Friday, May 16, 2025
5/16/2025
Determining a Central Locus for Temperature Modulation of Touch Sensitivity - Project Summary: The interactions between touch and temperature perception are essential for the human experience & behavior, object recognition, thermoregulation, and avoidance of harmful stimuli. Despite their importance, these modalities are mostly studied in isolation. Previous studies have shown that innocuous and noxious skin temperature alters the perception of tactile stimulation, and evidence suggests that thermo-tactile modulation may occur both peripherally and centrally. However, it remains unclear whether innocuous and noxious thermo-tactile interactions occur centrally or solely in the periphery. Additionally, the neural substrates that reflect thermo-tactile interactions remain unknown in humans and non-human primates and it remains unknown whether Primary Somatosensory (S1) neurons encode cutaneous thermal information during these interactions. I hypothesize that innocuous and noxious thermo-tactile interactions have a central locus of interaction and further hypothesize that S1 neurons may reflect warm or cool temperatures via modulation of their neural firing rates to vibratory stimuli. To address these gaps, I propose three specific aims. First, Aim 1 will determine if illusory thermal cues modulate vibrotactile perception, where the vibration detection thresholds of human subjects under veridical and illusory thermal cues (thermal referral illusion) will be compared. Second, Aim 2 will determine if illusory thermal pain modulates vibrotactile perception, where the vibration detection thresholds of human subjects under veridical and illusory thermal pain (thermal grill illusion) conditions will be compared. Third, Aim 3 will determine if S1 neural responses to vibrations are modulated by skin temperature, where the neural firing rates of well-isolated single- or populations of S1 neurons in NHPs will be recorded while vibration cues are delivered to the finger pads under different thermal conditions. The findings of this study will provide the first evidence of a central locus of innocuous and noxious thermo-tactile modulation in humans and improve our understanding of the neural substrates that reflect thermo-tactile interactions. Ultimately, this study has the potential to inform the development of therapies for patients with impaired thermo-tactile perception.
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