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 whether 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 15 healthy adults (9 males, age = 30.3 ± 10.2 yr). 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 the pain was removed [MRCP: P = 1.0; alpha event-related spectral perturbation (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.NEW & NOTEWORTHY Our findings support a proactive suppression model of attention under unpredictability, in which cognitive resources are reallocated via enhanced alpha activity that aims to suppress forthcoming sensory processing to facilitate motor preparation of goal-directed movement. Furthermore, neural preparatory activity returns to baseline with the removal of pain suggesting preparatory activity is dynamic and current measures only provide a read-out of transient cortical states.