1
|
L'Esperance OJ, McGhee J, Davidson G, Niraula S, Smith AS, Sosunov AA, Yan SS, Subramanian J. Functional Connectivity Favors Aberrant Visual Network c-Fos Expression Accompanied by Cortical Synapse Loss in a Mouse Model of Alzheimer's Disease. J Alzheimers Dis 2024:JAD240776. [PMID: 39121131 DOI: 10.3233/jad-240776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/11/2024]
Abstract
Background While Alzheimer's disease (AD) has been extensively studied with a focus on cognitive networks, visual network dysfunction has received less attention despite compelling evidence of its significance in AD patients and mouse models. We recently reported c-Fos and synaptic dysregulation in the primary visual cortex of a pre-amyloid plaque AD-model. Objective We test whether c-Fos expression and presynaptic density/dynamics differ in cortical and subcortical visual areas in an AD-model. We also examine whether aberrant c-Fos expression is inherited through functional connectivity and shaped by light experience. Methods c-Fos+ cell density, functional connectivity, and their experience-dependent modulation were assessed for visual and whole-brain networks in both sexes of 4-6-month-old J20 (AD-model) and wildtype (WT) mice. Cortical and subcortical differences in presynaptic vulnerability in the AD-model were compared using ex vivo and in vivo imaging. Results Visual cortical, but not subcortical, networks show aberrant c-Fos expression and impaired experience-dependent modulation. The average functional connectivity of a brain region in WT mice significantly predicts aberrant c-Fos expression, which correlates with impaired experience-dependent modulation in the AD-model. We observed a subtle yet selective weakening of excitatory visual cortical synapses. The size distribution of cortical boutons in the AD-model is downscaled relative to those in WT mice, suggesting a synaptic scaling-like adaptation of bouton size. Conclusions Visual network structural and functional disruptions are biased toward cortical regions in pre-plaque J20 mice, and the cellular and synaptic dysregulation in the AD-model represents a maladaptive modification of the baseline physiology seen in WT conditions.
Collapse
Affiliation(s)
- Oliver J L'Esperance
- Department of Pharmacology and Toxicology, School of Pharmacy, University of Kansas, Lawrence, KS, USA
| | - Joshua McGhee
- Department of Pharmacology and Toxicology, School of Pharmacy, University of Kansas, Lawrence, KS, USA
| | - Garett Davidson
- Department of Pharmacology and Toxicology, School of Pharmacy, University of Kansas, Lawrence, KS, USA
| | - Suraj Niraula
- Department of Pharmacology and Toxicology, School of Pharmacy, University of Kansas, Lawrence, KS, USA
| | - Adam S Smith
- Department of Pharmacology and Toxicology, School of Pharmacy, University of Kansas, Lawrence, KS, USA
| | - Alexandre A Sosunov
- Department of Neurosurgery, Columbia University Medical Center, New York, NY, USA
| | - Shirley Shidu Yan
- Department of Neurosurgery, Columbia University Medical Center, New York, NY, USA
| | - Jaichandar Subramanian
- Department of Pharmacology and Toxicology, School of Pharmacy, University of Kansas, Lawrence, KS, USA
| |
Collapse
|
2
|
Sripinun P, Lu W, Nikonov S, Patel S, Hennessy S, Bell BA, Mitchell CH. Fluorescent identification of axons, dendrites and soma of neuronal retinal ganglion cells with a genetic marker as a tool for facilitating the study of neurodegeneration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.20.599589. [PMID: 38979248 PMCID: PMC11230212 DOI: 10.1101/2024.06.20.599589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
This study characterizes a fluorescent Slc17a6 -tdTomato neuronal reporter mouse line offering strong labeling in axons throughout the optic nerve, dendrites and soma in 99% of retinal ganglion cells (RGCs). The model facilitates neuronal assessment ex vivo with wholemounts quantified to show neurodegeneration following optic nerve crush or elevated IOP as related to glaucoma, in vitro with robust Ca 2+ responses to P2X7 receptor stimulation in neuronal cultures, and in vivo using a confocal scanning laser ophthalmoscope (cSLO). While the tdTomato signal showed strong overlap with RGC markers, BRN3A and RBPMS, there was no cross-labeling of displaced amacrine cells in the ganglion cell layer. Controls indicated no impact of Slc17a6 -tdTomato expression on light-dependent neuronal function, as determined with a microelectrode array (MEA), or on structure, as measured with optical coherence tomography (OCT). In summary, this novel neuronal reporter mouse model offers an effective means to increase the efficiency for real-time, specific visualization of retinal ganglion cells. It holds substantial promise for enhancing our understanding of RGC pathology in glaucoma and other diseases of the optic nerve, and could facilitate the screening of targeted therapeutic interventions for neurodegeneration. Abstract Figure
Collapse
|
3
|
Ding SL. Lamination, Borders, and Thalamic Projections of the Primary Visual Cortex in Human, Non-Human Primate, and Rodent Brains. Brain Sci 2024; 14:372. [PMID: 38672021 PMCID: PMC11048015 DOI: 10.3390/brainsci14040372] [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: 03/03/2024] [Revised: 04/08/2024] [Accepted: 04/09/2024] [Indexed: 04/28/2024] Open
Abstract
The primary visual cortex (V1) is one of the most studied regions of the brain and is characterized by its specialized and laminated layer 4 in human and non-human primates. However, studies aiming to harmonize the definition of the cortical layers and borders of V1 across rodents and primates are very limited. This article attempts to identify and harmonize the molecular markers and connectional patterns that can consistently link corresponding cortical layers of V1 and borders across mammalian species and ages. V1 in primates has at least two additional and unique layers (L3b2 and L3c) and two sublayers of layer 4 (L4a and L4b) compared to rodent V1. In all species examined, layers 4 and 3b of V1 receive strong inputs from the (dorsal) lateral geniculate nucleus, and V1 is mostly surrounded by the secondary visual cortex except for one location where V1 directly abuts area prostriata. The borders of primate V1 can also be clearly identified at mid-gestational ages using gene markers. In rodents, a novel posteromedial extension of V1 is identified, which expresses V1 marker genes and receives strong inputs from the lateral geniculate nucleus. This V1 extension was labeled as the posterior retrosplenial cortex and medial secondary visual cortex in the literature and brain atlases. Layer 6 of the rodent and primate V1 originates corticothalamic projections to the lateral geniculate, lateral dorsal, and reticular thalamic nuclei and the lateroposterior-pulvinar complex with topographic organization. Finally, the direct geniculo-extrastriate (particularly the strong geniculo-prostriata) projections are probably major contributors to blindsight after V1 lesions. Taken together, compared to rodents, primates, and humans, V1 has at least two unique middle layers, while other layers are comparable across species and display conserved molecular markers and similar connections with the visual thalamus with only subtle differences.
