Resting-state EEG microstate dynamics reflect individual differences in tactile angle discriminability.

Tactile spatial acuity, the ability to discriminate fine spatial details, is a fundamental sensory capacity modulated by both peripheral and central mechanisms. Here, we investigated whether resting-state EEG microstate dynamics are associated with individual differences in tactile spatial acuity. Following resting-state EEG recordings, 81 healthy right-handed participants performed a tactile angle discrimination (TAD) task. Five canonical microstate classes (A-E) were identified using k-means clustering (k = 5, explaining 78% of GFP variance). The primary analysis employed multiple linear regression with continuous TAD threshold as the outcome and microstate parameters (mean duration, occurrence, coverage) and transition probabilities as predictors, with sex included as a covariate. Regression analysis revealed that microstate A occurrence was the strongest predictor of TAD threshold (β = -0.40, p = 0.002), with higher occurrence associated with better tactile acuity; consistent patterns were observed for mean duration and coverage, although these parameters are algebraically interrelated with occurrence. The overall model for transition probabilities was significant (adjusted R 2 = 0.422, p < 0.001), but no individual transition reached statistical significance. Exploratory group comparisons showed numerically consistent patterns, with the low-threshold/high-acuity group exhibiting higher occurrence and coverage of microstate A and elevated transitions involving A→B, A↔D, and B↔D, whereas the high-threshold/low-acuity group showed higher C↔E transitions. This study suggests that specific EEG microstate parameters - particularly microstate A occurrence-may serve as promising candidate neurophysiological indices of tactile spatial acuity, underscoring the role of large-scale brain network dynamics in shaping fundamental sensory function.