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Lozano D, López JM, Jiménez S, Morona R, Ruíz V, Martínez A, Moreno N. Expression of SATB1 and SATB2 in the brain of bony fishes: what fish reveal about evolution. Brain Struct Funct 2023; 228:921-945. [PMID: 37002478 PMCID: PMC10147777 DOI: 10.1007/s00429-023-02632-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 03/15/2023] [Indexed: 04/03/2023]
Abstract
AbstractSatb1 and Satb2 belong to a family of homeodomain proteins with highly conserved functional and regulatory mechanisms and posttranslational modifications in evolution. However, although their distribution in the mouse brain has been analyzed, few data exist in other non-mammalian vertebrates. In the present study, we have analyzed in detail the sequence of SATB1 and SATB2 proteins and the immunolocalization of both, in combination with additional neuronal markers of highly conserved populations, in the brain of adult specimens of different bony fish models at key evolutionary points of vertebrate diversification, in particular including representative species of sarcopterygian and actinopterygian fishes. We observed a striking absence of both proteins in the pallial region of actinopterygians, only detected in lungfish, the only sarcopterygian fish. In the subpallium, including the amygdaloid complex, or comparable structures, we identified that the detected expressions of SATB1 and SATB2 have similar topologies in the studied models. In the caudal telencephalon, all models showed significant expression of SATB1 and SATB2 in the preoptic area, including the acroterminal domain of this region, where the cells were also dopaminergic. In the alar hypothalamus, all models showed SATB2 but not SATB1 in the subparaventricular area, whereas in the basal hypothalamus the cladistian species and the lungfish presented a SATB1 immunoreactive population in the tuberal hypothalamus, also labeled with SATB2 in the latter and colocalizing with the gen Orthopedia. In the diencephalon, all models, except the teleost fish, showed SATB1 in the prethalamus, thalamus and pretectum, whereas only lungfish showed also SATB2 in prethalamus and thalamus. At the midbrain level of actinopterygian fish, the optic tectum, the torus semicircularis and the tegmentum harbored populations of SATB1 cells, whereas lungfish housed SATB2 only in the torus and tegmentum. Similarly, the SATB1 expression in the rhombencephalic central gray and reticular formation was a common feature. The presence of SATB1 in the solitary tract nucleus is a peculiar feature only observed in non-teleost actinopterygian fishes. At these levels, none of the detected populations were catecholaminergic or serotonergic. In conclusion, the protein sequence analysis revealed a high degree of conservation of both proteins, especially in the functional domains, whereas the neuroanatomical pattern of SATB1 and SATB2 revealed significant differences between sarcopterygians and actinopterygians, and these divergences may be related to the different functional involvement of both in the acquisition of various neural phenotypes.
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Affiliation(s)
- Daniel Lozano
- Department of Cell Biology, Faculty of Biology, University Complutense, 28040, Madrid, Spain
| | - Jesús M López
- Department of Cell Biology, Faculty of Biology, University Complutense, 28040, Madrid, Spain
| | - Sara Jiménez
- Department of Cell Biology, Faculty of Biology, University Complutense, 28040, Madrid, Spain
| | - Ruth Morona
- Department of Cell Biology, Faculty of Biology, University Complutense, 28040, Madrid, Spain
| | - Víctor Ruíz
- Department of Cell Biology, Faculty of Biology, University Complutense, 28040, Madrid, Spain
| | - Ana Martínez
- Department of Cell Biology, Faculty of Biology, University Complutense, 28040, Madrid, Spain
| | - Nerea Moreno
- Department of Cell Biology, Faculty of Biology, University Complutense, 28040, Madrid, Spain.
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2
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Suzuki IK. Evolutionary innovations of human cerebral cortex viewed through the lens of high-throughput sequencing. Dev Neurobiol 2022; 82:476-494. [PMID: 35765158 DOI: 10.1002/dneu.22893] [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: 03/17/2022] [Revised: 04/26/2022] [Accepted: 05/24/2022] [Indexed: 11/10/2022]
Abstract
Humans had acquired a tremendously enlarged cerebral cortex containing a huge quantity and variety of cells during evolution. Such evolutionary uniqueness offers a neural basis of our cognitive innovation and human-specific features of neurodevelopmental and psychiatric disorders. Since human brain is hardly examined in vivo with experimental approaches commonly applied on animal models, the recent advancement of sequencing technologies offers an indispensable viewpoint of human brain anatomy and development. This review introduces the recent findings on the unique features in the adult and the characteristic developmental processes of the human cerebral cortex, based on high throughput DNA sequencing technologies. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Ikuo K Suzuki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
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3
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Nian FS, Hou PS. Evolving Roles of Notch Signaling in Cortical Development. Front Neurosci 2022; 16:844410. [PMID: 35422684 PMCID: PMC9001970 DOI: 10.3389/fnins.2022.844410] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 02/15/2022] [Indexed: 01/09/2023] Open
Abstract
Expansion of the neocortex is thought to pave the way toward acquisition of higher cognitive functions in mammals. The highly conserved Notch signaling pathway plays a crucial role in this process by regulating the size of the cortical progenitor pool, in part by controlling the balance between self-renewal and differentiation. In this review, we introduce the components of Notch signaling pathway as well as the different mode of molecular mechanisms, including trans- and cis-regulatory processes. We focused on the recent findings with regard to the expression pattern and levels in regulating neocortical formation in mammals and its interactions with other known signaling pathways, including Slit–Robo signaling and Shh signaling. Finally, we review the functions of Notch signaling pathway in different species as well as other developmental process, mainly somitogenesis, to discuss how modifications to the Notch signaling pathway can drive the evolution of the neocortex.