Collapse
Affiliation(s)
- Song-Lin Ding
- Allen Institute for Brain Science, Seattle, WA 98109, USA
| |
Collapse
|
4
|
Garcia-Marin V, Kelly JG, Hawken MJ. Neuronal composition of processing modules in human V1: laminar density for neuronal and non-neuronal populations and a comparison with macaque. Cereb Cortex 2024; 34:bhad512. [PMID: 38183210 PMCID: PMC10839852 DOI: 10.1093/cercor/bhad512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 12/07/2023] [Accepted: 12/08/2023] [Indexed: 01/07/2024] Open
Abstract
The neuronal composition of homologous brain regions in different primates is important for understanding their processing capacities. Primary visual cortex (V1) has been widely studied in different members of the catarrhines. Neuronal density is considered to be central in defining the structure-function relationship. In human, there are large variations in the reported neuronal density from prior studies. We found the neuronal density in human V1 was 79,000 neurons/mm3, which is 35% of the neuronal density previously determined in macaque V1. Laminar density was proportionally similar between human and macaque. In V1, the ocular dominance column (ODC) contains the circuits for the emergence of orientation preference and spatial processing of a point image in many mammalian species. Analysis of the total neurons in an ODC and of the full number of neurons in macular vision (the central 15°) indicates that humans have 1.3× more neurons than macaques even though the density of neurons in macaque is 3× the density in human V1. We propose that the number of neurons in a functional processing unit rather than the number of neurons under a mm2 of cortex is more appropriate for cortical comparisons across species.
Collapse
Affiliation(s)
| | - Jenna G Kelly
- Center for Neural Science, New York University, New York City, NY 10003, United States
| | - Michael J Hawken
- Center for Neural Science, New York University, New York City, NY 10003, United States
| |
Collapse
|
5
|
Petanjek Z, Banovac I, Sedmak D, Hladnik A. Dendritic Spines: Synaptogenesis and Synaptic Pruning for the Developmental Organization of Brain Circuits. ADVANCES IN NEUROBIOLOGY 2023; 34:143-221. [PMID: 37962796 DOI: 10.1007/978-3-031-36159-3_4] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Synaptic overproduction and elimination is a regular developmental event in the mammalian brain. In the cerebral cortex, synaptic overproduction is almost exclusively correlated with glutamatergic synapses located on dendritic spines. Therefore, analysis of changes in spine density on different parts of the dendritic tree in identified classes of principal neurons could provide insight into developmental reorganization of specific microcircuits.The activity-dependent stabilization and selective elimination of the initially overproduced synapses is a major mechanism for generating diversity of neural connections beyond their genetic determination. The largest number of overproduced synapses was found in the monkey and human cerebral cortex. The highest (exceeding adult values by two- to threefold) and most protracted overproduction (up to third decade of life) was described for associative layer IIIC pyramidal neurons in the human dorsolateral prefrontal cortex.Therefore, the highest proportion and extraordinarily extended phase of synaptic spine overproduction is a hallmark of neural circuitry in human higher-order associative areas. This indicates that microcircuits processing the most complex human cognitive functions have the highest level of developmental plasticity. This finding is the backbone for understanding the effect of environmental impact on the development of the most complex, human-specific cognitive and emotional capacities, and on the late onset of human-specific neuropsychiatric disorders, such as autism and schizophrenia.
Collapse
Affiliation(s)
- Zdravko Petanjek
- Department of Anatomy and Clinical Anatomy, School of Medicine, University of Zagreb, Zagreb, Croatia.
- Department of Neuroscience, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia.
- Center of Excellence for Basic, Clinical and Translational Neuroscience, School of Medicine, University of Zagreb, Zagreb, Croatia.
| | - Ivan Banovac
- Department of Anatomy and Clinical Anatomy, School of Medicine, University of Zagreb, Zagreb, Croatia
- Department of Neuroscience, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
- Center of Excellence for Basic, Clinical and Translational Neuroscience, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Dora Sedmak
- Department of Anatomy and Clinical Anatomy, School of Medicine, University of Zagreb, Zagreb, Croatia
- Department of Neuroscience, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
- Center of Excellence for Basic, Clinical and Translational Neuroscience, School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Ana Hladnik
- Department of Anatomy and Clinical Anatomy, School of Medicine, University of Zagreb, Zagreb, Croatia
- Department of Neuroscience, Croatian Institute for Brain Research, School of Medicine, University of Zagreb, Zagreb, Croatia
- Center of Excellence for Basic, Clinical and Translational Neuroscience, School of Medicine, University of Zagreb, Zagreb, Croatia
| |
Collapse
|
6
|
Woelfle S, Boeckers TM. Layer-Specific Vesicular Glutamate Transporter 1 Immunofluorescence Levels Delineate All Layers of the Human Hippocampus Including the Stratum lucidum. Front Cell Neurosci 2021; 15:789903. [PMID: 34955756 PMCID: PMC8696355 DOI: 10.3389/fncel.2021.789903] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 11/18/2021] [Indexed: 11/18/2022] Open
Abstract
The hippocampal formation consists of the Ammon’s horn (cornu Ammonis with its regions CA1-4), dentate gyrus, subiculum, and the entorhinal cortex. The rough extension of the regions CA1-3 is typically defined based on the density and size of the pyramidal neurons without clear-cut boundaries. Here, we propose the vesicular glutamate transporter 1 (VGLUT1) as a molecular marker for the CA3 region. This is based on its strong labeling of the stratum lucidum (SL) in fluorescently stained human hippocampus sections. VGLUT1 puncta of the intense SL band co-localize with synaptoporin (SPO), a protein enriched in mossy fibers (MFs). Owing to its specific intensity profile throughout all hippocampal layers, VGLUT1 could be implemented as a pendant to Nissl-staining in fluorescent approaches with the additional demarcation of the SL. Furthermore, by high-resolution confocal microscopy, we detected VGLUT2 in the human hippocampus, thus reconciling two previous studies. Finally, by VGLUT1/SPO co-staining, we provide evidence for the existence of infrapyramidal MFs in the human hippocampus and we show that SPO expression is not restricted to MF synapses as demonstrated for rodent tissue.
Collapse
Affiliation(s)
- Sarah Woelfle
- Institute for Anatomy and Cell Biology, Ulm University, Ulm, Germany.,International Graduate School in Molecular Medicine Ulm (IGradU), Ulm, Germany
| | - Tobias M Boeckers
- Institute for Anatomy and Cell Biology, Ulm University, Ulm, Germany.,Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Ulm, Germany
| |
Collapse
|
7
|
Brookhouser N, Raman S, Frisch C, Srinivasan G, Brafman DA. APOE2 mitigates disease-related phenotypes in an isogenic hiPSC-based model of Alzheimer's disease. Mol Psychiatry 2021; 26:5715-5732. [PMID: 33837271 PMCID: PMC8501163 DOI: 10.1038/s41380-021-01076-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 02/26/2021] [Accepted: 03/23/2021] [Indexed: 02/02/2023]
Abstract
Genome-wide association studies (GWAS) have identified polymorphism in the Apolipoprotein E gene (APOE) to be the most prominent risk factor for Alzheimer's disease (AD). Compared to individuals homozygous for the APOE3 variant, individuals with the APOE4 variant have a significantly elevated risk of AD. On the other hand, longitudinal studies have shown that the presence of the APOE2 variant reduces the lifetime risk of developing AD by 40 percent. While there has been significant research that has identified the risk-inducing effects of APOE4, the underlying mechanisms by which APOE2 influences AD onset and progression have not been extensively explored. In this study, we utilize an isogenic human induced pluripotent stem cell (hiPSC)-based system to demonstrate that conversion of APOE3 to APOE2 greatly reduced the production of amyloid-beta (Aβ) peptides in hiPSC-derived neural cultures. Mechanistically, analysis of pure populations of neurons and astrocytes derived from these neural cultures revealed that mitigating effects of APOE2 are mediated by cell autonomous and non-autonomous effects. In particular, we demonstrated the reduction in Aβ is potentially driven by a mechanism related to non-amyloidogenic processing of amyloid precursor protein (APP), suggesting a gain of the protective function of the APOE2 variant. Together, this study provides insights into the risk-modifying effects associated with the APOE2 allele and establishes a platform to probe the mechanisms by which APOE2 enhances neuroprotection against AD.
