EEG and eyeblink response to different acupuncture modalities: some preliminary results from four exploratory pilot studies

Abstract

This poster describes early findings from our first pilot studies. Encephalography (EEG) records electrical activity on the scalp, and is useful for investigating rapidly changing cortical brain states. Eyeblink rate (EBR) is a marker for central dopamine function, and is also inversely correlated with parasympathetic activity. We wanted to find out if EEG and EBR response varies (1) with stimulation at different acupoints, (2) with various modalities of stimulation (manual acupuncture [MA], electroacupuncture [EA], transcutaneous electrical acupoint stimulation [TEAS]), and (3) with electrical stimulation at 2.5 Hz or 10 Hz frequencies. As far as the EEG goes, we have not yet fully managed to answer question (3), our primary research question. However, we did find something quite unexpected (1), namely that the ‘relative spectral power’ in the EEG (the amount of electrical power found at each scalp measurement electrode in each EEG bandrange, from delta [1.5-4 Hz] to gamma [35-45 Hz]) appears to follow very specific patterns: - Stimulation on the Right resulted in greater EEG relative spectral power than on the Left - Stimulation of ST36 resulted in greater EEG relative spectral power than at LI4. These findings, although on a small sample, appear statistically robust (confirmed by Bootstrap resampling). It is possible that stimulation amplitude plays a role here. In our poster, we described seemingly similar findings for EBR, although the statistics for these are not (so far) as convincing. - EBR increased more with EA than MA - EBR increased more with 20 minutes than 5 minutes of EA - After EA, EBR decreased. These results were all statistically encouraging. - A nonsignificant finding was that EBR is usually greater for TEAS than MA. In addition (3), we observed that Blinks occurred with less delay following pulses during 10 Hz than 2.5 Hz TEAS (timescales normalised), suggesting that blink may be facilitated more by 10 Hz than by 2.5 Hz TEAS. Again, this was statistically significant.