1.Effects of a 15-days complete fast on dual cognitive control functioning—Evidence from an ERPs
Chao WANG ; Haibo QIN ; Ziqing CAO ; Liping TIAN ; Yuan JIANG ; Zhongquan DAI ; Lizhong CHI ; Bin WU
Space Medicine & Medical Engineering 2024;35(4):209-215,221
Objective In the future,during the landing and exploration of near-Earth planets(e.g.,Mars,Jupiter,etc.),astronauts may take the initiative to start fasting to reduce the amount of load;and it is even more likely that astronauts will take the initiative to fast in the process of manned deep-space exploration in the future,or they may enter a dormant low-metabolism state to save the amount of load to enable the spaceship to fly for a longer period,and to locate in a deeper and farther position.The ability of an individual to maintain cognitive ability and respond appropriately over a period in a long-term fasting state is important for survival.Therefore,the present study focused on investigating the effects of 15 days of complete fasting on dual cognitive control function and its neural mechanisms.Methods Twenty-four healthy volunteers were recruited to participate in the fasting experiment.Behavioral and electroencephalographic data from the AX-CPT Task were collected with event-related potentials(ERP)to assess the effects of 15 days of complete fasting on dual cognitive control in 16 volunteers.Results(1)Behavioral outcomes had significant main effects on response time[F(1,15)=99.41,P?0.001,η2p=0.87]and error rate[F(1,15)=7.75,P=0.014,η2p=0.34],and BX trials were significantly lower than AY trials for both response time and error rate.(2)EEG results were significant for a cue type main effect on P3b[F(1,15)=16.43,P=0.001,η2p=0.52],with cue B inducing a more positive wave amplitude than cue A,and a cue type main effect on CNV[F(1,15)=10.72,P=0.005,η2p=0.42],with cue A evoking a more negative amplitude than cue B,and a significant main effect of trial type on N2[F(1,15)=6.90,P=0.019,η2p=0.32],with BX trials inducing more negative wave amplitudes than AY trials.All these results suggest that volunteers tend to use proactive control processing.Conclusion The 15-days complete fasting experiment did not significantly affect the dual cognitive control function of the volunteers,suggesting that the volunteers also had sufficient cognitive resources to perform cognitive control during the 15-days complete fasting state.This helps to understand further the relationship between long-term fasting and the processing mode of dual cognitive control and provides theoretical support and reference basis for the survival and work of astronauts actively fasting during the future near-Earth planet landing or even deep space exploration.
2.Photoplethysmography Pulse Wave Signal Detection and Pulse Rate Characteristics Based on an in vitro Experiment
Weijun HE ; Yongtao LIU ; Dengji LIU ; Kai YIN ; Ying HE ; Qingzhuo CHI ; Lizhong MU
Journal of Medical Biomechanics 2024;39(4):712-717
Objective To investigate the influence of changes in blood flow parameters on pulse rate characteristics by taking the advantage of controllable parameters in an experimental cardiopulmonary bypass system.Methods A set of human circulatory system equipped with an in vitro wrist model was established.By changing parameters such as the heart rate,wrist flow,pressure,and system compliance,a photoplethysmography pulse wave signal was obtained from the wrist model,and the time-and frequency-domain indices of pulse rate variability were extracted.Results Changes in heart rate,pressure,and system compliance caused a change in pulse shape,but the time domain indices NN50 and PNN50,which indicate pulse rate variability,were zero,and the other indices and frequency domain indices were in the very low value category.Conclusions In the absence of heart rate variability,hemodynamic changes in heart rate,wrist flow,blood pressure,and system compliance did not produce significant pulse rate variability.This study can provide a reference for studies on pulse rate variability and heart rate using more convenient wrist acquisition equipment.
3.Effects of Coating Method on Fabrication Quality of Flexible Silicone Blood Vessels
Kai YIN ; Zhen CAO ; Qingzhuo CHI ; Mingliang WANG ; Lizhong MU ; Ying HE
Journal of Medical Biomechanics 2023;38(1):E135-E141
Objective To investigate the effect of different coating methods on production quality of complex and flexible silicone vascular replicas. Methods Based on models of anterior communicating artery aneurysms, several patient-specific models were made by using spray-coating method and brush-spin-coating method respectively, and two methods for making the same vascular structure were quantitatively compared in terms of thickness growth, circumferential uniformity and light transmittance. Results Brush-spin-coating method was better than spray-coating method in the thickness control and coating uniformity for fabrication of vessels with large curvature, variable diameter and straight tube, and the model had preferably light transmittance and surface smoothness. The relative deviation of thickness by brush-spin-coating method was decreased by 8. 9% , 10. 8% and 16. 9% respectively compared with spray-coating method. Conclusions At present stage, the brush-spin coating method has the advantage of thickness uniformity and light transmittance over the spray-coating method in making silicone phantoms, and it has promising application prospects in fluid mechanics field of in vitro experiment on large vessels.