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.

Social facilitation is a phenomenon in which the mere presence of others improves performance on skilled tasks and decreases performance on complex tasks [1‒3]. The type of observer influences the effect, increasing its effectiveness when the observer is evaluative [4] and decreasing performance and increasing state anxiety when the observer is an authority figure [5]. Electrophysiological studies have reported that the late positive components of the event-related potentials, such as P2 and P3, in the visual cortex are increased in the presence of others condition [6], which improves local and interbrain phase synchrony in the joint visual search task [7]. It has also been shown that viewing the face of an intimate other increases alpha wave inhibition [8] and that the presence of an observer increases theta band activity in the dorsolateral prefrontal cortex (dlPFC) and occipital lobe [9].

On the other hand, social buffering is a phenomenon whereby people recover better from avoidance experiences when they are with their peers [10]; social support from others makes the task seem less difficult and reduces heart rate and cortisol levels [11]. Social buffering has been shown to reduce pain perception, pre-pain heart rate, and theta activity derived from the anterior cingulate cortex (ACC) [12]. There are also reports of changes in brain activity, including activation of reward circuits, such as the caudate nucleus, lateral prefrontal cortex (PFC), amygdala, dlPFC, and limbic system [13]; decreased activity in the dorsal ACC and anterior insular cortex (aIns), which are associated with pain; activation of the ventral medial prefrontal cortex [14]; and involvement of oxytocin [15] and the PFC [16, 17]. The tend and befriend theory, which also explains women’s tendency to seek social support in stressful environments [18], has been extended to be relevant to men as well as women [19], and oxytocin promotes increased trust in those experiencing distress [20]. Surrounding oneself with familiar people rather than being alone increases feelings of safety, and feelings of safety are associated with increased parasympathetic nervous system activity [21].

Occupational therapy (OT) is a client-centered profession that promotes health and well-being through occupation [22]. OT is unique in that the therapeutic structure includes not only the individual-therapist relationship but also occupational activities and groups [23]. According to Kielhofner [24], there are eight modalities of intervention in OT, one of which is the “group work model” [25]. Groups are widely used in OT, particularly in psychiatry, and are more likely to be occupationally oriented than language-oriented groups [26]. Mosey investigated the use of groups as a therapeutic tool rather than a framework or model for relationships and proposed five stages of development of group interaction [27‒30]. The lowest of these is the parallel group, a group of individuals who work and play with minimal task sharing and mutual stimulation in the presence of others. The skill required here is to be aware of others and to engage in some form of verbal or nonverbal interaction with others, and it is often used clinically with psychiatric patients who are very tense [31, 32]. While subjective well-being, self-efficacy, independence in activities of daily living [33], and improvement in ADLs [34] have been reported with the use of groups, there are few studies of the effects of OT groups on more objective measures, such as physiological biomarkers.

Craft activities have been used as an intervention since the early history of OT [35], particularly in the psychiatric field [36‒38]. Craft activities have certain therapeutic effects in improving satisfaction with daily life and subjective well-being [39]; improving sense of self, values, and hope for the future [40]; improving occupational performance and interpersonal relationships [41]; and improving positive and negative symptoms [42]. Electrophysiological studies have reported that individuals with frontal midline theta rhythm (Fmθ), a biomarker of focused attention during craft activities, are relaxed and focused and have increased parasympathetic activity [43].

Fmθ is a 5–7 Hz theta wave discovered by Ishihara and Yoshii [44]. It is an EEG component that occurs during cognitive tasks requiring mental concentration, and its source is the bilateral medial PFC, including the ACC [45]. Fmθ has been correlated with the emotionally positive “bliss” experiences produced by meditative states [46], suggesting that the occurrence of Fmθ is related to autonomic nervous activity [47]. However, these studies examined occupational activities performed by a single person and did not consider the influence of the groups used in OT.

The aim of this study was to clarify the usefulness of the parallel groups used in OT with craft activities from the perspective of brain and autonomic activity. Specifically, we tried to show that the stress-reducing effects of the social-buffering effect and the tend and befriend theory also occur in OT situations. The hypothesis was that “parallel occupational activity with others and occupational activity in which Fmθ occurs results in a decrease in sympathetic activity and an increase in parasympathetic activity, resulting in changes in local brain activity in the PFC, ACC, and aIns and in the network containing these areas.”

The study design was an observational cross-sectional study.

Subjects

The population of participants in this study consisted of medical students. After the purpose of the study was verbally explained, an informed consent form was distributed or placed, and only those who were contacted for consent were included in the study. Subjects were 30 individuals aged 18–22 years who gave written consent to participate in the study. Individuals who had difficulty performing EEG/ECG measurements or occupational activities due to physical or mental disabilities and those with a history of brain disease, head trauma, or mental illness were excluded from recruitment.

Procedure

The occupational activity performed during the experiment was the same as in the previous study [43]: Netcraft, a simple repetitive task widely used in clinical OT settings. Three-minute tasks were performed in the following three conditions. A rest period of 1 min and 30 s was provided before and after each condition, and the order in which each condition was performed was randomized across subjects so that order effects were not reflected in the analysis results (see Fig. 1).

  • Alone condition: only one person sits down to do the craft activity.

  • Parallel condition: subject and experimenter sit on the right side of the room at 90°, each doing their own craft.

  • Nonparallel condition: the subject and the experimenter sit on the right side of the 90° method, the experimenter does not perform the craft activity but observes the subject’s craft activity, and only the subject performs the craft 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. 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.

Close modal

To avoid subject fatigue and increased drowsiness, as well as increased impedance of the electrodes on the scalp, it was desirable to complete the experiment in less than 1 h, including explanation of the experiment, placement of EEG electrodes and ECG, and practice and actual experiments with each device attached. Therefore, the crafts for each condition were set to the last 3 min, and the resting condition was set to the last 1 min and 30 s. The others placed in the parallel and nonparallel conditions were the same for each subject, and at the time of subject recruitment, others who were close to the subject were recruited together as experimenters.

Measurement Index

In addition to age, sex, and handedness, the following items were measured:

  • EEG activity: using an electroencephalograph (Polymate Pro MP6100; Miyuki Giken Co., Ltd.), 19-ch electrodes were placed on the scalp according to the international 10–20 method to measure EEG activity under various conditions. The sampling rate was 1,000 Hz, and the impedance of the electrodes was less than 10 kΩ.

  • Autonomic activity: ECGs were measured with an electrocardiograph (Portable Electrocardiogram Polyam [ECG] IIB: NIHON SANTEKU Co., Ltd.) under each craft condition, and the R-R interval (RRI) was extracted using MATLAB (R2022a). Lorenz plot analysis [48] is useful for analyzing autonomic activity during occupational activities because it allows evaluation of sympathetic and parasympathetic activity, is less sensitive to respiratory components [49], and has a sharper response [50]. Cardiac sympathetic index (CSI: sympathetic nerve activity index) and cardiac vagal index (CVI: parasympathetic nerve activity index) and RRI were calculated for the whole 3 min for each condition using the Lorenz plot program of Sato et al. [51]. The CSI, CVI, and RRI (baseline) for 50 heartbeats from the start of the task and the CSI, CVI, and RRI (post) for 50 heartbeats just before the end of the task were also calculated.

  • The level of closeness with other members of the group: the 10-point Likert method was used before the start of the first task.

