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Nadia Urbain" Sensory information transmission through the vibrissal system"

Abstract :

A central issue in sensory physiology is to understand how an animal endowed with highly sensitive sensory organs, and exploring the environment, can control the unending stream of sensory inputs it receives, and select those that are most relevant to an adaptive behaviour. For rodents, vibrissae serve as the primary tactile organ. Sensory stimuli evoke st
rong responses in thalamic relay cells of the lemniscal pathway, ensuring a faithful relay of information to the neocortex. However, relay cells of the posterior thalamic nuclear group (Po), despite receiving significant trigeminal input, respond only poorly to vibrissa deflection. Combining single-unit recordings with tract tracing, our work evidenced that the sensory transmission in this thalamic relay of the paralemniscal pathway is actually impeded by fast feedforward inhibition mediated by GABAergic neurons of the zona incerta. Short-latency whisker-evoked excitations are indeed unveiled after lesioning the zona incerta. Furthermore, the stimulation of the vibrissa motor cortex suppresses vibrissal responses in the zona incerta via an intra-incertal GABAergic circuit. These results suggest that sensory transmission through the paralemniscal pathway operates via a top-down disinhibitory mechanism that is contingent on motor activity. This gating mechanism, controlled by motor inputs, might filter out irrelevant sensory inputs according to the animal’s vigilance state or behaviour.

Selected publications

P. Lavallée, N. Urbain, C. Dufresne, H. Bokor, L. Acsádi and M. Deschênes (2005) Feedforward inhibitory control of sensory information in higher order thalamic nuclei. Journal of Neuroscience, 25: 7489-7498.

N. Urbain and M. Deschênes (2007) Motor cortex gates vibrissal responses in a thalamocortical projection pathway. Neuron, 56: 714-725.

Anne Taupignon