Loneliness and brain rhythmic activity in resting state: an exploratory report

Figures

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  Figure 1.. The workflow of the FC analysis. (a) The calculation of the analytical signals in the electrode and source space. The electroencephalography time-series signals were recorded by 60 electrodes on the scalp. These signals were then band-pass filtered and Hilbert transformed to obtain the band-limited analytical signals of the electrode space. The spatial imaging kernel was estimated using the minimum norm estimation approach. The kernel was multiplied by the analytical signals of the electrode space to obtain the analytical signals of the source space. (b) The calculation of the orthogonalized PE correlations between the analytical signals for each frequency band. The analytical signal on one electrode or vertex was selected to orthogonalize with the analytical signals on all other electrodes or vertices. The orthogonalized analytical signals on all other electrodes or vertices were obtained. The Fisher-transformed correlation coefficients of these PEs were calculated. The procedure was iterated 60 times in the electrode space or 15 002 times in the source space to obtain the orthogonalized PE correlation coefficients between the analytical signal on all electrodes or vertices. The…

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  Figure 2.. The procedure of leave-one-participant-out cross-validation in CPM analysis. (a) One participant was selected as a test sample, and all other participants as the training set. (b) A partial correlation was calculated between loneliness scores and edges of FC in the training set, and the significant edges were combined as features. (c) The features and loneliness scores of participants in the training set were submitted to SVR analysis to build a predictive model. (d) The features of the test sample were submitted to the predictive model, and a predicted score was obtained. (e) The (a)–(d) steps were iterated 139 times to obtain the predicted scores for all participants. (f) Spearman’s rank correlation between the predicted and actual loneliness scores was calculated.

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  Figure 3.. Performance of the prediction model based on FC for the five frequency bands in the electrode and source spaces. (a) Spearman’s rank correlations between the actual and predicted loneliness scores for the five frequency bands in the electrode space, and the null distributions of correlation coefficient obtained by permutation test with 1000 iterations. The dashed line indicates the correlation coefficients obtained by the actual prediction. (b) Spearman’s rank correlations between the actual and predicted loneliness scores for the five frequency bands in the source space, and the null distributions of correlation coefficient obtained by permutation test with 1000 iterations. The dashed line indicates the correlation coefficients obtained by the actual prediction. (c) The 227 edges of nodes showed significant positive correlations with the loneliness scores in every iteration, and the total number of these edges within and between 17 networks. †P < .1.