ABSTRACT
Physiological circuits differ across increasing isometric force levels during unilateral contraction. Therefore, we first explored the possibility of predicting the force level based on electroencephalogram (EEG) activity recorded during a single trial of unilateral 5% or 40% of maximal isometric voluntary contraction (MVC) in right-hand grip imagination. Nine healthy subjects were involved in this study. The subjects were required to randomly perform 20 trials for each force level while imagining a right-hand grip. We proposed the use of common spatial patterns (CSPs) and coherence between EEG signals as features in a support vector machine for force level prediction. The results showed that the force levels could be predicted through single-trial EEGs while imagining the grip (mean accuracy = 81.4 ± 13.29%). Additionally, we tested the possibility of online control of a ball game using the above paradigm through unilateral grip imagination at different force levels (i.e., 5% of MVC imagination and 40% of MVC imagination for right-hand movement control). Subjects played the ball games effectively by controlling direction with our novel BCI system (n = 9, mean accuracy = 76.67 ± 9.35%). Data analysis validated the use of our BCI system in the online control of a ball game. This information may provide additional commands for the control of robots by users through combinations with other traditional brain-computer interfaces, e.g., different limb imaginations.
ABSTRACT
Background Front-line power grid workers are required to face a variety of occupational hazards (such as aerial work), which make them susceptible to psychological problems and further reduce their performance efficiency and safety level. Objective To investigate the mental health status of front-line power grid workers and explore the influence of personality traits on mental health and the potential mediating role of work-family support between them. Methods This study was designed as a cross-sectional study. From January to June 2019, a cluster random sampling method was used to select two of the 20 power supply stations owned by a Guangdong power company. A total of 485 front-line power grid workers were included in the study. Sociodemographic characteristics were investigated, and NEO Five-Factor Inventory, Work-Family Support Scale, and Symptom Checklist 90 (SCL-90) were used in the survey. Spearman correlation analysis was conducted to analyze the correlations between measured variables. Structural equation modeling was used to analyze the relationships of personality traits, work-family support, and mental health, and Bootstrap analysis was used to test the mediating effect of work-family support on the relationship of personality traits and mental health. Results The M (P25, P75) of total SCL-90 score was 134.00 (110.00, 167.00）, and 139 (28.66%) front-line power grid workers showed positive mental health symptoms. The correlation analysis indicated that among the front-line power grid workers, neuroticism score was negatively correlated with work-family support total score (rs=−0.356, P<0.001), and positively correlated with the total score of SCL-90 (rs=0.557, P<0.001) as well as all the scores of its sub-dimensions (rs=0.436-0.550, P<0.001). Openness score was positively correlated with work-family support total score (rs=0.269, P<0.001), and except for paranoid ideation (P>0.05), openness score was negatively correlated with the scores of all the other sub-dimensions of SCL-90 (rs=−0.091-−0.147, P<0.05). The scores of the other three personality traits (extroversion, agreeableness, and conscientiousness) were positively correlated with work-family support total score (rs=0.331-0.466, P<0.001), and negatively correlated with the total score of SCL-90 as well as the scores of all its sub-dimensions (P<0.001). The modified structural equation modeling indicated that the direct effect of work-family support on mental health symptoms was −0.225 (P<0.001). The direct effects of extraversion and openness on work-family support were 0.241 (P<0.001) and 0.123 (P<0.05), respectively, while the effect on mental health symptoms was not statistically significant. The direct effects of neuroticism on work-family support and mental health symptoms were -0.152 (P<0.01) and 0.467 (P<0.001), respectively. The direct effects of conscientiousness on work-family support and mental health symptoms were not statistically significant (P>0.05). The direct effect of agreeableness on work-family support was not statistically significant (P>0.05), while the direct effect on mental health symptoms was −0.180 (P<0.001). Conclusion The front-line power grid workers show a high score of SCL-90. Workers with higher neuroticism are more vulnerable to mental health symptoms. Work-family support fully mediates the effects of extraversion and openness on mental health symptoms, and partially mediates the effects of neuroticism on mental health symptoms, while does not mediate the effects of agreeableness on mental health symptoms. Sufficient work-family support may improve mental health status.