Disrupted properties of functional brain networks in major depressive disorder during emotional face recognition: an EEG study via graph theory analysis.

Previous neuroimaging studies have revealed abnormal brain networks in patients with major depressive disorder (MDD) in emotional processing. While any cognitive task consists of a series of stages, little is yet known about the topology of functional brain networks in MDD for these stages during emotional face recognition. To address this problem, electroencephalography (EEG)-based functional brain networks of MDD patients at different stages of facial information processing were investigated in this study. First, EEG signals were collected from 16 patients with MDD and 18 age-, gender-, and education-matched normal subjects when performing an emotional face recognition task. Second, the global field power (GFP) method was employed to divide group-averaged event-related potentials into different stages. Third, using the phase transfer entropy (PTE) approach, the brain networks of MDD patients and normal individuals were constructed for each stage in negative and positive face processing, respectively. Finally, we compared the topological properties of brain networks of each stage between the two groups using graph theory approaches. The results showed that the analyzed three stages of emotional face processing corresponded to specific neurophysiological phases, namely, visual perception, face recognition, and emotional decision-making. It was also demonstrated that depressed patients showed abnormally decreased characteristic path length at the visual perception stage of negative face recognition and normalized characteristic path length in the stage of emotional decision-making during positive face processing compared to healthy subjects. Furthermore, while both the MDD and normal groups' brain networks were found to exhibit small-world network characteristics, the brain network of patients with depression tended to be randomized. Moreover, for patients with MDD, the centro-parietal region may lose its status as a hub in the process of facial expression identification. Together, our findings suggested that altered emotional function in MDD patients might be associated with disruptions in the topological organization of functional brain networks during emotional face recognition, which further deepened our understanding of the emotion processing dysfunction underlying MDD.

[Health Benefit Evaluation for PM2.5 as Well as O3-8h Pollution Control in Chengdu, China from 2016 to 2020].

Both particulate matter with aerodynamics of less than 2.5 (PM2.5) and ozone are the two main air pollutants in China, which seriously endanger human health. To estimate the adverse impacts of PM2.5 and ozone on human health during the implementation of air pollution prevention and control actions in Chengdu, both the generalized additive model and the nonlinear distribution lag model of epidemiology were adopted to explore the exposure-response relationship coefficients ß of daily ozone 8h maximum concentration average (O3-8h), as well as that of PM2.5 on disease deaths in Chengdu from 2014 to 2016. On this basis, the environmental risk model and environmental value assessment model were both adopted to evaluate the health effects and health benefits in Chengdu from 2016 to 2020, respectively, with the assumption that PM2.5 and O3-8h concentration were reduced to specified air pollution control limits (35 µg·m-3 and 70 µg·m-3, respectively). The results showed 1 the annual concentration of PM2.5 presented gradually decreasing trends in Chengdu from 2016 to 2020. Specifically, ρ(PM2.5) from 63 µg·m-3 in 2016 decreased to 40.92 µg·m-3 in 2020. The average annual decline rate was approximately 9.8%. In contrast, the annual concentration of O3-8h from 155 µg·m-3 in 2016 increased to 169 µg·m-3 in 2020, and the increasing rate was approximately 2.4%. 2 Both PM2.5 and O3-8h had lag effects on three types of disease deaths. Under the maximum lag effect, the corresponding exposure-response relationship coefficients ß of PM2.5were 0.0003600, 0.0005001, and 0.0009237 for all-cause, cardiovascular, and respiratory premature deaths, respectively, whereas the corresponding ß of O3-8h were 0.0003103, 0.0006726, and 0.0007002, respectively. 3 If ρ(PM2.5) was reduced to the national secondary standard limit (35 µg·m-3), the corresponding number of health beneficiaries and economic benefits declined yearly. Specifically, the health beneficiary number of all-cause, cardiovascular, and respiratory disease deaths were reduced from 1128, 416, and 328 in 2016 to 229, 96, and 54 in 2020, respectively. There were a total number of 3314 avoidable premature deaths for all-cause diseases during the five years, resulting in a total health economic benefit of 7.66 billion yuan. 4 If we assume that ρ(O3-8h) was reduced to the concentration limit specified by the World Health Organization (70 µg·m-3), the corresponding number of health beneficiaries and economic benefits were increasing yearly. Specifically, the health beneficiaries' numbers of all-cause, cardiovascular, and respiratory disease deaths rose from 1919, 779, and 606 in 2016 to 2429, 1157, and 635 in 2020, respectively. The annual average growth rates of avoidable all-cause and cardiovascular mortality were 6.85% and 10.72%, respectively, which was higher than the annual average rise rate of ρ(O3-8h). There were 10790 total avoidable deaths from all-cause diseases during the five years, resulting in a total health economic benefit of 26.62 billion yuan. These findings indicate that PM2.5 pollution in Chengdu had been well controlled, whereas O3 pollution had become more severe and had become another key air pollutant threatening human health. Therefore, the synchronous control of PM2.5 and ozone should be implemented in the future.

[Effects of Interaction between PM2.5 and O 3 8-h max on Mortality of Cardiovascular Diseases in Chengdu].

