (p < 0.001) and beaded axons (p = 0.021) at the caudal pole of the HF than controls. UCMS birds also had smaller spleens and lower baseline plasma corticosterone levels compared to controls. There were no differences in AHN at the rostral pole, nor were there differences in expression of genetic mediators of the HPA stress response in the pituitary or adrenal glands. Duration of tonic immobility and heterophil/lymphocyte (H/L) ratios were also not responsive to our UCMS treatment. These results support the hypothesised homology of the caudal pole of the avian HF to the ventral pole of the rodent hippocampus. Furthermore, quantifying neurogenesis in the caudal HF post-mortem may provide an objective, integrative measure of welfare in poultry, which may be more sensitive than current welfare measures.
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Affiliation(s)
- F Gualtieri
- Centre for Behaviour & Evolution, Newcastle University, Newcastle upon Tyne, UK.,Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - E A Armstrong
- Centre for Behaviour & Evolution, Newcastle University, Newcastle upon Tyne, UK.,Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - G K Longmoor
- Centre for Behaviour & Evolution, Newcastle University, Newcastle upon Tyne, UK.,Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - R B D'Eath
- Animal and Veterinary Science Research Group, SRUC, Edinburgh, UK
| | - V Sandilands
- Animal and Veterinary Science Research Group, SRUC, Edinburgh, UK
| | - T Boswell
- Centre for Behaviour & Evolution, Newcastle University, Newcastle upon Tyne, UK.,School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - T V Smulders
- Centre for Behaviour & Evolution, Newcastle University, Newcastle upon Tyne, UK. .,Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK.
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70
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Augusto-Oliveira M, Arrifano GPF, Malva JO, Crespo-Lopez ME. Adult Hippocampal Neurogenesis in Different Taxonomic Groups: Possible Functional Similarities and Striking Controversies. Cells 2019; 8:cells8020125. [PMID: 30764477 PMCID: PMC6406791 DOI: 10.3390/cells8020125] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 01/31/2019] [Accepted: 01/31/2019] [Indexed: 12/13/2022] Open
Abstract
Adult neurogenesis occurs in many species, from fish to mammals, with an apparent reduction in the number of both neurogenic zones and new neurons inserted into established circuits with increasing brain complexity. Although the absolute number of new neurons is high in some species, the ratio of these cells to those already existing in the circuit is low. Continuous replacement/addition plays a role in spatial navigation (migration) and other cognitive processes in birds and rodents, but none of the literature relates adult neurogenesis to spatial navigation and memory in primates and humans. Some models developed by computational neuroscience attribute a high weight to hippocampal adult neurogenesis in learning and memory processes, with greater relevance to pattern separation. In contrast to theories involving neurogenesis in cognitive processes, absence/rarity of neurogenesis in the hippocampus of primates and adult humans was recently suggested and is under intense debate. Although the learning process is supported by plasticity, the retention of memories requires a certain degree of consolidated circuitry structures, otherwise the consolidation process would be hampered. Here, we compare and discuss hippocampal adult neurogenesis in different species and the inherent paradoxical aspects.
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Affiliation(s)
- Marcus Augusto-Oliveira
- Laboratory of Molecular Pharmacology, Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, Brazil.
- Laboratory of Research on Neurodegeneration and Infection, University Hospital João de Barros Barreto, Federal University of Pará, Belém 66073-005, Brazil.
- Laboratory of Experimental Neuropathology, Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK.
| | - Gabriela P F Arrifano
- Laboratory of Molecular Pharmacology, Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, Brazil.
- Laboratory of Experimental Neuropathology, Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK.
| | - João O Malva
- Coimbra Institute for Clinical and Biomedical Research (iCBR), and Center for Neuroscience and Cell Biology and Institute for Biomedical Imaging and Life Sciences (CNC.IBILI), Faculty of Medicine, University of Coimbra, Coimbra 3000-548, Portugal.
| | - Maria Elena Crespo-Lopez
- Laboratory of Molecular Pharmacology, Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, Brazil.
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71
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Jung MW, Lee H, Jeong Y, Lee JW, Lee I. Remembering rewarding futures: A simulation-selection model of the hippocampus. Hippocampus 2018; 28:913-930. [PMID: 30155938 PMCID: PMC6587829 DOI: 10.1002/hipo.23023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 07/06/2018] [Accepted: 08/23/2018] [Indexed: 02/06/2023]
Abstract
Despite tremendous progress, the neural circuit dynamics underlying hippocampal mnemonic processing remain poorly understood. We propose a new model for hippocampal function-the simulation-selection model-based on recent experimental findings and neuroecological considerations. Under this model, the mammalian hippocampus evolved to simulate and evaluate arbitrary navigation sequences. Specifically, we suggest that CA3 simulates unexperienced navigation sequences in addition to remembering experienced ones, and CA1 selects from among these CA3-generated sequences, reinforcing those that are likely to maximize reward during offline idling states. High-value sequences reinforced in CA1 may allow flexible navigation toward a potential rewarding location during subsequent navigation. We argue that the simulation-selection functions of the hippocampus have evolved in mammals mostly because of the unique navigational needs of land mammals. Our model may account for why the mammalian hippocampus has evolved not only to remember, but also to imagine episodes, and how this might be implemented in its neural circuits.
