Cortical Output Is Gated by Horizontally Projecting Neurons in the Deep Layers

Egger, Robert; Narayanan, Rajeevan T.; Guest, Jason Mike; Bast, Arco; Udvary, Daniel; Messore, Fernando; Das, Suman; Kock, De; Oberlaender, Marcel

doi:10.1016/j.neuron.2019.10.011

Cited by 53 publications

(97 citation statements)

References 91 publications

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“…Because we recorded across multiple days during behavior, we did not attempt to recover cell morphology by juxtacellular filling. Thus, we could not differentiate cell types (e.g., thin- versus thick-tufted L5 pyramids, or L6A corticocortical cells [ 46 ]), their projection patterns (e.g., intertelencephalic [IT] versus pyramidal tract [PT]), or the extent to which whisker motion and object location tuning are segregated between these two classes as hypothesized in rat [ 47 ]. Half of object location–tuned units were also tuned to whisker angle during free-whisking, suggesting that these two features may not be cleanly divided between IT and PT cell types.…”

Section: Discussionmentioning

confidence: 99%

Independent representations of self-motion and object location in barrel cortex output

et al. 2020

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During active tactile exploration, the dynamic patterns of touch are transduced to electrical signals and transformed by the brain into a mental representation of the object under investigation. This transformation from sensation to perception is thought to be a major function of the mammalian cortex. In primary somatosensory cortex (S1) of mice, layer 5 (L5) pyramidal neurons are major outputs to downstream areas that influence perception, decision-making, and motor control. We investigated self-motion and touch representations in L5 of S1 with juxtacellular loose-seal patch recordings of optogenetically identified excitatory neurons. We found that during rhythmic whisker movement, 54 of 115 active neurons (47%) represented self-motion. This population was significantly more modulated by whisker angle than by phase. Upon active touch, a distinct pattern of activity was evoked across L5, which represented the whisker angle at the time of touch. Object location was decodable with submillimeter precision from the touch-evoked spike counts of a randomly sampled handful of these neurons. These representations of whisker angle during self-motion and touch were independent, both in the selection of which neurons were active and in the angle-tuning preference of coactive neurons. Thus, the output of S1 transiently shifts from a representation of self-motion to an independent representation of explored object location during active touch.

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Section: Discussionmentioning

confidence: 99%

Independent representations of self-motion and object location in barrel cortex output

et al. 2020

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“…In brain slice preparations, long-range axonal collaterals of CC and CCla PCs are massively truncated and consequently the length and fieldspan estimates are strongly underestimated (s. e.g. Egger et al 2020). Despite this, the distinct axonal and dendritic properties of the three L6A PC types allow an unambiguous cell type identification.…”

Section: Three Types Of Morphologically and Electrophysiologically DImentioning

confidence: 99%

“…In rat barrel cortex, layer 6 is the thickest layer and contains the highest number of neurons (Hutsler et al 2005;Meyer et al 2010). Pyramidal cells (PCs) in this layer 6 of the neocortex display a high degree of morphological, electrophysiological and molecular diversity (Zhang and Deschenes 1997;Kumar and Ohana 2008;Thomson 2010;Marx and Feldmeyer 2013;Gouwens et al 2019;Kast et al 2019;Egger et al 2020;Gouwens et al 2020). They project either intra-telencephalically (IT) within the cortex, to the striatum, and the claustrum or extra-telencephalically (ET) to e.g.…”

Section: Introductionmentioning

confidence: 99%

Layer 6A pyramidal cells subtypes form synaptic microcircuits with distinct functional and structural properties

Yang

Feldmeyer

2021

Preprint

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Neocortical layer 6 plays a crucial role in sensorimotor coordination and integration through functionally segregated circuits linking intracortical and subcortical areas. However, because of the high neuronal heterogeneity and sparse intralaminar connectivity data on the cell-type specific synaptic microcircuits in layer 6 remain few and far between. To address this issue, whole-cell recordings combined with morphological reconstructions have been used to identify morphoelectric types of layer 6A pyramidal cells (PCs) in rat barrel cortex. Cortico-thalamic (CT), corticocortical (CC) and cortico-claustral (CCla) pyramidal cells have been distinguished based on to their distinct dendritic and axonal morphologies as well as their different electrophysiological properties. Here we demonstrate that these three types of layer 6A pyramidal cells innervate neighboring excitatory neurons with distinct synaptic properties: CT PCs establish weak facilitating synapses to other L6A PCs; CC PCs form synapses of moderate efficacy; while synapses made by putative CCla PCs display the highest release probability and a marked short-term depression. Furthermore, for excitatory-inhibitory synaptic connections in layer 6 we were able to show that both the presynaptic PC type and the postsynaptic interneuron type govern the dynamic properties of the of the respective synaptic connections. We have identified a functional division of local layer 6A excitatory microcircuits which may be responsible of the differential temporal engagement of layer 6 feed-forward and feedback networks. Our results provides a basis for further investigations on the long-range cortico-cortical, cortico-thalamic and cortico-claustral pathways.

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“…is that VPL inputs are notably weak to corticospinal neurons, representing a major subtype of pyramidal-tract type neurons in L5B, whereas VPM inputs to L5B neurons in whisker S1 appear relatively stronger and are implicated in early cortical processing of somatosensory signals (Petreanu et al, 2009;Wimmer et al, 2010;Constantinople and Bruno, 2013;Rah et al, 2013;432 Sermet et al, 2019;Egger et al, 2020).…”

Section: Thalamocortical and Corticocortical Connectionsmentioning

confidence: 99%

Circuit organization of the excitatory sensorimotor loop through hand/forelimb S1 and M1

Yamawaki

Tapies

Stults

et al. 2021

Preprint

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Sensory-guided limb control relies on communication across sensorimotor loops. For active touch with the hand, the longest loop is the transcortical continuation of ascending pathways, particularly the lemnisco-cortical and corticocortical pathways carrying tactile signals via the cuneate nucleus, ventral posterior lateral (VPL) thalamus, and primary somatosensory (S1) and motor (M1) cortices to reach corticospinal neurons and influence descending activity. We characterized excitatory connectivity along this pathway in the mouse. In the lemnisco-cortical leg, disynaptic cuneate→VPL→S1 connections excited mainly layer (L) 4 neurons. In the corticocortical leg, S1→M1 connections from L2/3 and L5A neurons mainly excited downstream L2/3 neurons, which excite corticospinal neurons. The findings provide a detailed new wiring diagram for the hand/forelimb-related transcortical circuit, delineating a basic but complex set of cell-type-specific feedforward excitatory connections that selectively and extensively engage diverse intratelencephalic projection neurons, thereby polysynaptically linking subcortical somatosensory input to cortical motor output to spinal cord.

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Cortical Output Is Gated by Horizontally Projecting Neurons in the Deep Layers

Cited by 53 publications

References 91 publications

Independent representations of self-motion and object location in barrel cortex output

Independent representations of self-motion and object location in barrel cortex output

Layer 6A pyramidal cells subtypes form synaptic microcircuits with distinct functional and structural properties

Circuit organization of the excitatory sensorimotor loop through hand/forelimb S1 and M1

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