Cerebral Responses to Warmth and Heat and Cold Pain Measured by Positron Emission Tomography.

Phasic heat and tonic cold stimuli that have different temporal patterns, afferent fiber activations, and perceived pain characteristics produce a shared pattern of cerebral activation in addition to modality specific activations. These patterns are different from the cerebral representation of innocuous temperature sensation. Functional brain imaging techniques provide an opportunity to study somatosensory organization in conscious humans under physiologic conditions, despite certain limitations of imaging modalities.