Enhancement of cognitive behavior and hippocampal neural oscillations by rhythmic unipolar pulsed magnetic stimulation in 5xFAD Alzheimer's disease mice

Alzheimer's disease (AD) imposes a heavy burden on families and society. Rhythmic magnetic stimulation has emerged as a promising non-invasive therapy to mitigate AD-related cognitive decline. In this study, we applied a rhythmic unipolar compound pulsed magnetic field (cPMF; carrier frequency: 40 Hz, repetition rate: 5 Hz, magnetic flux density: 0-20 mT) incorporating both theta and gamma rhythms to evaluate its effects on behavior and neural oscillations in AD mice and to explore the underlying mechanisms. 5xFAD mice received unipolar cPMF stimulation for 1 h/d over 8 consecutive weeks. Learning and memory were assessed using the novel object recognition (NOR) and the Morris water maze (MWM) tests. In NOR test, unipolar cPMF-treated mice showed a higher cognitive index in test phase 2, and in MWM test, exhibited shorter escape latencies in the training trial and spent less time to first cross the precise former platform location with a higher crossing frequency over this target area in the probe trial. Local field potentials (LFPs) in the hippocampal CA1 area were recorded via in vivo electrophysiology. LFP analysis showed that unipolar cPMF treatment enhanced power of cognitive-related neural oscillations and strengthened theta-gamma phase-amplitude coupling. RNA sequencing analysis further indicated that unipolar cPMF-treated mice exhibited differential gene expression in molecular function and multiple neurotransmitter synaptic signaling pathways. In conclusion, unipolar cPMF might improve cognitive function in 5xFAD mice by modulating cognitive-related neural oscillations. These findings could provide experimental support for the low-intensity pulsed magnetic stimulation as a potential therapeutic strategy for AD.