Event-related potential correlates of interference between cognitive performance and tonic experimental pain

In this study, we examined cognitive function during experimental pain induced by an ischemic upper-arm tourniquet. During pain and control conditions, individuals performed a memory search task and an oddball task. Reaction time, errors, and event-related potentials in response to task stimuli were evaluated. Pain reduced accuracy and changed the response-type dependency of errors and the reaction time within the memory search task: false rejections but not false acceptances increased, and rejections were faster than acceptances during pain, whereas the opposite occurred during control conditions. The memory probes elicited an N275 that increased and a P300 that decreased in amplitude during pain. Pain also reduced amplitudes of P200 and P300 from the oddball task. N275 enhancement was greater in nonaffected than affected individuals, suggesting its association with focused attention that inhibited disruption by pain. P300 attenuation is interpreted as an indication that cognitive involvement in pain diminishes the attention resources allocated to a concurrent cognitive task.