Control Of Rapid Movements Research Articles

Manual Asymmetries in Reaching Movement Control. I: Study of Right-Handers

Two experiments investigated manual asymmetries in the control of rapid reaching movements according to the movement parameters to be controlled. Single- and double-step reaching movements were performed by right-handed subjects with both hands. Pro and retroactive processes involved in rapid movement control were investigated. Manual performances and kinematic properties of hand movements showed that various forms of hemispheric specialization were involved in sensori-motor information processing. It was shown that the effects of hemispheric specialization were specific to the task constraints, that is, to the various operations involved in movement control.

Manual Asymmetries in Reaching Movement Control. II: Study of Left-Handers

Two experiments performed with left-handed subjects investigated how the manual asymmetries and hemispheric specialization involved in visuo-manual coordination are associated with handedness. Pro and retroactive processes involved in rapid movement control were analyzed according to the different movement parameters to be controlled, similar to studies performed with right-handers (Boulinguez, Nougier and Velay, 2001). Manual performances and kinematic properties of reaching movements showed that the left and right hands of left-handers behaved in the same way as the left and right hands of right-handers. Results are discussed in the light of the independence of handedness and other forms of cerebral dominance in sensori-motor information processing involved in hand movements.

EMG area scaling and velocity modulations in a spatiotemporally constrained movement

Research examining the electromyographic (EMG) burst structure of rapid discrete limb movements has led to discordant findings concerning agonist burst duration. Some research has shown that duration varies as a function of movement speed while other research has shown burst constancy. Unfortunately, much of this research may be confounded by not carefully controlling movement termination accuracy and movement time (MT). Due to these potential problems, the present study was conducted to determine the effects of strict spatiotemporal constraints on EMG characteristics of a rapid elbow flexion-extension response under two movement extent conditions across five different MTs. Results revealed that a decreased MT was accompanied by a decreased agonist (biceps) burst duration and increased agonist burst amplitude. The burst duration and amplitude both increased as the movement extent increased with MT held constant. None of three current theoretical perspectives of rapid movement control (the impulse-timing model, the speed-control system hypothesis, or the speed-sensitive strategy) could fully account for these results. Instead, a control strategy was exhibited in which moving faster was accomplished by relative scaling of burst area via concomitant expansion of burst amplitude and compression of burst duration.

The responses of trochanteral hair plate sensilla in the cockroach to periodic and random displacements

Two types of sensillum have previously been described in the trochanteral hair plate of the cockroach with differences in physical size, extracellularly recorded impulse amplitude and response to displacement. We have now examined the dynamic behaviour of the two types of sesillum in response to sinusoidal and random displacements. Type I sensilla have a frequency threshold of about 6 Hz, below which there is no response to sinusoidal displacement. Above the frequency threshold they behave as velocity sensors with a 90° phase lead of response over displacement and increasing response with increasing frequency. Type II sensilla have no detectable frequency threshold and behave as position sensors at low frequencies. With increasing frequency they display a phase lead over the stimulus but it nerver exceeds about 60°. Random stimulation followed by spectral analysis of the input-output relations give similar descriptions to the sinusoidal results except that low frequency position sensitivity is revealed in the Type I sensilla. The coherence function for both types of sensillum is low, indicating that the linear frequency response functions are poor approximations to the total behaviour of the sensilla. Earlier investigations of these receptors in a range of insects suggested that they are primarily involved in the control of joint positions during very slow movements. However, the present results, together with other recent work, indicates that they are also important in the control of rapid movements.