Visuo-motor learning with combination of different rates of motor imagery and physical practice.
Imagery Rehearsal Found Critical in Motor Rehab for Stroke, Better than Physical Practice Alone
Researchers from the University of Lyon in Bron Cedex, France tested whether "mental rehearsal" (motor imagery) is equivalent to physical learning in restoring motor function in hemiplegic patients (paralyzed on one side), and examined what would be optimal proportions of real execution vs. rehearsal.
Subjects were asked to grasp an object and insert it into an adapted slot. One group (G0) practiced the task only by physical execution (240 trials); three groups imagined performing the task in different rates of trials (25%, G25; 50%, G50; 75%, G75), and physically executed movements for the remaining trials; a fourth, control group imagined a visual rotation task in 75% of the trials and then performed the same motor task as the other groups.Movement time (MT) was compared for the first and last physical trials, together with other key trials, across groups. The study found that all groups learned, suggesting that mental rehearsal is equivalent to physical motor learning.
More importantly, when subjects rehearsed the task for large numbers of trials (G50 and G75), the movement time of the first executed trial was significantly shorter than the first executed trial in the physical group (G0), indicating that mental practice is better than no practice at all.
Comparison of the first executed trial in G25, G50 and G75 with the corresponding trials in G0 (61, 121 and 181 trials), showed equivalence between mental and physical practice. At the end of training, the performance was much better with high rates of mental practice (G50/G75) compared to physical practice alone (G0), especially when the task was difficult.
These findings confirm that mental rehearsal can be beneficial for motor learning and suggest that imagery might be used to supplement or partly replace physical practice in clinical rehabilitation.
Citation: Allami N, Paulignan Y, Brovelli A, Boussaoud D. Visuo-motor learning with combination of different rates of motor imagery and physical practice. Experimental Brain Research. 2008 Jan; 184 (1): pages 105-13. Epub 2007 Sep 12.