Central Neural Networks of Verbal Working Memory and Visuospatial Attention: An Interference Approach Using Low-frequency Repetitive Transcranial Magnetic Stimulation

ABSTRACT

OBJECTIVE: We evaluated a role of prefrontal and parietal cortex in verbal working memory and visuospatial attention using repetitive transcranial magnetic stimulation (rTMS). METHOD: In six healthy volunteers, bilateral prefrontal and parietal cortex was stimulated with rTMS (90% of motor threshold, 10 trains of 1 Hz rTMS) during performed cognitive tasks (two-back verbal working memory task and endogenous visuospatial attention task). rTMS was applied to 4 different sites over left prefrontal, right prefrontal, left parietal and right parietal areas at F3, F4, P3 and P4 location on the scalp, according to the 10/20 EEG system. The sham stimulation was applied with the coil placed perpendicular to the scalp. RESULTS: Reaction time (RT) was significantly prolonged by left prefrontal TMS in verbal working memory. In addition, performance deterioration was also observed during rTMS over the right prefrontal and left parietal areas. In visuospatial attention task, RT was significantly prolonged by right parietal TMS. CONCLUSION: These results show that left prefrontal cortex play a major role in the network of working memory, and right parietal cortex is important area in the visuospatial attention. We suggest that an rTMS could be a useful method for evaluation of neural network in human brain.