Mesoscale cortical dynamics reflect the interaction of sensory evidence and temporal expectation during perceptual decision-making

How sensory evidence is transformed across multiple brain regions to influence behavior remains poorly understood. We trained mice in a visual change detection task designed to separate the covert antecedents of choices from activity associated with their execution. Widefield calcium imaging across dorsal cortex revealed fundamentally different dynamics of activity underlying these processes. While signals related to execution of choice were widespread, fluctuations in sensory evidence in the absence of overt motor responses triggered a confined activity cascade, beginning with transient modulation of visual cortex, followed by sustained recruitment of secondary and primary motor cortex. The activation of motor cortex by sensory evidence was selectively gated by animals expectation of when the stimulus was likely to change. These results identify distinct activation profiles of specific cortical areas during decision-making, and show that the recruitment of motor cortex depends on the interaction of sensory evidence and expectation.