This is how the skin distinguishes hot from cold

Discovery opens up ideas for research on pain and sensory disorders The nervous system uses a single cell population to distinguish hot from cold. This is what emerges from a study published in Neuron by researchers from the Max Delbrück Center which calls into question a consolidated theory on thermal perception, opening up new ideas for research on pain and sensory disorders. “Instead of relying on separate sensors for heat and cool, says Clarissa Whitmire, co-author of the research with Phillip Bokiniec, “most temperature-sensitive nerve cells activate in response to cooling, simply reducing their activity as the skin heats up.

In practice, cells react to the actual temperature of the skin, rather than simply detecting the extent of the thermal change. Not only that: "Scientists have known about the existence of these neurons for years - adds Poulet - but they were thought to be relatively rare. Instead it emerged that they constitute the majority of the cells responsible for the perception of temperature".

To monitor the functioning of these cells, the researchers used advanced imaging techniques on mice, recording the activity of individual neurons while the animals' paws were heated and cooled. The team then blocked the TRPM8 protein, long known as the body's main sensor for detecting cold temperatures. Data in hand showed that a single molecular sensor is capable of generating signals for both cold and heat.

Temperature perception is fundamental to daily life, but is impaired in many medical conditions, including neuropathic pain, diabetic neuropathy, chemotherapy-induced nerve damage, and disorders that cause abnormal sensitivity to cold. "Understanding how it works - concludes Whitmire - is a prerequisite for understanding what is altered in the presence of pathologies.