Arithmetic calculation, deep inspiration or handgrip exercise-mediated pre-operational active palmar sweating responses in humans

We examined the effects of repetitive mental stimulation such as arithmetic calculations with sequential subtraction or physical tasks such as handgrip exercise and deep breathing on active palmar sweating responses in humans. Thirty-three healthy, male and female volunteer students (20.4±2.1 years) participated in the present study. The responses of active palmar sweating were evaluated by using the newly developed ratemeter. The galvanic skin response (GSR) was also recorded in 10 out of 33 subjects. The oral explanation of the stimulation or tasks caused a rapid and wavy active palmar sweating response. The pre-operational responses of active palmar sweating to the stimulation or tasks were also observed by the GSR recording. The mental stimulation- and physical tasks-mediated pre-operational responses were significantly reduced by the trials. The mental stimulation or physical tasks also caused a rapid and oscillatory response of active palmar sweating during operation of the stimulation or tasks. The operation-mediated responses to physical tasks were observed ipsilaterally and contralaterally. The physical task-mediated responses were also reproducible, resulting in no habituation. In contrast, the operation-mediated responses to mental stimulation were reduced significantly by the trials, resulting in a marked habituation. The findings suggest that the mental stimulation- and physical tasks-mediated pre-operational responses of active palmar sweating obtained by using the newly developed ratemeter will make useful tests for evaluating neuronal activity of limbic system including amygdala, sympathetic sudomotor activity in the palmar skin and functional properties of the palmar sweat glands.