Date: April 16, 2018. 12:00
Location: CCU Seminar Room
Title: The high-gain state of visual cortex: a gateway to adult plasticity.
Affiliation: Center for Integrative Neuroscience, Department of Physiology, University of California, San Francisco, CA USA
The brain’s response to sensory input can strikingly be modulated during behavior. The regulation of brain state, the mechanisms responsible for it, and the effects of changing state remain some of the biggest questions in neuroscience. In the primary visual cortex (V1) of the mouse, responses to visual stimuli are dramatically enhanced by locomotion (Niell & Stryker, Neuron 2010), a tractable and accessible example of a time-locked change in cortical state. The high-gain state of V1 produced by locomotion contains more information, which allows better decoding of stimuli from the visual responses of recorded neurons (Dadarlat & Stryker, J Neurosci 2017). The neural circuit that produces this modulation originates in the midbrain locomotor center (Lee et al., Neuron 2014) and activates vasoactive intestinal peptide (VIP)- positive neurons in V1 through nicotinic inputs from basal forebrain. Optogenetic activation of VIP neurons mimics the effect of locomotion in enhancing cortical responses, and photolytic damage of VIP neurons abolishes it (Fu et al, Cell 2014; Fu et al eLife 2015). Responses to visual stimuli viewed while the mouse cortex was in the high-gain state produced by locomotion are dramatically enhanced (Kaneko & Stryker, eLife 2014). Neither visual stimulation nor locomotion alone work. Blocking synaptic transmission from VIP and SST cells or optogenetic stimulation of VIP cells revealed that the plasticity depended much more on the activation of the VIP-SST disinhibitory circuit than on some aerobic or metabolic consequence of locomotion (Fu et al, eLife 2015). Stimulus-specific short-term plasticity in adults was also dramatically enhanced by activation of this circuit (Kaneko & Stryker, J Neurosci 2017). Taken together, these findings suggest that the global state of cortical activity is modulated by a specific neural circuit that also modulates rapid, stimulus-specific plasticity.
Supported by US NIH grant EY-02874 and the Simons Collaboration on the Global Brain. M.P. Stryker is a recipient of the Research to Prevent Blindness (RPB) Stein Innovation Award.