Thermoception

Thermoception is the sensory perception of temperature, a somatosensory modality that allows organisms to detect environmental and contact temperatures. It relies on peripheral thermoreceptors—free nerve endings in the skin and mucous membranes—that detect cool and warmth or heat. In humans, cold detection is largely mediated by cold-sensitive receptors associated with TRPM8, which is activated by cool temperatures and compounds like menthol. Warmth is sensed by receptors linked to TRPV3 and TRPV4, with higher temperatures engaging additional channels such as TRPV1.

These thermoreceptors are connected to small-diameter nerve fibers, primarily unmyelinated C fibers and some thinly myelinated Aδ fibers, which relay signals to the dorsal horn of the spinal cord and ascend via the spinothalamic tract to the thalamus and then to cortical areas. The brain regions involved include the primary somatosensory cortex and the insular cortex, which together process the intensity and quality of temperature. The hypothalamus participates in autonomic and behavioral thermoregulation, integrating thermal information with homeostatic needs.

Perception of temperature includes the discrimination of cold, cool, warm, and hot, with thresholds and sensitivity shaped by ambient conditions and adaptation. Temperature sensation can be distinct from nociception; temperatures that are dangerously hot or cold can activate nociceptors, producing pain.

Clinical aspects include impaired or altered thermal sensation due to nerve injury, diabetic neuropathy, or lesions in the somatosensory pathways. Thermoception interacts with broader homeostatic systems to maintain core temperature while guiding conscious comfort and behavior.