  • Task performance: the number of tasks completed on time (number of steps reached by Netcraft) was measured.

Analysis

EEG data were downsampled to 500 Hz using EEGLAB (v2021.1) on MATLAB and bandpass filtered at 0.5–100 Hz. Independent component analysis (ICA) was performed on EEGLAB (v2021.1) using the runica [52]. ICA was used to remove and subtract artifacts embedded in the data (muscle, blink, eye movement) without removing the affected portions of the data. When strong electrical artifacts were present in the data, the “extended” ICA option of runica [53], which allows the algorithm to detect sources with sub-Gaussian activity distributions, such as line-current artifacts and/or slow activity, sources with activity distributions [54]. Among the independent components obtained by ICA, the frontal component, which appeared to be blinking and eye movements, and the occipital component, which appeared to be mainly electromyograms for neck retention, were removed. In addition, where EMGs were mixed with unconscious clenching of teeth or increased head muscle tone, we visually removed those sections. EEG analysis was performed using exact low-resolution electromagnetic tomography (eLORETA) [55] to assess EEG activity and functional connectivity (FC) during occupational activities. eLORETA calculates current source density (CSD) as the electrical activity of neurons with no assumption of a specific number of active sources. The nonlinear functional coupling technique known as lagged phase synchronization (LPS) is also robust to nonphysiological artifacts, especially low-spatial resolution and volume propagation problems [56], and LPS can be used for frequency resolution of filtered data and brain function coupling [57]. The EEG data were analyzed using the LORETA-KEY software package (a product of the KEY Institute for Brain-Mind Research). The eLORETA head model and electrode coordinates are based on the MNI mean MRI brain map (MNI152) [58]. The solution space is restricted to the cortical gray matter and contains 6,239 voxels with a spatial resolution of 5 mm. In this study, CSD values were used to estimate the electrical source in the brain generating scalp-recording potentials for each frequency band. The eLORETA cortical CSD at 0.5–100 Hz is calculated from EEG data preprocessed in EEGLAB. The CSDs of the eLORETA cortical functional images were calculated for eight frequency bands: δ (1–3.5 Hz), θ (4–8 Hz), α1 (8.5–10 Hz), α2 (10.5–13 Hz), β1 (13.5–20 Hz), β2 (20.5–30 Hz), low γ (30.5–60 Hz), and high γ (60.5–100 Hz). For the analysis of FC, a method was used to determine the cortical region of interest (ROI) for each voxel. In eLORETA, the ROI was generated by defining the MNI coordinates of cortical voxels below the electrode site. Based on previous studies of FC using EEG and fMRI [59], 19 ROIs were defined (Table 1). The association between CSD and LPS levels and other indicators was analyzed by regression analysis using eLORETA software. Statistical nonparametric mapping (SnPM) was used in eLORETA for statistical analysis. For multiplicity, the critical threshold for establishing p values was set at p = 0.05 and determined by SnPM with correction for multiple comparisons at all frequencies; the use of SnPM for LORETA images has been validated in several studies [60, 61]. In the 3D statistical images obtained, functional connections between ROIs showing significant differences were identified by a nonparametric randomization/permutation procedure. By estimating the empirical probability distribution of the “maximum statistics” under the null hypothesis, randomization and permutation tests have been shown to be effective in controlling family-wise error rates in neuroimaging studies [62]. In eLORETA, we used 5,000 data randomizations to determine the threshold for marginal detection, correcting for multiple comparisons with total FC and total frequency without relying on Gaussianity [63]. Details of the nonparametric randomization procedure are described in a study by Nichols and Holmes [62]. In addition, an eLORETA nonparametric randomization procedure based on “maximum statistics” was used to correct for multiple comparisons. The omnibus null hypothesis was rejected if at least one t-value exceeded a critical threshold of p = 0.05, determined by 5,000 data randomizations. A similar approach has been used in previous studies of FC using eLORETA [64].

Table 1.

ROI generated in this study

x, y, zRegionIncluded region
−25, −8, 50 FEF SFG, mPFC, MFG, Ins, PrG, CC, PoG, sub-gyral, PCL 
27, −8, 50 
−27, −52, 57 SPL SPL, IPL, PCu, Cu, CC, PoG, PCL, PrG, sub-gyral, mPFC 
24, −56, 55 
−36, 57, 9 aPFC mPFC, SFG, IFG, MFG, sub-gyral, ACC 
34, 52, 10 
−50, 20, 34 dlPFC MFG, SFG, IFG, STG, TTG, PrG, PoG, Ins, sub-gyral 
46, 14, 43 
 3, 31, 27 ACC ACC, mPFC, SFG, CC, MFG, sub-gyral 
10 −52, −49, 47 aIPL IPL, SPL, STG, TTG, PoG, Ins, SMG, sub-gyral, PrG 
11 52, −46, 46 
12 −31, 21, −1 aIns Ins, MTG, STG, ITG, UN, OrG, GRe, IFG, MFG, OFG, mPFC, subcallosal, sub-gyral, extra-nuclear, ACC, PrG 
13 31, 22, −2 
14 −21, −25, −14 HF PHG, Ins, STG, ITG, MTG, TTG, UN, FuG, OFG, sub-gyral, LiG, ACC, subcallosal 
15 24, −19, −21 
16  0, 51, −7 vmPFC mPFC, IFG, SFG, MFG, GRe, OrG, ACC 
17  1, −55, 17 PCC PCC, PCu, CC, Cu, Ins, FuG, LiG, IOG, MOG, OFG 
18 −47, −71, 29 pIPL IPL, SPL, PCC, PCu, Cu, FuG, IOG, MOG, ITG, MTG, STG, TTG, LiG, SMG, Ins, SOG, sub-gyral, AnG 
19 50, −64, 27 
x, y, zRegionIncluded region
−25, −8, 50 FEF SFG, mPFC, MFG, Ins, PrG, CC, PoG, sub-gyral, PCL 
27, −8, 50 
−27, −52, 57 SPL SPL, IPL, PCu, Cu, CC, PoG, PCL, PrG, sub-gyral, mPFC 
24, −56, 55 
−36, 57, 9 aPFC mPFC, SFG, IFG, MFG, sub-gyral, ACC 
34, 52, 10 
−50, 20, 34 dlPFC MFG, SFG, IFG, STG, TTG, PrG, PoG, Ins, sub-gyral 
46, 14, 43 
 3, 31, 27 ACC ACC, mPFC, SFG, CC, MFG, sub-gyral 
10 −52, −49, 47 aIPL IPL, SPL, STG, TTG, PoG, Ins, SMG, sub-gyral, PrG 
11 52, −46, 46 
12 −31, 21, −1 aIns Ins, MTG, STG, ITG, UN, OrG, GRe, IFG, MFG, OFG, mPFC, subcallosal, sub-gyral, extra-nuclear, ACC, PrG 
13 31, 22, −2 
14 −21, −25, −14 HF PHG, Ins, STG, ITG, MTG, TTG, UN, FuG, OFG, sub-gyral, LiG, ACC, subcallosal 
15 24, −19, −21 
16  0, 51, −7 vmPFC mPFC, IFG, SFG, MFG, GRe, OrG, ACC 
17  1, −55, 17 PCC PCC, PCu, CC, Cu, Ins, FuG, LiG, IOG, MOG, OFG 
18 −47, −71, 29 pIPL IPL, SPL, PCC, PCu, Cu, FuG, IOG, MOG, ITG, MTG, STG, TTG, LiG, SMG, Ins, SOG, sub-gyral, AnG 
19 50, −64, 27 