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Affiliation(s)
- Fang-Shin Nian
- Institute of Anatomy and Cell Biology, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Institute of Brain Science, College of Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Pei-Shan Hou
- Institute of Anatomy and Cell Biology, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
- *Correspondence: Pei-Shan Hou,
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4
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Puelles L. Current status of the hypothesis of a claustro-insular homolog in sauropsids. BRAIN, BEHAVIOR AND EVOLUTION 2021; 96:212-241. [PMID: 34753135 DOI: 10.1159/000520742] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 11/07/2021] [Indexed: 11/19/2022]
Abstract
The author worked before on the wide problem of the evolution of the vertebrate pallium. He proposed various Bauplan models based in the definition of a set of pallial sectors with characteristic (topologically invariant) mutual relationships and distinct molecular profiles. Out of one of these models, known as the 'updated tetrapartite pallium model', a modified definition of the earlier lateral pallium sector (LPall) emerged, which characterized it in mammals as consisting of an unitary claustro-insular transitional (mesocortical) complex intercalated between neocortex or dorsal pallium (DPall) above and olfactory cortex or ventral pallium (VPall) underneath. A distinctive molecular marker of the early-born deep claustral component of the LPall was found to be the transcription factor Nr4a2, which is not expressed significantly in the overlying insular cortex or in adjoining cortical territories (Puelles 2014). Given that earlier comparative studies had identified molecularly and topologically comparable VPall, LPall and DPall sectors in the avian pallium, an avian Nr4a2 probe was applied aiming to identify the reportedly absent avian claustro-insular complex. An early-born superficial subpopulation of the avian LPall that expresses selectively this marker through development was indeed found. This was proposed to be a claustrum homolog, whereas the remaining Nr4a2-negative avian LPall cells were assumed to represent a possible insular homolog (Puelles et al. 2016a). This last notion was supported by comparable selective expression of the mouse insular marker Cyp26b, also found restricted to the avian LPall (Puelles 2017). Some published data suggested that similar molecular properties and structure apply at the reptilian LPall. This analysis was reviewed in Puelles et al. (2017). The present commentary discusses 3-4 years later some international publications accrued in the interval that touch on the claustro-insular homology hypothesis. Some of them are opposed to the hypothesis whereas others corroborate or support it. This raises a number of secondary issues of general interest.
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Affiliation(s)
- Luis Puelles
- Department of Human Anatomy, University of Murcia, Institute of Biomedical Research (IMIB-Arrixaca), El Palmar, Spain
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5
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Gedman G, Haase B, Durieux G, Biegler MT, Fedrigo O, Jarvis ED. As above, so below: Whole transcriptome profiling demonstrates strong molecular similarities between avian dorsal and ventral pallial subdivisions. J Comp Neurol 2021; 529:3222-3246. [PMID: 33871048 PMCID: PMC8251894 DOI: 10.1002/cne.25159] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 03/16/2021] [Accepted: 03/19/2021] [Indexed: 12/19/2022]
Abstract
Over the last two decades, beginning with the Avian Brain Nomenclature Forum in 2000, major revisions have been made to our understanding of the organization and nomenclature of the avian brain. However, there are still unresolved questions on avian pallial organization, particularly whether the cells above the vestigial ventricle represent distinct populations to those below it or similar populations. To test these two hypotheses, we profiled the transcriptomes of the major avian pallial subdivisions dorsal and ventral to the vestigial ventricle boundary using RNA sequencing and a new zebra finch genome assembly containing about 22,000 annotated, complete genes. We found that the transcriptomes of neural populations above and below the ventricle were remarkably similar. Each subdivision in dorsal pallium (Wulst) had a corresponding molecular counterpart in the ventral pallium (dorsal ventricular ridge). In turn, each corresponding subdivision exhibited shared gene co‐expression modules that contained gene sets enriched in functional specializations, such as anatomical structure development, synaptic transmission, signaling, and neurogenesis. These findings are more in line with the continuum hypothesis of avian brain subdivision organization above and below the vestigial ventricle space, with the pallium as a whole consisting of four major cell populations (intercalated pallium, mesopallium, hyper‐nidopallium, and arcopallium) instead of seven (hyperpallium apicale, interstitial hyperpallium apicale, intercalated hyperpallium, hyperpallium densocellare, mesopallium, nidopallium, and arcopallium). We suggest adopting a more streamlined hierarchical naming system that reflects the robust similarities in gene expression, neural connectivity motifs, and function. These findings have important implications for our understanding of overall vertebrate brain evolution.
