Neuroscience:Models of Visuomotor Coordination in Frog and Monkey

Neuroscience: Models of Visuomotor Coordination in Frog and Monkey

The escape direction in response to the approach of a large moving object may be briefly characterized as a compromise between the forward direction of the animal and the direction immediately away from the looming stimulus. Barriers can modify avoidance behavior, just as they modify approach behavior. If a barrier is interposed to block the preferred direction of escape for a stimulus coming from a particular direction, then the behavior of the animal changes and it tends to jump just to the left or just to the right of the barrier. When a limb moves, it needs a burst of agonist contraction to accelerate the limb in the desired direction, followed by an appropriately timed antagonist burst to decelerate it to rest at the desired position (with a possible small agonist correction thereafter). A new resting level of muscle contraction holds the limb in its new position. By contrast, the eye has little inertia and therefore, no antagonist burst is required; the eye has no changing load to require feedback.