Cognitive resilience in microgravity: Synergy of mental rotation training and high‐definition transcranial direct current stimulation

Abstract Microgravity significantly challenges cognitive functions, especially spatial tasks, making effective countermeasures essential. Cognitive training improves cognitive performance, and high‐definition transcranial direct current stimulation (HD‐tDCS), a non‐invasive neurostimulation, also improves cognition. However, their effects under microgravity remain unclear. This study investigates whether mental rotation (MR) training alone or combined with parietal HD‐tDCS enhances MR and working memory (WM) under microgravity. Using a single‐blind between‐subjects design, participants were assigned to a no‐treatment control group, a cognitive training group that received MR training, and a CT + tDCS group that received MR training combined with HD‐tDCS. Participants performed MR and WM tasks before, during, and after 15‐day head‐down bed rest (HDBR) with behavioral and EEG recording. Microgravity exposure induced reversible behavioral declines and long‐term negative neurophysiological effects on MR. Both MR training alone and combined with HD‐tDCS effectively countered cognitive damage and exhibited lasting effects. HD‐tDCS further enhanced the MR training benefits, improving neural efficiency. Both interventions enhanced WM and promoted re‐adaptation after microgravity. Furthermore, the combined intervention increased WM resistance to interference. These results support that MR training, especially with HD‐tDCS, effectively counter microgravity‐induced cognitive damage, and further support non‐invasive neurostimulation as a method to enhance cognitive functions and optimize training protocols under microgravity.