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Affiliation(s)
- Gregory Gedman
- Laboratory of the Neurogenetics of Language, The Rockefeller University, New York, New York, USA
| | - Bettina Haase
- Laboratory of the Neurogenetics of Language, The Rockefeller University, New York, New York, USA.,Vertebrate Genome Laboratory, The Rockefeller University, New York, New York, USA
| | - Gillian Durieux
- Behavioural Genomics, Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Matthew T Biegler
- Laboratory of the Neurogenetics of Language, The Rockefeller University, New York, New York, USA
| | - Olivier Fedrigo
- Laboratory of the Neurogenetics of Language, The Rockefeller University, New York, New York, USA.,Vertebrate Genome Laboratory, The Rockefeller University, New York, New York, USA
| | - Erich D Jarvis
- Laboratory of the Neurogenetics of Language, The Rockefeller University, New York, New York, USA.,Vertebrate Genome Laboratory, The Rockefeller University, New York, New York, USA.,Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
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6
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Biegler MT, Cantin LJ, Scarano DL, Jarvis ED. Controlling for activity-dependent genes and behavioral states is critical for determining brain relationships within and across species. J Comp Neurol 2021; 529:3206-3221. [PMID: 33855704 PMCID: PMC8205984 DOI: 10.1002/cne.25157] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 03/16/2021] [Accepted: 03/19/2021] [Indexed: 12/16/2022]
Abstract
The genetic profile of vertebrate pallia has long driven debate on homology across distantly related clades. Based on an expression profile of the orphan nuclear receptor NR4A2 in mouse and chicken brains, Puelles et al. (The Journal of Comparative Neurology, 2016, 524, 665–703) concluded that the avian lateral mesopallium is homologous to the mammalian claustrum, and the medial mesopallium homologous to the insula cortex. They argued that their findings contradict conclusions by Jarvis et al. (The Journal of Comparative Neurology, 2013, 521, 3614–3665) and Chen et al. (The Journal of Comparative Neurology, 2013, 521, 3666–3701) that the hyperpallium densocellare is instead a mesopallium cell population, and by Suzuki and Hirata (Frontiers in Neuroanatomy, 2014, 8, 783) that the avian mesopallium is homologous to mammalian cortical layers 2/3. Here, we find that NR4A2 is an activity‐dependent gene and cannot be used to determine brain organization or species relationships without considering behavioral state. Activity‐dependent NR4A2 expression has been previously demonstrated in the rodent brain, with the highest induction occurring within the claustrum, amygdala, deep and superficial cortical layers, and hippocampus. In the zebra finch, we find that NR4A2 is constitutively expressed in the arcopallium, but induced in parts of the mesopallium, and in sparse cells within the hyperpallium, depending on animal stimulus or behavioral state. Basal and induced NR4A2 expression patterns do not discount the previously named avian hyperpallium densocellare as dorsal mesopallium and conflict with proposed homology between the avian mesopallium and mammalian claustrum/insula at the exclusion of other brain regions. Broadly, these findings highlight the importance of controlling for behavioral state and neural activity to genetically define brain cell population relationships within and across species.
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Affiliation(s)
- Matthew T Biegler
- Department of Neurobiology, Duke University Medical Center, Durham, North Carolina, USA.,Laboratory of Neurogenetics of Language, The Rockefeller University, New York, New York, USA
| | - Lindsey J Cantin
- Laboratory of Neurogenetics of Language, The Rockefeller University, New York, New York, USA
| | - Danielle L Scarano
- Department of Neurobiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Erich D Jarvis
- Department of Neurobiology, Duke University Medical Center, Durham, North Carolina, USA.,Laboratory of Neurogenetics of Language, The Rockefeller University, New York, New York, USA.,Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
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7
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García-Moreno F, Molnár Z. Variations of telencephalic development that paved the way for neocortical evolution. Prog Neurobiol 2020; 194:101865. [PMID: 32526253 PMCID: PMC7656292 DOI: 10.1016/j.pneurobio.2020.101865] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 05/29/2020] [Accepted: 06/05/2020] [Indexed: 12/13/2022]
Abstract
Charles Darwin stated, "community in embryonic structure reveals community of descent". Thus, to understand how the neocortex emerged during mammalian evolution we need to understand the evolution of the development of the pallium, the source of the neocortex. In this article, we review the variations in the development of the pallium that enabled the production of the six-layered neocortex. We propose that an accumulation of subtle modifications from very early brain development accounted for the diversification of vertebrate pallia and the origin of the neocortex. Initially, faint differences of expression of secretable morphogens promote a wide variety in the proportions and organization of sectors of the early pallium in different vertebrates. It prompted different sectors to host varied progenitors and distinct germinative zones. These cells and germinative compartments generate diverse neuronal populations that migrate and mix with each other through radial and tangential migrations in a taxon-specific fashion. Together, these early variations had a profound influence on neurogenetic gradients, lamination, positioning, and connectivity. Gene expression, hodology, and physiological properties of pallial neurons are important features to suggest homologies, but the origin of cells and their developmental trajectory are fundamental to understand evolutionary changes. Our review compares the development of the homologous pallial sectors in sauropsids and mammals, with a particular focus on cell lineage, in search of the key changes that led to the appearance of the mammalian neocortex.
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Affiliation(s)
- Fernando García-Moreno
- Achucarro Basque Center for Neuroscience, Scientific Park of the University of the Basque Country (UPV/EHU), 48940, Leioa, Spain; IKERBASQUE Foundation, María Díaz de Haro 3, 6th Floor, 48013, Bilbao, Spain; Department of Neuroscience, Faculty of Medicine and Odontology, UPV/EHU, Barrio Sarriena s/n, 48940, Leioa, Bizkaia, Spain.
| | - Zoltán Molnár
- Department of Physiology, Anatomy and Genetics, Sherrington Building, University of Oxford, Oxford, OX1 3QX, UK.
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8
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Stacho M, Herold C, Rook N, Wagner H, Axer M, Amunts K, Güntürkün O. A cortex-like canonical circuit in the
avian forebrain. Science 2020; 369:369/6511/eabc5534. [DOI: 10.1126/science.abc5534] [Citation(s) in RCA: 78] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 08/13/2020] [Indexed: 12/15/2022]
Abstract
Although the avian pallium seems to lack
an organization akin to that of the cerebral
cortex, birds exhibit extraordinary cognitive
skills that are comparable to those of mammals. We
analyzed the fiber architecture of the avian
pallium with three-dimensional polarized light
imaging and subsequently reconstructed local and
associative pallial circuits with tracing
techniques. We discovered an iteratively repeated,
column-like neuronal circuitry across the
layer-like nuclear boundaries of the hyperpallium
and the sensory dorsal ventricular ridge. These
circuits are connected to neighboring columns and,
via tangential layer-like connections, to higher
associative and motor areas. Our findings indicate
that this avian canonical circuitry is similar to
its mammalian counterpart and might constitute the
structural basis of neuronal computation.
