Control of visual input gain by serotonin and acetylcholine
Controlling the input that arrives at the primary visual cortex (V1) from the eyes is a powerful means for altering the outcome of all subsequent processing of visual information. While this is widely acknowledged to be a critical process, debate continues regarding the means by which this gain control is achieved. In particular, the control of sensory processing by behavioral and cognitive states (such as attention) almost certainly arises, at least in part, from circuits outside the cortex. This control of cortical circuits by subcortical nuclei is poorly understood. Previous anatomical data tell us that modulation by the subcortical cholinergic and serotonergic systems is strongly directed toward the site of visual input to cortex. This localization positions the cholinergic and serotonergic systems to control the extent to which information from the eyes gets processed, and therefore whether and how it is perceived. In this project, we causally manipulate this modulatory control during active vision, and determine the resulting effects on both neural responses and behavior.