scholarly journals Characterizing the morphology of somatostatin‐expressing interneurons and their synaptic innervation pattern in the barrel cortex of the GFP‐expressing inhibitory neurons mouse

2019 ◽  
Vol 528 (2) ◽  
pp. 244-260 ◽  
Author(s):  
Xiaojuan Zhou ◽  
Ima Mansori ◽  
Tatjana Fischer ◽  
Mirko Witte ◽  
Jochen F. Staiger
Keyword(s):  
Barrel Cortex ◽  
Inhibitory Neurons ◽  
Innervation Pattern

Neuronal Circuits in Barrel Cortex for Whisker Sensory Perception

2021 ◽  
Vol 101 (1) ◽  
pp. 353-415
Author(s):  
Jochen F. Staiger ◽  
Carl C. H. Petersen
Keyword(s):  
Barrel Cortex ◽  
Specific Activity ◽  
Sensory Information ◽  
Inhibitory Neurons ◽  
Future Research ◽  
Cell Type ◽  
Molecular Features ◽  
Somatotopic Map ◽  
Cell Type Specific ◽  
The Impact

The array of whiskers on the snout provides rodents with tactile sensory information relating to the size, shape and texture of objects in their immediate environment. Rodents can use their whiskers to detect stimuli, distinguish textures, locate objects and navigate. Important aspects of whisker sensation are thought to result from neuronal computations in the whisker somatosensory cortex (wS1). Each whisker is individually represented in the somatotopic map of wS1 by an anatomical unit named a ‘barrel’ (hence also called barrel cortex). This allows precise investigation of sensory processing in the context of a well-defined map. Here, we first review the signaling pathways from the whiskers to wS1, and then discuss current understanding of the various types of excitatory and inhibitory neurons present within wS1. Different classes of cells can be defined according to anatomical, electrophysiological and molecular features. The synaptic connectivity of neurons within local wS1 microcircuits, as well as their long-range interactions and the impact of neuromodulators, are beginning to be understood. Recent technological progress has allowed cell-type-specific connectivity to be related to cell-type-specific activity during whisker-related behaviors. An important goal for future research is to obtain a causal and mechanistic understanding of how selected aspects of tactile sensory information are processed by specific types of neurons in the synaptically connected neuronal networks of wS1 and signaled to downstream brain areas, thus contributing to sensory-guided decision-making.

scholarly journals Pathway-, layer- and cell-type-specific thalamic input to mouse barrel cortex

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
B Semihcan Sermet ◽  
Pavel Truschow ◽  
Michael Feyerabend ◽  
Johannes M Mayrhofer ◽  
Tess B Oram ◽  
...  
Keyword(s):  
Thalamic Nucleus ◽  
Barrel Cortex ◽  
Sensory Information ◽  
Cell Types ◽  
Excitatory Input ◽  
Higher Order ◽  
Inhibitory Neurons ◽  
Thalamic Nuclei ◽  
Thalamic Input ◽  
Layer 4

Mouse primary somatosensory barrel cortex (wS1) processes whisker sensory information, receiving input from two distinct thalamic nuclei. The first-order ventral posterior medial (VPM) somatosensory thalamic nucleus most densely innervates layer 4 (L4) barrels, whereas the higher-order posterior thalamic nucleus (medial part, POm) most densely innervates L1 and L5A. We optogenetically stimulated VPM or POm axons, and recorded evoked excitatory postsynaptic potentials (EPSPs) in different cell-types across cortical layers in wS1. We found that excitatory neurons and parvalbumin-expressing inhibitory neurons received the largest EPSPs, dominated by VPM input to L4 and POm input to L5A. In contrast, somatostatin-expressing inhibitory neurons received very little input from either pathway in any layer. Vasoactive intestinal peptide-expressing inhibitory neurons received an intermediate level of excitatory input with less apparent layer-specificity. Our data help understand how wS1 neocortical microcircuits might process and integrate sensory and higher-order inputs.

scholarly journals Vigilance and behavioral state-dependent modulation of cortical neuronal activity throughout the sleep/wake cycle

2021 ◽  
Author(s):  
Aurelie Brecier ◽  
Melodie Borel ◽  
Nadia Urbain ◽  
Luc J Gentet
Keyword(s):  
Neuronal Activity ◽  
Rem Sleep ◽  
Barrel Cortex ◽  
Field Potential ◽  
Nrem Sleep ◽  
Inhibitory Neurons ◽  
Sleep Stages ◽  
Theta Waves ◽  
Physiological Diversity ◽  
Activity Dynamics

