Differential associations between brain 5-HT(1A) receptor binding and response to pain versus touch.

We studied whether brain serotonin 5-HT(1A) receptor availability is associated with response to noxious heat versus tactile stimuli, and short-term memory for heat pain. Psychophysical performance was assessed in 16 healthy subjects who had participated in a positron emission tomography study using [carbonyl-11C]WAY-100635 ligand for the assessment of 5-HT(1A) receptor binding potential (BP (ND)). Signal detection theory was applied to allow separate analysis of the subject's sensory-discriminative capacity (sensory factor) and the attitude toward reporting a sensation (response criterion; non-sensory factor). Subject's response criterion for heat pain was inversely correlated with 5-HT(1A) BP (ND) in the dorsal raphe, middle temporal gyrus, orbitofrontal cortex and posterior cingulum, whereas the subject's discriminative capacity for touch was inversely correlated with 5-HT(1A) BP (ND) in the cingulum, inferior temporal gyrus, and medial prefrontal cortex. Certainty ratings of the responses, but not hit rates, in the pain memory task were correlated with 5-HT(1A) BP (ND) in the dorsal raphe.