Current events

Date: February 1st

Time: 09:30 am

Place : Gonda 2303

Title : “Mechanisms controlling the gain of the visual cortex neurons during wakefulness”

Speaker: Pierre-Olivier Polack

Abstract: Reliable acquisition and amplification of sensory input is the first essential step for learning and memory. During wakefulness the gain of sensory neurons can change with behavior. In particular, visual cortical neurons fire at higher rates to visual stimuli during locomotion than during immobility while maintaining orientation selectivity. The mechanisms underlying this change in gain are not understood. We performed whole cell recordings from layer 2/3 and layer 4 visual cortical excitatory neurons as well as from parvalbumin-positive and somatostatin-positive inhibitory neurons in mice free to rest or run on a spherical treadmill. We found that the membrane potential of all cell types became more depolarized and (with the exception of somatostatin-positive interneurons) less variable during locomotion. Cholinergic input was essential for maintaining the unimodal membrane potential distribution during immobility, while noradrenergic input was necessary for the tonic depolarization associated with locomotion. Our results provide a mechanism for how neuromodulation controls the gain and signal-to-noise ratio of visual cortical neurons during changes in the state of vigilance. We are now investigating whether the same mechanism is responsible for controlling selective attention to visual input during a perceptual learning task.