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Affiliation(s)
- Min Whan Jung
- Center for Synaptic Brain Dysfunctions, Institute for Basic ScienceDaejeonSouth Korea
- Department of Biological SciencesKorea Advanced Institute of Science and TechnologyDaejeonSouth Korea
| | - Hyunjung Lee
- Department of AnatomyKyungpook National University School of MedicineDaeguSouth Korea
| | - Yeongseok Jeong
- Center for Synaptic Brain Dysfunctions, Institute for Basic ScienceDaejeonSouth Korea
- Department of Biological SciencesKorea Advanced Institute of Science and TechnologyDaejeonSouth Korea
| | - Jong Won Lee
- Center for Synaptic Brain Dysfunctions, Institute for Basic ScienceDaejeonSouth Korea
| | - Inah Lee
- Department of Brain and Cognitive SciencesSeoul National UniversitySeoulSouth Korea
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Raghanti MA, Wicinski B, Meierovich R, Warda T, Dickstein DL, Reidenberg JS, Tang CY, George JC, Hans Thewissen JGM, Butti C, Hof PR. A Comparison of the Cortical Structure of the Bowhead Whale (Balaena mysticetus), a Basal Mysticete, with Other Cetaceans. Anat Rec (Hoboken) 2018; 302:745-760. [PMID: 30332717 DOI: 10.1002/ar.23991] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 09/12/2017] [Accepted: 10/16/2017] [Indexed: 12/13/2022]
Abstract
Few studies exist of the bowhead whale brain and virtually nothing is known about its cortical cytoarchitecture or how it compares to other cetaceans. Bowhead whales are one of the least encephalized cetaceans and occupy a basal phylogenetic position among mysticetes. Therefore, the bowhead whale is an important specimen for understanding the evolutionary specializations of cetacean brains. Here, we present an overview of the structure and cytoarchitecture of the bowhead whale cerebral cortex gleaned from Nissl-stained sections and magnetic resonance imaging (MRI) in comparison with other mysticetes and odontocetes. In general, the cytoarchitecture of cetacean cortex is consistent in displaying a thin cortex, a thick, prominent layer I, and absence of a granular layer IV. Cell density, composition, and width of layers III, V, and VI vary among cortical regions, and cetacean cortex is cell-sparse relative to that of terrestrial mammals. Notably, all regions of the bowhead cortex possess high numbers of von Economo neurons and fork neurons, with the highest numbers observed at the apex of gyri. The bowhead whale is also distinctive in having a significantly reduced hippocampus that occupies a space below the corpus callosum within the lateral ventricle. Consistent with other balaenids, bowhead whales possess what appears to be a blunted temporal lobe, which is in contrast to the expansive temporal lobes that characterize most odontocetes. The present report demonstrates that many morphological and cytoarchitectural characteristics are conserved among cetaceans, while other features, such as a reduced temporal lobe, may characterize balaenids among mysticetes. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc. Anat Rec, 302:745-760, 2019. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Mary Ann Raghanti
- Department of Anthropology and School of Biomedical Sciences, Kent State University, Kent, Ohio
| | - Bridget Wicinski
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Rachel Meierovich
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York.,Convent of the Sacred Heart School, New York, New York
| | - Tahia Warda
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Dara L Dickstein
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York.,Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Joy S Reidenberg
- Center for Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Cheuk Y Tang
- Department of Radiology and Translational Medicine Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - John C George
- Department of Wildlife Management, North Slope Borough, Barrow, Alaska
| | - J G M Hans Thewissen
- Department of Anatomy and Neurobiology, Northeastern Ohio Medical University, Rootstown, Ohio
| | - Camilla Butti
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Patrick R Hof
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, New York
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73
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Atoji Y, Sarkar S. Prox1 mRNA expression in the medial cortex of the turtle (Pseudemys scripta elegans). Neurosci Lett 2018; 687:285-289. [PMID: 30218766 DOI: 10.1016/j.neulet.2018.09.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 09/11/2018] [Indexed: 11/18/2022]
Abstract
The medial cortex of the cerebrum in reptiles is thought to be homologous to the mammalian dentate gyrus, based on cytoarchitectures, fiber connections, and neurochemical profiles. To support this hypothesis, we examined the mRNA expression of vesicular glutamate transporter 1 (vGluT1), a glutamatergic gene marker, and Prox1, a selective gene marker for granule cells of the dentate gyrus, in the turtle medial cortex (zone 2). Reverse transcription-polymerase chain reaction revealed the presence of both mRNAs in the turtle cerebrum. In situ hybridization of zone 2, which is a layer of densely packed neurons in Nissl stains, intensely expressed vGluT1 and Prox1. In zone 3, which is a loosely packed layer, vGluT1 was intensely expressed, whereas Prox1 signals gradated from strong to negative toward zone 4. These findings demonstrate that zone 2 contains glutamatergic neurons and expresses Prox1 mRNA and suggest that zone 2 in the turtle cerebrum is homologous to the mammalian dentate gyrus.
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Affiliation(s)
- Yasuro Atoji
- Laboratory of Veterinary anatomy, Faculty of Applied Biological Sciences, Gifu University, Gifu 501-1193, Japan.
| | - Sonjoy Sarkar
- Laboratory of Veterinary anatomy, Faculty of Applied Biological Sciences, Gifu University, Gifu 501-1193, Japan
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Libourel PA, Barrillot B, Arthaud S, Massot B, Morel AL, Beuf O, Herrel A, Luppi PH. Partial homologies between sleep states in lizards, mammals, and birds suggest a complex evolution of sleep states in amniotes. PLoS Biol 2018; 16:e2005982. [PMID: 30307933 PMCID: PMC6181266 DOI: 10.1371/journal.pbio.2005982] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 08/30/2018] [Indexed: 12/19/2022] Open
Abstract
It is crucial to determine whether rapid eye movement (REM) sleep and slow-wave sleep (SWS) (or non-REM sleep), identified in most mammals and birds, also exist in lizards, as they share a common ancestor with these groups. Recently, a study in the bearded dragon (P. vitticeps) reported states analogous to REM and SWS alternating in a surprisingly regular 80-s period, suggesting a common origin of the two sleep states across amniotes. We first confirmed these results in the bearded dragon with deep brain recordings and electro-oculogram (EOG) recordings. Then, to confirm a common origin and more finely characterize sleep in lizards, we developed a multiparametric approach in the tegu lizard, a species never recorded to date. We recorded EOG, electromyogram (EMG), heart rate, and local field potentials (LFPs) and included data on arousal thresholds, sleep deprivation, and pharmacological treatments with fluoxetine, a serotonin reuptake blocker that suppresses REM sleep in mammals. As in the bearded dragon, we demonstrate the existence of two sleep states in tegu lizards. However, no clear periodicity is apparent. The first sleep state (S1 sleep) showed high-amplitude isolated sharp waves, and the second sleep state (S2 sleep) displayed 15-Hz oscillations, isolated ocular movements, and a decrease in heart rate variability and muscle tone compared to S1. Fluoxetine treatment induced a significant decrease in S2 quantities and in the number of sharp waves in S1. Because S2 sleep is characterized by the presence of ocular movements and is inhibited by a serotonin reuptake inhibitor, as is REM sleep in birds and mammals, it might be analogous to this state. However, S2 displays a type of oscillation never previously reported and does not display a desynchronized electroencephalogram (EEG) as is observed in the bearded dragons, mammals, and birds. This suggests that the phenotype of sleep states and possibly their role can differ even between closely related species. Finally, our results suggest a common origin of two sleep states in amniotes. Yet, they also highlight a diversity of sleep phenotypes across lizards, demonstrating that the evolution of sleep states is more complex than previously thought. Until recently, the general understanding about sleep was that only mammals and birds show two sleep states: slow-wave sleep and rapid eye movement (REM) sleep. Consequently, it was thought that these two states appeared independently in these warm-blooded animals. However, a recent paper reported the presence of these two states in the bearded dragon lizard (Pogona vitticeps), suggesting that these two states arose with the common ancestor of mammals, birds, and reptiles. We confirmed the presence of two sleep states in the bearded dragon and compared its sleep with that of another lizard, the Argentine tegu (Salvator merianae). Our results show that both lizard species have two sleep states with similarities to the two sleep states observed in mammals and birds. Additionally, our study of behavioral and physiological parameters as well as the brain activity associated with sleep in these lizards allowed us to also show important differences between these two species of lizards and between lizards, birds, and mammals. Our findings indicate that sleep in lizards is more complex than previously thought and raise further questions about the nature, function, and evolution of these two sleep states.
