Influence of Alternate Hot and Cold Thermal Stimulation in Cortical Excitability in Healthy Adults: An fMRI Study

摘要

Stroke rehabilitation using alternate hot and cold thermal stimulation ( TS) has been reported to improve motor function in hemiplegia; however, the influence of brain excitability induced by TS remains unclear. This study examined cortical activation induced by TS in healthy adults, focusing on motor-related areas. This involved a repeated crossover experimental design with two temperature settings (innocuous TS with alternate heat-pain and cold-pain thermal and noxious TS with alternate heat and cold thermal) testing both arms (left side and right side). Thirty-one healthy, right-handed participants received four episodes of TS on four separate days. Functional magnetic resonance imaging scans were performed both before and after each intervention to determine whether TS intervention affects cortical excitability, while participants performed a finger-tapping task during scanning. The findings revealed greater response intensity of cortical excitability in participants who received noxious TS in the primary motor cortex, supplementary motor cortex, and somatosensory cortex than in those who received innocuous TS. Moreover, there was more motor-related excitability in the contra-lateral brain when heat was applied to the dominant arm, and more sensory-associated excitability in the contra-lateral brain when heat was applied to the nondominant arm. The findings highlight the effect of heat on cortical excitability and provide insights into the application of TS in stroke rehabilitation.