Contribution of extrastriate area V4 to the surface-recorded flash VEP in the awake macaque.

This study compared striate and extrastriate contributions to the surface-recorded flash VEP. Laminar visual evoked potential, current source density and multiunit activity profiles were obtained with multicontact electrodes from areas V1 and V4 in three awake macaques. As found earlier, the major striate contribution is to early (N40, P55-80) components. Major contributions to the later (N95, P120, Late Negativity) components arise from V4. Early, afferent-triggered inhibition in V4 also produces a small contribution to N40. Response latencies in V4 vs V1 suggest an input to V4, bypassing V1, emphasizing a parallel processing component of visual system organization.