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Affiliation(s)
- Paul-Antoine Libourel
- Neuroscience Research Center of Lyon, SLEEP Team, UMR 5292 CNRS/U1028 INSERM, Université Claude Bernard Lyon 1, Lyon, France
- * E-mail:
| | - Baptiste Barrillot
- Neuroscience Research Center of Lyon, SLEEP Team, UMR 5292 CNRS/U1028 INSERM, Université Claude Bernard Lyon 1, Lyon, France
| | - Sébastien Arthaud
- Neuroscience Research Center of Lyon, SLEEP Team, UMR 5292 CNRS/U1028 INSERM, Université Claude Bernard Lyon 1, Lyon, France
| | - Bertrand Massot
- Nanotechnologies Institute of Lyon, UMR5270 CNRS, INSA Lyon, Université Claude Bernard Lyon 1, France
| | - Anne-Laure Morel
- Neuroscience Research Center of Lyon, SLEEP Team, UMR 5292 CNRS/U1028 INSERM, Université Claude Bernard Lyon 1, Lyon, France
| | - Olivier Beuf
- Health Image Processing and Acquisition Research Center of Lyon, UMR 5220 CNRS/U1206 INSERM, INSA Lyon, Université Claude Bernard Lyon 1, LYON, France
| | - Anthony Herrel
- MECADEV, UMR7179 CNRS, National Museum of Natural History, Paris, France
- University of Antwerp, Department of Biology, Antwerpen, Belgium
- Ghent University, Evolutionary Morphology of Vertebrates, Ghent, Belgium
| | - Pierre-Hervé Luppi
- Neuroscience Research Center of Lyon, SLEEP Team, UMR 5292 CNRS/U1028 INSERM, Université Claude Bernard Lyon 1, Lyon, France
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de Araujo JL, Rodrigues-Hoffmann A, Giaretta PR, Guo J, Heatley J, Tizard I, Rech RR. Distribution of Viral Antigen and Inflammatory Lesions in the Central Nervous System of Cockatiels ( Nymphicus hollandicus) Experimentally Infected with Parrot Bornavirus 2. Vet Pathol 2018; 56:106-117. [PMID: 30235986 DOI: 10.1177/0300985818798112] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Neurotropism is a striking characteristic of bornaviruses, including parrot bornavirus 2 (PaBV-2). Our study evaluated the distribution of inflammatory foci and viral nucleoprotein (N) antigen in the brain and spinal cord of 27 cockatiels ( Nymphicus hollandicus) following experimental infection with PaBV-2 by injection into the pectoral muscle. Tissue samples were taken at 12 timepoints between 5 and 114 days post-inoculation (dpi). Each experimental group had approximately 3 cockatiels per group and usually 1 negative control. Immunolabeling was first observed within the ventral horns of the thoracic spinal cord at 20 dpi and in the brain (thalamic nuclei and hindbrain) at 25 dpi. Both inflammation and viral antigen were restricted to the central core of the brain until 40 dpi. The virus then spread quickly at 60 dpi to both gray and white matter of all analyzed sections of the central nervous system (CNS). Encephalitis was most severe in the thalamus and hindbrain, while myelitis was most prominent in the gray matter and equally distributed in the cervical, thoracic, and lumbosacral spinal cord. Our results demonstrate a caudal to rostral spread of virus in the CNS following experimental inoculation of PABV-2 into the pectoral muscle, with the presence of viral antigen and inflammatory lesions first in the spinal cord and progressing to the brain.
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Affiliation(s)
- Jeann Leal de Araujo
- 1 Department of Veterinary Pathobiology, Texas A&M University, College Station, TX, USA
| | | | - Paula R Giaretta
- 1 Department of Veterinary Pathobiology, Texas A&M University, College Station, TX, USA
| | - Jianhua Guo
- 1 Department of Veterinary Pathobiology, Texas A&M University, College Station, TX, USA
| | - Jill Heatley
- 2 Department of Small Animal Clinical Sciences, Texas A&M University, College Station, TX, USA
| | - Ian Tizard
- 1 Department of Veterinary Pathobiology, Texas A&M University, College Station, TX, USA
| | - Raquel R Rech
- 1 Department of Veterinary Pathobiology, Texas A&M University, College Station, TX, USA
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76
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Tosches MA, Yamawaki TM, Naumann RK, Jacobi AA, Tushev G, Laurent G. Evolution of pallium, hippocampus, and cortical cell types revealed by single-cell transcriptomics in reptiles. Science 2018; 360:881-888. [DOI: 10.1126/science.aar4237] [Citation(s) in RCA: 232] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 03/12/2018] [Indexed: 12/14/2022]
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77
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Abstract
The evolutionary relationships of the mammalian neocortex and avian dorsal telencephalon (DT) nuclei have been debated for more than a century. Despite their central importance to this debate, nonavian reptiles remain underexplored with modern molecular techniques. Reptile studies harbor great potential for understanding the changes in DT organization that occurred in the early evolution of amniotes. They may also help clarify the specializations in the avian DT, which comprises a massive, cell-dense dorsal ventricular ridge (DVR) and a nuclear dorsal-most structure, the Wulst. Crocodilians are phylogenetically and anatomically attractive for DT comparative studies: they are the closest living relatives of birds and have a strikingly bird-like DVR, but they also possess a highly differentiated reptile cerebral cortex. We studied the DT of the American alligator, Alligator mississippiensis, at late embryonic stages with a panel of molecular marker genes. Gene expression and cytoarchitectonic analyses identified clear homologs of all major avian DVR subdivisions including a mesopallium, an extensive nidopallium with primary sensory input territories, and an arcopallium. The alligator medial cortex is divided into three components that resemble the mammalian dentate gyrus, CA fields, and subiculum in gene expression and topography. The alligator dorsal cortex contains putative homologs of neocortical input, output, and intratelencephalic projection neurons and, most notably, these are organized into sublayers similar to mammalian neocortical layers. Our findings on the molecular anatomy of the crocodilian DT are summarized in an atlas of the alligator telencephalon.
