scholarly journals Delineating the Organization of Projection Neuron Subsets with Multi-fluorescent Rabies Virus Tracing Tool

2019 ◽  
Author(s):  
Liang Li ◽  
Yajie Tang ◽  
Leqiang Sun ◽  
Jinsong Yu ◽  
Hui Gong ◽  
...  
Keyword(s):  
Rabies Virus ◽  
Functional Organization ◽  
Projection Neuron ◽  
Projection Neurons ◽  
Thalamic Nuclei ◽  
Corticothalamic Projection ◽  
Virus Tracing ◽  
Layer V ◽  
The Brain ◽  
Layer Vi

AbstractThe elegant functions of the brain are facilitated by sophisticated connections between neurons, the architecture of which is frequently characterized by one nucleus connecting to multiple targets via projection neurons. Delineating the sub-nucleus fine architecture of projection neurons in a certain nucleus could greatly facilitate its circuit, computational, and functional resolution. Here, we developed multi-fluorescent rabies virus to delineate the fine organization of corticothalamic projection neuron subsets in the primary visual cortex (V1). By simultaneously labeling multiple distinct subsets of corticothalamic projection neurons in V1 from their target nuclei in thalamus (dLGN, LP, LD), we observed that V1-dLGN corticothalamic neurons were densely concentrated in layer VI, except for several sparsely scattered neurons in layer V, while V1-LP and V1-LD corticothalamic neurons were localized to both layers V and VI. Meanwhile, we observed a fraction of V1 corticothalamic neurons targeting multiple thalamic nuclei, which was further confirmed by fMOST whole-brain imaging. We further conceptually proposed an upgraded sub-nucleus tracing system with higher throughput (21 subsets) for more complex architectural tracing. The multi-fluorescent RV tracing tool can be extensively applied to resolve architecture of projection neuron subsets, with a strong potential to delineate the computational and functional organization of these nuclei.

Differential Involvement of Projection Neurons During Emergence of Spontaneous Activity in the Developing Avian Hindbrain

2009 ◽  
Vol 101 (2) ◽  
pp. 591-602 ◽  
Author(s):  
Hiraku Mochida ◽  
Gilles Fortin ◽  
Jean Champagnat ◽  
Joel C. Glover
Keyword(s):  
Spontaneous Activity ◽  
Projection Neuron ◽  
Projection Neurons ◽  
Charge Coupled Device ◽  
Neuron Populations ◽  
Motor Nerves ◽  
Differential Involvement ◽  
A Charge ◽  
The Brain ◽  
Calcium Green

To better characterize the emergence of spontaneous neuronal activity in the developing hindbrain, spontaneous activity was recorded optically from defined projection neuron populations in isolated preparations of the brain stem of the chicken embryo. Ipsilaterally projecting reticulospinal (RS) neurons and several groups of vestibuloocular (VO) neurons were labeled retrogradely with Calcium Green-1 dextran amine and spontaneous calcium transients were recorded using a charge-coupled-device camera mounted on a fluorescence microscope. Simultaneous extracellular recordings were made from one of the trigeminal motor nerves (nV) to register the occurrence of spontaneous synchronous bursts of activity. Two types of spontaneous activity were observed: synchronous events (SEs), which occurred in register with spontaneous bursts in nV once every few minutes and were tetrodotoxin (TTX) dependent, and asynchronous events (AEs), which occurred in the intervals between SEs and were TTX resistant. AEs occurred developmentally before SEs and were in general smaller and more variable in amplitude than SEs. SEs appeared at the same stage as nV bursts early on embryonic day 4, first in RS neurons and then in VO neurons. All RS neurons participated equally in SEs from the outset, whereas different subpopulations of VO neurons participated differentially, both in terms of the proportion of neurons that exhibited SEs, the fidelity with which the SEs in individual neurons followed the nV bursts, and the developmental stage at which SEs appeared and matured. The results show that spontaneous activity is expressed heterogeneously among hindbrain projection neuron populations, suggesting its differential involvement in the formation of different functional neuronal circuits.

scholarly journals Increased Callosal Connectivity in Reeler Mice Revealed by Brain-Wide Input Mapping of VIP Neurons in Barrel Cortex

2020 ◽  
Author(s):  
Georg Hafner ◽  
Julien Guy ◽  
Mirko Witte ◽  
Pavel Truschow ◽  
Alina Rüppel ◽  
...  
Keyword(s):  
Long Range ◽  
Cortical Neurons ◽  
Barrel Cortex ◽  
Projection Neurons ◽  
Subcortical Structures ◽  
Virus Tracing ◽  
Cortical Inputs ◽  
Callosal Projection ◽  
To Receive ◽  
The Brain