Collapse
Affiliation(s)
- Nicholas Brookhouser
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA
- Graduate Program in Clinical Translational Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Sreedevi Raman
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA
| | - Carlye Frisch
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA
| | - Gayathri Srinivasan
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA
| | - David A Brafman
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ, USA.
| |
Collapse
|
8
|
Rockland KS. Cytochrome oxidase "blobs": a call for more anatomy. Brain Struct Funct 2021; 226:2793-2806. [PMID: 34382115 DOI: 10.1007/s00429-021-02360-2] [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] [Received: 03/13/2021] [Accepted: 07/31/2021] [Indexed: 11/29/2022]
Abstract
An ordered relation of structure and function has been a cornerstone in thinking about brain organization. Like the brain itself, however, this is not straightforward and is confounded both by functional intricacy and structural plasticity (many routes to a given outcome). As a striking case of putative structure-function correlation, this mini-review focuses on the relatively well-characterized pattern of cytochrome oxidase (CO) blobs (aka "patches" or "puffs") in the supragranular layers of macaque monkey visual cortex. The pattern is without doubt visually compelling, and the semi-dichotomous array of CO+ blobs and CO- interblobs is consistent with multiple studies reporting compartment-specific preferential connectivity and distinctive physiological response properties. Nevertheless, as briefly reviewed here, the finer anatomical organization of this system is surprisingly under-investigated, and the relation to functional aspects, therefore, unclear. Microcircuitry, cell type, and three-dimensional spatiotemporal level investigations of the CO+ CO- pattern are needed and may open new views to structure-function organization of visual cortex, and to phylogenetic and ontogenetic comparisons across nonhuman primates (NHP), and between NHP and humans.
Collapse
Affiliation(s)
- Kathleen S Rockland
- Department of Anatomy and Neurobiology, Boston University School of Medicine, 72 East Concord St., Boston, MA, 02118, USA.
| |
Collapse
|
9
|
Villalba RM, Behnke JA, Pare JF, Smith Y. Comparative Ultrastructural Analysis of Thalamocortical Innervation of the Primary Motor Cortex and Supplementary Motor Area in Control and MPTP-Treated Parkinsonian Monkeys. Cereb Cortex 2021; 31:3408-3425. [PMID: 33676368 PMCID: PMC8599722 DOI: 10.1093/cercor/bhab020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 12/29/2020] [Accepted: 01/19/2021] [Indexed: 12/15/2022] Open
Abstract
The synaptic organization of thalamic inputs to motor cortices remains poorly understood in primates. Thus, we compared the regional and synaptic connections of vGluT2-positive thalamocortical glutamatergic terminals in the supplementary motor area (SMA) and the primary motor cortex (M1) between control and MPTP-treated parkinsonian monkeys. In controls, vGluT2-containing fibers and terminal-like profiles invaded layer II-III and Vb of M1 and SMA. A significant reduction of vGluT2 labeling was found in layer Vb, but not in layer II-III, of parkinsonian animals, suggesting a potential thalamic denervation of deep cortical layers in parkinsonism. There was a significant difference in the pattern of synaptic connectivity in layers II-III, but not in layer Vb, between M1 and SMA of control monkeys. However, this difference was abolished in parkinsonian animals. No major difference was found in the proportion of perforated versus macular post-synaptic densities at thalamocortical synapses between control and parkinsonian monkeys in both cortical regions, except for a slight increase in the prevalence of perforated axo-dendritic synapses in the SMA of parkinsonian monkeys. Our findings suggest that disruption of the thalamic innervation of M1 and SMA may underlie pathophysiological changes of the motor thalamocortical loop in the state of parkinsonism.
Collapse
Affiliation(s)
- Rosa M Villalba
- Division of Neuropharmacology and Neurological Diseases, Yerkes National Primate Research Center, Emory University, Atlanta, GA 30329, USA
- UDALL Center for Excellence for Parkinson’s Disease, Emory University, Atlanta, GA 30329, USA
| | - Joseph A Behnke
- Division of Neuropharmacology and Neurological Diseases, Yerkes National Primate Research Center, Emory University, Atlanta, GA 30329, USA
- UDALL Center for Excellence for Parkinson’s Disease, Emory University, Atlanta, GA 30329, USA
| | - Jean-Francois Pare
- Division of Neuropharmacology and Neurological Diseases, Yerkes National Primate Research Center, Emory University, Atlanta, GA 30329, USA
- UDALL Center for Excellence for Parkinson’s Disease, Emory University, Atlanta, GA 30329, USA
| | - Yoland Smith
- Division of Neuropharmacology and Neurological Diseases, Yerkes National Primate Research Center, Emory University, Atlanta, GA 30329, USA
- UDALL Center for Excellence for Parkinson’s Disease, Emory University, Atlanta, GA 30329, USA
- Department of Neurology, School of Medicine, Emory University, Atlanta, GA 30329, USA
| |
Collapse
|
10
|
Yao S, Zhou Q, Li S, Takahata T. Immunoreactivity of Vesicular Glutamate Transporter 2 Corresponds to Cytochrome Oxidase-Rich Subcompartments in the Visual Cortex of Squirrel Monkeys. Front Neuroanat 2021; 15:629473. [PMID: 33679337 PMCID: PMC7930324 DOI: 10.3389/fnana.2021.629473] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Accepted: 01/21/2021] [Indexed: 11/13/2022] Open
Abstract
Cytochrome oxidase (CO) histochemistry has been used to reveal the cytoarchitecture of the primate brain, including blobs/puffs/patches in the striate cortex (V1), and thick, thin and pale stripes in the middle layer of the secondary visual cortex (V2). It has been suggested that CO activity is coupled with the spiking activity of neurons, implying that neurons in these CO-rich subcompartments are more active than surrounding regions. However, we have discussed possibility that CO histochemistry represents the distribution of thalamo-cortical afferent terminals that generally use vesicular glutamate transporter 2 (VGLUT2) as their main glutamate transporter, and not the activity of cortical neurons. In this study, we systematically compared the labeling patterns observed between CO histochemistry and immunohistochemistry (IHC) for VGLUT2 from the system to microarchitecture levels in the visual cortex of squirrel monkeys. The two staining patterns bore striking similarities at all levels of the visual cortex, including the honeycomb structure of V1 layer 3Bβ (Brodmann's layer 4A), the patchy architecture in the deep layers of V1, the superficial blobs of V1, and the V2 stripes. The microarchitecture was more evident in VGLUT2 IHC, as expected. VGLUT2 protein expression that produced specific IHC labeling is thought to originate from the thalamus since the lateral geniculate nucleus (LGN) and the pulvinar complex both show high expression levels of VGLUT2 mRNA, but cortical neurons do not. These observations support our theory that the subcompartments revealed by CO histochemistry represent the distribution of thalamo-cortical afferent terminals in the primate visual cortex.
