Thierry Bal Team

Homeostasis, Perception and States (HOPES)

In brief

Sensory perception, selective attention or perceptual awareness are intimately linked to the states of neuronal assemblies during wake and sleep; presumably depending on the level, frequencies and localizations of synchronized/de-synchonized activities, and may rely for their establishment and maintenance on plasticity homeostasis at various scales, from the synapse to the system. We study selected questions concerning these broad issues, by bringing together neurophysiologists with expertise on a large variety of techniques applied at scales ranging from the single synapse to dendrites, cells and systems, in vitro and in vivo.

Our research

The emphasis is on cortical structures (visual, entorhinal, insular); their various states of activity (oscillations vs asynchronous irregular states); their link to cognitive functions, with emphasis on visual perception, including their relationships with the claustrum (a thin structure reciprocally and topographically connecting all cortical areas, and hypothesized to amplify or adjust their level of excitability or of oscillations). Computational modeling, via daily basis collaboration with other ICN teams, is combined with our experimental studies.

In the initial stage of visual perception, visual information collected at the retina, flows through the thalamus to the primary visual cortical area (V1) where it interacts with horizontal inputs intrinsic to V1, feedback inputs coming from higher-order brain areas, and sub-cortical inputs such as from the claustrum or modulatory inputs which are known to regulate brain states. The aim of our work carried in vivo in higher mammals (cat and marmoset) is to better understand how visual information is processed through the interplay between feed-forward and feedback visual cortical areas both in the absence of attention-related processes (i.e. under anesthesia) but also in the awake attentive brain. It is also to explore the still largely unknown role of cortico-claustral reciprocal connections, which could be involved in attention, salience detection or state-dependant oscillation regulation.

Our approaches in vitro in thalamic and cortical brain slices, and in cell culture, are complementary to the in vivo and modeling explorations of neuronal networks and synaptic plasticity, in various sensory systems and brain states in the department of Integrative and Computational Neuroscience. Our recent findings range from demonstrating homeostatic synaptic plasticity in vertebrates preparations, to testing theories on the cellular mechanisms of attention using artificial conductance injection in biological neurons. Our goal is to explore the excitability and state-dependent dynamics of thalamic and cortical neurons and circuits, and more recently the claustrum, from the synapse and dendritic branches, up to the whole network.
The originality is the use of “active networks” in brain slices, in which neurons are examined within a more natural synaptically active environment that mimics sleep-wake states and their transitions. We have used and pioneered novel strategies to monitor the magnetic field produced by biological cells, and the voltage in axon and dendrites of individual neurons with high spatial and temporal resolution.

Selected Publications

> Gilles Ouanounou, Baux Gérard and Thierry Bal, A novel synaptic plasticity rule explains homeostasis of neuromuscular transmission, eLife 5 : , (2016)

> Florian Gerard-Mercier, Pedro Carelli, Marc Pananceau, Xoana Troncoso and Yves Frégnac, Synaptic Correlates of Low-Level Perception in V1, Journal of Neuroscience 36 : 3925–3942, (2016)

> Sébastien Béhuret, Charlotte Deleuze and Thierry Bal, Corticothalamic Synaptic Noise as a Mechanism for Selective Attention in Thalamic Neurons, Frontiers in Neural Circuits 9 : 11633, (2015)

> Amanda Casale, Amanda Foust, Thierry Bal and David A. McCormick, Cortical Interneuron Subtypes Vary in Their Axonal Action Potential Properties, Journal of Neuroscience 35 : 15555, (2015)

> Fournier, J., Monier, C., Levy, M., Marre, O., Sári, K., Kisvárday, Z. F., & Frégnac, Y. (2014). Hidden complexity of synaptic receptive fields in cat V1. The Journal of Neuroscience, 34(16), 5515–5528. doi.org

> Fournier, J., Monier, C., Pananceau, M., & Frégnac, Y. (2011). Adaptation of the simple or complex nature of V1 receptive fields to visual statistics. Nature Neuroscience, 14(8), 1053–1060. doi.org

> Jakob Wolfart, Damien Debay, Gwendal Le Masson, Alain Destexhe and Thierry Bal, Synaptic background activity controls spike transfer from thalamus to cortex, Nat Neurosci 8 : 1760-7, (2005)

> Gwendal Le Masson, Sylvie Renaud-Le Masson, Damien Debay and Thierry Bal, Feedback inhibition controls spike transfer in hybrid thalamic circuits,
Nature 417 : 854-8, (2002)

Team members