Abstract
<title>Abstract</title> <p>As human spaceflight enters an era of prolonged missions, the fundamental question is how prolonged exposure to microgravity reshapes human cognition and its underlying neural dynamics. Here, we conducted a 60-day head-down tilt bed rest (HDBR) experiment and 26 participants were exposed to this simulated microgravity environment. We assessed short-term working memory task performance and its underlying EEG-derived intrinsic neural timescales at baseline (BDC-10), acute HDBR (HDBR-4), late HDBR (HDBR-58) and recovery (R-11). First, we found a progressive decline in accuracy and faster responses during the task across HDBR phases, which reflects the cognitive impairment of reduced perceptual discriminability rather than a speed-accuracy trade-off according to the signal detection theory. Second, we observed a transient increase in intrinsic neural timescales of EEG signals in the delta band (1–4 Hz) at HDBR-4, and a prolonged decrease in the theta band (4–8 Hz) during HDBR, but both of them recovered to baseline at R-11. Then, we found significant correlations between task behavior and delta-band neural timescales, and revealed that the spatial organization of brain-behavior mapping was changed by HDBR, but recovered after HDBR. Finally, we constructed a Jansen–Rit model to study the phase-dependent shift of neural timescales, and found an increase in the ratio of excitatory to inhibitory rate constants at HDBR-4, and a decrease in the ratio of excitatory to inhibitory gain constants during HDBR. These findings suggest that the coordinated alterations in band-limited neural timescales underlie the phase-dependent changes in working memory performance during simulated microgravity and may reflect adaptive reorganizations of cortical excitatory/inhibitory balance.</p>