Abstract
To provide the basis and reference to further insights into the neural activity of the human brain in a microgravity environment, we discuss the amplitude changes of low-frequency brain activity fluctuations using a simulated microgravity model. Twelve male participants between 24 and 31 years old received resting-state fMRI scans in both a normal condition and after 72 hours in a −6° head down tilt (HDT). A paired sample t-test was used to test the amplitude differences of low-frequency brain activity fluctuations between these two conditions. With 72 hours in a −6° HDT, the participants showed a decreased amplitude of low-frequency fluctuations in the left thalamus compared with the normal condition (a combined threshold of P<0.005 and a minimum cluster size of 351 mm3 (13 voxels), which corresponded with the corrected threshold of P<0.05 determined by AlphaSim). Our findings indicate that a gravity change-induced redistribution of body fluid may disrupt the function of the left thalamus in the resting state, which may contribute to reduced motor control abilities and multiple executive functions in astronauts in a microgravity environment.
Highlights
Maintaining an astronaut’s performance at an optimal level is of importance to space medical and psychological researchers
The ALFF results between the normal condition and a simulated microgravity condition are shown in Fig. 1 and Table 1
Compared to the normal condition, a decreased ALFF was observed in the left thalamus in the simulated microgravity condition
Summary
Maintaining an astronaut’s performance at an optimal level is of importance to space medical and psychological researchers. Several studies indicated that planning movements and goal-directed actions, which require fine motor control, are impaired in microgravity [2,5,6,7,8,9] These degradations in behavioral and cognitive functions may cause potential risks in space exploration. Some researchers have attempted to determine how brain physiological changes contribute to a decrease in performance using new methods [14,15,16,17] The authors of these studies performed pioneering work using an electroencephalograph (EEG) to directly record the altered brain electrical activity to provide more reasonable explanations for performance degradations in microgravity. The results of this study may support the findings of previous studies and serve as a foundation for additional studies of individual altered brain activities in a microgravity environment
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