Publications by authors named "Charly V Rousseau"

6 Publications

  • Page 1 of 1

A Circuit for Integration of Head- and Visual-Motion Signals in Layer 6 of Mouse Primary Visual Cortex.

Neuron 2018 04 15;98(1):179-191.e6. Epub 2018 Mar 15.

The Sainsbury Wellcome Centre for Neural Circuits and Behaviour, University College London, 25 Howland Street, London W1T 4JG, UK. Electronic address:

To interpret visual-motion events, the underlying computation must involve internal reference to the motion status of the observer's head. We show here that layer 6 (L6) principal neurons in mouse primary visual cortex (V1) receive a diffuse, vestibular-mediated synaptic input that signals the angular velocity of horizontal rotation. Behavioral and theoretical experiments indicate that these inputs, distributed over a network of 100 L6 neurons, provide both a reliable estimate and, therefore, physiological separation of head-velocity signals. During head rotation in the presence of visual stimuli, L6 neurons exhibit postsynaptic responses that approximate the arithmetic sum of the vestibular and visual-motion response. Functional input mapping reveals that these internal motion signals arrive into L6 via a direct projection from the retrosplenial cortex. We therefore propose that visual-motion processing in V1 L6 is multisensory and contextually dependent on the motion status of the animal's head.
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http://dx.doi.org/10.1016/j.neuron.2018.02.023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5896233PMC
April 2018

A subcortical inhibitory signal for behavioral arrest in the thalamus.

Nat Neurosci 2015 Apr 23;18(4):562-568. Epub 2015 Feb 23.

Laboratory of Thalamus Research, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, H-1083, Hungary.

Organization of behavior requires rapid coordination of brainstem and forebrain activity. The exact mechanisms of effective communication between these regions are presently unclear. The intralaminar thalamic nuclei (IL) probably serves as a central hub in this circuit by connecting the critical brainstem and forebrain areas. We found that GABAergic and glycinergic fibers ascending from the pontine reticular formation (PRF) of the brainstem evoked fast and reliable inhibition in the IL via large, multisynaptic terminals. This inhibition was fine-tuned through heterogeneous GABAergic and glycinergic receptor ratios expressed at individual synapses. Optogenetic activation of PRF axons in the IL of freely moving mice led to behavioral arrest and transient interruption of awake cortical activity. An afferent system with comparable morphological features was also found in the human IL. These data reveal an evolutionarily conserved ascending system that gates forebrain activity through fast and powerful synaptic inhibition of the IL.
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http://dx.doi.org/10.1038/nn.3951DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4885661PMC
April 2015

The stimulus selectivity and connectivity of layer six principal cells reveals cortical microcircuits underlying visual processing.

Neuron 2014 Sep 28;83(6):1431-43. Epub 2014 Aug 28.

The Division of Neurophysiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK; Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK. Electronic address:

Sensory computations performed in the neocortex involve layer six (L6) cortico-cortical (CC) and cortico-thalamic (CT) signaling pathways. Developing an understanding of the physiological role of these circuits requires dissection of the functional specificity and connectivity of the underlying individual projection neurons. By combining whole-cell recording from identified L6 principal cells in the mouse primary visual cortex (V1) with modified rabies virus-based input mapping, we have determined the sensory response properties and upstream monosynaptic connectivity of cells mediating the CC or CT pathway. We show that CC-projecting cells encompass a broad spectrum of selectivity to stimulus orientation and are predominantly innervated by deep layer V1 neurons. In contrast, CT-projecting cells are ultrasparse firing, exquisitely tuned to orientation and direction information, and receive long-range input from higher cortical areas. This segregation in function and connectivity indicates that L6 microcircuits route specific contextual and stimulus-related information within and outside the cortical network.
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http://dx.doi.org/10.1016/j.neuron.2014.08.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4175007PMC
September 2014

Differential GABAergic and glycinergic inputs of inhibitory interneurons and Purkinje cells to principal cells of the cerebellar nuclei.