Abstract The neocortex is composed of layers. Whether layers constitute an essential framework for the formation of functional circuits is not well understood. We investigated the brain-wide input connectivity of vasoactive intestinal polypeptide (VIP) expressing neurons in the reeler mouse. This mutant is characterized by a migration deficit of cortical neurons so that no layers are formed. Still, neurons retain their properties and reeler mice show little cognitive impairment. We focused on VIP neurons because they are known to receive strong long-range inputs and have a typical laminar bias toward upper layers. In reeler, these neurons are more dispersed across the cortex. We mapped the brain-wide inputs of VIP neurons in barrel cortex of wild-type and reeler mice with rabies virus tracing. Innervation by subcortical inputs was not altered in reeler, in contrast to the cortical circuitry. Numbers of long-range ipsilateral cortical inputs were reduced in reeler, while contralateral inputs were strongly increased. Reeler mice had more callosal projection neurons. Hence, the corpus callosum was larger in reeler as shown by structural imaging. We argue that, in the absence of cortical layers, circuits with subcortical structures are maintained but cortical neurons establish a different network that largely preserves cognitive functions.

scholarly journals Glutamatergic Nonpyramidal Neurons From Neocortical Layer VI and Their Comparison With Pyramidal and Spiny Stellate Neurons

2009 ◽  
Vol 101 (2) ◽  
pp. 641-654 ◽  
Author(s):  
Sofija Andjelic ◽  
Thierry Gallopin ◽  
Bruno Cauli ◽  
Elisa L. Hill ◽  
Lisa Roux ◽  
...  
Keyword(s):  
Pyramidal Neurons ◽  
Glutamate Transporter ◽  
Gabaergic Interneuron ◽  
Acid Decarboxylase ◽  
Projection Neurons ◽  
Heterogeneous Cluster ◽  
Glutamatergic Neurons ◽  
Layer V ◽  
Nonpyramidal Neurons ◽  
Layer Vi

The deeper part of neocortical layer VI is dominated by nonpyramidal neurons, which lack a prominent vertically ascending dendrite and predominantly establish corticocortical connections. These neurons were studied in rat neocortical slices using patch-clamp, single-cell reverse transcription–polymerase chain reaction, and biocytin labeling. The majority of these neurons expressed the vesicular glutamate transporter but not glutamic acid decarboxylase, suggesting that a high proportion of layer VI nonpyramidal neurons are glutamatergic. Indeed, they exhibited numerous dendritic spines and established asymmetrical synapses. Our sample of glutamatergic nonpyramidal neurons displayed a wide variety of somatodendritic morphologies and a subset of these cells expressed the Nurr1 mRNA, a marker for ipsilateral, but not commissural corticocortical projection neurons in layer VI. Comparison with spiny stellate and pyramidal neurons from other layers showed that glutamatergic neurons consistently exhibited a low occurrence of GABAergic interneuron markers and regular spiking firing patterns. Analysis of electrophysiological diversity using unsupervised clustering disclosed three groups of cells. Layer V pyramidal neurons were segregated into a first group, whereas a second group consisted of a subpopulation of layer VI neurons exhibiting tonic firing. A third heterogeneous cluster comprised spiny stellate, layer II/III pyramidal, and layer VI neurons exhibiting adaptive firing. The segregation of layer VI neurons in two different clusters did not correlate either with their somatodendritic morphologies or with Nurr1 expression. Our results suggest that electrophysiological similarities between neocortical glutamatergic neurons extend beyond layer positioning, somatodendritic morphology, and projection specificity.

scholarly journals The mouse cortico–basal ganglia–thalamic network

Nature ◽  
2021 ◽  
Vol 598 (7879) ◽  
pp. 188-194
Author(s):  
Nicholas N. Foster ◽  
Joshua Barry ◽  
Laura Korobkova ◽  
Luis Garcia ◽  
Lei Gao ◽  
...  
Keyword(s):  
Basal Ganglia ◽  
Closed Loop ◽  
Functional Organization ◽  
Dorsal Striatum ◽  
Thalamic Nuclei ◽  
Indirect Pathway ◽  
History Of ◽  
Bona Fide ◽  
External Part ◽  
The Brain

