EEG & eyeblink

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

© David Mayor (University of Hertfordshire) and Tony Steffert (Open University)

Background Infomation (PDF)
Poster (PDF)

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:

o Stimulation on the Right resulted in greater EEG relative spectral power than on the Left
o 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.

o EBR increased more with EA than MA
o EBR increased more with 20 minutes than 5 minutes of EA
After EA, EBR decreased.
These results were all statistically encouraging.

o 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.

Our findings inevitably raise more questions than they answer (one of the joys of research is that it is never-ending!). We would therefore like to ASK YOU FOR YOUR INPUT at this stage, as we start to design further pilots and a final clinical study.

Can you think of a traditional acupuncture or neurophysiological explanation for any of our findings?
What do you think we should explore next, given limited time and resources:
o The effects of stimulation at yet other acupoints (e.g. P6 or LIV3)
o The effects of other modalities, such as tuina or laser acupuncture
o The effects of treatment for a particular condition (if so, which)
Questions such as:
o Whether baseline EBR indicates responsiveness to acupuncture, or
o Does acupuncture have a ‘balancing’ effect on EBR
o Whether we should just go back and repeat our Pilots with larger samples
o Other.
We would also like to ask whether you would be interested in taking part in any of our future research, either as a participant (‘subject’), practitioner, in recruiting participants, or to help with data analysis.

You can let us know by emailing David Mayor (details below).

* Left: Left LI4 to ST36; Right: Right LI4 to ST36; LI42: LI4 to LI4; ST362: ST36 to ST36

To Mark Bovey for allowing Cap ‘n Zap back for another ARRC presentation, to Professor Tim Watson, our ever-patient project supervisor, and to Robert Kozarski and Jade Collard for their statistical assistance. External funding has not been sought or obtained for this project so far.

Contact details
David Mayor acupuncture practitioner