Diverging roles of TRPV1 and TRPM2 in warm-temperature detection.

The perception of innocuous temperatures is crucial for thermoregulation. The TRP ion channels TRPV1 and TRPM2 have been implicated in warmth detection, yet their precise roles remain unclear. A key challenge is the low prevalence of warmth-sensitive sensory neurons, comprising fewer than 10% of rodent dorsal root ganglion (DRG) neurons. Using calcium imaging of >20,000 cultured mouse DRG neurons, we uncovered distinct contributions of TRPV1 and TRPM2 to warmth sensitivity. TRPV1's absence - and to a lesser extent absence of TRPM2 - reduces the number of neurons responding to warmth. Additionally, TRPV1 mediates the rapid, dynamic response to a warmth challenge. Behavioural tracking in a whole-body thermal preference assay revealed that these cellular differences shape nuanced thermal behaviours. Drift diffusion modelling of decision-making in mice exposed to varying temperatures showed that TRPV1 deletion impairs evidence accumulation, reducing the precision of thermal choice, while TRPM2 deletion increases overall preference for warmer environments that wildtype mice avoid. It remains unclear whether TRPM2 in DRG sensory neurons or elsewhere mediates thermal preference. Our findings suggest that different aspects of thermal information, such as stimulation speed and temperature magnitude, are encoded by distinct TRP channel mechanisms.