Effects of prolonged head-down bed rest on working memory

Abstract

Qing Liu,1,2 Renlai Zhou,1–4 Xin Zhao,5 Tian Po S Oei6 1Beijing Key Lab of Applied Experimental Psychology, School of Psychology, 2Research Center of Emotion Regulation, 3State Key Laboratory of Cognitive Neuroscience and Learning, International Data Group/McGovern Institute for Brain Research, Beijing Normal University, Beijing, People’s Republic of China; 4Department of Psychology, School of Social and Behavioral Science, Nanjing University, Nanjing, People’s Republic of China; 5Behavior Rehabilitation Training Research Institution, School of Psychology, Northwest Normal University, Lanzhou, People’s Republic of China; 6School of Psychology, University of Queensland, Brisbane, QLD, Australia Background: The weightlessness caused by prolonged bed rest results in changes in cerebral circulation and thus, brain functions, which is of interest. Methods: We investigated the effects of 45-day, -6° head-down bed rest, which stimulated microgravity, on working memory in 16 healthy male participants. The 2-back task was used to test the working memory variations on the 2nd day before bed rest (R-2); on the 11th (R11), 20th (R20), 32nd (R32), and 40th (R40) days of bed rest; and on the eighth day after bed rest (R+8). The cognitive response and the physiological reactivity (such as galvanic skin response, heart rate, and heart rate variability) under the 2-back task were recorded simultaneously. Results: The results showed that compared with R-2, on the R+8, the participants’ galvanic skin response increased significantly, and the high frequency of heart rate variability (HF), low frequency of heart rate variability (LF), and reaction time in the 2-back task decreased significantly. There were positive correlations between the participants’ reaction time of working memory and the LF/HF under head-down bed rest (at R11, R20, and R32). Conclusion: The results suggested that the prolonged head-down bed rest may have a detrimental effect on individual physiology and working memory. Physiology indices, such as galvanic skin response and heart rate variability, were sensitive to the prolonged bed rest. Keywords: galvanic skin response, heart rate, heart rate variability