L, left; R, right; FEF, frontal eye field; Ins, insula; MFG, middle frontal gyrus; SFG, superior frontal gyrus; mPFC, medial frontal gyrus; IPL, inferior parietal lobule; SPL, superior parietal lobule; IFG, inferior frontal gyrus; ACC, anterior cingulate cortex; STG, superior temporal gyrus; TTG, transverse temporal gyrus; CC, cingulate; SMG, supramarginal gyrus; MTG, middle temporal gyrus; UN, uncus; PCL, paracentral lobule; PrG, precentral gyrus; PoG, postcentral gyrus; OrG, orbital gyrus; ITG, inferior temporal gyrus; PHG, parahippocampal gyrus; PCu, precuneus; Cu, cuneus; GRe, rectal gyrus; FuG, fusiform gyrus; LiG, lingual gyrus; IOG, inferior occipital gyrus; MOG, middle occipital gyrus; PCC, posterior cingulate; SOG, superior occipital gyrus; AnG, angular gyrus; vmPFC, ventral medial prefrontal cortex; aIPL, anterior inferior parietal lobule.

To decipher the appearance of Fmθ, the raw waveform and independent components of the EEG data were visually inspected and selected according to the criterion that the θ wave with the maximum amplitude of at least 1 s at the Fz electrode was Fmθ. Each index was compared using Student’s t test for the Fmθ appearance and no-Fmθ appearance groups within each condition.

Autonomic activity and occupational performance were compared between conditions using one-way ANOVA. Autonomic activity was subtracted from the baseline post-value, and the change from task start to task end was calculated. The change in each of the craft conditions was also compared between conditions using one-way ANOVA. IBM SPSS Statistics (version: 28.0.0) was used to process these statistics. The significance level for each test was less than 5%.

Thirty subjects (18 males and 12 females) completed the experiment. The mean age was 20.17 ± 0.91 years, and the median closeness was 8.00 (6.00–9.25). Task performance did not differ significantly between conditions (p = 0.881).

Autonomic Activity

The results of the comparison of autonomic activity between the three conditions are shown in Table 2. Significant differences in the CVI change were found among the three conditions (p = 0.029), and multiple comparison tests showed that the CVI change in the parallel condition was significantly greater in the positive direction than in the alone condition (p = 0.026).

Table 2.

Comparison of autonomic activity between the three conditions

AloneParallelNonparallelp
AVGSDAVGSDAVGSD
Total CSI 2.51 0.94 2.55 0.90 2.51 0.86 0.978  
Total CVI 4.29 0.37 4.29 0.34 4.32 0.31 0.924  
Total RRI 790.03 120.67 783.22 114.90 789.99 113.78 0.967  
CSI change −0.20 0.69 −0.16 0.80 −0.39 0.75 0.462  
CVI change −0.11 0.23 0.05 0.22 −0.05 0.25 0.029* 
RRI change −7.63 28.65 −3.55 39.44 10.98 42.06 0.132  
AloneParallelNonparallelp
AVGSDAVGSDAVGSD
Total CSI 2.51 0.94 2.55 0.90 2.51 0.86 0.978  
Total CVI 4.29 0.37 4.29 0.34 4.32 0.31 0.924  
Total RRI 790.03 120.67 783.22 114.90 789.99 113.78 0.967  
CSI change −0.20 0.69 −0.16 0.80 −0.39 0.75 0.462  
CVI change −0.11 0.23 0.05 0.22 −0.05 0.25 0.029* 
RRI change −7.63 28.65 −3.55 39.44 10.98 42.06 0.132  

Results of multiple comparisons of the CVI change showed that the Bonferroni correction alone was < parallel, p = 0.026.

* p < 0.05, one-way ANOVA.

There were 15 Fmθ and 15 no-Fmθ groups in the alone and parallel conditions and 12 Fmθ and 18 no-Fmθ groups in the nonparallel condition. The results of the group comparisons with and without Fmθ are shown in Table 3. In all three conditions, alone, parallel, and nonparallel, the CVI change was significantly greater in the positive direction in the Fmθ group than in the no-Fmθ group (p = 0.002, 0.025, 0.021). In the nonparallel condition, the RRI change in the positive direction was significantly greater in the Fmθ group (p = 0.017). The results of the three-condition comparison of CVI change and the comparison by Fmθ occurrence are shown in Figure 2.

Table 3.

Comparison of autonomic activity by Fmθ occurrence

FmθNo Fmθp value
AVGSDAVGSD
Alone 
 Age 20.27 0.96 20.07 0.88 0.558 
 Total CSI 2.34 0.68 2.68 1.13 0.326 
 Total CVI 4.31 0.35 4.26 0.40 0.673 
 Total RRI 793.78 105.32 786.29 137.99 0.868 
 CSI change 0.01 0.52 −0.40 0.79 0.100 
 CVI change 0.01 0.20 −0.23 0.19 0.002** 
 RRI change −5.08 25.18 −10.18 32.45 0.634 
 Closeness 7.20 2.18 7.93 1.94 0.339 
Parallel 
 Age 20.33 0.90 20.00 0.93 0.326 
 Total CSI 2.39 0.87 2.72 0.93 0.322 
 Total CVI 4.34 0.30 4.25 0.38 0.490 
 Total RRI 783.59 88.64 782.85 139.61 0.986 
 CSI change −0.16 0.76 −0.16 0.87 0.999 
 CVI change 0.14 0.18 −0.04 0.23 0.025* 
 RRI change −3.08 37.98 −4.03 42.18 0.949 
 Closeness 7.27 2.19 7.87 1.96 0.435 
Nonparallel 
 Age 20.17 0.72 20.17 1.04 1.000 
 Total CSI 2.61 1.15 2.45 0.64 0.614 
 Total CVI 4.34 0.37 4.31 0.28 0.790 
 Total RRI 795.17 95.93 786.54 126.88 0.843 
 CSI change −0.60 0.93 −0.25 0.59 0.217 
 CVI change 0.08 0.31 −0.13 0.15 0.021* 
 RRI change 32.92 47.60 −3.65 31.40 0.017* 
 Closeness 8.08 1.88 7.22 2.16 0.270 
FmθNo Fmθp value
AVGSDAVGSD
Alone 
 Age 20.27 0.96 20.07 0.88 0.558 
 Total CSI 2.34 0.68 2.68 1.13 0.326 
 Total CVI 4.31 0.35 4.26 0.40 0.673 
 Total RRI 793.78 105.32 786.29 137.99 0.868 
 CSI change 0.01 0.52 −0.40 0.79 0.100 
 CVI change 0.01 0.20 −0.23 0.19 0.002** 
 RRI change −5.08 25.18 −10.18 32.45 0.634 
 Closeness 7.20 2.18 7.93 1.94 0.339 
Parallel 
 Age 20.33 0.90 20.00 0.93 0.326 
 Total CSI 2.39 0.87 2.72 0.93 0.322 
 Total CVI 4.34 0.30 4.25 0.38 0.490 
 Total RRI 783.59 88.64 782.85 139.61 0.986 
 CSI change −0.16 0.76 −0.16 0.87 0.999 
 CVI change 0.14 0.18 −0.04 0.23 0.025* 
 RRI change −3.08 37.98 −4.03 42.18 0.949 
 Closeness 7.27 2.19 7.87 1.96 0.435 
Nonparallel 
 Age 20.17 0.72 20.17 1.04 1.000 
 Total CSI 2.61 1.15 2.45 0.64 0.614 
 Total CVI 4.34 0.37 4.31 0.28 0.790 
 Total RRI 795.17 95.93 786.54 126.88 0.843 
 CSI change −0.60 0.93 −0.25 0.59 0.217 
 CVI change 0.08 0.31 −0.13 0.15 0.021* 
 RRI change 32.92 47.60 −3.65 31.40 0.017* 
 Closeness 8.08 1.88 7.22 2.16 0.270 

**p < 0.01, *p < 0.05, Student’s t test.

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. 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).

