The present study investigated transcranial alternating current stimulation (tACS) effects on working memory (WM) maintenance and memory consolidation in healthy human participants. We examined the behavioral effects of theta-frequency stimulation to the dorsolateral prefrontal cortex (DLPFC) as recent electrophysiological findings indicated that increased DLPFC theta synchronization predicts WM function and successful verbal-memory encoding. We utilized a verbal n-Back task known to be associated with DLPFC function and frontal theta activity to assess tACS manipulation effects on online (stimulation during WM task) WM accuracy, as well as on post-stimulation (immediately after stimulation) WM accuracy. Additionally, to investigate possible after-effects of tACS 20 minutes post-stimulation, we administered a free-recall procedure to evaluate episodic retrieval accuracy as an indication of successful memory consolidation. Results indicated enhanced online WM accuracy in the active bilateral DLPFC tACS condition. Significant implicit episodic memory after-effects were found in the active left DLPFC tACS condition as well as in the active bilateral DLPFC tACS condition. Most interestingly, explicit episodic retrieval was enhanced only in the active bilateral DLPFC condition. Our findings imply that bilateral DLPFC oscillatory stimulation may be used to increase functional connectivity in order to improve WM function and episodic memory formation.
|Title of host publication||Working Memory|
|Subtitle of host publication||Developmental Differences, Component Processes and Improvement Mechanisms|
|Publisher||Nova Science Publishers, Inc.|
|Number of pages||17|
|State||Published - 2013|