Sensory processing sensitivity is associated with localized, band-specific increases in resting-state EEG synchrony

Sensory processing sensitivity (SPS) has been linked to heightened responsiveness to external input, yet its neurophysiological basis remains unclear. In this study, we examined whether local phase synchrony correlates with individual differences in SPS. We evaluated SPS in 188 healthy adults using the Japanese version of the Highly Sensitive Person Scale (HSPS- J19), originally proposed by Aron and Aron (1997). We also estimated the phase-locking value (PLV) of EEG during resting state. We observed a localized, frequency-band-specific association in a right frontotemporal patch (the triangular region defined by the three adjacent electrode lattice points F4-C4-T4): PLV was positively correlated with the ease of excitation subscale, specifically in the theta and beta bands (false discovery rate controlled). No effects survived in the left homolog, other frequency bands, or other SPS subscales. This pattern suggests that individuals with higher SPS exhibit increased right frontotemporal synchrony at rest, consistent with increased salience detection and control initiation and with maintained top-down prediction and sensory gating. These findings identify localized, band-specific synchrony as a potential electrophysiological signature of SPS.