Gating and control of primary visual cortex by pulvinar

The primary visual cortex (V1) receives its driving input from the eyes via the lateral geniculate nucleus (LGN) of the thalamus. The lateral pulvinar nucleus of the thalamus also projects to V1 but this input is little understood. We manipulated lateral pulvinar neural activity and assessed the effect on supra-granular layers of V1 that project to higher visual cortex. Reversibly inactivating lateral pulvinar prevented supra-granular V1 neurons from responding to visual stimulation. Reversible, focal excitation of lateral pulvinar receptive fields increased 4-fold the visual responses in coincident V1 receptive fields and shifted partially overlapping V1 receptive fields towards the center of excitation. V1 responses to regions surrounding the excited lateral pulvinar receptive fields were suppressed. LGN responses were unaffected by these lateral pulvinar manipulations. Excitation of lateral pulvinar after LGN lesion activated supra-granular layer V1 neurons. Thus, lateral pulvinar is able to powerfully control and gate information outflow from V1. The primate visual system is currently viewed as a rough hierarchy of 30 or more cortical areas1–4. Area V1 is at the bottom of this hierarchy and contains a representation o