Fig. 4.

Sensory responses evoked during UP state are spatially confined. Sensory responses evoked by whisker deflection were collected, and each trial was analyzed. Responses were divided into those evoked from UP state or DOWN state. The WC recording of a layer 2/3 pyramidal neuron (membrane potential in the left column) indicates small and brief sensory responses from UP state and large responses from DOWN state. In this experiment, four of six responses from DOWN state evoked APs, but no APs were observed in the four trials evoked from the UP state. VSD imaging of the same sweeps indicates that responses from UP and DOWN states are initiated at the same cortical location, with smaller amplitude responses occurring from UP state. In the next milliseconds, the response from DOWN state propagated across a large area of neocortex, whereas the response evoked during UP state remained localized.