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Affiliation(s)
- Steven D Briscoe
- Committee on Development, Regeneration, and Stem Cell Biology, University of Chicago, Chicago, Illinois
| | - Clifton W Ragsdale
- Committee on Development, Regeneration, and Stem Cell Biology, University of Chicago, Chicago, Illinois.,Department of Neurobiology, University of Chicago, Chicago, Illinois.,Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois
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78
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Briscoe SD, Albertin CB, Rowell JJ, Ragsdale CW. Neocortical Association Cell Types in the Forebrain of Birds and Alligators. Curr Biol 2018; 28:686-696.e6. [PMID: 29456143 PMCID: PMC11098552 DOI: 10.1016/j.cub.2018.01.036] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 11/22/2017] [Accepted: 01/12/2018] [Indexed: 01/17/2023]
Abstract
The avian dorsal telencephalon has two vast territories, the nidopallium and the mesopallium, both of which have been shown to contribute substantially to higher cognitive functions. From their connections, these territories have been proposed as equivalent to mammalian neocortical layers 2 and 3, various neocortical association areas, or the amygdala, but whether these are analogies or homologies by descent is unknown. We investigated the molecular profiles of the mesopallium and the nidopallium with RNA-seq. Gene expression experiments established that the mesopallium, but not the nidopallium, shares a transcription factor network with the intratelencephalic class of neocortical neurons, which are found in neocortical layers 2, 3, 5, and 6. Experiments in alligators demonstrated that these neurons are also abundant in the crocodilian cortex and form a large mesopallium-like structure in the dorsal ventricular ridge. Together with previous work, these molecular findings indicate a homology by descent for neuronal cell types of the avian dorsal telencephalon with the major excitatory cell types of mammalian neocortical circuits: the layer 4 input neurons, the deep layer output neurons, and the multi-layer intratelencephalic association neurons. These data raise the interesting possibility that avian and primate lineages evolved higher cognitive abilities independently through parallel expansions of homologous cell populations.
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Affiliation(s)
- Steven D Briscoe
- Committee on Development, Regeneration, and Stem Cell Biology, University of Chicago, Chicago, IL, 60637, USA.
| | - Caroline B Albertin
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL, 60637, USA; Department of Neurobiology, University of Chicago, Chicago, IL, 60637, USA
| | - Joanna J Rowell
- Department of Neurobiology, University of Chicago, Chicago, IL, 60637, USA
| | - Clifton W Ragsdale
- Committee on Development, Regeneration, and Stem Cell Biology, University of Chicago, Chicago, IL, 60637, USA; Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL, 60637, USA; Department of Neurobiology, University of Chicago, Chicago, IL, 60637, USA.
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79
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Dheerendra P, Lynch NM, Crutwell J, Cunningham MO, Smulders TV. In vitro characterization of gamma oscillations in the hippocampal formation of the domestic chick. Eur J Neurosci 2018; 48:2807-2815. [PMID: 29120510 PMCID: PMC6220815 DOI: 10.1111/ejn.13773] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 10/28/2017] [Accepted: 11/02/2017] [Indexed: 11/30/2022]
Abstract
Avian and mammalian brains have evolved independently from each other for about 300 million years. During that time, the hippocampal formation (HF) has diverged in morphology and cytoarchitecture, but seems to have conserved much of its function. It is therefore an open question how seemingly different neural organizations can generate the same function. A prominent feature of the mammalian hippocampus is that it generates different neural oscillations, including the gamma rhythm, which plays an important role in memory processing. In this study, we investigate whether the avian hippocampus also generates gamma oscillations, and whether similar pharmacological mechanisms are involved in this function. We investigated the existence of gamma oscillations in avian HF using in vitro electrophysiology in P0–P12 domestic chick (Gallus gallus domesticus) HF brain slices. Persistent gamma frequency oscillations were induced by the bath application of the cholinergic agonist carbachol, but not by kainate, a glutamate receptor agonist. Similar to other species, carbachol‐evoked gamma oscillations were sensitive to GABAA, AMPA/kainate and muscarinic (M1) receptor antagonism. Therefore, similar to mammalian species, muscarinic receptor‐activated avian HF gamma oscillations may arise via a pyramidal‐interneuron gamma (PING)‐based mechanism. Gamma oscillations are most prominent in the ventromedial area of the hippocampal slices, and gamma power is reduced more laterally and dorsally in the HF. We conclude that similar micro‐circuitry may exist in the avian and mammalian hippocampal formation, and this is likely to relate to the shared function of the two structures.
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Affiliation(s)
- Pradeep Dheerendra
- Institute of Neuroscience, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Nicholas M Lynch
- Institute of Neuroscience, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK.,University of Louisville, Louisville, KY, USA
| | - Joseph Crutwell
- Institute of Neuroscience, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Mark O Cunningham
- Institute of Neuroscience, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Tom V Smulders
- Institute of Neuroscience, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK.,Centre for Behaviour and Evolution, Newcastle University, Newcastle upon Tyne, UK
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80
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Fournier J, Müller CM, Schneider I, Laurent G. Spatial Information in a Non-retinotopic Visual Cortex. Neuron 2018; 97:164-180.e7. [DOI: 10.1016/j.neuron.2017.11.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 08/25/2017] [Accepted: 11/10/2017] [Indexed: 02/04/2023]
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81
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Food restriction reduces neurogenesis in the avian hippocampal formation. PLoS One 2017; 12:e0189158. [PMID: 29211774 PMCID: PMC5718509 DOI: 10.1371/journal.pone.0189158] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 11/20/2017] [Indexed: 02/08/2023] Open
Abstract
The mammalian hippocampus is particularly vulnerable to chronic stress. Adult neurogenesis in the dentate gyrus is suppressed by chronic stress and by administration of glucocorticoid hormones. Post-natal and adult neurogenesis are present in the avian hippocampal formation as well, but much less is known about its sensitivity to chronic stressors. In this study, we investigate this question in a commercial bird model: the broiler breeder chicken. Commercial broiler breeders are food restricted during development to manipulate their growth curve and to avoid negative health outcomes, including obesity and poor reproductive performance. Beyond knowing that these chickens are healthier than fully-fed birds and that they have a high motivation to eat, little is known about how food restriction impacts the animals' physiology. Chickens were kept on a commercial food-restricted diet during the first 12 weeks of life, or released from this restriction by feeding them ad libitum from weeks 7–12 of life. To test the hypothesis that chronic food restriction decreases the production of new neurons (neurogenesis) in the hippocampal formation, the cell proliferation marker bromodeoxyuridine was injected one week prior to tissue collection. Corticosterone levels in blood plasma were elevated during food restriction, even though molecular markers of hypothalamic-pituitary-adrenal axis activation did not differ between the treatments. The density of new hippocampal neurons was significantly reduced in the food-restricted condition, as compared to chickens fed ad libitum, similar to findings in rats at a similar developmental stage. Food restriction did not affect hippocampal volume or the total number of neurons. These findings indicate that in birds, like in mammals, reduction in hippocampal neurogenesis is associated with chronically elevated corticosterone levels, and therefore potentially with chronic stress in general. This finding is consistent with the hypothesis that the response to stressors in the avian hippocampal formation is homologous to that of the mammalian hippocampus.