J Neurosci 2014 Jul;34(28):9418-31

Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), Inserm U1024, and CNRS UMR 8197, F-75005 Paris, France,

The principal neurons of the cerebellar nuclei (CN), the sole output of the olivo-cerebellar system, receive a massive inhibitory input from Purkinje cells (PCs) of the cerebellar cortex. Morphological evidence suggests that CN principal cells are also contacted by inhibitory interneurons, but the properties of this connection are unknown. Using transgenic, tracing, and immunohistochemical approaches in mice, we show that CN interneurons form a large heterogeneous population with GABA/glycinergic phenotypes, distinct from GABAergic olive-projecting neurons. CN interneurons are found to contact principal output neurons, via glycine receptor (GlyR)-enriched synapses, virtually devoid of the main GABA receptor (GABAR) subunits α1 and γ2. Those clusters account for 5% of the total number of inhibitory receptor clusters on principal neurons. Brief optogenetic stimulations of CN interneurons, through selective expression of channelrhodopsin 2 after viral-mediated transfection of the flexed gene in GlyT2-Cre transgenic mice, evoked fast IPSCs in principal cells. GlyR activation accounted for 15% of interneuron IPSC amplitude, while the remaining current was mediated by activation of GABAR. Surprisingly, small GlyR clusters were also found at PC synapses onto principal CN neurons in addition to α1 and γ2 GABAR subunits. However, GlyR activation was found to account for <3% of the PC inhibitory synaptic currents evoked by electrical stimulation. This work establishes CN glycinergic neurons as a significant source of inhibition to CN principal cells, forming contacts molecularly distinct from, but functionally similar to, Purkinje cell synapses. Their impact on CN output, motor learning, and motor execution deserves further investigation.
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http://dx.doi.org/10.1523/JNEUROSCI.0401-14.2014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6608357PMC
July 2014

Mixed inhibitory synaptic balance correlates with glutamatergic synaptic phenotype in cerebellar unipolar brush cells.

J Neurosci 2012 Mar;32(13):4632-44

Inhibitory Transmission Team, Institut de Biologie de l'ENS, IBENS, Inserm, U1024, CNRS, UMR 8197, Paris, F-75005 France.

Inhibitory synapses display a great diversity through varying combinations of presynaptic GABA and glycine release and postsynaptic expression of GABA and glycine receptor subtypes. We hypothesized that increased flexibility offered by this dual transmitter system might serve to tune the inhibitory phenotype to the properties of afferent excitatory synaptic inputs in individual cells. Vestibulocerebellar unipolar brush cells (UBC) receive a single glutamatergic synapse from a mossy fiber (MF), which makes them an ideal model to study excitatory-inhibitory interactions. We examined the functional phenotypes of mixed inhibitory synapses formed by Golgi interneurons onto UBCs in rat slices. We show that glycinergic IPSCs are present in all cells. An additional GABAergic component of large amplitude is only detected in a subpopulation of UBCs. This GABAergic phenotype is strictly anti-correlated with the expression of type II, but not type I, metabotropic glutamate receptors (mGluRs) at the MF synapse. Immunohistochemical stainings and agonist applications show that global UBC expression of glycine and GABA(A) receptors matches the pharmacological profile of IPSCs. Paired recordings of Golgi cells and UBCs confirm the postsynaptic origin of the inhibitory phenotype, including the slow kinetics of glycinergic components. These results strongly suggest the presence of a functional coregulation of excitatory and inhibitory phenotypes at the single-cell level. We propose that slow glycinergic IPSCs may provide an inhibitory tone, setting the gain of the MF to UBC relay, whereas large and fast GABAergic IPSCs may in addition control spike timing in mGluRII-negative UBCs.
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http://dx.doi.org/10.1523/JNEUROSCI.5122-11.2012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6622075PMC
March 2012