Temporal Precision of 40-Hz Burst Transcutaneous Auricular Vagus Nerve Stimulation Improves Working Memory in Healthy Volunteers

Improving working memory (WM) is crucial for navigating current information-rich environments. Transcutaneous auricular vagus nerve stimulation (taVNS) shows promise for enhancing cognition, although its impact on WM varies significantly with stimulation parameters.

Eighty participants were randomized into one of four stimulation groups: Sham (no stimulation), 5 Hz (30 seconds ON/OFF), 25 Hz (30 seconds ON/OFF), or 40-Hz-Burst (40-Hz-B; 5 seconds ON/OFF). Each group received a 30-minute session of their assigned taVNS protocol. After stimulation, WM was evaluated using a three-back task. Concurrent electroencephalography was recorded during the task to analyze event-related potentials (P3b a subcomponent of the P300) and oscillatory activity, specifically, theta event-related synchronization (ERS) and alpha event-related desynchronization (ERD).

Significant WM enhancement was observed after a single 40-Hz-B taVNS session, with three-back task performance showing improved accuracy and reaction times. These behavioral gains were accompanied by consistent neural changes, including increased P3b amplitudes, elevated theta ERS, and enhanced alpha ERD.

The observed results suggest that 40-Hz-B taVNS synchronizes activity in fundamental neuromodulatory systems supporting attention and inhibitory control. Such synchronization promotes superior WM performance by optimizing neural resource utilization and strengthening interference suppression.

The Chinese Clinical Trial Registry (http://www.chictr.org.cn/) number for the study is ChiCTR2300078459.