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Affiliation(s)
- Martin Stacho
- Department of Biopsychology,
Institute of Cognitive Neuroscience, Faculty of
Psychology, Ruhr-University Bochum, 44801 Bochum,
Germany
- Department of Neurophysiology,
Institute of Physiology, Faculty of Medicine,
Ruhr-University Bochum, 44801 Bochum,
Germany
| | - Christina Herold
- Cécile and Oskar Vogt Institute for
Brain Research, Medical Faculty, Heinrich Heine
University of Düsseldorf, 40225 Düsseldorf,
Germany
| | - Noemi Rook
- Department of Biopsychology,
Institute of Cognitive Neuroscience, Faculty of
Psychology, Ruhr-University Bochum, 44801 Bochum,
Germany
| | - Hermann Wagner
- Institute for Biology II, RWTH Aachen
University, 52074 Aachen, Germany
| | - Markus Axer
- Institute of Neuroscience and
Medicine INM-1, Research Center Jülich, 52425
Jülich, Germany
| | - Katrin Amunts
- Cécile and Oskar Vogt Institute for
Brain Research, Medical Faculty, Heinrich Heine
University of Düsseldorf, 40225 Düsseldorf,
Germany
- Institute of Neuroscience and
Medicine INM-1, Research Center Jülich, 52425
Jülich, Germany
| | - Onur Güntürkün
- Department of Biopsychology,
Institute of Cognitive Neuroscience, Faculty of
Psychology, Ruhr-University Bochum, 44801 Bochum,
Germany
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9
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Iwashita M, Nomura T, Suetsugu T, Matsuzaki F, Kojima S, Kosodo Y. Comparative Analysis of Brain Stiffness Among Amniotes Using Glyoxal Fixation and Atomic Force Microscopy. Front Cell Dev Biol 2020; 8:574619. [PMID: 33043008 PMCID: PMC7517470 DOI: 10.3389/fcell.2020.574619] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Accepted: 08/21/2020] [Indexed: 12/17/2022] Open
Abstract
Brain structures are diverse among species despite the essential molecular machinery of neurogenesis being common. Recent studies have indicated that differences in the mechanical properties of tissue may result in the dynamic deformation of brain structure, such as folding. However, little is known about the correlation between mechanical properties and species-specific brain structures. To address this point, a comparative analysis of mechanical properties using several animals is required. For a systematic measurement of the brain stiffness of remotely maintained animals, we developed a novel strategy of tissue-stiffness measurement using glyoxal as a fixative combined with atomic force microscopy. A comparison of embryonic and juvenile mouse and songbird brain tissue revealed that glyoxal fixation can maintain brain structure as well as paraformaldehyde (PFA) fixation. Notably, brain tissue fixed by glyoxal remained much softer than PFA-fixed brains, and it can maintain the relative stiffness profiles of various brain regions. Based on this method, we found that the homologous brain regions between mice and songbirds exhibited different stiffness patterns. We also measured brain stiffness in other amniotes (chick, turtle, and ferret) following glyoxal fixation. We found stage-dependent and species-specific stiffness in pallia among amniotes. The embryonic chick and matured turtle pallia showed gradually increasing stiffness along the apico-basal tissue axis, the lowest region at the most apical region, while the ferret pallium exhibited a catenary pattern, that is, higher in the ventricular zone, the inner subventricular zone, and the cortical plate and the lowest in the outer subventricular zone. These results indicate that species-specific microenvironments with distinct mechanical properties emerging during development might contribute to the formation of brain structures with unique morphology.
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Affiliation(s)
| | - Tadashi Nomura
- Developmental Neurobiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Taeko Suetsugu
- RIKEN Center for Biosystems Dynamics Research, Kobe, Japan
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10
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Lovell PV, Wirthlin M, Kaser T, Buckner AA, Carleton JB, Snider BR, McHugh AK, Tolpygo A, Mitra PP, Mello CV. ZEBrA: Zebra finch Expression Brain Atlas-A resource for comparative molecular neuroanatomy and brain evolution studies. J Comp Neurol 2020; 528:2099-2131. [PMID: 32037563 DOI: 10.1002/cne.24879] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 01/22/2020] [Accepted: 01/25/2020] [Indexed: 12/14/2022]
Abstract
An in-depth understanding of the genetics and evolution of brain function and behavior requires a detailed mapping of gene expression in functional brain circuits across major vertebrate clades. Here we present the Zebra finch Expression Brain Atlas (ZEBrA; www.zebrafinchatlas.org, RRID: SCR_012988), a web-based resource that maps the expression of genes linked to a broad range of functions onto the brain of zebra finches. ZEBrA is a first of its kind gene expression brain atlas for a bird species and a first for any sauropsid. ZEBrA's >3,200 high-resolution digital images of in situ hybridized sections for ~650 genes (as of June 2019) are presented in alignment with an annotated histological atlas and can be browsed down to cellular resolution. An extensive relational database connects expression patterns to information about gene function, mouse expression patterns and phenotypes, and gene involvement in human diseases and communication disorders. By enabling brain-wide gene expression assessments in a bird, ZEBrA provides important substrates for comparative neuroanatomy and molecular brain evolution studies. ZEBrA also provides unique opportunities for linking genetic pathways to vocal learning and motor control circuits, as well as for novel insights into the molecular basis of sex steroids actions, brain dimorphisms, reproductive and social behaviors, sleep function, and adult neurogenesis, among many fundamental themes.
