The role of the dorsolateral prefrontal cortex in control of skin sympathetic nerve activity in humans

The dorsolateral prefrontal cortex (dlPFC) is primarily involved in higher order executive functions, with there being evidence of lateralization. Brain imaging studies have revealed its link to the generation of skin sympathetic nerve activity (SSNA), which is elevated in states of emotional arousal or anxiety. However, no studies have directly explored dlPFC influences on SSNA. Transcranial alternating current stimulation (-2 to 2 mA, 0.08 Hz, 100 cycles) was applied between the left or right dlPFC and nasion via surface electrodes. Spontaneous bursts of SSNA were recorded from the common peroneal nerve via a tungsten microelectrode in 21 healthy participants. The modulation index was calculated for each stimulation paradigm by constructing cross-correlation histograms between SSNA and the sinusoidal stimulus. Stimulation of the dlPFC caused significant modulation of SSNA, but there was no significant difference in the median modulation index across sides. Stimulation also caused cyclic modulation of skin blood flow and sweat release. We have shown for the first time that stimulation of the dlPFC causes modulation of SSNA, also reflected in the effector-organ responses. This supports a role for the dlPFC in the control of SSNA, which likely contributes to the ability of emotions to bring about cutaneous vasoconstriction and sweat release.