CONTRIBUTION OF EXTRASTRIATE AREA V4 TO THE SURFACE-RECORDED FLASH VEP IN THE AWAKE MACAQUE

This study compared striate and extrastriate contributions to the surf ace-recorded flash VEP. Laminar visual evoked potential, current sourc e density and multiunit activity profiles were obtained with multicont act electrodes from areas V1 and V4 in three awake macaques. As found earlier, the major striate contribution is to early (N40, P55-80) comp onents. Major contributions to the later (V95, P120, Late Negativity) components arise from V4. Early, afferent-triggered inhibition in V4 a lso produces a small contribution to N40. Response latencies in V4 vs V1 suggest an input to V4, bypassing V1, emphasizing a parallel proces sing component of visual system organization.