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Affiliation(s)
- Peter V Lovell
- Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, Oregon
| | - Morgan Wirthlin
- Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, Oregon
| | - Taylor Kaser
- Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, Oregon
| | - Alexa A Buckner
- Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, Oregon
| | - Julia B Carleton
- Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, Oregon
| | - Brian R Snider
- Center for Spoken Language Understanding, Institute on Development and Disability, Oregon Health and Science University, Portland, Oregon
| | - Anne K McHugh
- Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, Oregon
| | | | - Partha P Mitra
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York
| | - Claudio V Mello
- Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, Oregon
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11
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Suzuki IK. Molecular drivers of human cerebral cortical evolution. Neurosci Res 2019; 151:1-14. [PMID: 31175883 DOI: 10.1016/j.neures.2019.05.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 05/30/2019] [Accepted: 05/31/2019] [Indexed: 01/10/2023]
Abstract
One of the most important questions in human evolutionary biology is how our ancestor has acquired an expanded volume of the cerebral cortex, which may have significantly impacted on improving our cognitive abilities. Recent comparative approaches have identified developmental features unique to the human or hominid cerebral cortex, not shared with other animals including conventional experimental models. In addition, genomic, transcriptomic, and epigenomic signatures associated with human- or hominid-specific processes of the cortical development are becoming identified by virtue of technical progress in the deep nucleotide sequencing. This review discusses ontogenic and phylogenetic processes of the human cerebral cortex, followed by the introduction of recent comprehensive approaches identifying molecular mechanisms potentially driving the evolutionary changes in the cortical development.
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Affiliation(s)
- Ikuo K Suzuki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 Japan; VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; Department of Neurosciences, Leuven Brain Institute, KULeuven, 3000 Leuven, Belgium; Université Libre de Bruxelles (U.L.B.), Institut de Recherches en Biologie Humaine et Moléculaire (IRIBHM), ULB Neuroscience Institute (UNI), 1070 Brussels, Belgium.
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12
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Tosches MA, Laurent G. Evolution of neuronal identity in the cerebral cortex. Curr Opin Neurobiol 2019; 56:199-208. [PMID: 31103814 DOI: 10.1016/j.conb.2019.04.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 03/04/2019] [Accepted: 04/22/2019] [Indexed: 12/20/2022]
Abstract
To understand neocortex evolution, we must define a theory for the elaboration of cell types, circuits, and architectonics from an ancestral structure that is consistent with developmental, molecular, and genetic data. To this end, cross-species comparison of cortical cell types emerges as a very informative approach. We review recent results that illustrate the contribution of molecular and transcriptomic data to the construction of plausible models of cortical cell-type evolution.
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Affiliation(s)
| | - Gilles Laurent
- Max Planck Institute for Brain Research, Frankfurt am Main, Germany
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13
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García-Moreno F, Anderton E, Jankowska M, Begbie J, Encinas JM, Irimia M, Molnár Z. Absence of Tangentially Migrating Glutamatergic Neurons in the Developing Avian Brain. Cell Rep 2019; 22:96-109. [PMID: 29298437 PMCID: PMC5770341 DOI: 10.1016/j.celrep.2017.12.032] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 07/29/2017] [Accepted: 12/08/2017] [Indexed: 12/16/2022] Open
Abstract
Several neuronal populations orchestrate neocortical development during mammalian embryogenesis. These include the glutamatergic subplate-, Cajal-Retzius-, and ventral pallium-derived populations, which coordinate cortical wiring, migration, and proliferation, respectively. These transient populations are primarily derived from other non-cortical pallial sources that migrate to the dorsal pallium. Are these migrations to the dorsal pallium conserved in amniotes or are they specific to mammals? Using in ovo electroporation, we traced the entire lineage of defined chick telencephalic progenitors. We found that several pallial sources that produce tangential migratory neurons in mammals only produced radially migrating neurons in the avian brain. Moreover, ectopic expression of VP-specific mammalian Dbx1 in avian brains altered neurogenesis but did not convert the migration into a mammal-like tangential movement. Together, these data indicate that tangential cellular contributions of glutamatergic neurons originate from outside the dorsal pallium and that pallial Dbx1 expression may underlie the generation of the mammalian neocortex during evolution.
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Affiliation(s)
- Fernando García-Moreno
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK; Achucarro Basque Center for Neuroscience, Parque Científico UPV/EHU Edif. Sede, 48940 Leioa, Spain; IKERBASQUE Foundation, María Díaz de Haro 3, 6th Floor, 48013 Bilbao, Spain.
| | - Edward Anderton
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Marta Jankowska
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK; College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, University of Warsaw, Banacha 2C, 02-097 Warsaw, Poland; Faculty of Biology, University of Warsaw, Ilji Miecznikowa 1, 02-096 Warsaw, Poland
| | - Jo Begbie
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK
| | - Juan Manuel Encinas
- Achucarro Basque Center for Neuroscience, Parque Científico UPV/EHU Edif. Sede, 48940 Leioa, Spain; IKERBASQUE Foundation, María Díaz de Haro 3, 6th Floor, 48013 Bilbao, Spain
| | - Manuel Irimia
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), Barcelona Institute for Science and Technology, 08003 Barcelona, Spain; Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain
| | - Zoltán Molnár
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK.
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14
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Puelles L, Alonso A, García-Calero E, Martínez-de-la-Torre M. Concentric ring topology of mammalian cortical sectors and relevance for patterning studies. J Comp Neurol 2019; 527:1731-1752. [PMID: 30737959 DOI: 10.1002/cne.24650] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 01/05/2019] [Accepted: 01/28/2019] [Indexed: 01/07/2023]
Abstract
Models aiming to explain causally the evolutionary or ontogenetic emergence of the pallial isocortex and its regional/areal heterogeneity in mammals use simple or complex assumptions about the pallial structure present in basal mammals and nonmammals. The question arises: how complex is the pattern that needs to be accounted for in causal models? This topic is also paramount for comparative purposes, since some topological relationships may be explained as being ancestral, rather than newly emerged. The mouse pallium is apt to be reexamined in this context, due to the breadth of available molecular markers and correlative experimental patterning results. We center the present essay on a recapitulative glance at the classic theory of concentric mammalian allo-, meso-, and neocortex domains. In its simplest terms, this theory postulates a central neocortical island (6 layers) separated by a surrounding mesocortical ring (4-5 layers) from a peripheral allocortical ring (3 layers). These territories show additional partition into regional or areal subdivisions. There are also borderline amygdalar, claustral, and septal areas of the pallium, nuclear in structure. There has been little effort so far to contemplate the full concentric ring model in current "cortex patterning" models. In this essay, we recapitulate the ring idea in mammals (mouse) and consider a potential causal patterning scenario using topologic models. Finally, we briefly explore how far this theory may apply to pallium models proposed recently for sauropsids.
