Water Immersion as a Model of Hypogravity.

We studied the effects of hypogravity modeled by water immersion on cognitive functions and physiological parameters of monkeys. Cognitive capacities of monkeys were evaluated using computer-controlled joystick task with food reward in case of target hit. Water immersion (3 days for 3 h) affected in cognitive functions, body temperature, and blood parameters. The intensity of changes depended on the type of monkey behavior. In animals with non-aggressive behavior, the number of target hits did not decrease after water immersion, and even slightly increased. On the contrary, aggressive monkeys showed poorer test performance. Body temperature after each cycle of water immersion was decreased slightly in non-aggressive monkeys, while in aggressive animals, the changes were significant. At the same time, changes in the erythrocyte count, hemoglobin concentration, and hematocrit were significant in non-aggressive monkeys. Our results are in line with previous data performed on BION biosatellites and correspond to changes of physiological parameters in astronauts during space flights.