Close modal

Correlation of CSD and FC with Other Indicators

Considering the possibility that the dominant hand may influence the lateralization of the brain, we present the results of the analysis of 27 subjects, excluding 3 left-handed subjects. There were no significant differences in CSD and FC between the different construction conditions. In the alone condition, there was no significant correlation between CSD and FC and other indicators.

In the parallel condition, there was a significant negative correlation (p = 0.01220) between CSD and total CVI in the right insula (Ins) and parietal lobes of the α1 band (Fig. 3a). There was also a significant negative correlation (p = 0.03360) between FC and total CVI in the right anterior inferior parietal lobule, left hippocampal body, and posterior insula (pIns) peripheral regions of the α1 band (Fig. 3b). There was a trend toward a positive correlation between FC and proximity in the right dlPFC-right hippocampus and right pIns in the δ band and a trend toward a negative correlation between FC and proximity in the left aIns-right aIns in the low γ band (p = 0.07840).

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. 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.

Close modal

In the nonparallel condition, there was a significant positive correlation between CSD and total CSI in the right superior, middle, and inferior frontal gyrus in the β1 band (p = 0.02420) (Fig. 4a). We also found a significant negative correlation between ACC-right hippocampal body and right pIns peri-regional FC and total CVI in the α1 band (p = 0.01720) (Fig. 4b). No significant differences in CSD and FC were found between the Fmθ and no-Fmθ groups in each condition.

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.

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.

Close modal

The aim of this study was to determine the usefulness of the parallel groups used in OT and the focus on craft activities in terms of brain activity and autonomic activity. Of the initial hypotheses, the occupational activities in which parallel groups and Fmθ appeared resulted in increased parasympathetic activity, proving that changes in autonomic activity are associated with changes in CSD and FC.

Regarding the increase in parasympathetic activity in the parallel condition, the total CVI was not significantly different between conditions, but the change in the total CVI was significantly different between conditions. The total CVI is calculated for the entire 3 min of craft activity and should be considered the effects of baseline, post, and rest conditions. In this study, the Lorenz plot of 50 beats immediately after the start of the task was taken as baseline, and the Lorenz plot of 50 beats immediately before the end of the task was taken as post, and the extent to which each index changed within the task condition was calculated. As a result, the change was more sensitive than the values for the whole interval, and the differences were more likely to occur. Previous research has reported that physical contact with an intimate partner [65, 66], the presence of supportive others [67] and social support [68], social interactions with close others [69], and a high sense of security in attachment relationships [70] activate parasympathetic activity in the cardiovascular and other systems and reduce hormones and other stress indicators [71]. It is suggested that not only actual support but also interaction with others and feelings of attachment are related to this effect. In the parallel conditions of this study, there was no physical contact or actual support. Nevertheless, activation of parasympathetic activity occurred, suggesting a stress-relieving effect of the presence of others, as in previous studies that observed changes in blood pressure and heart rate [72]. In addition to the relaxing effect of performing craft activities [43], the social-buffering effect [11] of performing craft activities in parallel with intimate others may have led to activation of the parasympathetic nervous system. These may be related to social buffering, a phenomenon in which people recover better from avoidance experiences when in the company of peers [10]. Social buffering reduces stress indicators such as heart rate and cortisol [11], i.e., it produces an autonomic buffering effect. The activation of parasympathetic activity in the present study may have a similar effect to this social buffering. On the other hand, the social-buffering effect is thought to produce a decrease in ACC-derived theta activity [12] and activation of the dlPFC [13] and ventral medial prefrontal cortex [14]. In the present study, we did not find any involvement of activity at these sites. This may be due to the fact that in the present experimental conditions, handicrafts were implemented to test their effects in OT situations. Performing the crafts may have generated hand movements, anticipation of outcomes, and various thoughts related to the task. They may have caused brain activity other than that associated with the pure social-buffering effect to be recorded, offsetting the original activity. Therefore, we could not find differences in brain activity between the conditions.

The appearance of Fmθ has been suggested to be related to autonomic activity [43, 47], and in this study, the Fmθ appearance group showed significantly higher CVI change in both conditions. Our previous MEG study already showed that the current sources of the Fmθ were located in bilateral medial PFC and ACC [45]. Previous studies also reported that electrical stimulation of ACC induced autonomic changes, suggesting a link between ACC and autonomic activity [73, 74]. These findings are consistent with the results of the present study, in which the Fmθ appearance group showed more parasympathetic activity than the no-Fmθ group. In conclusion, the results of this study provide valuable evidence of the therapeutic effects of group and craft activities included in the OT treatment system in terms of autonomic nervous activity, which could serve as evidence of the therapeutic effects of OT. Regarding the fact that no significant differences in CSD and FC were found between the Fmθ and no-Fmθ groups, in this study the Fz electrodes were used for the maximum. This may be because the presence or absence of specific EEG activity for 1 s during the 3-min period was not sufficient to affect CSD or FC. However, this study showed that even a short period of time around 1 s can affect autonomic activity, and the occurrence of Fmθ is considered significant.

Although EEG analysis showed no significant differences between conditions for both CSD and FC, correlation between CSD, FC, and autonomic activity showed that total CVI was negatively correlated with CSD in the region centered on the right Ins of the α1 band in the parallel condition. Increased right Ins activity leads to increased tachycardia and baroreflex response [75], and right Ins tumor resection is associated with a significant increase in parasympathetic activity [76]. In other words, increased right Ins activity is associated with decreased parasympathetic activity and, conversely, decreased right Ins activity is associated with increased parasympathetic activity. This finding that lower right Ins activity is associated with higher parasympathetic activity is consistent with the explanation of brain and autonomic activity in previous studies.

Total CVI in the parallel condition was negatively correlated with FC in the region surrounding the right anterior inferior parietal lobule, the left hippocampal body, and the region surrounding the area centered on the left pIns of the α1 band. Regional decreases in inferior parietal lobe activity are associated with improved performance on social judgment tasks [77]. The network involving the right IPL and left Ins is also associated with skilled behavioral prediction [78]. The finding in this study that this network and total CVI were negatively correlated in the parallel condition may reflect the state of being unable to predict the behavior of others. Parallel groups in OT are groups of individuals who work and play with minimal task sharing and mutual stimulation in the presence of others. It has been suggested that those who are more likely to relax or increase parasympathetic activity by using this group may be those who are less concerned about the behavior and the presence of others.

