State-dependent alterations in neural activity induced by the personalized ventrolateral prefrontal cortex stimulation during viewing emotional film clips

Emotion regulation is crucial for maintaining normal social interactions and individual psychological health. Using transcranial magnetic stimulation (TMS) to modulate emotional regulation may be a powerful method for neurological or psychiatric disorders. However, TMS efficacy varies between protocols and individuals, with the brain's state during treatment being an often-overlooked factor. This study aimed to explore the influence of emotional brain state on TMS effects. Ninety-nine healthy participants were randomly assigned to three groups: one watched neutral film clips and received active TMS (neutral group), while the other two watched sadness film clips and received either active or sham TMS (sad and sham groups, respectively). The amplitude of low-frequency fluctuations (ALFF) and functional connectivity (FC) were investigated using resting-state functional magnetic resonance imaging. Compared with the neutral group, the sad group showed different changes in neural activity (as measured by ALFF) in the right superior occipital gyrus and right middle frontal gyrus after TMS. In the neutral group, the ALFF change in the right superior occipital gyrus was correlated with the baseline FC between this region and the TMS target. Additionally, changes in neural activity in the right superior occipital gyrus and right middle frontal gyrus were related to changes in depression scale scores in the sad group. These findings may suggest that TMS during different emotional states can induce state-dependent alterations in neural activity. By combining emotional induction, TMS, and fMRI, this study offers a unique perspective on state-dependent effects and may improve TMS treatment outcomes.