Acquisition and consolidation processes following motor imagery practice

Abstract

It well-known that mental training improves skill performance. Here, we evaluated skill acquisition and consolidation after physical or motor imagery practice, by means of an arm pointing task requiring speed-accuracy trade-off. In the main experiment, we showed a significant enhancement of skill after both practices (72 training trials), with a better acquisition after physical practice. Interestingly, we found a positive impact of the passage of time (+ 6 h post training) on skill consolidation for the motor imagery training only, without any effect of sleep (+ 24 h post training) for none of the interventions. In a control experiment, we matched the gain in skill learning after physical training (new group) with that obtained after motor imagery training (main experiment) to evaluate skill consolidation after the same amount of learning. Skill performance in this control group deteriorated with the passage of time and sleep. In another control experiment, we increased the number of imagined trials (n = 100, new group) to compare the acquisition and consolidation processes of this group with that observed in the motor imagery group of the main experiment. We did not find significant differences between the two groups. These findings suggest that physical and motor imagery practice drive skill learning through different acquisition and consolidation processes.

Figure 1

(A) Participants’ position and location of the targets on the graphic tablet. One trial comprised 12 successive point-to-point arm movements between the targets in the following order: Ts-T1-Ts-T2-Ts-T3-Ts-T4-Ts-T5-Ts-T6-Ts. The participants, using a pencil held in their right hand, were requested to point between the targets as accurately and as fast as possible. (B) Experimental procedure. The whole protocol comprised 5 sessions: Pretest, Training, Post0h (immediately after training), Post6h (6 h after training), and Post24h (1 day after the Pretest session). In the training session of the main experiment, the Physical Training group executed 72 actual trials, the Motor Imagery Training group accomplished 72 mental trials, and the Control Training group performed 72 trials by moving only the eyes between the targets. In the first control experiment, the participants executed physical trials to obtain the same gain than the Motor Imagery Training group of the main experiment. In the second control group, the participants accomplished 100 mental trials. In the other sessions, all participants executed 4 trials.

Figure 2

Average values (+ SE) of gains (%) in error rate (A), movement duration (B), and motor skill (C) between sessions for the three groups. Stars indicate significant differences from the value zero (0). Arrows indicate significant differences between groups. PT, Physical Training; MIT, Motor Imagery Training; C, control group.

Figure 3

Average values (+ SE) of gains (%) in skill performance between the pretest and the posttest sessions. Star indicates significant differences between the control group and the two other groups (PT and MIT).

Figure 4

Control Experiment 1. Average values (+ SE) of gains (%) in motor skill between sessions. Stars indicate significant differences from the value zero (0).

Figure 5

Control Experiment 2. Average values (+ SE) of gains (%) in motor skill between sessions. Stars indicate significant differences from the value zero (0).