In the nonparallel condition, total CVI was negatively correlated with FC in the ACC-right hippocampal body and in the region centered on the right pIns of the α1 band. Increased activity in the ACC and Ins has been positively correlated with self-reported pain [14] and embarrassment and witnessing threatening scenes of others [79, 80] and negatively correlated with parasympathetic activity [81, 82], suggesting that they are key sites involved in heart rate regulation, especially in emotional situations [83]. The present negative correlation between total CVI and FC in this region is consistent with the previous studies described above, showing a link between brain activity and autonomic activity. However, this correlation was only found in the nonparallel condition and not in the other conditions. ACC and Ins activities have been reported to be positively correlated with empathy scores [84‒86]. In both the parallel and nonparallel conditions in this study, close others were present in close proximity, which is also a situation in which empathy is likely to occur. Conflicting results were expected: from the perspective of increased parasympathetic activity, decreased ACC and Ins activity would be expected; from the perspective of empathy, increased ACC and Ins activity would be expected. This discrepancy may have contributed to the negative correlation between CVI and ACC-Ins FC, which was found only in the nonparallel condition and not in the parallel condition.

Regarding low-frequency alpha rhythms, several studies have suggested that these rhythms diffusely regulate global tonic arousal in the brain [87‒89]. The low-frequency alpha rhythm of 8.5–10 Hz observed in this study may have resulted in inhibitory control of the Ins periaqueductal region and ACC, leading to a reduction in CSD and FC.

Total CSI was positively correlated with the CSD of the right PFC in the β1 band under nonparallel conditions. It has been previously reported that unpleasant stimuli significantly enlarged the right inferior frontal gyrus, suggesting a link between the right PFC and sympathetic activity [80‒92]. The positive correlation between CSI and right PFC found in this study is consistent with these previous studies, but this correlation was not found in the parallel condition and was specific to the nonparallel condition. Although the differences between conditions did not reach significance, as mentioned above, increased parasympathetic activity and relative attenuation of sympathetic activity would have been dominant in the parallel condition. In the nonparallel condition, on the other hand, even intimate others are exposed to the environment of being watched. The presence of observers has been reported to increase sympathetic activity [93], and this effect may have facilitated the increase in sympathetic activity in the nonparallel condition. This difference in autonomic activity may have influenced the finding that only CSI was positively correlated with the right PFC in the nonparallel condition.

Limitations

Significant differences in parasympathetic activity were found between the alone and parallel conditions and were not significantly different from the nonparallel condition. Social facilitation is thought to occur in situations where there is observation by others, and in particular, the type of observer influences effectiveness [5]. In the parallel and nonparallel condition settings of this study, the placement of others in close proximity in both conditions may have influenced the lack of significant differences. Also, the results should be interpreted with caution, as they do not indicate differences from others not in close proximity. In actual OT situations, it is common for patients to perform crafts for longer periods of time than 3 min. In this study, measurements were made in an experimental setting, but in the future, it will be necessary to measure EEG and autonomic nervous system activity in an environment more similar to a clinical setting to determine clinical efficacy. In addition, the resting condition was set at 1 min and 30 s to avoid fatigue and an increase in the impedance of the electrodes on the scalp, but it is possible that the effects of the immediately preceding experimental conditions were not sufficiently refreshed. Counterbalancing the experimental sequence may have minimized this problem, but more stringent environmental conditions are also needed. Subjects were healthy young adults and were set up to avoid verbal and physical interactions. Craft activities in clinical OT typically last longer than 3 min, involve a wide age range of participants with mental disorders such as schizophrenia and mood disorders, and often involve verbal and physical interaction. While the present findings provide evidence for the effectiveness of the treatment structure in the OT population, it should be noted that these are basic findings and should be validated in future studies in clinical settings. Although artifact removal was performed using ICA, there is a possibility that gamma-band activity may be electromyographic in origin [94], which is a limitation of EEG measurement from the scalp electrodes. The use of magnetoencephalography or other methods to accurately capture gamma-band activity is also a future challenge.

This study provides electrophysiological evidence for the effectiveness of the parallel group and craft activity focus used in OT and reports that social buffering occurs despite the absence of physical contact and social support. Parallel tasks with close others and craft activities that elicited Fmθ increased parasympathetic activity, and increased parasympathetic activity was associated with attenuation of CSD in Ins and FC between Ins and ACC or IPL. Future clinical research is expected to further establish the usefulness of OT treatment structures in the presence of non-intimate others, in the presence of specific interactions, and across a wide range of age-groups and mental disorders.

We would like to thank Hideki Kaneko and Hisao Yoshida for their expert technical assistance in obtaining the physiological data. We also thank the experimental subjects who cooperated in this study and all those who assisted in the acquisition of physiological data (Akira Iwasado, Taichiro Sakaue, Kohei Tanaka, Sora Ohara, Atsushi Takei, Kenji Nakahara, Haruka Yamamoto, and Rico Onishi).

This study was conducted with the approval of the Ethics Committee of the Graduate School of Rehabilitation Sciences of Osaka Metropolitan University (2022-212) and the Research Ethics Committee of Osaka Kawasaki Rehabilitation University (OKRU-RA0032). Written informed consent was obtained from the participants.

The authors have no conflicts of interest to declare.

This work was partially supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI Grant No. JP22K11453; however, the funding agency were not involved in the conduct of the research or preparation of the article.

Junya Orui and Keigo Shiraiwa designed the study. Junya Orui, Keigo Shiraiwa, Fumie Tazaki, and Takao Inoue contributed to the acquisition of data. Junya Orui, Keigo Shiraiwa, Masaya Ueda, Keita Ueno, Yasuo Naito, and Ryouhei Ishii conducted the analyses. Junya Orui and Ryouhei Ishii wrote the first draft of the manuscript. Junya Orui, Ryouhei Ishii, Keigo Shiraiwa, Fumie Tasaki, Takao Inoue, Masaya Ueda, Keita Ueno, and Yasuo Naito revised and approved the final version.

Although all data that were generated or analyzed in this study are not publicly available due to ethical reasons, it will be available from the corresponding authors on reasonable request and after additional ethics approval regarding data provision to individual institutions. Further inquiries can be directed to the corresponding author.

