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.

Keywords

cognitive training / EEG / HD-tDCS / mental rotation / microgravity / working memory

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