Collapse
Affiliation(s)
- Songping Yao
- Key Laboratory for Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, China.,Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, China
| | - Qiuying Zhou
- Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, China.,Department of Neurology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Shuiyu Li
- Key Laboratory for Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, China.,Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, China
| | - Toru Takahata
- Key Laboratory for Biomedical Engineering of Ministry of Education, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, China.,Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University School of Medicine, Hangzhou, China.,Department of Neurology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| |
Collapse
|
11
|
Turner EC, Gabi M, Liao CC, Kaas JH. The postnatal development of MT, V1, LGN, pulvinar and SC in prosimian galagos (Otolemur garnettii). J Comp Neurol 2020; 528:3075-3094. [PMID: 32067231 DOI: 10.1002/cne.24885] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 02/11/2020] [Accepted: 02/11/2020] [Indexed: 11/05/2022]
Abstract
Considerable evidence supports the premise that the visual system of primates develops hierarchically, with primary visual cortex developing structurally and functionally first, thereby influencing the subsequent development of higher cortical areas. An apparent exception is the higher order middle temporal visual area (MT), which appears to be histologically distinct near the time of birth in marmosets. Here we used a number of histological and immunohistological markers to evaluate the maturation of cortical and subcortical components of the visual system in galagos ranging from newborns to adults. Galagos are representative of the large strepsirrhine branch of primate evolution, and studies of these primates help identify brain features that are broadly similar across primate taxa. The histological results support the view that MT is functional at or near the time of birth, as is primary visual cortex. Likewise, the superior colliculus, dorsal lateral geniculate nucleus, and the posterior nucleus of the pulvinar are well-developed by birth. Thus, these subcortical structures likely provide visual information directly or indirectly to cortex in newborn galagos. We conclude that MT resembles a primary sensory area by developing early, and that the early development of MT may influence the subsequent development of dorsal stream visual areas.
Collapse
Affiliation(s)
- Emily C Turner
- Department of Psychology, Vanderbilt University, Nashville, Tennessee
| | - Mariana Gabi
- Department of Psychology, Vanderbilt University, Nashville, Tennessee
| | - Chia-Chi Liao
- Department of Psychology, Vanderbilt University, Nashville, Tennessee
| | - Jon H Kaas
- Department of Psychology, Vanderbilt University, Nashville, Tennessee
| |
Collapse
|
12
|
Kelly JG, Hawken MJ. GABAergic and non-GABAergic subpopulations of Kv3.1b-expressing neurons in macaque V2 and MT: laminar distributions and proportion of total neuronal population. Brain Struct Funct 2020; 225:1135-1152. [PMID: 32266458 DOI: 10.1007/s00429-020-02065-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 03/27/2020] [Indexed: 11/26/2022]
Abstract
The Kv3.1b potassium channel subunit, which facilitates the fast-spiking phenotype characteristic of parvalbumin (PV)-expressing inhibitory interneurons, is also expressed by subpopulations of excitatory neurons in macaque cortex. We have previously shown that V1 neurons expressing Kv3.1b but not PV or GABA were largely concentrated within layers 4Cα and 4B of V1, suggesting laminar or pathway specificity. In the current study, the distribution and pattern of co-immunoreactivity of GABA, PV, and Kv3.1b across layers in extrastriate cortical areas V2 and MT of the macaque monkey were measured using the same triple immunofluorescence labeling, confocal microscopy, and partially automated cell-counting strategies used in V1. For comparison, densities of the overall cell and neuronal populations were also measured for each layer of V2 and MT using tissue sections immunofluorescence labeled for the pan-neuronal marker NeuN. GABAergic neurons accounted for 14% of the total neuronal population in V2 and 25% in MT. Neurons expressing Kv3.1b but neither GABA nor PV were present in both areas. This subpopulation was most prevalent in the lowest subcompartment of layer 3, comprising 5% of the total neuronal population in layer 3C of both areas, and 41% and 36% of all Kv3.1b+ neurons in this layer in V2 and MT, respectively. The prevalence and laminar distribution of this subpopulation were remarkably consistent between V2 and MT and showed a striking similarity to the patterns observed previously in V1, suggesting a common contribution to the cortical circuit across areas.
Collapse
Affiliation(s)
- Jenna G Kelly
- Center for Neural Science, New York University, 4 Washington Place, New York, NY, 10003, USA
| | - Michael J Hawken
- Center for Neural Science, New York University, 4 Washington Place, New York, NY, 10003, USA.
| |
Collapse
|
13
|
Functional Clusters of Neurons in Layer 6 of Macaque V1. J Neurosci 2020; 40:2445-2457. [PMID: 32041896 DOI: 10.1523/jneurosci.1394-19.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 01/26/2020] [Accepted: 01/27/2020] [Indexed: 12/11/2022] Open
Abstract
Layer 6 appears to perform a very important role in the function of macaque primary visual cortex, V1, but not enough is understood about the functional characteristics of neurons in the layer 6 population. It is unclear to what extent the population is homogeneous with respect to their visual properties or if one can identify distinct subpopulations. Here we performed a cluster analysis based on measurements of the responses of single neurons in layer 6 of primary visual cortex in male macaque monkeys (Macaca fascicularis) to achromatic grating stimuli that varied in orientation, direction of motion, spatial and temporal frequency, and contrast. The visual stimuli were presented in a stimulus window that was also varied in size. Using the responses to parametric variation in these stimulus variables, we extracted a number of tuning response measures and used them in the cluster analysis. Six main clusters emerged along with some smaller clusters. Additionally, we asked whether parameter distributions from each of the clusters were statistically different. There were clear separations of parameters between some of the clusters, particularly for f1/f0 ratio, direction selectivity, and temporal frequency bandwidth, but other dimensions also showed differences between clusters. Our data suggest that in layer 6 there are multiple parallel circuits that provide information about different aspects of the visual stimulus.SIGNIFICANCE STATEMENT The cortex is multilayered and is involved in many high-level computations. In the current study, we have asked whether there are subpopulations of neurons, clusters, in layer 6 of cortex with different functional tuning properties that provide information about different aspects of the visual image. We identified six major functional clusters within layer 6. These findings show that there is much more complexity to the circuits in cortex than previously demonstrated and open up a new avenue for experimental investigation within layers of other cortical areas and for the elaboration of models of circuit function that incorporate many parallel pathways with different functional roles.
Collapse
|
14
|
Quantitative organization of the excitatory synapses of the primate cerebellar nuclei: further evidence for a specialized architecture underlying the primate cerebellum. Brain Struct Funct 2019; 224:1987-1998. [PMID: 31101974 PMCID: PMC6591209 DOI: 10.1007/s00429-019-01888-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 05/04/2019] [Indexed: 11/17/2022]
Abstract
The cerebellar intrinsic connectivity is of remarkable regularity with a similar build repeated many times over. However, several modifications of this basic circuitry occur that can provide important clues to evolutionary adaptations. We have observed differences in the wiring of the cerebellar output structures (the deep cerebellar nuclei, DCN) with higher dendritic length density in the phylogenetically newer DCN. In rats, we showed that an increase in wiring is associated with an increase in the presynaptic vesicular glutamate transporter 1 (vGluT1). In this study, we have extended our analysis to the rhesus monkey and can show similarities and differences between the two species. The similarities confirm a higher density in vGluT1+ boutons in the lateral (LN/dentate) and posterior interpositus nucleus compared to the phylogenetically older DCN. In general, we also observe a lower density of vGluT1 and 2+ boutons in the monkey, which however, yields a similar number of excitatory boutons per neuron in both species. The only exception is the vGlut1+ boutons in the macaque LN/dentate, which showed a significantly lower number of vGluT1+ boutons per neuron. We also detected a higher percentage of co-labelled vGluT1 and 2 boutons in the macaque than we found in the rat. In summary, these results confirm that the hyposcalled dendrites of the monkey LN/dentate also show a lower number of vGluT1+ boutons per neuron. These results provide further support of our model relating the dendritic morphology of the LN/dentate neurons to the morphology of the specially enlarged LN/dentate nucleus in primates.