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82
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Representation of environmental shape in the hippocampus of domestic chicks (Gallus gallus). Brain Struct Funct 2017; 223:941-953. [DOI: 10.1007/s00429-017-1537-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 10/05/2017] [Indexed: 10/18/2022]
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83
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Murray EA, Wise SP, Graham KS. Representational specializations of the hippocampus in phylogenetic perspective. Neurosci Lett 2017; 680:4-12. [PMID: 28473258 PMCID: PMC5665731 DOI: 10.1016/j.neulet.2017.04.065] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 04/28/2017] [Accepted: 04/29/2017] [Indexed: 11/28/2022]
Abstract
In a major evolutionary transition that occurred more than 520 million years ago, the earliest vertebrates adapted to a life of mobile, predatory foraging guided by distance receptors concentrated on their heads. Vision and olfaction served as the principal sensory systems for guiding their search for nutrients and safe haven. Among their neural innovations, these animals had a telencephalon that included a homologue of the hippocampus. Experiments on goldfish, turtles, lizards, rodents, macaque monkeys and humans have provided insight into the initial adaptive advantages provided by the hippocampus homologue. These findings indicate that it housed specialized map-like representations of odors and sights encountered at various locations in an animal's home range, including the order and timing in which they should be encountered during a journey. Once these representations emerged in early vertebrates, they also enabled a variety of behaviors beyond navigation. In modern rodents and primates, for example, the specialized representations of the hippocampus enable the learning and performance of tasks involving serial order, timing, recency, relations, sequences of events and behavioral contexts. During primate evolution, certain aspects of these representations gained particular prominence, in part due to the advent of foveal vision in haplorhines. As anthropoid primates-the ancestors of monkeys, apes and humans-changed from small animals that foraged locally into large ones with an extensive home range, they made foraging choices at a distance based on visual scenes. Experimental evidence shows that the hippocampus of monkeys specializes in memories that reflect the representation of such scenes, rather than spatial processing in a general sense. Furthermore, and contrary to the idea that the hippocampus functions in memory to the exclusion of perception, brain imaging studies and lesion effects in humans show that its specialized representations support both the perception and memory of scenes and sequences.
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Affiliation(s)
- Elisabeth A Murray
- Laboratory of Neuropsychology, NIMH, Building 49, Suite 1B80, 49 Convent Drive, Bethesda, MD 20892-4415, USA.
| | - Steven P Wise
- Olschefskie Institute for the Neurobiology of Knowledge, Potomac, MD 20854, USA
| | - Kim S Graham
- Cognitive Neuroscience, School of Psychology, Cardiff University, CUBRIC Building, Maindy Road, Cardiff, CF24 4HQ, UK
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84
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Ray S, Burgalossi A, Brecht M, Naumann RK. Complementary Modular Microcircuits of the Rat Medial Entorhinal Cortex. Front Syst Neurosci 2017; 11:20. [PMID: 28443003 PMCID: PMC5385340 DOI: 10.3389/fnsys.2017.00020] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 03/24/2017] [Indexed: 11/13/2022] Open
Abstract
The parahippocampal region is organized into different areas, with the medial entorhinal cortex (MEC), presubiculum and parasubiculum prominent in spatial memory. Here, we also describe a region at the extremity of the MEC and bordering the subicular complex, the medial-most part of the entorhinal cortex. While the subdivisions of hippocampus proper form more or less continuous cell sheets, the superficial layers of the parahippocampal region have a distinct modular architecture. We investigate the spatial distribution, laminar position, and putative connectivity of zinc-positive modules in layer 2 of the MEC of rats and relate them to the calbindin-positive patches previously described in the entorhinal cortex. We found that the zinc-positive modules are complementary to the previously described calbindin-positive patches. We also found that inputs from the presubiculum are directed toward the zinc-positive modules while the calbindin-positive patches received inputs from the parasubiculum. Notably, the dendrites of neurons from layers 3 and 5, positive for Purkinje Cell Protein 4 expression, overlap with the zinc modules. Our data thus indicate that these two complementary modular systems, the calbindin patches and zinc modules, are part of parallel information streams in the hippocampal formation.
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Affiliation(s)
- Saikat Ray
- Bernstein Center for Computational Neuroscience, Humboldt University of BerlinBerlin, Germany
| | - Andrea Burgalossi
- Werner-Reichardt Centre for Integrative NeuroscienceTübingen, Germany
| | - Michael Brecht
- Bernstein Center for Computational Neuroscience, Humboldt University of BerlinBerlin, Germany
- German Center for Neurodegenerative DiseasesBerlin, Germany
| | - Robert K. Naumann
- Bernstein Center for Computational Neuroscience, Humboldt University of BerlinBerlin, Germany
- Max-Planck-Institute for Brain ResearchFrankfurt, Germany
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85
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Barkan S, Yom-Tov Y, Barnea A. Exploring the Relationship between Brain Plasticity, Migratory Lifestyle, and Social Structure in Birds. Front Neurosci 2017; 11:139. [PMID: 28396621 PMCID: PMC5367377 DOI: 10.3389/fnins.2017.00139] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 03/07/2017] [Indexed: 12/28/2022] Open
Abstract
Studies in Passerines have found that migrating species recruit more new neurons into brain regions that process spatial information, compared with resident species. This was explained by the greater exposure of migrants to spatial information, indicating that this phenomenon enables enhanced navigational abilities. The aim of the current study was to test this hypothesis in another order-the Columbiformes - using two closely-related dove species-the migrant turtle-dove (Streptopelia turtur) and the resident laughing dove (S. senegalensis), during spring, summer, and autumn. Wild birds were caught, treated with BrdU, and sacrificed 5 weeks later. New neurons were recorded in the hyperpallium apicale, hippocampus and nidopallium caudolaterale regions. We found that in doves, unlike passerines, neuronal recruitment was lower in brains of the migratory species compared with the resident one. This might be due to the high sociality of doves, which forage and migrate in flocks, and therefore can rely on communal spatial knowledge that might enable a reduction in individual navigation efforts. This, in turn, might enable reduced levels of neuronal recruitment. Additionally, we found that unlike in passerines, seasonality does not affect neuronal recruitment in doves. This might be due to their non-territorial and explorative behavior, which exposes them to substantial spatial information all year round. Finally, we discuss the differences in neuronal recruitment between Columbiformes and Passeriformes and their possible evolutionary explanations. Our study emphasizes the need to further investigate this phenomenon in other avian orders and in additional species.
