The effects of a heterotopic cold pain stimulus applied to
the hand on the scalp-recorded negative difference potential
(NDP) and subjective pain ratings elicited by electrical
stimulation of the sural nerve were examined in 24 participants.
Our previous work strongly suggests that the NDP is generated
in part by the cognitive division of the anterior cingulate
cortex (ACCcd). The latency and magnitude of the ACCcd activity
were estimated from the NDP and from the dipole source localization
analysis of the NDP. As expected, the sural nerve pain ratings
were smaller in the cold pain condition than in the control
condition. The ACCcd activity underlying the 125-ms peak of
the NDP did not change across conditions, whereas the ACCcd
activity underlying the 210-ms NDP peak was largest in the cold
pain condition. The dissociation between pain-evoked ACCcd activity
and pain ratings observed here and elsewhere suggest that not
all of the nociresponsive neurons in the ACCcd are involved
in pain sensation. Rather, differences in the cognitive demands
of the control and cold pain conditions suggest that the
pain-evoked 210-ms ACCcd activity reflects response selection
processes, perhaps response competition monitoring.