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

Abstract

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-β peptide (Aβ) 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 Aβ 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 Aβ-induced gamma oscillation dysfunction during working memory remains unclear. The present study aims to investigate the effect of rTMS to the Aβ-induced gamma oscillation dysfunction during working memory.

Method: The present study investigates the rTMS-modulated gamma oscillation in Aβ1-42-induced memory deficit. Adult SD rats were divided into four groups: Aβ, Con, Aβ+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 Aβ-injected subjects.

Conclusion: These results indicate that rTMS may reserve the Aβ-induced dysfunction in gamma oscillation during working memory and thus result in potential benefits for working memory.

Keywords: Amyloid-β peptide (Aβ); Repetitive transcranial magnetic stimulation (rTMS); gamma oscillation; local field potentials (LFPs); rat; working memory..