Microcurrent stimulation at shenmen acupoint facilitates EEG associated with sleepiness and positive mood: a randomized controlled electrophysiological study

Abstract

To examine the electrophysiological effects of microcurrent stimulation at the Shenmen acupoint, 40 healthy normal subjects were randomly assigned to a placebo group (sham stimulation) and an experimental group (bilateral electrocutaneous stimulation at the Shenmen). The following two electroencephalographic indicators were used to measure brain activity. (1) Arousal level was measured with reference to log-transformed absolute alpha power and power source and analyzed using low-resolution electromagnetic tomography and (2) frontal alpha asymmetry was used as an indicator of mood. After real stimulation for 10 minutes, absolute alpha power was globally reduced in the experimental group, particularly in the anterior and centrotemporal regions of the brain. This indicates a decline in the brain activity associated with arousal. Moreover, the reduction was more prominent in the left frontal region, as compared to the right frontal region, resulting in significant increase from negative to positive frontal alpha asymmetry scores and reflecting an increase in the brain activity associated with enhanced mood. However, the placebo group exhibited no significant changes in two indicators after sham stimulation. This study provides initial electrophysiological evidence of changes in brain activity associated with reduced arousal (and thus greater sleepiness) and enhanced mood after microcurrent stimulation at the Shenmen acupoint.

Figure 1

Diagram of study design.

Figure 2

Reduced absolute alpha power in (a) the experimental group after stimulation as compared to the baseline but not (b) the placebo group. After stimulation at Shenmen acupoint, significant reduction occurred bilaterally in the superior frontal gyrus (BA 11, left: X = −10, Y = 66, Z = −13; BA 10, right: X = 9, Y = 66, Z = −10), medial frontal gyrus (BA 10, left: X = −8, Y = 66, Z = 4; right: X = 11, Y = 66, Z = −4), and inferior frontal gyrus (BA 47, left: X = −42, Y = 23, Z = −13; right: X = 35, Y = 18, Z = −13), as well as in the right superior temporal gyrus (BA 38, X = 50, Y = 16, Z = −13), right middle temporal gyrus (BA 21, X = 60, Y = 2, Z = −13), anterior cingulate (BA 32, X = −10, Y = 45, Z = −6), and cingulate gyrus (BA 24, X = −10, Y = −20, Z = 42). The most pronounced decrease was found in the left superior frontal gyrus (BA 11, X = −10, Y = 66, Z = −13). Blue color indicates the locations of significantly reduced absolute alpha power in the experimental group.

Figure 3

Frontal alpha asymmetry (F3-F4) at baseline and after stimulation for the placebo and experimental groups. A significant increase in the frontal alpha asymmetry score from the baseline to poststimulation was found in the experimental group, suggesting greater left-sided frontal brain activation associated with positive mood, after stimulation at the Shenmen acupoint (^** P < 0.01).