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How might TRP channels help explain the silver Thaler illusion?

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thermoreception in polar bears — Thermoreception Warm-blooded animals, such as polar bears, maintain stable body temperatures and adapt to substantial geographic and seasonal temperature fluctuations. Thermal adaptation is supported by the function of sensory structures called thermoreceptors.

The silver Thaler illusion, identified by Ernst Heinrich Weber in the 1830s, describes the phenomenon where a cold metal object, such as a silver coin, feels heavier than an identical object at a warmer temperature.1

This illusion is linked to the physiology of mechanoreceptors, which are nerve endings in the skin responsible for detecting pressure. These receptors are not exclusively sensitive to mechanical stimuli; they also exhibit increased spontaneous discharge frequency when exposed to cold.1

It is hypothesized that the presence of transient receptor potential (TRP) channels within these specific mechanoreceptors underlies this spontaneous cold sensitivity. Because these channels respond to temperature changes by regulating ion flow—leading to membrane depolarization and nerve impulses—their activation by the cold metal likely enhances the neural signal associated with the object's weight. Consequently, the brain interprets this heightened sensory input as increased pressure, creating the illusion that the cold object is heavier than it actually is.123