Cold stimuli evoke potentials that can be recorded directly from parasylvian cortex in humans

Anatomic, imaging, and lesion studies suggest that insular or parietal opercular cortical structures mediate the sensation of nonpainful cold. We have now tested the hypothesis that cold stimuli evoke electrical responses from these cortical structures in humans. We recorded the response to cold stimuli from electrodes implanted directly over parasylvian cortex for the investigation of intractable seizures. The results demonstrate that slow potentials can be evoked consistently over structures adjacent to the sylvian fissure in response to nonpainful cold. The polarity of these cold evoked potentials (EPs) for electrodes above the sylvian fissure is opposite to those below. These results suggest that the generator of cold EPs is close to the sylvian fissure in the parietal operculum or insula.