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Affiliation(s)
- Shay Barkan
- Department of Zoology, Tel-Aviv University Tel-Aviv, Israel
| | - Yoram Yom-Tov
- Department of Zoology, Tel-Aviv University Tel-Aviv, Israel
| | - Anat Barnea
- Department of Natural and Life Sciences, The Open University of Israel Ra'anana, Israel
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86
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LaDage LD, Roth TC, Downs CJ, Sinervo B, Pravosudov VV. Increased Testosterone Decreases Medial Cortical Volume and Neurogenesis in Territorial Side-Blotched Lizards ( Uta stansburiana). Front Neurosci 2017; 11:97. [PMID: 28298883 PMCID: PMC5331184 DOI: 10.3389/fnins.2017.00097] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Accepted: 02/14/2017] [Indexed: 01/18/2023] Open
Abstract
Variation in an animal's spatial environment can induce variation in the hippocampus, an area of the brain involved in spatial cognitive processing. Specifically, increased spatial area use is correlated with increased hippocampal attributes, such as volume and neurogenesis. In the side-blotched lizard (Uta stansburiana), males demonstrate alternative reproductive tactics and are either territorial—defending large, clearly defined spatial boundaries—or non-territorial—traversing home ranges that are smaller than the territorial males' territories. Our previous work demonstrated cortical volume (reptilian hippocampal homolog) correlates with these spatial niches. We found that territorial holders have larger medial cortices than non-territory holders, yet these differences in the neural architecture demonstrated some degree of plasticity as well. Although we have demonstrated a link among territoriality, spatial use, and brain plasticity, the mechanisms that underlie this relationship are unclear. Previous studies found that higher testosterone levels can induce increased use of the spatial area and can cause an upregulation in hippocampal attributes. Thus, testosterone may be the mechanistic link between spatial area use and the brain. What remains unclear, however, is if testosterone can affect the cortices independent of spatial experiences and whether testosterone differentially interacts with territorial status to produce the resultant cortical phenotype. In this study, we compared neurogenesis as measured by the total number of doublecortin-positive cells and cortical volume between territorial and non-territorial males supplemented with testosterone. We found no significant differences in the number of doublecortin-positive cells or cortical volume among control territorial, control non-territorial, and testosterone-supplemented non-territorial males, while testosterone-supplemented territorial males had smaller medial cortices containing fewer doublecortin-positive cells. These results demonstrate that testosterone can modulate medial cortical attributes outside of differential spatial processing experiences but that territorial males appear to be more sensitive to alterations in testosterone levels compared with non-territorial males.
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Affiliation(s)
- Lara D LaDage
- Division of Mathematics and Natural Sciences, Penn State University Altoona Altoona, PA, USA
| | - Timothy C Roth
- Department of Psychology, Franklin and Marshall College Lancaster, PA, USA
| | | | - Barry Sinervo
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, CA, USA
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87
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The avian hippocampus and the hypothetical maps used by navigating migratory birds (with some reflection on compasses and migratory restlessness). J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2017; 203:465-474. [DOI: 10.1007/s00359-017-1161-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 02/16/2017] [Accepted: 02/21/2017] [Indexed: 12/31/2022]
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88
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Lee JW, Jung MW. Separation or binding? Role of the dentate gyrus in hippocampal mnemonic processing. Neurosci Biobehav Rev 2017; 75:183-194. [PMID: 28174077 DOI: 10.1016/j.neubiorev.2017.01.049] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 11/26/2016] [Accepted: 01/05/2017] [Indexed: 01/15/2023]
Abstract
As a major component of the hippocampal trisynaptic circuit, the dentate gyrus (DG) relays inputs from the entorhinal cortex to the CA3 subregion. Although the anatomy of the DG is well characterized, its contribution to hippocampal mnemonic processing is still unclear. A currently popular theory proposes that the primary function of the DG is to orthogonalize incoming input patterns into non-overlapping patterns (pattern separation). We critically review the available data and conclude that the theoretical support and empirical evidence for this theory are not strong. We then review an alternative theory that posits a role for the DG in binding together different types of incoming sensory information. We conclude that 'binding' better captures the contribution of the DG to memory encoding than 'pattern separation'.
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Affiliation(s)
- Jong Won Lee
- Center for Synaptic Brain Dysfunctions, Institute for Basic Science, Daejeon 34141, Republic of Korea
| | - Min Whan Jung
- Center for Synaptic Brain Dysfunctions, Institute for Basic Science, Daejeon 34141, Republic of Korea; Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea.
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89
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Manshack LK, Conard CM, Bryan SJ, Deem SL, Holliday DK, Bivens NJ, Givan SA, Rosenfeld CS. Transcriptomic alterations in the brain of painted turtles ( Chrysemys picta) developmentally exposed to bisphenol A or ethinyl estradiol. Physiol Genomics 2017; 49:201-215. [PMID: 28159858 DOI: 10.1152/physiolgenomics.00103.2016] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 02/01/2017] [Accepted: 02/01/2017] [Indexed: 12/25/2022] Open
Abstract
Developmental exposure of turtles and other reptiles to endocrine-disrupting chemicals (EDCs), including bisphenol A (BPA) and ethinyl estradiol (EE), can stimulate partial to full gonadal sex-reversal in males. We have also recently shown that in ovo exposure to either EDC can induce similar sex-dependent behavioral changes typified by improved spatial learning and memory or possibly feminized brain responses. Observed behavioral changes are presumed to be due to BPA- and EE-induced brain transcriptomic alterations during development. To test this hypothesis, we treated painted turtles (Chrysemys picta) at developmental stage 17, incubated at 26°C (male-inducing temperature), with 1) BPA (1 ng/µl), 2) EE (4 ng/µl), or 3) vehicle ethanol (control group). Ten months after hatching and completion of the behavioral tests, juvenile turtles were euthanized, brains were collected and frozen in liquid nitrogen, and RNA was isolated for RNA-Seq analysis. Turtles exposed to BPA clustered separately from EE-exposed and control individuals. More transcripts and gene pathways were altered in BPA vs. EE individuals. The one transcript upregulated in both BPA- and EE-exposed individuals was the mitochondrial-associated gene, ND5, which is involved in oxidative phosphorylation. Early exposure of turtles to BPA increases transcripts linked with ribosomal and mitochondrial functions, especially bioenergetics, which has been previously linked with improved cognitive performance. In summary, even though both BPA and EE resulted in similar behavioral alterations, they diverge in the pattern of neural transcript alterations with early BPA significantly upregulating several genes involved in oxidative phosphorylation, mitochondrial activity, and ribosomal function, which could enhance cognitive performance.