AbstractThe cortico–basal ganglia–thalamo–cortical loop is one of the fundamental network motifs in the brain. Revealing its structural and functional organization is critical to understanding cognition, sensorimotor behaviour, and the natural history of many neurological and neuropsychiatric disorders. Classically, this network is conceptualized to contain three information channels: motor, limbic and associative1–4. Yet this three-channel view cannot explain the myriad functions of the basal ganglia. We previously subdivided the dorsal striatum into 29 functional domains on the basis of the topography of inputs from the entire cortex5. Here we map the multi-synaptic output pathways of these striatal domains through the globus pallidus external part (GPe), substantia nigra reticular part (SNr), thalamic nuclei and cortex. Accordingly, we identify 14 SNr and 36 GPe domains and a direct cortico-SNr projection. The striatonigral direct pathway displays a greater convergence of striatal inputs than the more parallel striatopallidal indirect pathway, although direct and indirect pathways originating from the same striatal domain ultimately converge onto the same postsynaptic SNr neurons. Following the SNr outputs, we delineate six domains in the parafascicular and ventromedial thalamic nuclei. Subsequently, we identify six parallel cortico–basal ganglia–thalamic subnetworks that sequentially transduce specific subsets of cortical information through every elemental node of the cortico–basal ganglia–thalamic loop. Thalamic domains relay this output back to the originating corticostriatal neurons of each subnetwork in a bona fide closed loop.

Micro-periodic functional organization in layer V composed of subcerebral projection neurons

2010 ◽  
Vol 68 ◽  
pp. e152
Author(s):  
Hisato Maruoka ◽  
Kazumasa Kubota ◽  
Shun Turuno ◽  
Rumi Kurokawa ◽  
Toshihiko Hosoya
Keyword(s):  
Functional Organization ◽  
Projection Neurons ◽  
Layer V

scholarly journals The mouse cortico-basal ganglia-thalamic network

2020 ◽  
Author(s):  
Nicholas N. Foster ◽  
Laura Korobkova ◽  
Luis Garcia ◽  
Lei Gao ◽  
Marlene Becerra ◽  
...  
Keyword(s):  
Basal Ganglia ◽  
Functional Organization ◽  
Network Motif ◽  
Dorsal Striatum ◽  
Thalamic Nuclei ◽  
Cortical Areas ◽  
Neuropsychiatric Diseases ◽  
History Of ◽  
Input Source ◽  
The Brain

ABSTRACTThe cortico-basal ganglia-thalamic loop is one of the fundamental network motifs in the brain. Revealing its structural and functional organization is critical to understanding cognition, sensorimotor behavior, and the natural history of many neurological and neuropsychiatric diseases. Classically, the basal ganglia is conceptualized to contain three primary information output channels: motor, limbic, and associative. However, given the roughly 65 cortical areas and two dozen thalamic nuclei that feed into the dorsal striatum, a three-channel view is overly simplistic for explaining the myriad functions of the basal ganglia. Recent works from our lab and others have subdivided the dorsal striatum into numerous functional domains based on convergent and divergent inputs from the cortex and thalamus. To complete this work, we generated a comprehensive data pool of ∼700 injections placed across the striatum, external globus pallidus (GPe), substantia nigra pars reticulata (SNr), thalamic nuclei, and cortex. We identify 14 domains of SNr, 36 in the GPe, and 6 in the parafascicular and ventromedial thalamic nuclei. Subsequently, we identify 6 parallel cortico-basal ganglia-thalamic subnetworks that sequentially transduce specific subsets of cortical information with complex patterns of convergence and divergence through every elemental node of the entire cortico-basal ganglia loop. These experiments reveal multiple important novel features of the cortico-basal ganglia network motif. The prototypical sub-network structure is characterized by a highly interconnected nature, with cortical information processing through one or more striatal nodes, which send a convergent output to the SNr and a more parallelized output to the GPe; the GPe output then converges with the SNr. A domain of the thalamus receives the nigral output, and is interconnected with both the striatal domains and the cortical areas that filter into its nigral input source. This study provides conceptual advancement of our understanding of the structural and functional organization of the classic cortico-basal ganglia network.

Cytoarchitecture and thalamic connectivity of third somatosensory area of cat cerebral cortex

1978 ◽  
Vol 41 (2) ◽  
pp. 268-284 ◽  
Author(s):  
D. G. Tanji ◽  
S. P. Wise ◽  
R. W. Dykes ◽  
E. G. Jones
Keyword(s):  
Cerebral Cortex ◽  
Pyramidal Cells ◽  
Thalamic Nuclei ◽  
Somatosensory Area ◽  
Posterior Group ◽  
Layer V ◽  
Evoked Activity ◽  
To Receive ◽  
The Brain ◽  
Cat Cerebral Cortex

