Intermediate effects of mindfulness practice on the brain activity of college students: An EEG study

Abstract

Mindfulness is an intervention that was used in many psychiatry treatments. In this study, the subject experienced two different states: (1) attention (i.e., listening to a podcast) and (2) mindfulness (i.e., meditation). Twenty-two students were included in a Mindfulness-Based Stress Reduction (MBSR) course with EEG recording sessions on week four and week six. Brain dynamics were investigated to elucidate the complexity and connectivity of the brain. The alpha PSD increased in all brain areas during mindfulness in both weeks. For complexity, Fractal Dimension (FD) increased significantly during meditation in the week six recording. When comparing the FD in the mindfulness state of week four and week six, we also witnessed a significant increase in the following week. The coherence of the interhemispheric frontal and temporal regions increased significantly in both weeks. In conclusion, the subject successfully transferred from attention to mindfulness, demonstrated by the alpha changes when going from podcast to meditating. An enhancement in brain complexity was found, suggesting an augmentation in cognitive function. Finally, the coherence exhibits strengthened connections in the frontal area.

Keywords: Attention; Coherence; Consciousness; Fractal Dimension; Meditation; Mindfulness.

Fig. 1

Diagram of project procedure.

Fig. 2

Emotiv EPOC+ Headset (a) and Electrode mapping on the scalp (b).

Fig. 3

The signal before and after removing noise using MEMD. (A) The raw signal (blue) versus the signal after removing high and low frequency artifacts (red). (B) The IMFs components with the first (high frequency noise) and four last components (low frequency oscillation) were removed when reconstruct into EEG signal. (C) The Power Spectral Density of IMFs components with gray lines are PSD of removed components.

Fig. 4

The schematic shows the steps of the preprocessing pipeline.

Fig. 5

The three main clusters are being used in the coherence analysis. The electrode coherences are computed pairwise. For the interhemispheric cluster, the electrode in the left hemisphere is pairwise with the electrodes in the right hemisphere.

Fig. 6

The distribution of Power Density during mindfulness. The Power Density Spectrogram illustrates the change of energy of channel O2 of Subject I19 (week 6) in Podcast (A) versus Meditation (B). The topo maps of subject I19 in the first 100 s of both states for three frequency bands. (C). Summary of changes of the Relative Power in four brain areas (frontal, occipital, left temporal, right temporal) for three frequency bands (alpha, beta, theta), in both week four (N = 21) and week six (N = 20) (D).

Fig. 7

Effects of mindfulness on the brain signal complexity demonstrated by Fractal Dimension. (A) The signal of the O2 channel of subject 19 in week 6 during podcast state (FD = 1.899) and meditation state (FD = 1.966) in the first 100 s with the corresponding FD value. (B) The Fractal Dimension distribution in both states (podcast and meditation) in week four and week six. Each dot represents an average FD value across all channels of one subject.

Fig. 8

The coherence between regions of the brain in two states: listening to podcast and meditation. A. The heatmaps demonstrate the coherence level in pairs of electrodes in both weeks and in two different states. B. The coherence distribution of two states in both weeks in three different regions: (i) left frontal-temporal, (ii) right frontal-temporal, and (iii) left-right frontal-temporal. Each dot represents the coherence of a pair of electrodes.

Fig. 9

The outcomes of the SMS in three subscales (A) and the correlation between SMS total score and brain response (B) throughout week four and week six.