Thermosensation

Thermosensation is the sensory process by which organisms detect changes in environmental and body temperature. In humans, it arises from specialized thermoreceptors in the skin and mucous membranes, as well as central mechanisms that monitor core temperature to coordinate behavior and autonomic responses.

Peripheral thermoreceptors include a family of transient receptor potential (TRP) channels and related sensors. Cool temperatures activate receptors such as TRPM8; warm temperatures engage TRPV3 and TRPV4; heat-activated TRPV1 responds to noxious heat. TRPA1 has been implicated in cold and chemical nociception in some species. The receptors are primarily expressed on small-diameter A-delta and C fibers, conveying signals toward the central nervous system.

Afferent fibers project to the dorsal horn of the spinal cord and ascend via the anterolateral (spinothalamic) pathway to the thalamus, and thence to somatosensory cortex. Additional projections reach insular and cingulate cortices, contributing to the affective and motivational aspects of temperature experience.

Central processing in the hypothalamus and especially the preoptic area integrates core temperature information to regulate autonomic and endocrine responses, such as vasoconstriction, sweating, shivering, and non-shivering thermogenesis, as well as behaviorally driven actions to seek warmth or cool environments.

Thermosensation is distinct from, but related to, thermoreception that conveys noxious heat or cold through nociceptors. Extreme temperatures can activate pain pathways, and thermosensory perception can be altered by aging, peripheral neuropathies, diabetes, or nerve injuries.

Clinically, assessment of thermosensation informs neuropathy evaluation and helps understand deficits in temperature discrimination. Experimental methods include psychophysical testing and imaging techniques.