Repetitive Arm Movements Research Articles

Reinforced drawing in Macaca mulatta

Two male Macaca mulatta were trained with food reinforcement to make marks with a crayon on an opaque plastic surface. Both subjects used repetitive arm movements in their drawing. One monkey produced fanlike patterns which have also appeared in the drawings of other primate species, including humans. It is suggested that the forms produced by reinforced drawing are similar to those found in the non-reinforced artwork of other primates and that the development of all primate art may be dependent on simple mechanical arm movements.

Influence of direction on the rapidity of bilateral arm movements

An experimental study of the influence of direction on the rapidity of repetitive bilateral arm movements was undertaken in 20 healthy right-handed subjects. The test situation required the subjects to tap alternately with a metal stylus held in each hand. The results confirm previous observations indicating that repetitive movements of the right arm are faster than those of the left. They also show that the direction in which the movements are made influences the rapidity of performance with the left but not with the right arm, left arm movements being faster in the antero-posterior than in the latero-medial plane. The findings further reveal that bilateral movements performed with the two arms together are significantly slower than the same movements performed by either arm alone, the extent of this slowing depending upon the direction in which the bilateral movements are made. Thus, the reduction in the rapidity of movement is least with identical antero-posterior movements, followed by latero-medial movements directed towards and away from the midline of the body. Left-right latero-medial movements, and alternating antero-posterior movements, are associated with the maximum reduction in the rapidity of movement. Some theoretical interpretations of the findings are discussed.

Response of Neurones in the Motor Cortex during Performance of a Simple Repetitive Arm Movement

ANALYSIS of the firing pattern of single cells in the brains of unanaesthetized animals promises to be a useful approach towards understanding brain mechanisms involved in the control of movement. Evarts1, studying reaction time in monkeys, observed that the firing rate of some pyramidal-tract neurones changes before the electromyographic potential associated with the behavioural response. Evarts's study provided valuable data on the response latency of pyramidal tract cell discharge before a conditioned arm movement. The reaction time task with non-human subjects has the disadvantage that protracted training is necessary to establish fast and stable responses2, and relatively few behavioural responses are available each day for analysis in relation to unit activity.