Short term simulated microgravity models improve executive function
LE3 .A278 2022
Bachelor of Kinesiology
The purpose of the study was to determine whether executive function is altered due to variations on standard simulated microgravity head down tilt protocols. 28 healthy volunteers (19 females and 7 males; 20.00 ± 1.70 years; 165.60 ± 24.50 cm; 71.14 ± 15.89 kg; mean±SD) took part in two randomly assigned separate simulated microgravity sessions consisting of head down tilt (HDT) sessions. Each testing session lasted approximately 2.5 hours. One session consisted of the broadly used -6° HDT facing up (HDT-FU), while the other consisted of a -6° HDT facing down (HDT-FD), modification of the standard method. For each condition, the participant completed a computerized Stroop Color and Word Test during a thirty-minute horizontal position (0° tilt) prior to the interventions and again prior to the end of the 1.5-hour HDT protocols. The Stroop Color and Word test constituted of 3 tasks (60 trials per task) including a: 1) a Naming task, 2) an Inhibition task, and 3) an Inhibition/Switching task. To minimize the learning effect, both the HDT-FU and HDT-FD sessions were counterbalanced amongst all participants and were separated by a minimum of 48 hours. Our cognitive reaction time results demonstrate a main effect of time (pre HDT 777.60 ± 18.08ms vs post HDT 749.30 ± 19.11ms, p<0.01) and a main effect of Stroop test (Naming < Inhibition < Inhibition/Switching, p<0.01). Additionally, we observed that the 1.5-hour protocol selectively improved the Inhibition/Switching reaction times (the most executive component) for both the HDT-FU (pre HDT-FU 945.68 ± 32.87ms vs post HDT-FU 903.16 ± 33.78ms, p=0.02) and HDT-FD (pre HDT-FD 961.25 ± 38.55ms vs post HDT-FD 868.91 ± 30.40ms, p<0.01). When executive demand is increased under short-term simulated microgravity head down tilt conditions, regardless of the position (face up or face down), cognitive reaction time is decreased, suggesting an improvement in overall cognitive function.
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