Social Buffering Effects during Craft Activities in Parallel Group Session Revealed by EEG Analysis and Parasympathetic Activity

Abstract

Introduction: The therapeutic structure of occupational therapy (OT) includes groups. Although the presence of others is expected to be relaxing due to the social buffering effect and the tend and befriend theory, it has not been sufficiently validated in accordance with the therapeutic structure of OT. The aim of this study was to investigate the electrophysiological evidence for the effectiveness of parallel groups and states of concentration on craft activities used in OT.

Methods: Thirty healthy young adults were used as controls to measure EEG and autonomic activity during craft activities in three conditions: alone, parallel, and nonparallel. EEG was analyzed using exact low-resolution electromagnetic tomography, and autonomic activity was analyzed using Lorenz plot analysis.

Results: Parasympathetic activity was significantly higher in the parallel condition than in the alone condition. A significant negative correlation was found between current source density and parasympathetic activity in the region centered on the right insular cortex in the α1 band, and functional connectivity in regions including the anterior cingulate cortex and insular cortex was associated with autonomic activity.

Conclusion: Craft activities that occurred during frontal midline theta rhythm also increased parasympathetic activity. The results suggest that the parallel groups used in OT and the intensive state of craft activities induce a social buffering effect that increases parasympathetic activity despite the absence of physical contact or social support. This provides evidence for the effectiveness of the therapeutic structure of occupational activities and groups in OT.

Keywords: Craft activity; EEG; Exact low-resolution electromagnetic tomography; Frontal midline theta rhythm; Lorenz plot; Occupational therapy; Parallel group; Parasympathetic activity.

Fig. 1.

Experimental conditions and procedures. From left to right as follows: alone, parallel, and nonparallel conditions; 1 min 30 s rest before and after a 3-min craft task. The order of the craft tasks was counterbalanced.

Fig. 2.

Result of the CVI change. The CVI change in the positive direction was significantly greater in the parallel condition than in the alone condition. In all three conditions, the Fmθ group showed significantly greater CVI changes in the positive direction than the no-Fmθ group. CVI, cardiac vagal index (parasympathetic nerve activity index).

Fig. 3.

Correlation between CSD and total CVI (a) and correlation between FC and total CVI (b) under parallel conditions. a Correlation between CSD and total CVI. The color scale means that the larger the t-value of the negative correlation, i.e., the smaller the p value, the lighter blue it is displayed. There was a significant negative correlation between CSD and total CVI in the right Ins and precuneus peripheral regions of the α1 band. b Correlation between FC and total CVI. Significant negative correlations were found between FC and total CVI in the right aIPL-left hippocampal body and pIns in the α1 band. CSD, current source density; FC, functional connectivity; CVI, cardiac vagal index (parasympathetic nerve activity index); Ins, insula; aIPL, anterior inferior parietal lobule; pIns, posterior insula.

Fig. 4.

Correlation between CSD and total CSI (a) and correlation between FC and total CVI (b) under nonparallel conditions. a Correlation between CSD and total CSI. The color scale means that the larger the t-value of the positive correlation, i.e., the smaller the p value, the more yellow it appears. There was a significant positive correlation between CSD and total CSI in the right superior, middle and inferior frontal gyrus in the β1 band. b Correlation between FC and total CVI. Significant negative correlations were found between FC in ACC-right hippocampal body and pIns and total CVI in α1 band. CSD, current source density; FC, functional connectivity; CSI, cardiac sympathetic index (sympathetic nerve activity index); CVI, cardiac vagal index (parasympathetic nerve activity index); ACC, anterior cingulate cortex; pIns, posterior insula.