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Affiliation(s)
- Luis Puelles
- Department of Human Anatomy and IMIB-Arrixaca Institute, School of Medicine, University of Murcia, Murcia, Spain
| | - Antonia Alonso
- Department of Human Anatomy and IMIB-Arrixaca Institute, School of Medicine, University of Murcia, Murcia, Spain
| | - Elena García-Calero
- Department of Human Anatomy and IMIB-Arrixaca Institute, School of Medicine, University of Murcia, Murcia, Spain
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15
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Nomura T, Yamashita W, Gotoh H, Ono K. Species-Specific Mechanisms of Neuron Subtype Specification Reveal Evolutionary Plasticity of Amniote Brain Development. Cell Rep 2018; 22:3142-3151. [DOI: 10.1016/j.celrep.2018.02.086] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 11/19/2017] [Accepted: 02/22/2018] [Indexed: 10/17/2022] Open
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16
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Martínez-Cerdeño V, García-Moreno F, Tosches MA, Csillag A, Manger PR, Molnár Z. Update on forebrain evolution: From neurogenesis to thermogenesis. Semin Cell Dev Biol 2017; 76:15-22. [PMID: 28964836 DOI: 10.1016/j.semcdb.2017.09.034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 09/22/2017] [Accepted: 09/26/2017] [Indexed: 01/25/2023]
Abstract
Comparative developmental studies provide growing understanding of vertebrate forebrain evolution. This short review directs the spotlight to some newly emerging aspects, including the evolutionary origin of the proliferative region known as the subventricular zone (SVZ) and of intermediate progenitor cells (IPCs) that populate the SVZ, neural circuits that originated within homologous regions across all amniotes, and the role of thermogenesis in the acquisition of an increased brain size. These data were presented at the 8th European Conference on Comparative Neurobiology.
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Affiliation(s)
- Verónica Martínez-Cerdeño
- Department of Pathology and Laboratory Medicine, UC Davis, USA; Institute for Pediatric Regenerative Medicine and Shriners Hospitals for Children Northern California, USA; MIND Institute, UC Davis School of Medicine, CA, USA.
| | - Fernando García-Moreno
- Achucarro Basque Center for Neuroscience, Parque Científico UPV/EHU Edif. Sede, E-48940 Leioa, Spain
| | | | - András Csillag
- Department of Anatomy, Histology and Embryology, Semmelweis University, Faculty of Medicine, Budapest, Hungary
| | - Paul R Manger
- School of Anatomical Sciences, Faculty of Health Sciences, University of Witwatersrand, South Africa
| | - Zoltán Molnár
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK.
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Desfilis E, Abellán A, Sentandreu V, Medina L. Expression of regulatory genes in the embryonic brain of a lizard and implications for understanding pallial organization and evolution. J Comp Neurol 2017; 526:166-202. [PMID: 28891227 PMCID: PMC5765483 DOI: 10.1002/cne.24329] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 08/13/2017] [Accepted: 09/01/2017] [Indexed: 02/03/2023]
Abstract
The comparison of gene expression patterns in the embryonic brain of mouse and chicken is being essential for understanding pallial organization. However, the scarcity of gene expression data in reptiles, crucial for understanding evolution, makes it difficult to identify homologues of pallial divisions in different amniotes. We cloned and analyzed the expression of the genes Emx1, Lhx2, Lhx9, and Tbr1 in the embryonic telencephalon of the lacertid lizard Psammodromus algirus. The comparative expression patterns of these genes, critical for pallial development, are better understood when using a recently proposed six‐part model of pallial divisions. The lizard medial pallium, expressing all genes, includes the medial and dorsomedial cortices, and the majority of the dorsal cortex, except the region of the lateral cortical superposition. The latter is rich in Lhx9 expression, being excluded as a candidate of dorsal or lateral pallia, and may belong to a distinct dorsolateral pallium, which extends from rostral to caudal levels. Thus, the neocortex homolog cannot be found in the classical reptilian dorsal cortex, but perhaps in a small Emx1‐expressing/Lhx9‐negative area at the front of the telencephalon, resembling the avian hyperpallium. The ventral pallium, expressing Lhx9, but not Emx1, gives rise to the dorsal ventricular ridge and appears comparable to the avian nidopallium. We also identified a distinct ventrocaudal pallial sector comparable to the avian arcopallium and to part of the mammalian pallial amygdala. These data open new venues for understanding the organization and evolution of the pallium.
