Transcranial alternating current stimulation (tACS) above individual peak alpha frequency (PAF) does not shift PAF or...

Peak alpha frequency (PAF) is negatively associated with experimental pain sensitivity. Transcranial alternating current stimulation (tACS) enables shifting neural frequency to modulate sensory perception, yet it has not been tested in pain perception. We hypothesized that tACS application at 1 Hz above the individual PAF (iPAF) would increase PAF and reduce experimental pain ratings.

This is a double-blind, sham-controlled, crossover, exploratory study with 15 healthy participants who completed 2 sessions; 20 min of tACS was applied to the somatosensory cortex at 1 Hz above the iPAF or sham stimulation (Intervention), administered in random order. Pain reports (4 time points) in response to a tonic heat pain (THP) stimulus were recorded before and after tACS. Five-minute electroencephalography was recorded in 4 conditions: baseline (iPAF identification), after THP stimulus, after tACS to test its effect on iPAF, and after another THP stimulus to test pain effects on iPAF following tACS. This paradigm examines associations between iPAF and pain, and the effects of pain and tACS on iPAF.

There was no effect of real vs. sham tACS on iPAF, with a non-significant Condition × Intervention interaction and a small effect size (partial η ² 0.01 and 0.03). Pain intensity increased across rating time points (p < 0.001), but tACS had no effects.

In this small-sample preliminary study, a single tACS session did not affect iPAF or pain ratings in response to THP stimulus. The current study may help shape methodologies for future pain studies investigating the effects of tACS on PAF and pain.