1.
Crowne
DP
,
Liverant
S
.
Conformity under varying conditions of personal commitment
.
J Abnorm Soc Psychol
.
1963 Jun
66
6
547
55
.
2.
Zajonc
RB
.
Social facilitation
.
Science
.
1965 Jul
149
3681
269
74
.
3.
Bowman
ND
,
Weber
R
,
Tamborini
R
,
Sherry
J
.
Facilitating game play: how others affect performance at and enjoyment of video games
.
Media Psychol
.
2013 Jan
16
1
39
64
.
4.
Hoyt
CL
,
Blascovich
J
,
Swinth
KR
.
Social inhibition in immersive virtual environments
.
Presence
.
2003 Apr
12
2
183
95
.
5.
Kao
D
.
The effects of observation in video games: how remote observation influences player experience, motivation, and behaviour
.
Behav Inf Technol
.
2022 Jul
41
9
1905
27
.
6.
Pozharliev
R
,
Verbeke
WJMI
,
van Strien
JW
,
Bagozzi
RP
.
Merely being with you increases my attention to luxury products: using EEG to understand consumers’ emotional experience with luxury branded products
.
J Market Res
.
2015 Aug
52
4
546
58
.
7.
Szymanski
C
,
Pesquita
A
,
Brennan
AA
,
Perdikis
D
,
Enns
JT
,
Brick
TR
.
Teams on the same wavelength perform better: inter-brain phase synchronization constitutes a neural substrate for social facilitation
.
Neuroimage
.
2017 May
152
425
36
.
8.
Heyselaar
E
,
Mazaheri
A
,
Hagoort
P
,
Segaert
K
.
Changes in alpha activity reveal that social opinion modulates attention allocation during face processing
.
Neuroimage
.
2018 Jul
174
432
40
.
9.
Darfler
M
,
Cruz-Garza
JG
,
Kalantari
S
.
An EEG-based investigation of the effect of perceived observation on visual memory in virtual environments
.
Brain Sci
.
2022 Feb
12
2
269
.
10.
Kikusui
T
,
Winslow
JT
,
Mori
Y
.
Social buffering: relief from stress and anxiety
.
Philos Trans R Soc Lond B Biol Sci
.
2006 Dec
361
1476
2215
28
.
11.
Thorsteinsson
EB
,
James
JE
,
Gregg
ME
.
Effects of video-relayed social support on hemodynamic reactivity and salivary cortisol during laboratory-based behavioral challenge
.
Health Psychol
.
1998
;
17
(
5
):
436
44
.
12.
Che
X
,
Cash
R
,
Fitzgerald
P
,
Fitzgibbon
BM
.
The social regulation of pain: autonomic and neurophysiological changes associated with perceived threat
.
J Pain
.
2018 May
19
5
496
505
.
13.
Younger
J
,
Aron
A
,
Parke
S
,
Chatterjee
N
,
Mackey
S
.
Viewing pictures of a romantic partner reduces experimental pain: involvement of neural reward systems
.
PLoS One
.
2010 Oct
5
10
e13309
.
14.
Eisenberger
NI
,
Master
SL
,
Inagaki
TK
,
Taylor
SE
,
Shirinyan
D
,
Lieberman
MD
.
Attachment figures activate a safety signal-related neural region and reduce pain experience
.
Proc Natl Acad Sci U S A
.
2011 Jul
108
28
11721
6
.
15.
Smith
AS
,
Wang
Z
.
Hypothalamic oxytocin mediates social buffering of the stress response
.
Biol Psychiatry
.
2014 Aug
76
4
281
8
.
16.
Rilling
JK
,
Winslow
JT
,
O’Brien
D
,
Gutman
DA
,
Hoffman
JM
,
Kilts
CD
.
Neural correlates of maternal separation in rhesus monkeys
.
Biol Psychiatry
.
2001 Jan
49
2
146
57
.
17.
Hostinar
CE
,
Sullivan
RM
,
Gunnar
MR
.
Psychobiological mechanisms underlying the social buffering of the hypothalamic–pituitary–adrenocortical axis: a review of animal models and human studies across development
.
Psychol Bull
.
2014 Jan
140
1
256
82
.
18.
Taylor
SE
,
Klein
LC
,
Lewis
BP
,
Gruenewald
TL
,
Gurung
RAR
,
Updegraff
JA
.
Biobehavioral responses to stress in females: tend-and-befriend, not fight-or-flight
.
Psychol Rev
.
2000
;
107
(
3
):
411
29
.
19.
Geary
DC
,
Flinn
M
.
Sex differences in behavioral and hormonal response to social threat: commentary on Taylor et al. (2000)
.
Psychol Rev
.
2002
;
109
(
4
):
745
50
; discussion 751-3.
20.
Cardoso
C
,
Ellenbogen
MA
,
Serravalle
L
,
Linnen
AM
.
Stress-induced negative mood moderates the relation between oxytocin administration and trust: evidence for the tend-and-befriend response to stress
.
Psychoneuroendocrinology
.
2013 Nov
38
11
2800
4
.
21.
Schwerdtfeger
AR
,
Paul
L
,
Rominger
C
.
Momentary feelings of safety are associated with attenuated cardiac activity in daily life: preliminary evidence from an ecological momentary assessment study
.
Int J Psychophysiol
.
2022 Dec
182
231
9
.
22.
The World Federation of Occupational Therapists (WFOT)
. About Occupational Therapy [Internet] https://wfot.org/about/about-occupational-therapy.
2012
.
23.
McLean
H
.
Towards developing a frame of reference and defining a treatment model in occupational therapy as applied to psychiatry
.
Br J Occup Ther
.
1974 Nov
37
11
196
8
.
24.
Kielhofner
G
Conceptual foundations of occupational therapy practice
4th ed
Pennsylvania
The F. A. Davis Company
2009
.
25.
Howe
MC
,
Schwartzberg
SL
A functional approach to group work in occupational therapy
3rd ed
Philadelphia
Lippincott Williams & Wilkins
2001
.
26.
Duncombe
LW
,
Howe
MC
.
Group work in occupational therapy: a survey of practice
.
Am J Occup Ther
.
1985 Mar
39
3
163
70
.
27.
Mosey
AC
.
Recapitulation of ontogenesis: a theory for practice of occupational therapy
.
Am J Occup Ther
.
1968
;
22
(
5
):
426
38
.
28.
Mosey
AC
Three frames of reference for mental health
New Jersey
Slack Inc
1970
.
29.
Mosey
AC
.
The concept and use of developmental groups
.
Am J Occup Ther
.
1970
;
24
(
4
):
272
5
.
30.
Mosey
AC
Activities therapy
New York
Raven Press
1973
.
31.
Mosey
AC
Psychosocial components of occupational therapy
1st ed
New York
Raven Press
1986
.
32.
Donohue
M
.
Theoretical bases of Mosey’s group interaction skills
.
Occup Ther Int
.
1999 Mar
6
1
35
51
.
33.
Toledano-González
A
,
Labajos-Manzanares
T
,
Romero-Ayuso
D
.
Well-being, self-efficacy and independence in older adults: a randomized trial of occupational therapy
.
Arch Gerontol Geriatr
.
2019 Jul
83
277
84
.
34.
Vestri
A
,
Peruch
F
,
Marchi
S
,
Frare
M
,
Guerra
P
,
Pizzighello
S
.
Individual and group treatment for patients with acquired brain injury in comprehensive rehabilitation
.
Brain Inj
.
2014 Jul
28
8
1102
8
.
35.
Harris
E
.
The meanings of craft to an occupational therapist
.