Collapse
|
15
|
Kelly JG, García-Marín V, Rudy B, Hawken MJ. Densities and Laminar Distributions of Kv3.1b-, PV-, GABA-, and SMI-32-Immunoreactive Neurons in Macaque Area V1. Cereb Cortex 2019; 29:1921-1937. [PMID: 29668858 PMCID: PMC6458914 DOI: 10.1093/cercor/bhy072] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 03/06/2018] [Indexed: 12/11/2022] Open
Abstract
The Kv3.1b potassium channel subunit is associated with narrow spike widths and fast-spiking properties. In macaque primary visual cortex (V1), subsets of neurons have previously been found to be Kv3.1b-immunoreactive (ir) but not parvalbumin (PV)-ir or not GABA-ir, suggesting that they may be both fast-spiking and excitatory. This population includes Meynert cells, the large layer 5/6 pyramidal neurons that are also labeled by the neurofilament antibody SMI-32. In the present study, triple immunofluorescence labeling and confocal microscopy were used to measure the distribution of Kv3.1b-ir, non-PV-ir, non-GABA-ir neurons across cortical depth in V1, and to determine whether, like the Meynert cells, other Kv3.1b-ir excitatory neurons were also SMI-32-ir pyramidal neurons. We found that Kv3.1b-ir, non-PV-ir, non-GABA-ir neurons were most prevalent in the M pathway-associated layers 4 Cα and 4B. GABAergic neurons accounted for a smaller fraction (11%) of the total neuronal population across layers 1-6 than has previously been reported. Of Kv3.1b-ir neurons, PV expression reliably indicated GABA expression. Kv3.1b-ir, non-PV-ir neurons varied in SMI-32 coimmunoreactivity. The results suggest the existence of a heterogeneous population of excitatory neurons in macaque V1 with the potential for sustained high firing rates, and these neurons were particularly abundant in layers 4B and 4 Cα.
Collapse
Affiliation(s)
- Jenna G Kelly
- Center for Neural Science, New York University, New York, NY, USA
| | | | - Bernardo Rudy
- New York University Neuroscience Institute, New York University School of Medicine, Smilow Research Building Sixth Floor, 522 First Ave., New York, NY, USA
| | - Michael J Hawken
- Center for Neural Science, New York University, New York, NY, USA
| |
Collapse
|
16
|
Garcia-Marin V, Kelly JG, Hawken MJ. Major Feedforward Thalamic Input Into Layer 4C of Primary Visual Cortex in Primate. Cereb Cortex 2019; 29:134-149. [PMID: 29190326 PMCID: PMC6490972 DOI: 10.1093/cercor/bhx311] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 09/29/2017] [Accepted: 10/30/2017] [Indexed: 01/28/2023] Open
Abstract
One of the underlying principles of how mammalian circuits are constructed is the relative influence of feedforward to recurrent synaptic drive. It has been dogma in sensory systems that the thalamic feedforward input is relatively weak and that there is a large amplification of the input signal by recurrent feedback. Here we show that in trichromatic primates there is a major feedforward input to layer 4C of primary visual cortex. Using a combination of 3D-electron-microscopy and 3D-confocal imaging of thalamic boutons we found that the average feedforward contribution was about 20% of the total excitatory input in the parvocellular (P) pathway, about 3 times the currently accepted values for primates. In the magnocellular (M) pathway it was around 15%, nearly twice the currently accepted values. New methods showed the total synaptic and cell densities were as much as 150% of currently accepted values. The new estimates of contributions of feedforward synaptic inputs into visual cortex call for a major revision of the design of the canonical cortical circuit.
Collapse
Affiliation(s)
| | - Jenna G Kelly
- Center for Neural Science, New York University, 4 Washington Place, New York, USA
| | - Michael J Hawken
- Center for Neural Science, New York University, 4 Washington Place, New York, USA
| |
Collapse
|
17
|
Xie F, You L, Cai D, Liu M, Yue Y, Wang Y, Yuan K. Fast Inhibitory Decay Facilitates Adult-like Temporal Processing in Layer 5 of Developing Primary Auditory Cortex. Cereb Cortex 2018; 28:4319-4335. [PMID: 29121216 DOI: 10.1093/cercor/bhx284] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 10/06/2017] [Indexed: 11/12/2022] Open
Abstract
The protracted maturational process of temporal processing in layer 4 (L4) of primary auditory cortex (A1) has been extensively studied. Accumulating evidences show that layer 5 (L5) receives direct thalamic inputs as well. How the temporal responses in L5 may developmentally emerge remains unclear. Using in vivo loose-patch recordings in rat A1, we found that putative pyramidal (Pyr) neurons in developing L5 exhibited adult-like stimulus-following ability but less bursting shortly after hearing onset. L5 Pyr neurons in adult A1 exhibited phase-locking similar to L4 neurons, while L5 fast-spiking (FS) neurons showed greater phase-locking at 7 and 12.5 pps. In developing L5, whole-cell recordings revealed inhibition with decay constant comparable to that in adult L5, thereby avoiding the summation of inhibition that contributed to the strong adaptation in L4. Given the targets of L5 outputs, the relatively precocious temporal processing in L5 might contribute to temporal response maturation in connected cortical and subcortical areas. Our findings were in agreement with the idea that L5 may be a "hub" for processing cortical inputs and outputs that can operate independently of L4.
Collapse
Affiliation(s)
- Fenghua Xie
- Department of Biomedical Engineering, School of Medicine, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China
| | - Ling You
- Department of Biomedical Engineering, School of Medicine, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China
| | - Dongqin Cai
- Department of Biomedical Engineering, School of Medicine, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China
| | - Miaomiao Liu
- Department of Biomedical Engineering, School of Medicine, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China
| | - Yin Yue
- Department of Biomedical Engineering, School of Medicine, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China
| | - Yiwei Wang
- Department of Biomedical Engineering, School of Medicine, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China
| | - Kexin Yuan
- Department of Biomedical Engineering, School of Medicine, IDG/McGovern Institute for Brain Research, Center for Brain-Inspired Computing Research, Tsinghua University, Beijing, China
| |
Collapse
|
18
|
Wang H, Magnain C, Sakadžić S, Fischl B, Boas DA. Characterizing the optical properties of human brain tissue with high numerical aperture optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2017; 8:5617-5636. [PMID: 29296492 PMCID: PMC5745107 DOI: 10.1364/boe.8.005617] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 11/06/2017] [Accepted: 11/08/2017] [Indexed: 05/22/2023]
Abstract
Quantification of tissue optical properties with optical coherence tomography (OCT) has proven to be useful in evaluating structural characteristics and pathological changes. Previous studies primarily used an exponential model to analyze low numerical aperture (NA) OCT measurements and obtain the total attenuation coefficient for biological tissue. In this study, we develop a systematic method that includes the confocal parameter for modeling the depth profiles of high NA OCT, when the confocal parameter cannot be ignored. This approach enables us to quantify tissue optical properties with higher lateral resolution. The model parameter predictions for the scattering coefficients were tested with calibrated microsphere phantoms. The application of the model to human brain tissue demonstrates that the scattering and back-scattering coefficients each provide unique information, allowing us to differentially identify laminar structures in primary visual cortex and distinguish various nuclei in the midbrain. The combination of the two optical properties greatly enhances the power of OCT to distinguish intricate structures in the human brain beyond what is achievable with measured OCT intensity information alone, and therefore has the potential to enable objective evaluation of normal brain structure as well as pathological conditions in brain diseases. These results represent a promising step for enabling the quantification of tissue optical properties from high NA OCT.
