Dissociation of subjective pain report and pain-related late positive components of cerebral evoked potentials in subjects with brain lesions

Abstract

Several studies have described a correlation between subjective pain report and late positive components (LPCs) of cerebral evoked potentials occurring with latencies ranging from 150 to 400 msec after the onset of painful stimuli. We report here human subjects with brain lesions who revealed very small LPCs in response to painful electrical skin stimuli applied to the finger pads even though they described strong subjective pain for the same stimuli. A decrease in pain-related LPCs was observed regardless of whether the stimuli were applied to the finger pads ipsilateral or contralateral to the brain lesions. Based on this observation, it is suggested that the pain-related LPCs may reflect neural processes which are presumably associated with information processing of painful input rather than neural processes of pain perception per se.