Repetitive Transcranual Magnetic Stimulation Reverses Aβ1-42-induced Dysfunction in Gamma Oscillation during Working Memory

Background: Alzheimer's disease (AD) is a neurodegenerative disease that gradually induces cognitive deficits in the elderly and working memory impairment is typically observed in AD. Amyloid-1 beta peptide (A beta) is a causative factor for the cognitive impairments in AD. Gamma oscillations have been recognized to play important roles in various cognitive functions including working memory. Previous study reported that A beta induces gamma oscillation dysfunction in working memory. Objective: Although repetitive transcranial magnetic stimulation (rTMS) represents a technique for noninvasive stimulation to induce cortical activity and excitability changes and has been accepted for increasing brain excitability and regulating cognitive behavior, the question whether rTMS can reserve the A beta-induced gamma oscillation dysfunction during working memory remains unclear. The present study aims to investigate the effect of rTMS to the A beta-inducedgamma oscillation dysfunction during working memory. Method: The present study investigates the rTMS-modulated gamma oscillation in A beta(1-42)-induced memory deficit. Adult SD rats were divided into four groups: A beta, Con, A beta+rTMS and Con+rTMS. 16-channel local field potentials (LFPs) were recorded from rat medial prefrontal cortex while the rats performed a Y-maze working memory task. Gamma oscillation among LFPs was measured by coherence. Results: The results show that rTMS improved the behavior performance and enhanced gamma oscillation for the A beta-injected subjects. Conclusion: These results indicate that rTMS may reserve the A beta-induced dysfunction in gamma oscillation during working memory and thus result in potential benefits for working memory.