Collapse
|
19
|
Glausier JR, Roberts RC, Lewis DA. Ultrastructural analysis of parvalbumin synapses in human dorsolateral prefrontal cortex. J Comp Neurol 2017; 525:2075-2089. [PMID: 28074478 PMCID: PMC5397325 DOI: 10.1002/cne.24171] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 12/19/2016] [Accepted: 12/20/2016] [Indexed: 12/11/2022]
Abstract
Coordinated activity of neural circuitry in the primate dorsolateral prefrontal cortex (DLPFC) supports a range of cognitive functions. Altered DLPFC activation is implicated in a number of human psychiatric and neurological illnesses. Proper DLPFC activity is, in part, maintained by two populations of neurons containing the calcium-binding protein parvalbumin (PV): local inhibitory interneurons that form Type II synapses, and long-range glutamatergic inputs from the thalamus that form Type I synapses. Understanding the contributions of each PV neuronal population to human DLPFC function requires a detailed examination of their anatomical properties. Consequently, we performed an electron microscopic analysis of (1) the distribution of PV immunoreactivity within the neuropil, (2) the properties of dendritic shafts of PV-IR interneurons, (3) Type II PV-IR synapses from PV interneurons, and (4) Type I PV-IR synapses from long-range projections, within the superficial and middle laminar zones of the human DLPFC. In both laminar zones, Type II PV-IR synapses from interneurons comprised ∼60% of all PV-IR synapses, and Type I PV-IR synapses from putative thalamocortical terminals comprised the remaining ∼40% of PV-IR synapses. Thus, the present study suggests that innervation from PV-containing thalamic nuclei extends across superficial and middle layers of the human DLPFC. These findings contrast with previous ultrastructural studies in monkey DLPFC where Type I PV-IR synapses were not identified in the superficial laminar zone. The presumptive added modulation of DLPFC circuitry by the thalamus in human may contribute to species-specific, higher-order functions.
Collapse
Affiliation(s)
- Jill R. Glausier
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213
| | - Rosalinda C. Roberts
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - David A. Lewis
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213
- Department of Neuroscience, University of Pittsburgh School of Arts and Sciences, Pittsburgh, PA 15213
| |
Collapse
|
20
|
Kelly JG, Hawken MJ. Quantification of neuronal density across cortical depth using automated 3D analysis of confocal image stacks. Brain Struct Funct 2017; 222:3333-3353. [PMID: 28243763 DOI: 10.1007/s00429-017-1382-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 01/31/2017] [Indexed: 10/20/2022]
Abstract
A new framework for measuring densities of immunolabeled neurons across cortical layers was implemented that combines a confocal microscopy sampling strategy with automated analysis of 3D image stacks. Its utility was demonstrated by quantifying neuronal density in macaque cortical areas V1 and V2. A series of overlapping confocal image stacks were acquired, each spanning from the pial surface to the white matter. DAPI channel images were automatically thresholded, and contiguous regions that included multiple clumped nuclear profiles were split using k-means clustering of image pixels for a set of candidate k values determined based on the clump's area; the most likely candidate segmentation was selected based on criteria that capture expected nuclear profile shape and size. The centroids of putative nuclear profiles estimated from 2D images were then grouped across z planes in an image stack to identify the positions of nuclei in x-y-z. 3D centroids falling outside user-specified exclusion boundaries were deleted, nuclei were classified by the presence or absence of signal in a channel corresponding to an immunolabeled antigen (e.g., the pan-neuronal marker NeuN) at the nuclear centroid location, and the set of classified cells was combined across image stacks to estimate density across cortical depth. The method was validated by comparison with conventional stereological methods. The average neuronal density across cortical layers was 230 × 103 neurons per mm3 in V1 and 130 × 103 neurons per mm3 in V2. The method is accurate, flexible, and general enough to measure densities of neurons of various molecularly identified types.
Collapse
Affiliation(s)
- Jenna G Kelly
- Center for Neural Science, New York University, 4 Washington Place, New York, NY, 10003, USA
| | - Michael J Hawken
- Center for Neural Science, New York University, 4 Washington Place, New York, NY, 10003, USA.
| |
Collapse
|
21
|
Takahata T. What Does Cytochrome Oxidase Histochemistry Represent in the Visual Cortex? Front Neuroanat 2016; 10:79. [PMID: 27489537 PMCID: PMC4951485 DOI: 10.3389/fnana.2016.00079] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 07/06/2016] [Indexed: 11/13/2022] Open
Affiliation(s)
- Toru Takahata
- Laboratory of Comparative Molecular Neuroanatomy, Interdisciplinary Institute of Neuroscience and Technology, Zhejiang University Hangzhou, China
| |
Collapse
|
22
|
Pundir AS, Singh UA, Ahuja N, Makhija S, Dikshit PC, Radotra B, Kumar P, Shankar SK, Mahadevan A, Roy TS, Iyengar S. Growth and refinement of excitatory synapses in the human auditory cortex. Brain Struct Funct 2015; 221:3641-74. [PMID: 26438332 DOI: 10.1007/s00429-015-1124-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 09/25/2015] [Indexed: 02/03/2023]
Abstract
We had earlier demonstrated a neurofilament-rich plexus of axons in the presumptive human auditory cortex during fetal development which became adult-like during infancy. To elucidate the origin of these axons, we studied the expression of the vesicular glutamate transporters (VGLUT) 1 and 2 in the human auditory cortex at different stages of development. While VGLUT-1 expression predominates in intrinsic and cortico-cortical synapses, VGLUT-2 expression predominates in thalamocortical synapses. Levels of VGLUT-2 mRNA were higher in the auditory cortex before birth compared to postnatal development. In contrast, levels of VGLUT-1 mRNA were low before birth and increased during postnatal development to peak during childhood and then began to decrease in adolescence. Both VGLUT-1 and VGLUT-2 proteins were present in the human auditory cortex as early as 15GW. Further, immunohistochemistry revealed that the supra- and infragranular layers were more immunoreactive for VGLUT-1 compared to that in Layer IV at 34GW and this pattern was maintained until adulthood. As for VGLUT-1 mRNA, VGLUT-1 synapses increased in density between prenatal development and childhood in the human auditory cortex after which they appeared to undergo attrition or pruning. The adult pattern of VGLUT-2 immunoreactivity (a dense band of VGLUT-2-positive terminals in Layer IV) also began to appear in the presumptive Heschl's gyrus at 34GW. The density of VGLUT-2-positive puncta in Layer IV increased between prenatal development and adolescence, followed by a decrease in adulthood, suggesting that thalamic axons which innervate the human auditory cortex undergo pruning comparatively late in development.
