Different temperature paths influence brain's reception, study reveals
In a groundbreaking discovery, researchers have mapped the neural pathways responsible for cool and warmth sensations in mice. This study, published in the journal Nature Communications, has shed light on the intricate workings of the nervous system and could pave the way for future therapies.
The research, which earned part of its team the 2021 Nobel Prize in Physiology or Medicine, has shown that cool temperatures (around 15-28°C) are detected by TRPM8-expressing primary sensory neurons in the dorsal root ganglia (DRG), which innervate the skin. These cool-sensitive neurons transmit signals to the dorsal horn of the spinal cord, where specialized interneurons amplify the cool signal before it's relayed to the brain.
In contrast, warmth detection involves TRPV1+ neurons that respond to noxious heat and help signal warm temperatures via a distinct neural pathway.
The study has revealed that cool and warm temperature sensations travel along separate pathways from the skin to the brain, suggesting that the nervous system processes warmth and coolness on completely different neural circuits. This finding challenges the previous belief that all temperature sensations traveled on the same general pathway to the brain.
The spinal cord plays a crucial role in this process, not just as a relay but also as an amplifier of cool temperature signals to increase perception fidelity. This separation of circuits enables the body to differentiate warmth and coolness efficiently and underlies precise temperature perception.
The researchers are now planning to explore the interaction of the newly discovered cool-sensing pathway with other sensory circuits, such as those for pain and itch. They hope to learn how disruptions in these systems might contribute to temperature sensitivities.
Advanced imaging techniques, electrical monitoring of the heart, behavioral analyses, and in-depth genetic data were used to determine how mice transmit the sensation of cooler temperatures from their skin to their brains. The team observed specific sensors on the skin that are tuned to temperatures between 15 to 25°C, which are considered cool.
This study marks an important step in mapping key sensory pathways in the brain. While the findings are based on research conducted on mice, the researchers believe that the same principle likely applies in humans.
Understanding the specific circuit for cool sensation may lead to the development of therapies to reduce side effects like cold allodynia in cancer patients undergoing chemotherapy. However, the study does not provide information on a new prosthetic device that detects temperature.
As Duan, one of the researchers, mentioned, there are still many sensory circuits in the brain that are not fully understood, and this study is an example of how mapping them can lead to exciting new discoveries. This research represents an important shift in how we understand sensory perception.
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This groundbreaking study has highlighted the potential for future health-and-wellness therapies, as the discovery of separate neural pathways for cool and warm temperature sensations suggests that targeting these areas could lead to innovative treatments. Furthermore, the research team is intrigued by the interaction of the cool-sensing pathway with other sensory circuits, such as those for pain and itch, which could potentially lead to new therapies for reducing temperature sensitivities.