Aust Occup Ther J
.
2007 Nov
55
2
133
42
.
36.
Taylor
E
,
Manguno
J
.
Use of treatment activities in occupational therapy
.
Am J Occup Ther
.
1991 Apr
45
4
317
22
.
37.
Craik
C
,
Chacksfield
JD
,
Richards
G
.
A survey of occupational therapy practitioners in mental health
.
Br J Occup Ther
.
1998 May
61
5
227
34
.
38.
Griffiths
S
,
Corr
S
.
The use of creative activities with people with mental health problems: a survey of occupational therapists
.
Br J Occup Ther
.
2007 Mar
70
3
107
14
.
39.
Reynolds
F
,
Vivat
B
,
Prior
S
.
Women’s experiences of increasing subjective well-being in CFS/ME through leisure-based arts and crafts activities: a qualitative study
.
Disabil Rehabil
.
2008 Jan
30
17
1279
88
.
40.
Kaunnil
A
,
Kaunnil
K
,
Permpoonputtana
K
,
Sirisatayawong
P
,
Srikhamjak
T
,
Chupradit
S
.
Craft activities as a meaningful occupation among clients with schizophrenia in Thailand
.
Occup Ther Ment Health
.
2022 Jul
38
3
236
57
.
41.
Buchain
PC
,
Vizzotto
ADB
,
Henna Neto
J
,
Elkis
H
.
Randomized controlled trial of occupational therapy in patients with treatment-resistant schizophrenia
.
Braz J Psychiatry
.
2003 Mar
25
1
26
30
.
42.
Foruzandeh
N
,
Parvin
N
.
Occupational therapy for inpatients with chronic schizophrenia: a pilot randomized controlled trial
.
Jpn J Nurs Sci
.
2013 Jun
10
1
136
41
.
43.
Shiraiwa
K
,
Yamada
S
,
Nishida
Y
,
Toichi
M
.
Changes in electroencephalography and cardiac autonomic function during craft activities: experimental evidence for the effectiveness of occupational therapy
.
Front Hum Neurosci
.
2020 Dec
14
621826
.
44.
Ishihara
T
,
Yoshi
N
.
Multivariate analytic study of EEG and mental activity in Juvenile delinquents
.
Electroencephalogr Clin Neurophysiol
.
1972 Jul
33
1
71
80
.
45.
Ishii
R
,
Shinosaki
K
,
Ukai
S
,
Inouye
T
,
Ishihara
T
,
Yoshimine
T
.
Medial prefrontal cortex generates frontal midline theta rhythm
.
Neuroreport
.
1999 Mar
10
4
675
9
.
46.
Aftanas
LI
,
Golocheikine
SA
.
Human anterior and frontal midline theta and lower alpha reflect emotionally positive state and internalized attention: high-resolution EEG investigation of meditation
.
Neurosci Lett
.
2001 Sep
310
1
57
60
.
47.
Kubota
Y
,
Sato
W
,
Toichi
M
,
Murai
T
,
Okada
T
,
Hayashi
A
.
Frontal midline theta rhythm is correlated with cardiac autonomic activities during the performance of an attention demanding meditation procedure
.
Brain Res Cogn Brain Res
.
2001 Apr
11
2
281
7
.
48.
Toichi
M
,
Sugiura
T
,
Murai
T
,
Sengoku
A
.
A new method of assessing cardiac autonomic function and its comparison with spectral analysis and coefficient of variation of R–R interval
.
J Auton Nerv Syst
.
1997 Jan
62
1–2
79
84
.
49.
Penttilä
J
,
Helminen
A
,
Jartti
T
,
Kuusela
T
,
Huikuri
HV
,
Tulppo
MP
.
Time domain, geometrical and frequency domain analysis of cardiac vagal outflow: effects of various respiratory patterns
.
Clin Physiol
.
2001 May
21
3
365
76
.
50.
Gamelin
FX
,
Berthoin
S
,
Bosquet
L
.
Validity of the polar S810 heart rate monitor to measure R-R intervals at rest
.
Med Sci Sports Exerc
.
2006 May
38
5
887
93
.
51.
Sato
W
,
Imamura
K
,
Toichi
M
Lorenz plot analysis of cardiac autonomic function
.
2002
. [unpublished computer software].
52.
Makeig
S
,
Jung
TP
,
Bell
AJ
,
Ghahremani
D
,
Sejnowski
TJ
.
Blind separation of auditory event-related brain responses into independent components
.
Proc Natl Acad Sci U S A
.
1997 Sep
94
20
10979
84
.
53.
Lee
TW
,
Girolami
M
,
Sejnowski
TJ
.
Independent component analysis using an extended infomax algorithm for mixed subgaussian and supergaussian sources
.
Neural Comput
.
1999 Feb
11
2
417
41
.
54.
Delorme
A
,
Makeig
S
.
EEGLAB: an open source toolbox for analysis of single-trial EEG dynamics including independent component analysis
.
J Neurosci Methods
.
2004 Mar
134
1
9
21
.
55.
Pascual-Marqui
RD
,
Lehmann
D
,
Koukkou
M
,
Kochi
K
,
Anderer
P
,
Saletu
B
.
Assessing interactions in the brain with exact low-resolution electromagnetic tomography
.
Philos Trans A Math Phys Eng Sci
.
2011 Oct
369
1952
3768
84
.
56.
Stam
CJ
,
Nolte
G
,
Daffertshofer
A
.
Phase lag index: assessment of functional connectivity from multi channel EEG and MEG with diminished bias from common sources
.
Hum Brain Mapp
.
2007 Nov
28
11
1178
93
.
57.
Derks
J
,
Kulik
SD
,
Numan
T
,
de Witt Hamer
PC
,
Noske
DP
,
Klein
M
.
Understanding global brain network alterations in glioma patients
.
Brain Connect
.
2021 Dec
11
10
865
74
.
58.
Mazziotta
J
,
Toga
A
,
Evans
A
,
Fox
P
,
Lancaster
J
,
Zilles
K
.
A probabilistic atlas and reference system for the human brain: International Consortium for Brain Mapping (ICBM)
.
Philos Trans R Soc Lond B Biol Sci
.
2001 Aug
356
1412
1293
322
.
59.
Vincent
JL
,
Kahn
I
,
Snyder
AZ
,
Raichle
ME
,
Buckner
RL
.
Evidence for a frontoparietal control system revealed by intrinsic functional connectivity
.
J Neurophysiol
.
2008 Dec
100
6
3328
42
.
60.
Anderer
P
,
Pascual-Marqui
RD
,
Semlitsch
HV
,
Saletu
B
.
Electrical sources of P300 event-related brain potentials revealed by low resolution electromagnetic tomography. 1. Effects of normal aging
.
Neuropsychobiology
.
1998
;
37
(
1
):
20
7
.
61.
Pascual-Marqui
RD
,
Lehmann
D
,
Koenig
T
,
Kochi
K
,
Merlo
MCG
,
Hell
D
.
Low resolution brain electromagnetic tomography (LORETA) functional imaging in acute, neuroleptic-naive, first-episode, productive schizophrenia
.
Psychiatry Res
.
1999 Jun
90
3
169
79
.
62.
Nichols
TE
,
Holmes
AP
.
Nonparametric permutation tests for functional neuroimaging: a primer with examples
.
Hum Brain Mapp
.
2002 Jan
15
1
1
25
.
63.
Pascual-Marqui
RD
,
Esslen
M
,
Kochi
K
,
Lehmann
D
.
Functional imaging with Low-Resolution brain Electromagnetic Tomography (LORETA): a review
.
Methods Find Exp Clin Pharmacol
.
2002
24
Suppl C
91
5
.
64.
Ueda
M
,
Usami
K
,
Yamao
Y
,
Yamawaki
R
,
Umaba
C
,
Liang
N
.
Correlation between brain functional connectivity and neurocognitive function in patients with left frontal glioma