Collapse
Affiliation(s)
- Arvind Singh Pundir
- Division of Systems Neuroscience, National Brain Research Centre (Deemed University), NH-8, Manesar, Gurgaon, Haryana, 122051, India
| | - Utkarsha A Singh
- Division of Systems Neuroscience, National Brain Research Centre (Deemed University), NH-8, Manesar, Gurgaon, Haryana, 122051, India
| | - Nikhil Ahuja
- Division of Systems Neuroscience, National Brain Research Centre (Deemed University), NH-8, Manesar, Gurgaon, Haryana, 122051, India
| | - Sonal Makhija
- Division of Systems Neuroscience, National Brain Research Centre (Deemed University), NH-8, Manesar, Gurgaon, Haryana, 122051, India
| | - P C Dikshit
- Department of Forensic Medicine, Maulana Azad Medical College, Bahadur Shah Zafar Marg, New Delhi, 110002, India
| | - Bishan Radotra
- Department of Histopathology, Post Graduate Institute of Medical Education and Research, Sector-12, Chandigarh, 160012, India
| | - Praveen Kumar
- Department of Obstetrics and Gynecology, Base Hospital, Delhi Cantonment, Delhi, 110010, India
| | - S K Shankar
- Department of Neuropathology, National Institute of Mental Health and Allied Sciences, Hosur Road, Bangalore, 560029, India
| | - Anita Mahadevan
- Department of Neuropathology, National Institute of Mental Health and Allied Sciences, Hosur Road, Bangalore, 560029, India
| | - T S Roy
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi, 110002, India
| | - Soumya Iyengar
- Division of Systems Neuroscience, National Brain Research Centre (Deemed University), NH-8, Manesar, Gurgaon, Haryana, 122051, India.
| |
Collapse
|
23
|
Balaram P, Isaamullah M, Petry HM, Bickford ME, Kaas JH. Distributions of vesicular glutamate transporters 1 and 2 in the visual system of tree shrews (Tupaia belangeri). J Comp Neurol 2015; 523:1792-808. [PMID: 25521420 DOI: 10.1002/cne.23727] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 12/08/2014] [Accepted: 12/09/2014] [Indexed: 12/13/2022]
Abstract
Vesicular glutamate transporter (VGLUT) proteins regulate the storage and release of glutamate from synapses of excitatory neurons. Two isoforms, VGLUT1 and VGLUT2, are found in most glutamatergic projections across the mammalian visual system, and appear to differentially identify subsets of excitatory projections between visual structures. To expand current knowledge on the distribution of VGLUT isoforms in highly visual mammals, we examined the mRNA and protein expression patterns of VGLUT1 and VGLUT2 in the lateral geniculate nucleus (LGN), superior colliculus, pulvinar complex, and primary visual cortex (V1) in tree shrews (Tupaia belangeri), which are closely related to primates but classified as a separate order (Scandentia). We found that VGLUT1 was distributed in intrinsic and corticothalamic connections, whereas VGLUT2 was predominantly distributed in subcortical and thalamocortical connections. VGLUT1 and VGLUT2 were coexpressed in the LGN and in the pulvinar complex, as well as in restricted layers of V1, suggesting a greater heterogeneity in the range of efferent glutamatergic projections from these structures. These findings provide further evidence that VGLUT1 and VGLUT2 identify distinct populations of excitatory neurons in visual brain structures across mammals. Observed variations in individual projections may highlight the evolution of these connections through the mammalian lineage.
Collapse
Affiliation(s)
- P Balaram
- Department of Psychology, Vanderbilt University, Nashville, Tennessee, 37240
| | - M Isaamullah
- School of Medicine, University of Illinois at Chicago, Chicago, Illinois, 60607
| | - H M Petry
- Department of Psychological and Brain Sciences, University of Louisville, Louisville, Kentucky, 40292
| | - M E Bickford
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky, 40292
| | - J H Kaas
- Department of Psychology, Vanderbilt University, Nashville, Tennessee, 37240
| |
Collapse
|
24
|
Balaram P, Young NA, Kaas JH. Histological features of layers and sublayers in cortical visual areas V1 and V2 of chimpanzees, macaque monkeys, and humans. Eye Brain 2014; 2014:5-18. [PMID: 25788835 PMCID: PMC4360995 DOI: 10.2147/eb.s51814] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The layers and sublayers of primary visual cortex, or V1, in primates are easily distinguishable compared to those in other cortical areas, and are especially distinct in anthropoid primates – monkeys, apes, and humans – where they also vary in histological appearance. This variation in primate-specific specialization has led to a longstanding confusion over the identity of layer 4 and its proposed sublayers in V1. As the application of different histological markers relate to the issue of defining and identifying layers and sublayers, we applied four traditional and four more recent histological markers to brain sections of V1 and adjoining secondary visual cortex (V2) in macaque monkeys, chimpanzees, and humans in order to compare identifiable layers and sublayers in both cortical areas across these species. The use of Nissl, neuronal nuclear antigen (NeuN), Gallyas myelin, cytochrome oxidase (CO), acetylcholinesterase (AChE), nonphosphorylated neurofilament H (SMI-32), parvalbumin (PV), and vesicular glutamate transporter 2 (VGLUT2) preparations support the conclusion that the most popular scheme of V1 lamination, that of Brodmann, misidentifies sublayers of layer 3 (3Bβ and 3C) as sublayers of layer 4 (4A and 4B), and that the specialized sublayer of layer 3 in monkeys, 3Bβ, is not present in humans. These differences in interpretation are important as they relate to the proposed functions of layer 4 in primate species, where layer 4 of V1 is a layer that receives and processes information from the visual thalamus, and layer 3 is a layer that transforms and distributes information to other cortical areas.
Collapse
Affiliation(s)
- Pooja Balaram
- Department of Psychology, Vanderbilt University, Nashville, TN, USA
| | - Nicole A Young
- Department of Psychology, Vanderbilt University, Nashville, TN, USA
| | - Jon H Kaas
- Department of Psychology, Vanderbilt University, Nashville, TN, USA
| |
Collapse
|
25
|
Rockoff EC, Balaram P, Kaas JH. Patchy distributions of myelin and vesicular glutamate transporter 2 align with cytochrome oxidase blobs and interblobs in the superficial layers of the primary visual cortex. Eye Brain 2014; 6:19-27. [PMID: 26097384 PMCID: PMC4474605 DOI: 10.2147/eb.s59797] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Blobs are a modular component of the primary visual cortex (area 17) of all primates, but not of other mammals closely related to primates. They are characterized as an even distribution of patches, puffs, or blobs of dense cytochrome oxidase (CO) expression in layer III of area 17, and are now known to differ from surrounding, nonblob cortex in thalamic, intrinsic, and extrastriate connections. Previous studies have also recognized a blob-like pattern of myelin-dense patches in layer III of area 17 of primates, and more recently the vesicular glutamate transporter (VGLUT)-2 isoform of the VGLUT family has been found to selectively distribute to layer III patches in a similar blob-like pattern. Here, we sought to determine if the blob-like patterns all identify the same modular structures in area 17 of primates by staining alternate brain sections cut parallel to the surface of area 17 of a prosimian primate (Otolemur garnettii) for CO, myelin, and VGLUT2. By aligning the sections from the three preparations, we provide clear evidence that the three preparations all identify the same modular blob structures. The results provide a further understanding of the functional nature of the blobs by demonstrating that their higher level of CO activity is related to thalamic inputs from the lateral geniculate nucleus that use VGLUT2 as their main glutamate transporter, and via myelinated axons.