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Affiliation(s)
- Ester Desfilis
- Laboratory of Evolutionary and Developmental Neurobiology, Department of Experimental Medicine, Faculty of Medicine, University of Lleida, Lleida Institute for Biomedical Research Dr. Pifarré Foundation (IRBLleida), 25198, Lleida, Spain
| | - Antonio Abellán
- Laboratory of Evolutionary and Developmental Neurobiology, Department of Experimental Medicine, Faculty of Medicine, University of Lleida, Lleida Institute for Biomedical Research Dr. Pifarré Foundation (IRBLleida), 25198, Lleida, Spain
| | - Vicente Sentandreu
- Servicio Central de Apoyo a la Investigación Experimental (SCSIE), Sección de Genómica, University of València, 46100, València, Spain
| | - Loreta Medina
- Laboratory of Evolutionary and Developmental Neurobiology, Department of Experimental Medicine, Faculty of Medicine, University of Lleida, Lleida Institute for Biomedical Research Dr. Pifarré Foundation (IRBLleida), 25198, Lleida, Spain
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18
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Moreno N, González A. Pattern of Neurogenesis and Identification of Neuronal Progenitor Subtypes during Pallial Development in Xenopus laevis. Front Neuroanat 2017; 11:24. [PMID: 28396626 PMCID: PMC5366753 DOI: 10.3389/fnana.2017.00024] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 03/08/2017] [Indexed: 11/13/2022] Open
Abstract
The complexity of the pallium during evolution has increased dramatically in many different respects. The highest level of complexity is found in mammals, where most of the pallium (cortex) shows a layered organization and neurons are generated during development following an inside-out order, a sequence not observed in other amniotes (birds and reptiles). Species-differences may be related to major neurogenetic events, from the neural progenitors that divide and produce all pallial cells. In mammals, two main types of precursors have been described, primary precursor cells in the ventricular zone (vz; also called radial glial cells or apical progenitors) and secondary precursor cells (called basal or intermediate progenitors) separated from the ventricle surface. Previous studies suggested that pallial neurogenetic cells, and especially the intermediate progenitors, evolved independently in mammalian and sauropsid lineages. In the present study, we examined pallial neurogenesis in the amphibian Xenopus laevis, a representative species of the only group of tetrapods that are anamniotes. The pattern of pallial proliferation during embryonic and larval development was studied, together with a multiple immunohistochemical analysis of putative progenitor cells. We found that there are two phases of progenitor divisions in the developing pallium that, following the radial unit concept from the ventricle to the mantle, finally result in an outside-in order of mature neurons, what seems to be the primitive condition of vertebrates. Gene expressions of key transcription factors that characterize radial glial cells in the vz were demonstrated in Xenopus. In addition, although mitotic cells were corroborated outside the vz, the expression pattern of markers for intermediate progenitors differed from mammals.
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Affiliation(s)
- Nerea Moreno
- Department of Cell Biology, Faculty of Biology, Complutense University of Madrid Madrid, Spain
| | - Agustín González
- Department of Cell Biology, Faculty of Biology, Complutense University of Madrid Madrid, Spain
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19
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Suzuki IK, Vanderhaeghen P. Is this a brain which I see before me? Modeling human neural development with pluripotent stem cells. Development 2016; 142:3138-50. [PMID: 26395142 DOI: 10.1242/dev.120568] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The human brain is arguably the most complex structure among living organisms. However, the specific mechanisms leading to this complexity remain incompletely understood, primarily because of the poor experimental accessibility of the human embryonic brain. Over recent years, technologies based on pluripotent stem cells (PSCs) have been developed to generate neural cells of various types. While the translational potential of PSC technologies for disease modeling and/or cell replacement therapies is usually put forward as a rationale for their utility, they are also opening novel windows for direct observation and experimentation of the basic mechanisms of human brain development. PSC-based studies have revealed that a number of cardinal features of neural ontogenesis are remarkably conserved in human models, which can be studied in a reductionist fashion. They have also revealed species-specific features, which constitute attractive lines of investigation to elucidate the mechanisms underlying the development of the human brain, and its link with evolution.
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Affiliation(s)
- Ikuo K Suzuki
- Université Libre de Bruxelles (ULB), Institute for Interdisciplinary Research (IRIBHM), and ULB Institute of Neuroscience (UNI), 808 Route de Lennik, Brussels B-1070, Belgium
| | - Pierre Vanderhaeghen
- Université Libre de Bruxelles (ULB), Institute for Interdisciplinary Research (IRIBHM), and ULB Institute of Neuroscience (UNI), 808 Route de Lennik, Brussels B-1070, Belgium WELBIO, Université Libre de Bruxelles, 808 Route de Lennik, Brussels B-1070, Belgium
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20
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Puelles L, Ayad A, Alonso A, Sandoval J, MartÍnez-de-la-Torre M, Medina L, Ferran J. Selective early expression of the orphan nuclear receptorNr4a2identifies the claustrum homolog in the avian mesopallium: Impact on sauropsidian/mammalian pallium comparisons. J Comp Neurol 2015; 524:665-703. [DOI: 10.1002/cne.23902] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 09/10/2015] [Accepted: 09/11/2015] [Indexed: 12/17/2022]
Affiliation(s)
- L. Puelles
- Department of Human Anatomy, Faculty of Medicine; University of Murcia, and Instituto Murciano de Investigación Biosanitaria; Murcia 30071 Spain
| | - A. Ayad
- Department of Human Anatomy, Faculty of Medicine; University of Murcia, and Instituto Murciano de Investigación Biosanitaria; Murcia 30071 Spain
| | - A. Alonso
- Department of Human Anatomy, Faculty of Medicine; University of Murcia, and Instituto Murciano de Investigación Biosanitaria; Murcia 30071 Spain
| | - J.E. Sandoval
- Department of Human Anatomy, Faculty of Medicine; University of Murcia, and Instituto Murciano de Investigación Biosanitaria; Murcia 30071 Spain
| | - M. MartÍnez-de-la-Torre
- Department of Human Anatomy, Faculty of Medicine; University of Murcia, and Instituto Murciano de Investigación Biosanitaria; Murcia 30071 Spain
| | - L. Medina
- Laboratory of Brain Development and Evolution, Department of Experimental Medicine, Faculty of Medicine; University of Lleida, and IRBLleida Institute of Biomedical Research of Lleida; Lleida 25198 Spain
| | - J.L. Ferran
- Department of Human Anatomy, Faculty of Medicine; University of Murcia, and Instituto Murciano de Investigación Biosanitaria; Murcia 30071 Spain
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21
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De Juan Romero C, Borrell V. Coevolution of radial glial cells and the cerebral cortex. Glia 2015; 63:1303-19. [PMID: 25808466 PMCID: PMC5008138 DOI: 10.1002/glia.22827] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 03/09/2015] [Indexed: 12/14/2022]
Abstract
Radial glia cells play fundamental roles in the development of the cerebral cortex, acting both as the primary stem and progenitor cells, as well as the guides for neuronal migration and lamination. These critical functions of radial glia cells in cortical development have been discovered mostly during the last 15 years and, more recently, seminal studies have demonstrated the existence of a remarkable diversity of additional cortical progenitor cell types, including a variety of basal radial glia cells with key roles in cortical expansion and folding, both in ontogeny and phylogeny. In this review, we summarize the main cellular and molecular mechanisms known to be involved in cerebral cortex development in mouse, as the currently preferred animal model, and then compare these with known mechanisms in other vertebrates, both mammal and nonmammal, including human. This allows us to present a global picture of how radial glia cells and the cerebral cortex seem to have coevolved, from reptiles to primates, leading to the remarkable diversity of vertebrate cortical phenotypes.
