Thermosensory

Thermosensory refers to the sensory processes that detect and encode temperature changes. In biology, the term describes both the sense of temperature in organisms and the molecular and neural mechanisms that enable that sense. Thermosensation relies on peripheral thermoreceptors located in the skin and mucosal surfaces that transduce temperature variations into neural signals. These receptors include free nerve endings that respond to warming or cooling and a family of ion channels that gate in response to temperature changes, most notably the transient receptor potential (TRP) channels.

Molecular sensors: TRPM8 detects cool temperatures (and menthol), with activation at roughly room temperature or cooler; TRPV1 detects heat, activated by temperatures above about 43 C and by capsaicin; other TRP channels such as TRPV3/4 and TRPA1 contribute to warm or noxious stimuli and chemical irritants. The exact contributions vary by tissue and species, and multiple receptors can cooperate to shape the percept.

Neural pathways: Thermosensory signals travel via primary afferent neurons to the spinal cord or brainstem, then ascend to the thalamus and somatosensory cortex for conscious perception. Separate circuits in the hypothalamus and brainstem regulate autonomic and behavioral responses, including vasomotion, sweating, shivering, and seeking favored temperatures to maintain core temperature.

Functions and scope: Thermosensation supports homeostasis, protective nociception, and behavioral choices. It operates across vertebrates and invertebrates, enabling organisms to detect environmental temperatures and adjust physiology and behavior accordingly.