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Affiliation(s)
- Lindsey K Manshack
- Bond Life Sciences Center, University of Missouri, Columbia, Missouri.,Biomedical Sciences, University of Missouri, Columbia, Missouri
| | - Caroline M Conard
- Bond Life Sciences Center, University of Missouri, Columbia, Missouri.,Biomedical Sciences, University of Missouri, Columbia, Missouri
| | - Sara J Bryan
- Veterinary Medicine and Surgery, University of Missouri, Columbia, Missouri
| | - Sharon L Deem
- Veterinary Medicine and Surgery, University of Missouri, Columbia, Missouri.,Saint Louis Zoo Institute for Conservation Medicine, St. Louis, Missouri
| | - Dawn K Holliday
- Pathology and Anatomical Sciences, School of Medicine, University of Missouri, Columbia, Missouri.,Department of Biology and Environmental Sciences, Westminster College, Fulton, Missouri
| | - Nathan J Bivens
- DNA Core Facility, University of Missouri, Columbia, Missouri
| | - Scott A Givan
- Bond Life Sciences Center, University of Missouri, Columbia, Missouri.,Informatics Research Core Facility, University of Missouri, Columbia, Missouri.,Molecular Microbiology and Immunology, University of Missouri, Columbia, Missouri
| | - Cheryl S Rosenfeld
- Bond Life Sciences Center, University of Missouri, Columbia, Missouri; .,Biomedical Sciences, University of Missouri, Columbia, Missouri.,Genetics Area Program, University of Missouri, Columbia, Missouri; and.,Thompson Center for Autism and Neurobehavioral Disorders, University of Missouri, Columbia, Missouri
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90
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Macedo-Lima M, Freire MAM, de Carvalho Pimentel H, Rodrigues Ferreira Lins LC, Amador de Lucena Medeiros KA, Viola GG, dos Santos JR, Marchioro M. Characterization of NADPH Diaphorase- and Doublecortin-Positive Neurons in the Lizard Hippocampal Formation. BRAIN, BEHAVIOR AND EVOLUTION 2017; 88:222-234. [DOI: 10.1159/000453105] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 11/06/2016] [Indexed: 11/19/2022]
Abstract
The lizard cortex has remarkable similarities with the mammalian hippocampus. Both regions process memories, have similar cytoarchitectural properties, and are important neurogenic foci in adults. Lizards show striking levels of widespread neurogenesis in adulthood and can regenerate entire cortical areas after injury. Nitric oxide (NO) is an important regulatory factor of mammalian neurogenesis and hippocampal function. However, little is known about its role in nonmammalian neurogenesis. Here, we analyzed the distribution, morphology, and dendritic complexity (Neurolucida reconstructions) of NO-producing neurons through NADPH diaphorase (NADPHd) activity, and how they compare with the distribution of doublecortin-positive (DCX+) neurons in the hippocampal formation of the neotropical lizard Tropidurus hispidus. NADPHd-positive (NADPHd+) neurons in the dorsomedial cortex (DMC; putatively homologous to mammalian CA3) were more numerous and complex than the ones in the medial cortex (MC; putatively homologous to the dentate gyrus). We found that NADPHd+ DMC neurons send long projections into the MC. Interestingly, in the MC, NADPHd+ neurons existed in 2 patterns: small somata with low intensity of staining in the outer layer and large somata with high intensity of staining in the deep layer, a pattern similar to the mammalian cortex. Additionally, NADPHd+ neurons were absent in the granular cell layer of the MC. In contrast, DCX+ neurons were scarce in the DMC but highly numerous in the MC, particularly in the granular cell layer. We hypothesize that NO-producing neurons in the DMC provide important input to proliferating/migrating neurons in the highly neurogenic MC.
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91
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Grella SL, Guigueno MF, White DJ, Sherry DF, Marrone DF. Context-Dependent Egr1 Expression in the Avian Hippocampus. PLoS One 2016; 11:e0164333. [PMID: 27716817 PMCID: PMC5055351 DOI: 10.1371/journal.pone.0164333] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 09/25/2016] [Indexed: 11/22/2022] Open
Abstract
In mammals, episodic memory and spatial cognition involve context-specific recruitment of unique ensembles in the hippocampal formation (HF). Despite their capacity for sophisticated spatial (e.g., for migration) and episodic-like (e.g., for food-caching) memory, the mechanisms underlying contextual representation in birds is not well understood. Here we demonstrate environment-specific Egr1 expression as male brown-headed cowbirds (Molothrus ater) navigate environments for food reward, showing that the avian HF, like its mammalian counterpart, recruits distinct neuronal ensembles to represent different contexts.
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Affiliation(s)
- Stephanie L. Grella
- Department of Psychology, Wilfrid Laurier University, Waterloo, ON, Canada, N2L 3C5
| | - Mélanie F. Guigueno
- Department of Biology, University of Western Ontario, London, ON, Canada, N6A 3K7
| | - David J. White
- Department of Psychology, Wilfrid Laurier University, Waterloo, ON, Canada, N2L 3C5
| | - David F. Sherry
- Department of Psychology, University of Western Ontario, London, ON, Canada, N6A 3K7
| | - Diano F. Marrone
- Department of Psychology, Wilfrid Laurier University, Waterloo, ON, Canada, N2L 3C5
- McKnight Brain Institute, University of Arizona, Tucson, AZ, United States of America, 85719
- * E-mail:
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92
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Atoji Y, Sarkar S, Wild JM. Proposed homology of the dorsomedial subdivision and V-shaped layer of the avian hippocampus to Ammon's horn and dentate gyrus, respectively. Hippocampus 2016; 26:1608-1617. [DOI: 10.1002/hipo.22660] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2016] [Indexed: 12/18/2022]
Affiliation(s)
- Yasuro Atoji
- Laboratory of Veterinary Anatomy Faculty of Applied Biological Sciences; Gifu University; Gifu Japan
| | - Sonjoy Sarkar
- Laboratory of Veterinary Anatomy Faculty of Applied Biological Sciences; Gifu University; Gifu Japan
| | - J. Martin Wild
- Department of Anatomy and Medical Imaging Faculty of Medical and Health Sciences; University of Auckland; Auckland New Zealand
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93
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Shein-Idelson M, Ondracek JM, Liaw HP, Reiter S, Laurent G. Slow waves, sharp waves, ripples, and REM in sleeping dragons. Science 2016; 352:590-5. [PMID: 27126045 DOI: 10.1126/science.aaf3621] [Citation(s) in RCA: 127] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 04/01/2016] [Indexed: 12/12/2022]
Abstract
Sleep has been described in animals ranging from worms to humans. Yet the electrophysiological characteristics of brain sleep, such as slow-wave (SW) and rapid eye movement (REM) activities, are thought to be restricted to mammals and birds. Recording from the brain of a lizard, the Australian dragon Pogona vitticeps, we identified SW and REM sleep patterns, thus pushing back the probable evolution of these dynamics at least to the emergence of amniotes. The SW and REM sleep patterns that we observed in lizards oscillated continuously for 6 to 10 hours with a period of ~80 seconds. The networks controlling SW-REM antagonism in amniotes may thus originate from a common, ancient oscillator circuit. Lizard SW dynamics closely resemble those observed in rodent hippocampal CA1, yet they originate from a brain area, the dorsal ventricular ridge, that has no obvious hodological similarity with the mammalian hippocampus.
