Perception Deception: A Multimodal Approach to Modulating the Thermal Grill Illusion

The study of perceptual illusions is key to dissecting and unraveling the complex neural circuitry that underlie complex sensory phenomena. One such example is the thermal grill illusion (TGI), in which interlacing cold (20° C) and warm (40° C) stimuli–neither painful on their own–produces burning sensations. Although the mechanism is still unclear, theories attribute this to supraspinal interactions: while cold stimuli triggers both “cold” and nociceptive signals, administering “warm” stimuli counteracts only the “cold” signals and thus “unmasks” the nociceptive signals that register as painful. This study aims to develop a Peltier device to replicate the TGI and investigate how these paradoxical sensations can be modulated using a multimodal approach: vibrations of metal plates, topical application of chemicals (e.g. capsaicin, menthol), and temperature conditioning of the opposing arm. These findings can be translated to inform novel therapies for neuropathic pain management.