A neurophysiologic correlate of visual short-term memory in humans

Neurophysiological investigations in non-human primates and neuropsychological studies in patients with lesions indicate that the inferotemporal cortex is critically involved in visual object recognition. We have recorded event-related potentials from 31 electrodes in a group of healthy normal individuals performing a modified delayed matching to sample task. We have identified a visual memory potential (VMP) which indexes visual short-term memory in humans. This component of the event-related brain potential occurs as early as 170 msec, is maximal at 240 msec, and is generally located in the temporal region. Both the temporal and spatial characteristics of the VMP in humans are in keeping with single cell studies in monkeys.