.
Sci Rep
.
2022 Nov
12
1
18302
.
65.
Wilhelm
FH
,
Kochar
AS
,
Roth
WT
,
Gross
JJ
.
Social anxiety and response to touch: incongruence between self-evaluative and physiological reactions
.
Biol Psychol
.
2001 Dec
58
3
181
202
.
66.
Pishbin
T
,
Firoozabadi
SMP
,
Jafarnia Dabanloo
N
,
Mohammadi
F
,
Koozehgari
S
.
Effect of physical contact (Hand-Holding) on heart rate variability
.
World Acad Sci Eng Technol
.
2010
;
46
:
523
7
.
67.
Lepore
SJ
,
Allen
KA
,
Evans
GW
.
Social support lowers cardiovascular reactivity to an acute stressor
.
Psychosom Med
.
1993 Nov
55
6
518
24
.
68.
Teoh
AN
,
Hilmert
C
.
Social support as a comfort or an encouragement: a systematic review on the contrasting effects of social support on cardiovascular reactivity
.
Br J Health Psychol
.
2018 Nov
23
4
1040
65
.
69.
Schwerdtfeger
A
,
Friedrich-Mai
P
.
Social interaction moderates the relationship between depressive mood and heart rate variability: evidence from an ambulatory monitoring study
.
Health Psychol
.
2009 Jul
28
4
501
9
.
70.
Diamond
LM
,
Hicks
AM
.
Attachment style, current relationship security, and negative emotions: the mediating role of physiological regulation
.
J Soc Pers Relat
.
2005 Aug
22
4
499
518
.
71.
Thorsteinsson
EB
,
James
JE
.
A Meta-analysis of the effects of experimental manipulations of social support during laboratory stress
.
Psychol Health
.
1999 Oct
14
5
869
86
.
72.
Fontana
AM
,
Diegnan
T
,
Villeneuve
A
,
Lepore
SJ
.
Nonevaluative social support reduces cardiovascular reactivity in young women during acutely stressful performance situations
.
J Behav Med
.
1999
;
22
(
1
):
75
91
.
73.
Pool
JL
,
Ransohoff
J
.
Autonomic effects on stimulating rostral portion of cingulate gyri in man
.
J Neurophysiol
.
1949 Nov
12
6
385
92
.
74.
Kaada
BR
,
Jasper
H
.
respiratory responses to stimulation of temporal pole, insula, and hippocampal and limbic gyri in man
.
Arch Neurol Psychiatry
.
1952 Nov
68
5
609
19
.
75.
Oppenheimer
SM
,
Gelb
A
,
Girvin
JP
,
Hachinski
VC
.
Cardiovascular effects of human insular cortex stimulation
.
Neurology
.
1992 Sep
42
9
1727
32
.
76.
de Morree
HM
,
Rutten
GJ
,
Szabó
BM
,
Sitskoorn
MM
,
Kop
WJ
.
Effects of insula resection on autonomic nervous system activity
.
J Neurosurg Anesthesiol
.
2016 Apr
28
2
153
8
.
77.
Yoshie
M
,
Nagai
Y
,
Critchley
HD
,
Harrison
NA
.
Why I tense up when you watch me: inferior parietal cortex mediates an audience’s influence on motor performance
.
Sci Rep
.
2016 Jan
6
1
19305
.
78.
Xu
H
,
Wang
P
,
Ye
Z
,
Di
X
,
Xu
G
,
Mo
L
.
The role of medial frontal cortex in action anticipation in professional badminton players
.
Front Psychol
.
2016 Nov
7
1817
.
79.
Morita
T
,
Tanabe
HC
,
Sasaki
AT
,
Shimada
K
,
Kakigi
R
,
Sadato
N
.
The anterior insular and anterior cingulate cortices in emotional processing for self-face recognition
.
Soc Cogn Affect Neurosci
.
2014 May
9
5
570
9
.
80.
Müller-Pinzler
L
,
Rademacher
L
,
Paulus
FM
,
Krach
S
.
When your friends make you cringe: social closeness modulates vicarious embarrassment-related neural activity
.
Soc Cogn Affect Neurosci
.
2016 Mar
11
3
466
75
.
81.
Gianaros
PJ
,
van der Veen
FM
,
Jennings
JR
.
Regional cerebral blood flow correlates with heart period and high-frequency heart period variability during working-memory tasks: implications for the cortical and subcortical regulation of cardiac autonomic activity
.
Psychophysiology
.
2004 Jul
41
4
521
30
.
82.
Valenza
G
,
Sclocco
R
,
Duggento
A
,
Passamonti
L
,
Napadow
V
,
Barbieri
R
.
The central autonomic network at rest: uncovering functional MRI correlates of time-varying autonomic outflow
.
Neuroimage
.
2019 Aug
197
383
90
.
83.
Mccraty
R
,
Shaffer
F
.
Heart rate variability: new perspectives on physiological mechanisms, assessment of self-regulatory capacity, and health risk
.
Glob Adv Health Med
.
2015 Jan
4
1
46
61
.
84.
Singer
T
,
Seymour
B
,
O’Doherty
J
,
Kaube
H
,
Dolan
RJ
,
Frith
CD
.
Empathy for pain involves the affective but not sensory components of pain
.
Science
.
2004 Feb
303
5661
1157
62
.
85.
Jackson
PL
,
Brunet
E
,
Meltzoff
AN
,
Decety
J
.
Empathy examined through the neural mechanisms involved in imagining how I feel versus how you feel pain
.
Neuropsychologia
.
2006 Jan
44
5
752
61
.
86.
Fan
Y
,
Duncan
NW
,
de Greck
M
,
Northoff
G
.
Is there a core neural network in empathy? An fMRI based quantitative meta-analysis
.
Neurosci Biobehav Rev
.
2011 Jan
35
3
903
11
.
87.
Klimesch
W
.
Memory processes, brain oscillations and EEG synchronization
.
Int J Psychophysiol
.
1996 Nov
24
1–2
61
100
.
88.
Klimesch
W
,
Doppelmayr
M
,
Russegger
H
,
Pachinger
T
,
Schwaiger
J
.
Induced alpha band power changes in the human EEG and attention
.
Neurosci Lett
.
1998 Mar
244
2
73
6
.
89.
Klimesch
W
.
EEG alpha and theta oscillations reflect cognitive and memory performance: a review and analysis
.
Brain Res Rev
.
1999 Apr
29
2–3
169
95
.
90.
Coen
SJ
,
Yágüez
L
,
Aziz
Q
,
Mitterschiffthaler
MT
,
Brammer
M
,
Williams
SCR
.
Negative mood affects brain processing of visceral sensation
.
Gastroenterology
.
2009 Jul
137
1
253
61
. e1-2.
91.
Beissner
F
,
Meissner
K
,
Bar
KJ
,
Napadow
V
.
The autonomic brain: an activation likelihood estimation meta-analysis for central processing of autonomic function
.
J Neurosci
.
2013 Jun
33
25
10503
11
.
92.
Chang
C
,
Metzger
CD
,
Glover
GH
,
Duyn
JH
,
Heinze
HJ
,
Walter
M
.
Association between heart rate variability and fluctuations in resting-state functional connectivity
.
Neuroimage
.
2013 Mar
68
93
104
.
93.
Murray
NP
,
Raedeke
TD
.
Heart rate variability as an indicator of pre-competitive arousal
.
Int J Sport Psychol
.
2008
;
39
(
4
):
346
55
.
94.
Whitham
EM
,
Pope
KJ
,
Fitzgibbon
SP
,
Lewis
T
,
Clark
CR
,
Loveless
S
.
Scalp electrical recording during paralysis: quantitative evidence that EEG frequencies above 20 Hz are contaminated by EMG
.
Clin Neurophysiol
.
2007
;
118
(
8
):
1877
88
.