1. The third somatosensory area (SIII) was identified in the cat cerebral cortex by the recording of surface potentials evoked by deflection of a single contralateral mystacial vibrissa. A small amount of tritiated leucine was then injected at the center of the focus of evoked activity and, after a suitable survival period, the brain was prepared for autoradiography. 2. As defined by the presence of an autoradiographic injection, the SIII focus lay in a cytoarchitectonic field characterized in particular by the presence of very large pyramidal cells in layer V and corresponding to area 5a of Hassler and Muhs-Clement (24). 3. The terminal ramifications of corticothalamic cells, as outlined by axoplasmically transported label, formed clustered aggregations in the medial division of the posterior group of thalamic nuclei (Pom) and not in the ventrobasal complex (VB). This part of Pom is known to receive fibers from the spinal cord. 4. Injections of horseradish peroxidase primarily affecting area 5a retrogradely labeled cells in Pom but not in VB. 5. Injections of isotope in the two other foci of vibrissa-evoked activity usually recorded in each brain were invariably found to label a part of area 3b of the first somatosensory area (SI) in the case of the more anterior focus. The second focus sometimes lay in area 2 of SI and sometimes in the second somatosensory area (SII).

scholarly journals Neurog2 and Ascl1 together regulate a postmitotic derepression circuit to govern laminar fate specification in the murine neocortex

2017 ◽  
Vol 114 (25) ◽  
pp. E4934-E4943 ◽  
Author(s):  
Daniel J. Dennis ◽  
Grey Wilkinson ◽  
Saiqun Li ◽  
Rajiv Dixit ◽  
Lata Adnani ◽  
...  
Keyword(s):  
Cell Fate ◽  
Deep Layer ◽  
Projection Neurons ◽  
Cell Fate Specification ◽  
Transcriptional Repressors ◽  
Gain Of Function ◽  
Proneural Genes ◽  
Fate Specification ◽  
Layer V ◽  
Layer Vi

A derepression mode of cell-fate specification involving the transcriptional repressors Tbr1, Fezf2, Satb2, and Ctip2 operates in neocortical projection neurons to specify six layer identities in sequence. Less well understood is how laminar fate transitions are regulated in cortical progenitors. The proneural genes Neurog2 and Ascl1 cooperate in progenitors to control the temporal switch from neurogenesis to gliogenesis. Here we asked whether these proneural genes also regulate laminar fate transitions. Several defects were observed in the derepression circuit in Neurog2−/−;Ascl1−/− mutants: an inability to repress expression of Tbr1 (a deep layer VI marker) during upper-layer neurogenesis, a loss of Fezf2+/Ctip2+ layer V neurons, and precocious differentiation of normally late-born, Satb2+ layer II–IV neurons. Conversely, in stable gain-of-function transgenics, Neurog2 promoted differentiative divisions and extended the period of Tbr1+/Ctip2+ deep-layer neurogenesis while reducing Satb2+ upper-layer neurogenesis. Similarly, acute misexpression of Neurog2 in early cortical progenitors promoted Tbr1 expression, whereas both Neurog2 and Ascl1 induced Ctip2. However, Neurog2 was unable to influence the derepression circuit when misexpressed in late cortical progenitors, and Ascl1 repressed only Satb2. Nevertheless, neurons derived from late misexpression of Neurog2 and, to a lesser extent, Ascl1, extended aberrant subcortical axon projections characteristic of early-born neurons. Finally, Neurog2 and Ascl1 altered the expression of Ikaros and Foxg1, known temporal regulators. Proneural genes thus act in a context-dependent fashion as early determinants, promoting deep-layer neurogenesis in early cortical progenitors via input into the derepression circuit while also influencing other temporal regulators.

scholarly journals The unbalanced reorganization of weaker functional connections induces the altered brain network topology in schizophrenia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rossana Mastrandrea ◽  
Fabrizio Piras ◽  
Andrea Gabrielli ◽  
Nerisa Banaj ◽  
Guido Caldarelli ◽  
...  
Keyword(s):  
Resting State ◽  
Functional Organization ◽  
Functional Integration ◽  
Brain Network ◽  
Modular Organization ◽  
Node Degree ◽  
Imaging Data ◽  
Brain Disorder ◽  
Functional Connections ◽  
The Brain

AbstractNetwork neuroscience shed some light on the functional and structural modifications occurring to the brain associated with the phenomenology of schizophrenia. In particular, resting-state functional networks have helped our understanding of the illness by highlighting the global and local alterations within the cerebral organization. We investigated the robustness of the brain functional architecture in 44 medicated schizophrenic patients and 40 healthy comparators through an advanced network analysis of resting-state functional magnetic resonance imaging data. The networks in patients showed more resistance to disconnection than in healthy controls, with an evident discrepancy between the two groups in the node degree distribution computed along a percolation process. Despite a substantial similarity of the basal functional organization between the two groups, the expected hierarchy of healthy brains' modular organization is crumbled in schizophrenia, showing a peculiar arrangement of the functional connections, characterized by several topologically equivalent backbones. Thus, the manifold nature of the functional organization’s basal scheme, together with its altered hierarchical modularity, may be crucial in the pathogenesis of schizophrenia. This result fits the disconnection hypothesis that describes schizophrenia as a brain disorder characterized by an abnormal functional integration among brain regions.

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