TRANSCRANIAL MAGNETIC STIMULATION - DELAYS IN VISUAL SUPPRESSION DUE TO LUMINANCE CHANGES

TRANSCRANIAL magnetic stimulation (TMS) was used to investigate the de lays in visual processing time produced by changes in luminance. By ad ministering a magnetic pulse over the occipital pole 80-140 ms after t he onset of visual stimuli, we could suppress perception of a four-dig it number within a 30 ms time window. Commensurate with previous studi es of visual processing latencies, a drop in luminance from 3.52 logTd to 2.61 logTd delayed the peak of the suppression window by 8.9 ms, w hile a further drop from 2.61 logTD to 1.75 logTd delayed the peak by an additional 15.4 ms. This study validates the use of TMS as a psycho physical tool.