Influence of Water Immersion of Monkeys on the Activity of Posterior Parietal Cortex Structures Involved in Planning and Correcting Hand Movements in Performing a Motor Task

To assess the effect of support unloading on an intensity of neuronal activity (NA) in the areas of the posterior parietal cortex associated with planning and correction of reaching arm movements (5d, PRR, 7a, and LIP), NA of the studied areas of the cortex was recorded in two monkeys with a fixed head when performing the task of moving the cursor to a peripheral target using the joystick before and after 3-h water immersion. Fixation of the head in animals excluded the influence of changes in the vestibular entrance on the results obtained. The data obtained confirmed our assumption about the effect of support unloading on planning and correction of hand movements during the performance of the used motor task, which manifested itself in a decrease in the cursor movement accuracy and changes in the NA intensity in three PPC areas. However, in connection with the newest data on the dominance of the sensitivity of the region 7a (traditionally considered as visual) to the vestibular entrance, up to the inhibition of the visual entrance, it is much more important to conclude that it is necessary to first study various options for the interaction of the vestibular, visual and proprioceptive inputs in the areas of the cortex associated with reaching hand movements, from their convergence to the inhibition of one signal by another.