Cutaneous temperature receptors.

Specific thermoreceptors comprise an electrophysiologically distinct class of cutaneous receptors with a morphological substrate (free nerve endings) and plausible transduction mechanism (electrogenic Na pump with or without auxiliary temperature-dependent processes). Because responses to thermal and mechanical stimuli converge along the neural pathway, we have difficulty explaining the purity of cold and warm sensations; participation of dual-modality receptors in sensory discrimination cannot be ruled out. The field is now at a point where a leap in understanding would be achieved by intracellular recordings from the sensory receptor (for which patch clamp studies on isolated neuronal elements may provide the necessary technology) and from continued analysis of what information is lost and what retained in passage from one synapse to the next along the thermal pathway.