COORDINATION OF POSTURE AND ARM MOVEMENTS

DESCRIPTION The long-term goal
of this application is to determine how the nervous system coordinates
posture with arm movements. When man moves and interacts with the
environment, the reaction forces that the environment exerts back on the
body must be accommodated. These forces can change the posture of the
body and, consequently, alter the accuracy of the movements. When
movements themselves (and their possible interaction with the
environment) are about to be executed, the nervous system acts to
anticipate these reaction forces by contracting related postural muscles
prior to contracting the muscles that will actually carry out the
intended specific action. This postural activity has been termed
"anticipatory postural adjustments", and it is essential for carrying out
many normal, everyday movements. The investigators propose to carry out three sets of experiments to
develop a better understanding of how the nervous system controls the
posture of the body while it simultaneously moves the arm. Each set of
experiments addresses a specific aim: (1) To examine how kinesthetic
input is used to determine how long to wait after anticipatory postural
activity begins to trigger arm movements in an unfamiliar mechanical
environment. This will involve subjects who are neurologically intact
and subjects with multiple sclerosis. (2) To determine how the nervous
system learns to coordinate posture and arm movements in an unfamiliar
mechanical environment. This will involve only neurologically intact
subjects. (3) To examine how the nervous system organizes muscle
activity during targeted, and presumably purposeful, arm movements (only
normal subjects will participate). It is claimed that these experiments
will not only shed light on relatively unexplored areas of movement
control, but may also lead to better treatment of some motor disorders,
controlling limb prostheses, as well as moving accurately in the
microgravity of outer space.