Effects of Low Frequency Repetitive Transcranial Magnetic Stimulation on Visual Short Term Memory in Healthy Individuals

Oh, Hae Jeong; Kim, Won; Lee, Kyung Uk; Bahk, Won Myong; Jun, Tae Yun; Han, Jin Hee; Chae, Jeong Ho

Abstract

OBJECTIVES
Repetitive transcranial magnetic stimulation (rTMS) is a novel, noninvasive method of brain stimulation. Since conventional rTMS does not cause seizure, marked advantage over electroconvulsive therapy (ECT), rTMS can be used easily and widely. Once the effects of rTMS on cognitive function are elucidated, its application will be further extended. However, the effects of rTMS on cognitive function have not been well examined. This study aimed to evaluate the effect of low frequency rTMS on visual short term memory.
METHODS
Forty normal healthy volunteers were randomly assigned to rTMS (n=20) or sham (n=20) groups. The rTMS group were again randomly divided into left prefrontal (n=10) and right prefrontal (n=10) groups. For each group rTMS was given at 1 Hz for 20 minutes with 100% of motor threshold. As a cognitive task, Corsi Block Tapping Test (CORSI) in the computerized Vienna Test System, which can assess visual short term memory, was performed before, during, and after the rTMS.
RESULTS
No significant difference was found in the visual short term memories between the rTMS and the sham groups before, during, or after 1 Hz rTMS, nor between the left and right prefrontal rTMS groups.
CONCLUSION
This study demonstrates that rTMS, contrary to ECT, has no adverse visual short term memory effect when used as the standard treatment paradigm. Therefore, rTMS could be a new and safe treatment method in various neuropsychiatric fields without any interference of cognitive function.