The time course of cortical facilitation during cued shifts of spatial attention

Adaptive behavior requires the rapid switching of attention among potential ly relevant stimuli that appear in the environment. The present study used an electrophysiological approach to continuously measure the time course of visual pathway facilitation in human subjects as attention was shifted fro m one location to another. Steady-state visual evoked potentials (SSVEPs) w ere recorded to rapidly flickering lights at attended and unattended locati ons, and variations in SSVEP amplitude over time were calculated after a cu e to shift attention. The build-up of cortical facilitation reflected in SS VEP amplitude was found to bear a close temporal relationship with the emer gence of accurate target discriminations at the newly attended location.