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R G Marteniuk

Publications and source records attributed to R G Marteniuk.

12 recordsLinked to original sources

A sensorimotor basis for motor learning: evidence indicating specificity of practice.

Our previous work (Proteau, Marteniuk, Girouard, & Dugas, 1987) was concerned with determining whether with relatively extensive practice on a movement aiming task, as the skill theoretically starts becoming open-loop, there would be evidence for a decreasing emphasis on visual feedback for motor control. We eliminated vision of the moving limb after moderate and extensive practice and found that the movement became more dependent on this feedback with greater amounts of practice. In the present study, we wished to test the hypothesis, developed from our previous work, that at the base of movement learning is a sensorimotor representation that consists of integrated information from central processes and sensory feedback derived from previous experiences on the movement task. A strong test of this hypothesis would be the prediction that for an aiming task, the addition of vision, after moderate and relatively extensive practice without vision, would lead to an increasingly large movement decrement, relative to appropriate controls. We found good support for this prediction. From these and our previous results, and the idea of the sensorimotor representation underlying learning, we develop the idea that learning is specific to the conditions that prevail during skill acquisition. This has implications for the ideas of the generalized motor program and schema theory.

Feedback

Strategy and learning effects on perturbed movements: an electromyographic and kinematic study.

The effects of practice and movement strategy were studied in a goal-directed movement with different levels of perturbation applied in four independent groups (0%, 20%, 50% or 100%). The phase-plane trajectory data revealed that for all subjects there was a decrease in the mean trajectory variability with learning and that variability was affected by the level of uncertainty confronting the subjects. Both the average electromyographic (EMG) profiles and the mean subject variability for agonist and antagonist muscles decreased with learning. In each experimental group a specific interaction developed between reflex responses and voluntary activity to create a balanced level of EMG activity to improve the performance with learning.

Adult

How many strides are required for the analysis of electromyographic data in gait?

This study was conducted to obtain information on the number of strides of EMG data needed per subject in a gait study. Ten strides of EMG data were cumulated on eight subjects for each of the soleus, rectus femoris, biceps femoris, vastus medialis and tibialis anterior muscles. The linear envelope of the EMG, normalized in time and amplitude, demonstrated a very high level of stability for a given subject, relative to the variability that was found across subjects. It was concluded that three strides of EMG data per subject provides information as reliable as that obtained from twelve strides.

Adult

Bilateralism of EMG profiles in human locomotion.

In gait studies, minor importance has been generally given to the aspect of symmetry. Consequently, an unstated assumption has been that the right and left legs present symmetrical outcomes. The purpose of the present study was to verify this assumption throughout the use of electromyographic (EMG) profiles of activity from the two legs during gait. Eight subjects participated in the study. Two muscles, the soleus and rectus femoris, were recorded from both legs using surface electrodes. Foot switches placed under each heel served to indicate the gait cycles (N = 10) that were recorded per subject. The EMG signal was transformed into a linear envelope through full-wave rectification and filtering using second order low-pass filters (6 Hz). These envelopes were transformed in amplitude in percent of a maximum voluntary contraction (% MVC). These were digitized (50 Hz) and the sample points used to perform regression analyses contrasting left and right (homologus) muscles. Coefficients of correlation between the EMG linear envelopes of the homologous muscles showed high correlations and thus nearly identical shape. However important differences in EMG amplitude between the legs were found. Implications of these findings for future research in gait are discussed.

Adult