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Affiliation(s)
| | - Janie M Ondracek
- Max Planck Institute for Brain Research, Frankfurt am Main, Germany
| | - Hua-Peng Liaw
- Max Planck Institute for Brain Research, Frankfurt am Main, Germany
| | - Sam Reiter
- Max Planck Institute for Brain Research, Frankfurt am Main, Germany
| | - Gilles Laurent
- Max Planck Institute for Brain Research, Frankfurt am Main, Germany
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94
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Environmental experiences influence cortical volume in territorial and nonterritorial side-blotched lizards, Uta stansburiana. Anim Behav 2016. [DOI: 10.1016/j.anbehav.2016.01.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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95
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Aboitiz F, Montiel JF. Olfaction, navigation, and the origin of isocortex. Front Neurosci 2015; 9:402. [PMID: 26578863 PMCID: PMC4621927 DOI: 10.3389/fnins.2015.00402] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 10/12/2015] [Indexed: 11/23/2022] Open
Abstract
There are remarkable similarities between the brains of mammals and birds in terms of microcircuit architecture, despite obvious differences in gross morphology and development. While in reptiles and birds the most expanding component (the dorsal ventricular ridge) displays an overall nuclear shape and derives from the lateral and ventral pallium, in mammals a dorsal pallial, six-layered isocortex shows the most remarkable elaboration. Regardless of discussions about possible homologies between mammalian and avian brains, a main question remains in explaining the emergence of the mammalian isocortex, because it represents a unique phenotype across amniotes. In this article, we propose that the origin of the isocortex was driven by behavioral adaptations involving olfactory driven goal-directed and navigating behaviors. These adaptations were linked with increasing sensory development, which provided selective pressure for the expansion of the dorsal pallium. The latter appeared as an interface in olfactory-hippocampal networks, contributing somatosensory information for navigating behavior. Sensory input from other modalities like vision and audition were subsequently recruited into this expanding region, contributing to multimodal associative networks.
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Affiliation(s)
- Francisco Aboitiz
- Departamento de Psiquiatría, Escuela de Medicina, Centro Interdisciplinario de Neurociencia, Pontificia Universidad Católica de ChileSantiago, Chile
| | - Juan F. Montiel
- Facultad de Medicina, Centro de Investigación Biomédica, Universidad Diego PortalesSantiago, Chile
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of OxfordOxford, UK
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96
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Montiel JF, Aboitiz F. Pallial patterning and the origin of the isocortex. Front Neurosci 2015; 9:377. [PMID: 26512233 PMCID: PMC4604247 DOI: 10.3389/fnins.2015.00377] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 09/28/2015] [Indexed: 12/30/2022] Open
Abstract
Together with a complex variety of behavioral, physiological, morphological, and neurobiological innovations, mammals are characterized by the development of an extensive isocortex (also called neocortex) that is both laminated and radially organized, as opposed to the brain of birds and reptiles. In this article, we will advance a developmental hypothesis in which the mechanisms of evolutionary brain growth remain partly conserved across amniotes (mammals, reptiles and birds), all based on Pax6 signaling or related morphogens. Despite this conservatism, only in mammals there is an additional upregulation of dorsal and anterior signaling centers (the cortical hem and the anterior forebrain, respectively) that promoted a laminar and a columnar structure into the neocortex. It is possible that independently, some birds also developed an upregulated dorsal pallium.
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Affiliation(s)
- Juan F. Montiel
- Facultad de Medicina, Centro de Investigación Biomédica, Universidad Diego PortalesSantiago, Chile
- Medical Research Council Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of OxfordOxford, UK
| | - Francisco Aboitiz
- Departamento de Psiquiatría, Escuela de Medicina, and Centro Interdisciplinario de Neurociencia, Pontificia Universidad Católica de ChileSantiago, Chile
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97
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Hevner RF. Evolution of the mammalian dentate gyrus. J Comp Neurol 2015; 524:578-94. [PMID: 26179319 DOI: 10.1002/cne.23851] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 06/02/2015] [Accepted: 07/06/2015] [Indexed: 01/08/2023]
Abstract
The dentate gyrus (DG), a part of the hippocampal formation, has important functions in learning, memory, and adult neurogenesis. Compared with homologous areas in sauropsids (birds and reptiles), the mammalian DG is larger and exhibits qualitatively different phenotypes: 1) folded (C- or V-shaped) granule neuron layer, concave toward the hilus and delimited by a hippocampal fissure; 2) nonperiventricular adult neurogenesis; and 3) prolonged ontogeny, involving extensive abventricular (basal) migration and proliferation of neural stem and progenitor cells (NSPCs). Although gaps remain, available data indicate that these DG traits are present in all orders of mammals, including monotremes and marsupials. The exception is Cetacea (whales, dolphins, and porpoises), in which DG size, convolution, and adult neurogenesis have undergone evolutionary regression. Parsimony suggests that increased growth and convolution of the DG arose in stem mammals concurrently with nonperiventricular adult hippocampal neurogenesis and basal migration of NSPCs during development. These traits could all result from an evolutionary change that enhanced radial migration of NSPCs out of the periventricular zones, possibly by epithelial-mesenchymal transition, to colonize and maintain nonperiventricular proliferative niches. In turn, increased NSPC migration and clonal expansion might be a consequence of growth in the cortical hem (medial patterning center), which produces morphogens such as Wnt3a, generates Cajal-Retzius neurons, and is regulated by Lhx2. Finally, correlations between DG convolution and neocortical gyrification (or capacity for gyrification) suggest that enhanced abventricular migration and proliferation of NSPCs played a transformative role in growth and folding of neocortex as well as archicortex.
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Affiliation(s)
- Robert F Hevner
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, 98101
- Department of Neurological Surgery, University of Washington, Seattle, Washington, 98104
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