Timing and Torque Involvement in the Organisation of a Rapid Forearm Flexion

Abstract

The study was designed to determine whether the magnitude of force and the timing of force are response parameters involved in the organisation of a rapid forearm flexion to a target. The magnitude of torque and the timing of torque were manipulated independently through manipulations of the total moment of inertia and movement time, and the effect of these manipulations on premotor and motor reaction times was observed. Planned comparison analyses revealed that premotor and motor reaction times increased when a movement, which required the same magnitude of torque as in a fast movement, was performed slower. However, premotor and motor reaction times were not affected when movements were performed at the same speed, but differed with respect to the magnitude of torque required. These results indicate that a different timing requirement in the forthcoming movement is associated with a corresponding change in the amount of central processing time required. Therefore, the timing of torque appears to be a parameter of the movement that is organised in advance of movement execution. However, a change in the specification for the magnitude of torque does not affect the amount of time needed to organise the movement.

Invariant characteristics of horizontal-plane minimum-torque-change movements with one mechanical degree of freedom

“…It is necessary to recall, however, that all theorems apply exclusively to horizontal-plane movements with one mechanical DOF. We have found four studies (Baba and Marteniuk 1983;Moore and Marteniuk 1986;Nagasaki 1989;Wiegner and Wierzbicka 1992) which satisfy these requirements and which report data that are directly related to our results.…”

“…Here the results are mixed. Baba and Marteniuk (1983) find acceleration-peak locations at 33.3%-35.5% of total movement time for loaded and unloaded fast forearm flexions. These results are at variance with Theorem 6, which predicts that the first acceleration extremum of a minimum-torque-change movement must occur after less than 21.13% of total movement time.…”

“…A considerable body of experimental data about these is available (Baba and Marteniuk 1983;Cooke and Diggles 1984;Cooke et al 1989;Darling and Cooke 1987;Flament et al 1984;Moore and Marteniuk 1986;Nagasaki 1989Nagasaki , 1991Shapiro and Walter 1986;Sherwood et al 1988;Wiegner and Wierzbicka 1992). In the present context these movements are worth considering because the minimum-torque-change theory applies equally to all arm movements, regardless of the number of mechanical DOF involved.…”

Minimum Principles in Motor Control

“…Although these properties may hold for certain types of arm movements, a review of the experimental literature shows that they are not universally correct: As was mentioned above, there is evidence that the velocity profiles of slow movements are generally right-skewed (Moore 6 Marteniuk, 1986;Nagasaki, 1989), while those of extremely fast movements are left-skewed (Wiegner 6 Wierzbicka, 1992). Fast movements also tend to have ratios of peak to average velocity that significantly exceed 15Â8 (Nagasaki, 1989;Wiegner 6 Wierzbicka, 1992), and their acceleration peaks may occur significantly later than 21.13 0 of total movement duration (Baba 6 Marteniuk, 1983).…”

Force and Timing Components of the Motor Program

“…Klapp et a (1974) have found similar results in choice reaction time experiments. Both researchers (Baba and Marteniuk, 1983;Klapp and ErWin 1976) have speculated that the increase in latency as a function of increased movement duration may be related to the generation of more complex timing circuits.…”