GABAergic inhibitory neurons, through their molecular, anatomic and physiological diversity, provide a substrate for the modulation of ongoing cortical circuit activity throughout the sleep-wake cycle. Here, we investigated neuronal activity dynamics of parvalbumin (PV), vasoactive intestinal polypeptide (VIP) and somatostatin (SST) neurons in naturally-sleeping head-restrained mice at the level of layer 2/3 of the primary somatosensory barrel cortex of mice. Through calcium-imaging and targeted single-unit loose-patch or whole-cell recordings, we found that PV action potential (AP) firing activity was largest during both NREM (non-rapid eye movement) and REM sleep stages, that VIP neurons were activated during REM sleep and that the overall activity of SST neurons remained stable throughout the sleep/wake cycle. Analysis of neuronal activity dynamics uncovered rapid decreases in PV cell firing at wake onset followed by a progressive recovery during wake. Simultaneous local field potential (LFP) recordings further revealed that, except for SST neurons, a large proportion of neurons were modulated by ongoing delta and theta waves. During NREM sleep spindles, PV and SST activity increased and decreased, respectively. Finally, we uncovered the presence of whisking behavior in mice during REM sleep and show that the activity of VIP and SST is differentially modulated during awake and sleeping whisking bouts, which may provide a neuronal substrate for internal brain representations occurring during sleep.

Activation of a wide-spread network of inhibitory neurons in barrel cortex

1997 ◽  
Vol 14 (2) ◽  
pp. 138-147 ◽  
Author(s):  
James Mccasland ◽  
Lyndon Hibbard ◽  
Robert Rhoades ◽  
Thomas Woolsey
Keyword(s):  
Barrel Cortex ◽  
Inhibitory Neurons ◽  
Wide Spread

Thalamocortical Specificity and the Synthesis of Sensory Cortical Receptive Fields

2005 ◽  
Vol 94 (1) ◽  
pp. 26-32 ◽  
Author(s):  
Jose-Manuel Alonso ◽  
Harvey A. Swadlow
Keyword(s):  
Visual Cortex ◽  
Barrel Cortex ◽  
Receptive Fields ◽  
High Specificity ◽  
Inhibitory Neurons ◽  
Simple Cells ◽  
Layer 4 ◽  
Different Response ◽  
Cortical Receptive Fields ◽  
Visual Cortical

A persistent and fundamental question in sensory cortical physiology concerns the manner in which receptive fields of layer-4 neurons are synthesized from their thalamic inputs. According to a hierarchical model proposed more than 40 years ago, simple receptive fields in layer 4 of primary visual cortex originate from the convergence of highly specific thalamocortical inputs (e.g., geniculate inputs with on-center receptive fields overlap the on subregions of layer 4 simple cells). Here, we summarize studies in the visual cortex that provide support for this high specificity of thalamic input to visual cortical simple cells. In addition, we review studies of GABAergic interneurons in the somatosensory “barrel” cortex with receptive fields that are generated by a very different mechanism: the nonspecific convergence of thalamic inputs with different response properties. We hypothesize that these 2 modes of thalamocortical connectivity onto subpopulations of excitatory and inhibitory neurons constitute a general feature of sensory neocortex and account for much of the diversity seen in layer-4 receptive fields.

Response Sensitivity of Barrel Neuron Subpopulations to Simulated Thalamic Input

2010 ◽  
Vol 103 (6) ◽  
pp. 3001-3016 ◽  
Author(s):  
Michael J. Pesavento ◽  
Cynthia D. Rittenhouse ◽  
David J. Pinto
Keyword(s):  
Barrel Cortex ◽  
Brain Slices ◽  
Input Resistance ◽  
Inhibitory Neurons ◽  
Membrane Properties ◽  
Cortical Function ◽  
Thalamic Input ◽  
Intrinsic Membrane Properties

Our goal is to examine the relationship between neuron- and network-level processing in the context of a well-studied cortical function, the processing of thalamic input by whisker-barrel circuits in rodent neocortex. Here we focus on neuron-level processing and investigate the responses of excitatory and inhibitory barrel neurons to simulated thalamic inputs applied using the dynamic clamp method in brain slices. Simulated inputs are modeled after real thalamic inputs recorded in vivo in response to brief whisker deflections. Our results suggest that inhibitory neurons require more input to reach firing threshold, but then fire earlier, with less variability, and respond to a broader range of inputs than do excitatory neurons. Differences in the responses of barrel neuron subtypes depend on their intrinsic membrane properties. Neurons with a low input resistance require more input to reach threshold but then fire earlier than neurons with a higher input resistance, regardless of the neuron's classification. Our results also suggest that the response properties of excitatory versus inhibitory barrel neurons are consistent with the response sensitivities of the ensemble barrel network. The short response latency of inhibitory neurons may serve to suppress ensemble barrel responses to asynchronous thalamic input. Correspondingly, whereas neurons acting as part of the barrel circuit in vivo are highly selective for temporally correlated thalamic input, excitatory barrel neurons acting alone in vitro are less so. These data suggest that network-level processing of thalamic input in barrel cortex depends on neuron-level processing of the same input by excitatory and inhibitory barrel neurons.

