Researchers have discovered that the human body detects cold temperatures through distinct molecular systems in the skin and internal organs. This finding explains why surface chills differ from the cold felt deeper inside. The study highlights variations in sensory mechanisms across tissues.
Scientists at the Institute for Neurosciences, a collaboration between the Spanish National Research Council and Miguel Hernández University of Elche, have revealed that cold perception is not uniform across the body. Led by Félix Viana, co-director of the Sensory Transduction and Nociception laboratory, the team found that skin primarily relies on the TRPM8 ion channel to sense cool environmental conditions. In contrast, internal organs such as the lungs and stomach depend on the TRPA1 sensor for detecting temperature drops.
This distinction accounts for everyday experiences, like the sharp chill of wind on the skin versus the internal bite of cold air in the lungs. Viana noted, "The skin is equipped with specific sensors that allow us to detect environmental cold and adapt defensive behaviors." He further explained, "In contrast, cold detection inside the body appears to depend on different sensory circuits and molecular receptors, reflecting its deeper physiological role in internal regulation and responses to environmental stimuli."
To reach these conclusions, researchers examined sensory neurons via the trigeminal nerve, which handles skin and head sensations, and the vagus nerve, linking the brain to organs like the lungs and digestive system. Using calcium imaging, electrophysiological recordings, and drugs to block specific sensors, they observed real-time nerve responses. Experiments with genetically modified mice lacking TRPM8 or TRPA1 confirmed the sensors' unique roles in different tissues.
Katharina Gers-Barlag, the study's first author, highlighted its implications: "Our findings reveal a more complex and nuanced view of how sensory systems in different tissues encode thermal information. This opens new avenues to study how these signals are integrated and how they may be altered in pathological conditions, such as certain neuropathies in which cold sensitivity is disrupted."
The research, published in Acta Physiologica (2025; 241(11)), was funded by Spanish national and regional bodies, as well as the Human Frontier Science Program. It underscores how temperature detection aligns with each tissue's physiological needs, potentially informing treatments for temperature-related disorders.
