Visual working memory revealed by repetitive transcranial magnetic stimulation

We evaluated whether repetitive transcranial magnetic stimulation (rTMS) could be utilized for studying the hemispheric lateralization and anatomical localization of the cortical areas of the visual system that are concerned with object-related visual working memory. In eight normal volunteers, visual working memory was tested during rTMS delivery over nine regions in each hemisphere. Visual working memory was significantly disturbed by rTMS over the right hemisphere compared with the left (P<0.05). The disturbance in visual working memory by rTMS was significant over the right inferior frontal (F8), inferior temporal (T8), and middle parietal (P4) areas compared with the control region (P<0.05). This study suggests that visual working memory is lateralized to the right hemisphere and localized in the right inferior frontal, inferior temporal, and middle-parietal areas. As a non-invasive tool, rTMS may be useful for the functional localization of the working memory system.