Department of Psychology, Australian National University, Canberra, Australia
Studies of movement control in non-human primates have been largely descriptive, and assessments of deficits in non-human primate models of human neurological disease mainly qualitative. While such assessments can show that animals are impaired in particular movements or motor tasks, they give no insight as to the causes or nature of the deficits. The key may be computer-aided analysis of vieotaped movement patterns, as used increasingly in human patients. In the present study, reaching movements to a small target, or to a virtual target seen through prisms (which induce reaching errors for which the animal has to compensate) were videotaped using a lateral and/or a vertical view. Single frames were captured by framegrabber, digitised and the position of the hand in successive frames recorded in screen x-y and/or x-z coordinates. Thus, trajectories of the hand during a given reach could be mapped in one or both views. Using the trajectories and spatial x-y and/or x-z coordinates, direction, velocity, accelerations and decelerations, and the nature and correction of errors could be identified, quantified, and precisely timed. Using this quantitative analysis, monkeys with lesions of the brain's motor areas differed from normal animals in both the normal and prism-affected reaching, even though qualitatively, on inspection of the video records, reaching and errors did not necessarily look different. The same computer-aided analysis has been applied to a study of determinants of normal development of reaching, and of motor control in general, in infant monkeys. As yet, the frame-by-frame plotting is not fully automated. Despite this, the preliminary results show that this method will be extremely valuable in assessing motor control and in defining motor deficits in monkeys, both in normal animals, and in non human primate models of neurological disease.