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Affiliation(s)
- Camino De Juan Romero
- Instituto De Neurociencias, Consejo Superior De Investigaciones Científicas & Universidad Miguel Hernández, Sant Joan D'alacant, Spain
| | - Víctor Borrell
- Instituto De Neurociencias, Consejo Superior De Investigaciones Científicas & Universidad Miguel Hernández, Sant Joan D'alacant, Spain
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22
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Luzzati F. A hypothesis for the evolution of the upper layers of the neocortex through co-option of the olfactory cortex developmental program. Front Neurosci 2015; 9:162. [PMID: 26029038 PMCID: PMC4429232 DOI: 10.3389/fnins.2015.00162] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2015] [Accepted: 04/20/2015] [Indexed: 12/31/2022] Open
Abstract
The neocortex is unique to mammals and its evolutionary origin is still highly debated. The neocortex is generated by the dorsal pallium ventricular zone, a germinative domain that in reptiles give rise to the dorsal cortex. Whether this latter allocortical structure contains homologs of all neocortical cell types it is unclear. Recently we described a population of DCX+/Tbr1+ cells that is specifically associated with the layer II of higher order areas of both the neocortex and of the more evolutionary conserved piriform cortex. In a reptile similar cells are present in the layer II of the olfactory cortex and the DVR but not in the dorsal cortex. These data are consistent with the proposal that the reptilian dorsal cortex is homologous only to the deep layers of the neocortex while the upper layers are a mammalian innovation. Based on our observations we extended these ideas by hypothesizing that this innovation was obtained by co-opting a lateral and/or ventral pallium developmental program. Interestingly, an analysis in the Allen brain atlas revealed a striking similarity in gene expression between neocortical layers II/III and piriform cortex. We thus propose a model in which the early neocortical column originated by the superposition of the lateral olfactory and dorsal cortex. This model is consistent with the fossil record and may account not only for the topological position of the neocortex, but also for its basic cytoarchitectural and hodological features. This idea is also consistent with previous hypotheses that the peri-allocortex represents the more ancient neocortical part. The great advances in deciphering the molecular logic of the amniote pallium developmental programs will hopefully enable to directly test our hypotheses in the next future.
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Affiliation(s)
- Federico Luzzati
- Department of Life Sciences and Systems Biology (DBIOS), University of Turin Turin, Italy ; Neuroscience Institute Cavalieri Ottolenghi Orbassano, Truin, Italy
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Tosa Y, Hirao A, Matsubara I, Kawaguchi M, Fukui M, Kuratani S, Murakami Y. Development of the thalamo-dorsal ventricular ridge tract in the Chinese soft-shelled turtle, Pelodiscus sinensis. Dev Growth Differ 2014; 57:40-57. [PMID: 25494924 DOI: 10.1111/dgd.12186] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 10/07/2014] [Accepted: 10/07/2014] [Indexed: 01/04/2023]
Abstract
With the exception of that from the olfactory system, the vertebrate sensory information is relayed by the dorsal thalamus (dTh) to be carried to the telencephalon via the thalamo-telencephalic tract. Although the trajectory of the tract from the dTh to the basal telencephalon seems to be highly conserved among amniotes, the axonal terminals vary in each group. In mammals, thalamic axons project onto the neocortex, whereas they project onto the dorsal pallium and the dorsal ventricular ridge (DVR) in reptiles and birds. To ascertain the evolutionary development of the thalamo-telencephalic connection in amniotes, we focused on reptiles. Using the Chinese soft-shelled turtle (Pelodiscus sinensis), we studied the developmental course of the thalamic axons projecting onto the DVR. We found, during the developmental period when the thalamo-DVR connection forms, that transcripts of axon guidance molecules, including EphA4 and Slit2, were expressed in the diencephalon, similar to the mouse embryo. These results suggest that the basic mechanisms responsible for the formation of the thalamo-telencephalic tract are shared across amniote lineages. Conversely, there was a characteristic difference in the expression patterns of Slit2, Netrin1, and EphrinA5 in the telencephalon between synapsid (mammalian) and diapsid (reptilian and avian) lineages. This indicates that changes in the expression domains of axon guidance molecules may modify the thalamic axon projection and lead to the diversity of neuronal circuits in amniotes.
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Affiliation(s)
- Yasuhiko Tosa
- Graduate School of Science and Engineering, Ehime University, 2-5 Bunkyo-cho, Matsuyama, 790-8577, Japan
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