Unpredictable movement-evoked pain alters cortical motor preparatory activity.

Although there is substantial evidence that central motor system function is altered both during and after pain removal, the effect of pain on motor preparation remains poorly understood. The present study used electroencephalography (EEG) to examine whether the predictability of movement-evoked pain modulates cortical preparatory activity, and if changes in cortical activity persist after the removal of pain. The movement-related cortical potential (MRCP), alpha frequency band (8-12 Hz) oscillatory activity and the vertex laser-evoked potential (N2P2) were evaluated in fifteen healthy adults (9 male, age = 30.3 ± 10.2 years). Under unpredictable pain expectancy, peak MRCP amplitude (p = 0.044), premovement alpha activity (p = 0.002), and N2P2 amplitude (p < 0.001) all significantly increased. These preparatory changes did not persist once pain was removed (MRCP: p = 1.0; alpha ERSP: p = 1.0 ). These findings suggest that unpredictable pain expectancy modulates motor preparation through top-down attentional mechanisms that serve to suppress distractor sensorimotor processing and enhance task-relevant neural activity to support optimal motor programming.