Theta rTMS Enhances Verbal Memory Encoding by Modulating Fronto-Parietal Dynamics

This study investigated frequency-specific effects of left parietal rhythmic transcranial magnetic stimulation(rTMS) on verbal memory encoding by combining 5 Hz and 20 Hz stimulation with concurrent electroencephalogram (EEG) in three healthy subjects. Behaviorally, 5 Hz stimulation significantly enhanced memory accuracy compared to 20 ∼Hz (t=7.141, p=0.019). Neural oscillations revealed that while both frequencies increased power in their respective bands, 5 Hz stimulation produced stronger enhancement. Frontal-central θ power positively correlated with memory performance during 5 Hz stimulation, whereas frontotemporal β power predicted recall under 20 Hz stimulation. These findings demonstrate that 5 Hz parietal rTMS optimizes memory encoding through θ oscillation enhancement and frontal-parietal network synchronization, while 20 Hz stimulation yields weaker behavioral effects with distinct neural correlates. These findings establish a novel concurrent TMS-EEG paradigm for real-time observation of frequency-specific entrainment effects during cognition, surpassing traditional pre/post designs. Critically, prefrontal theta power emerged as a neurophysiological predictor of memory enhancement under theta-rhythmic stimulation, providing a biomarker for personalized neuromodulation.