TMS effect on visual search task

In this study, we examined the temporal aspects of the right posterior parietal cortex in easy feature and hard feature "pop-out" visual searches using transcranial magnetic stimulation (TMS). The transcranial magnetic stimulations were applied over the right posterior parietal cortex of subjects. Subjects received 4 tests which the TMS onset times were set as 100, 150, 200 and 250msec after visual stimulus presentation. We found that, when SOA=150msec, compared to no-TMS condition, There was a significant elevation in response time when the TMS pluses were applied. However for the other SOA cases, there was no significant difference between TMS and no-TMS conditions. Therefore, we considered that "pop-out" visual search was processed in the right posterior parietal cortex at about 150msec after stimulus present.