scholarly journals Fast activation of feedforward inhibitory neurons from thalamic input and its relevance to the regulation of spike sequences in the barrel cortex

2010 ◽  
Vol 588 (15) ◽  
pp. 2769-2787 ◽  
Author(s):  
Fumitaka Kimura ◽  
Chiaki Itami ◽  
Koji Ikezoe ◽  
Hiroshi Tamura ◽  
Ichiro Fujita ◽  
...  
Keyword(s):  
Barrel Cortex ◽  
Inhibitory Neurons ◽  
Thalamic Input ◽  
Spike Sequences ◽  
Fast Activation

scholarly journals Microcircuits of excitatory and inhibitory neurons in layer 2/3 of mouse barrel cortex

2012 ◽  
Vol 107 (11) ◽  
pp. 3116-3134 ◽  
Author(s):  
Michael Avermann ◽  
Christian Tomm ◽  
Celine Mateo ◽  
Wulfram Gerstner ◽  
Carl C. H. Petersen
Keyword(s):  
Barrel Cortex ◽  
Gabaergic Neurons ◽  
Network Activity ◽  
Inhibitory Neurons ◽  
Synaptic Connectivity ◽  
Postsynaptic Potentials ◽  
Optogenetic Stimulation ◽  
Layer 2 ◽  
Fast Spiking ◽  
Whole Cell Recordings

Synaptic interactions between nearby excitatory and inhibitory neurons in the neocortex are thought to play fundamental roles in sensory processing. Here, we have combined optogenetic stimulation, whole cell recordings, and computational modeling to define key functional microcircuits within layer 2/3 of mouse primary somatosensory barrel cortex. In vitro optogenetic stimulation of excitatory layer 2/3 neurons expressing channelrhodopsin-2 evoked a rapid sequence of excitation followed by inhibition. Fast-spiking (FS) GABAergic neurons received large-amplitude, fast-rising depolarizing postsynaptic potentials, often driving action potentials. In contrast, the same optogenetic stimulus evoked small-amplitude, subthreshold postsynaptic potentials in excitatory and non-fast-spiking (NFS) GABAergic neurons. To understand the synaptic mechanisms underlying this network activity, we investigated unitary synaptic connectivity through multiple simultaneous whole cell recordings. FS GABAergic neurons received unitary excitatory postsynaptic potentials with higher probability, larger amplitudes, and faster kinetics compared with NFS GABAergic neurons and other excitatory neurons. Both FS and NFS GABAergic neurons evoked robust inhibition on postsynaptic layer 2/3 neurons. A simple computational model based on the experimentally determined electrophysiological properties of the different classes of layer 2/3 neurons and their unitary synaptic connectivity accounted for key aspects of the network activity evoked by optogenetic stimulation, including the strong recruitment of FS GABAergic neurons acting to suppress firing of excitatory neurons. We conclude that FS GABAergic neurons play an important role in neocortical microcircuit function through their strong local synaptic connectivity, which might contribute to driving sparse coding in excitatory layer 2/3 neurons of mouse barrel cortex in vivo.

scholarly journals Distinct in vivo dynamics of excitatory synapses onto cortical pyramidal neurons and inhibitory interneurons

2021 ◽  
Author(s):  
Joshua B. Melander ◽  
Aran Nayebi ◽  
Bart C. Jongbloets ◽  
Dale A. Fortin ◽  
Maozhen Qin ◽  
...  
Keyword(s):  
Pyramidal Neurons ◽  
Synaptic Weight ◽  
Barrel Cortex ◽  
Inhibitory Neurons ◽  
Inhibitory Interneurons ◽  
Excitatory Synapses ◽  
Cell Type ◽  
Cortical Function ◽  
Cell Type Specific

SUMMARYCortical function relies on the balanced activation of excitatory and inhibitory neurons. However, little is known about the organization and dynamics of shaft excitatory synapses onto cortical inhibitory interneurons, which cannot be easily identified morphologically. Here, we fluorescently visualize the excitatory postsynaptic marker PSD-95 at endogenous levels as a proxy for excitatory synapses onto layer 2/3 pyramidal neurons and parvalbumin-positive (PV+) inhibitory interneurons in the mouse barrel cortex. Longitudinal in vivo imaging reveals that, while synaptic weights in both neuronal types are log-normally distributed, synapses onto PV+ neurons are less heterogeneous and more stable. Markov-model analyses suggest that the synaptic weight distribution is set intrinsically by ongoing cell type-specific dynamics, and substantial changes are due to accumulated gradual changes. Synaptic weight dynamics are multiplicative, i.e., changes scale with weights, though PV+ synapses also exhibit an additive component. These results reveal that cell type-specific processes govern cortical synaptic strengths and dynamics.

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