Alpha amplitude and phase locking in obsessive-compulsive disorder during working memory
Jin Young Park ; Jaewon Lee ; Se Joo Kim ; Kee Namkoong ; Jae-Jin Kim ; Hae-Jeong Park
International Journal of Psychophysiology, Vol.83(1) : 1~7, 2012
International Journal of Psychophysiology
Alpha event-related desynchronization (ERD) and synchronization are known to reflect brain activation and inhibition, respectively. Alpha phase locking seems to reflect the timing in the cortical process. In a previous study, lower alpha ERD was related to working memory in obsessive-compulsive disorder (OCD) patients than in controls during the retention and retrival phases, but not in the encoding phase. However, memory deficits in OCD patients are known to be related to executive failure during the encoding phase. Thus, focusing on the encoding phase, we tested the level of alpha amplitude and phase locking in OCD patients according to memory load. The EEGs of fifteen OCD patients and fifteen controls were recorded during a Sternberg working memory task. The behavioral performance of the OCD patients was normal. However, the OCD group yielded significantly lower ERD and stronger phase locking. As memory load rose, ERD and phase locking significantly increased in both groups. A difference in event-related alpha oscillation was observed in the encoding phase. Lower alpha modulation in the OCD patient simplied abnormality of the excitatory/inhibitory process in the brain, and increased phase locking might reflect excessive attentional excitability.