OBJECTIVE: To explore the health risks of the interactive effects between PM2.5 and ozone on cardiovascular mortality in Chengdu. METHODS: Daily data on the mortality of cardiovascular diseases, including data for both men and women, during 2014-2016 were collected. The meteorological data, the daily average of particulate matter with aerodynamic diameter less than 2.5 micrometers (PM2.5), and the daily ozone 8 h maximum concentration (O 3 8-h max) in Chengdu of the same period were also collected. Generalized Additive Models (GAMs) were adopted to explore the respective adverse health effects of PM2.5 and O 3 8-h max and the synergistic effects between PM2.5 and O 3 8-h max on the mortality of cardiovascular diseases in the city. RESULTS: The highest health risks of PM2.5 and O 3 8-h max for mortality of cardiovascular diseases were found to be the strongest for the cumulative effect of the lag of one day (lag01). For every 10 µg/m 3 increment in the mass concentration of PM2.5 (lag01), the associated increase in risks for total, male, and female cardiovascular mortalities was 0.35%, 0.26% and 0.38%, respectively. For every 10 µg/m 3 increment in the mass concentration of O 3 8-h max (lag01), the associated increase in risks for total, male, and female cardiovascular mortalities was 0.66%, 0.43%, and 1.05%, respectively. The total, male, and female cardiovascular mortalities all reached their maximum values when high concentration of PM2.5 coexisted with high concentrations of O 3 8-h max. CONCLUSION: There was a synergistic amplification effect between high concentrations of PM2.5 and high concentrations of O 3 8-h max on cardiovascular mortality.

Workload influence on fatigue related psychological and physiological performance changes of aviators.

OBJECTIVE: We evaluated a variety of non-invasive physiological technologies and a series of test approaches for examination of aviator performances under conditions of mental workload in order to provide a standard real-time test for physiological and psychological pilot fatigue assessments. METHODS: Twenty-one male aviators were selected for a simulated flight in a hypobaric cabin with artificial altitude conditions of 2400 meter above sea level. The simulated flight lasted for 1.5 h, and was repeated for two times with an intervening 0.5 h rest period outside the hypobaric cabin. Subjective criteria (a fatigue assessment instrument [FAI]) and objective criteria (a standing-position balance test as well as a critical flicker fusion frequency (CFF) test) were used for fatigue evaluations. RESULTS: No significant change was observed in the FAI scores before and after the simulated flight, indicating that there was no subjective fatigue feeling among the participants. However, significant differences were observed in the standing-position balance and CFF tests among the subjects, suggesting that psychophysiological indexes can reflect mental changes caused by workload to a certain extent. The CFF test was the simplest and clearly indicated the occurrence of workload influences on pilot performances after a simulated flight. CONCLUSIONS: Results showed that the CFF test was the easiest way to detect workload caused mental changes after a simulated flight in a hypobaric cabin and reflected the psychophysiological state of aviators. We suggest that this test might be used as an effective routine method for evaluating the workload influences on mental conditions of aviators.

Effects of sleep deprivation on human postural control, subjective fatigue assessment and psychomotor performance.

This study aimed to investigate the effects of sleep deprivation on postural control, subjective fatigue assessment and psychomotor performance, and to assess the efficiency of an objective posturographic test as an indicator of mental fatigue. Postural sway using static posturography (Romberg's test), subjective fatigue assessment (Stanford Sleepiness Scale) and psychomotor performance (Sternberg dual-task test) were assessed in 12 subjects before and after 24 h of sustained wakefulness. After sustained wakefulness, the Romberg test parameters of circumference area and rectangle area with the eyes-closed, and standard deviation in the anterior-posterior direction with the eyes-open were significantly higher compared with baseline values (before sustained wakefulness). Subjective fatigue assessment scores were also significantly increased, while psychomotor performance was unchanged. Sleep deprivation can arouse a feeling of fatigue and can affect postural stability, hence an objective posturographic test score may be useful as an indicator of mental fatigue.

Cerebral hemodynamics and brain functional activity during lower body negative pressure.

INTRODUCTION: Exposure to high +Gz acceleration forces on a centrifuge or in an aircraft can severely decrease cerebral blood perfusion and cause rapid G-induced loss of consciousness. However, milder acceleration may gradually reduce cerebral blood flow and affect cognitive function in subtler ways. This study used lower body negative pressure (LBNP) to mimic +Gz circulatory effects in order to study cerebral hemodynamics and brain function. METHODS: Subjects were 15 healthy men, 19-21 yr of age. They were exposed to LBNP at two levels for 5 min each separated by a 10-min recovery period. The conditions were low (LO), -4.00 kPa (-30 mmHg) and high (HI), -6.67 kPa (-50 mmHg).Variables measured before, during, and after LBNP included cerebral blood flow velocity (CBFV) in the middle cerebral artery, blood oxygen saturation (SaO2), heart rate (HR), blood pressure, P300 of event-related EEG potentials, reaction time, and tracking error. RESULTS: LO significantly reduced CBFV at 4 and 5 min, increased HR, and decreased the amplitude of P300, but none of the other variables changed from baseline. In contrast, HI produced significant changes in most variables: CBFV decreased at 2 min and then fell further at 4 and 5 min, HR increased, and SaO2 decreased. Significant neurocognitive changes included increased latency and reduced amplitude of P300, slower reaction time, and greater tracking error. CONCLUSION: The higher level of LBNP used here reduced cerebral perfusion sufficiently to impair neurocognitive function. This model may be useful for further studies of these and other variables under closely controlled conditions.