Collapse
Affiliation(s)
- Emily C Rockoff
- Department of Psychology, Vanderbilt University, Nashville, TN, USA
| | - Pooja Balaram
- Department of Psychology, Vanderbilt University, Nashville, TN, USA
| | - Jon H Kaas
- Department of Psychology, Vanderbilt University, Nashville, TN, USA ; Department of Cell and Molecular Biology, Vanderbilt University, Nashville, TN, USA
| |
Collapse
|
26
|
Balaram P, Kaas JH. Towards a unified scheme of cortical lamination for primary visual cortex across primates: insights from NeuN and VGLUT2 immunoreactivity. Front Neuroanat 2014; 8:81. [PMID: 25177277 PMCID: PMC4133926 DOI: 10.3389/fnana.2014.00081] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 07/23/2014] [Indexed: 12/02/2022] Open
Abstract
Primary visual cortex (V1) is clearly distinguishable from other cortical areas by its distinctive pattern of neocortical lamination across mammalian species. In some mammals, primates in particular, the layers of V1 are further divided into a number of sublayers based on their anatomical and functional characteristics. While these sublayers are easily recognizable across a range of primates, the exact number of divisions in each layer and their relative position within the depth of V1 has been inconsistently reported, largely due to conflicting schemes of nomenclature for the V1 layers. This conflict centers on the definition of layer 4 in primate V1, and the subdivisions of layer 4 that can be consistently identified across primate species. Brodmann’s (1909) laminar scheme for V1 delineates three subdivisions of layer 4 in primates, based on cellular morphology and geniculate inputs in anthropoid monkeys. In contrast, Hässler’s (1967) laminar scheme delineates a single layer 4 and multiple subdivisions of layer 3, based on comparisons of V1 lamination across the primate lineage. In order to clarify laminar divisions in primate visual cortex, we performed NeuN and VGLUT2 immunohistochemistry in V1 of chimpanzees, Old World macaque monkeys, New World squirrel, owl, and marmoset monkeys, prosimian galagos and mouse lemurs, and non-primate, but highly visual, tree shrews. By comparing the laminar divisions identified by each method across species, we find that Hässler’s (1967) laminar scheme for V1 provides a more consistent representation of neocortical layers across all primates, including humans, and facilitates comparisons of V1 lamination with non-primate species. These findings, along with many others, support the consistent use of Hässler’s laminar scheme in V1 research.
Collapse
Affiliation(s)
- Pooja Balaram
- Laboratory of Jon Kaas, Department of Psychology, Vanderbilt University Nashville, TN, USA
| | - Jon H Kaas
- Laboratory of Jon Kaas, Department of Psychology, Vanderbilt University Nashville, TN, USA
| |
Collapse
|
27
|
Reduced density of geniculocortical terminals in foveal layer 4A in the macaque primary visual cortex: relationship to S-cone density. Brain Struct Funct 2014; 220:2783-96. [PMID: 25009312 DOI: 10.1007/s00429-014-0826-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2013] [Accepted: 06/17/2014] [Indexed: 01/28/2023]
Abstract
The S-cone system is closely linked to the perception of blue/yellow. The trichromatic system of Old-World monkeys and humans has relatively few S-cones in the fovea. In this study, we investigated the distribution of putative S-cone afferents in macaques primary visual cortex (V1) which form a characteristic honeycomb arrangement in layer 4A. It was hypothesized that if there were a low number of S-cone opponent projecting neurons in central vision then this would be seen as a reduction in afferents in foveal layer 4A. Recent studies have shown that the vesicular glutamate transporter 2 (VGlut2) is a marker for thalamic afferent terminals in cortex. The distribution of VGlut2-immunoreactive (-ir) terminals was studied in the foveal and perifoveal representation of V1. It was found that there was a substantial reduction in the terminal density in the foveal representation: the density was 5-6 times lower in the foveal V1 than in regions representing perifoveal eccentricities of 1°-2° and beyond. These findings may provide the cortical substrate of foveal tritanopia, the reduced blue perceptual ability for small fields in the center of gaze.
Collapse
|
28
|
Abstract
The thalamocortical (TC) projection to layer 4 (L4) is thought to be the main route by which sensory organs communicate with cortex. Sensory information is believed to then propagate through the cortical column along the L4→L2/3→L5/6 pathway. Here, we show that sensory-evoked responses of L5/6 neurons in rats derive instead from direct TC synapses. Many L5/6 neurons exhibited sensory-evoked postsynaptic potentials with the same latencies as L4. Paired in vivo recordings from L5/6 neurons and thalamic neurons revealed substantial convergence of direct TC synapses onto diverse types of infragranular neurons, particularly in L5B. Pharmacological inactivation of L4 had no effect on sensory-evoked synaptic input to L5/6 neurons. L4 is thus not an obligatory distribution hub for cortical activity, and thalamus activates two separate, independent "strata" of cortex in parallel.
Collapse
Affiliation(s)
- Christine M Constantinople
- Department of Neuroscience and Kavli Institute for Brain Science, Columbia University, New York, NY 10032, USA
| | | |
Collapse
|
29
|
Differential expression of vesicular glutamate transporters 1 and 2 may identify distinct modes of glutamatergic transmission in the macaque visual system. J Chem Neuroanat 2013; 50-51:21-38. [PMID: 23524295 DOI: 10.1016/j.jchemneu.2013.02.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 02/26/2013] [Accepted: 02/27/2013] [Indexed: 11/21/2022]
Abstract
Glutamate is the primary neurotransmitter utilized by the mammalian visual system for excitatory neurotransmission. The sequestration of glutamate into synaptic vesicles, and the subsequent transport of filled vesicles to the presynaptic terminal membrane, is regulated by a family of proteins known as vesicular glutamate transporters (VGLUTs). Two VGLUT proteins, VGLUT1 and VGLUT2, characterize distinct sets of glutamatergic projections between visual structures in rodents and prosimian primates, yet little is known about their distributions in the visual system of anthropoid primates. We have examined the mRNA and protein expression patterns of VGLUT1 and VGLUT2 in the visual system of macaque monkeys, an Old World anthropoid primate, in order to determine their relative distributions in the superior colliculus, lateral geniculate nucleus, pulvinar complex, V1 and V2. Distinct expression patterns for both VGLUT1 and VGLUT2 identified architectonic boundaries in all structures, as well as anatomical subdivisions of the superior colliculus, pulvinar complex, and V1. These results suggest that VGLUT1 and VGLUT2 clearly identify regions of glutamatergic input in visual structures, and may identify common architectonic features of visual areas and nuclei across the primate radiation. Additionally, we find that VGLUT1 and VGLUT2 characterize distinct subsets of glutamatergic projections in the macaque visual system; VGLUT2 predominates in driving or feedforward projections from lower order to higher order visual structures while VGLUT1 predominates in modulatory or feedback projections from higher order to lower order visual structures. The distribution of these two proteins suggests that VGLUT1 and VGLUT2 may identify class 1 and class 2 type glutamatergic projections within the primate visual system (Sherman and Guillery, 2006).
Collapse
|