Analysis of vertical displacements of the center of gravity in the cat during limb flexion induced by cortical stimulation.

A limb movement and the associated postural adjustment result in a displacement of the center of gravity of the body. The vertical component of this displacement has been calculated from the variations in the sum of vertical forces at each limb. Through these variations, it is possible to measure the vertical acceleration of the center of gravity. Velocity and displacement are then obtained by two successive integrations of acceleration values. The magnitude of displacement of the center of gravity depends on the magnitude of limb displacement, and hindlimb flexion induces larger displacement than forelimb flexion. It is also directly linked to the time course of the vertical force variations recorded at each limb. The feed-forward character of the postural adjustment appears to minimize this amplitude, which leads us to discuss the functional significance of this postural adjustment.