Effect of Prefrontal Repetitive Transcranial Magnetic Stimulation on the Enhancement of Working Memory

Objective: To investigate the effect of repetitive transcranial magnetic stimulation (rTMS) applied over the left prefrontal cortex on the enhancement of verbal working memory in healthy persons. Method: High frequency (10 Hz) rTMS was applied over the left prefrontal cortex with the intensity of 100% resting motor threshold (RMT). A 3-back verbal working memory task was administered before, during (after applying 500 and 1,000 pulses, respectively), and 30 minutes after real or sham rTMS. Results: Real rTMS, compared with sham stimulation, significantly improved working memory performance. Accuracy of response increased significantly after applying 1,000 pulses of real rTMS (p< 0.05). This effect maintained for 30 minutes after completion of stimulation (p< 0.05). The error rate and reaction time did not change with rTMS. There was no noticeable side effect during or after rTMS. Conclusion: 1,000 pulses of 10 Hz rTMS administered to the left prefrontal cortex with the intensity of 100% RMT have positive impact on verbal working memory in healthy persons. Further study is necessary to address this effect of rTMS in patients with cognitive dysfunction.