Adaptation-induced plasticity of orientation tuning in adult visual cortex

A key emergent property of the primary visual cortex (V1) is the orientatio n selectivity of its neurons. The extent to which adult visual cortical neu rons can exhibit changes in orientation selectivity is unknown. Here we use single-unit recording and intrinsic signal imaging in V1 of adult cats to demonstrate systematic repulsive shifts in orientation preference following short-term exposure (adaptation) to one stimulus orientation. In contrast to the common view of adaptation as a passive process by which responses ar ound the adapting orientation are reduced, we show that changes in orientat ion tuning also occur due to response increases at orientations away from t he adapting stimulus. Adaptation-induced orientation plasticity is thus an active time-dependent process that involves network interactions and includ es both response depression and enhancement.