Comparison Of Learning Processes For Arm Pointing Movements Using Physical And Mental Practise

Introduction
Up to now, few experiments ([1],[2],[3]) have investigated how humans learn motor tasks using mental practise. Thus,
little information is available concerning motor learning, especially the learning process, after mental practice. The
purpose of this study is to examine and analyse the motor learning processes by comparing physical and mental
training.

Methods
Thirty subjects had to point towards twelve targets as accurately and fast as possible according to a given order. The
movement durations needed to accomplish the task was recorded before, after and during a training period involving
three groups: the first group of subjects was physically trained, the second group was mentally trained (no overt
movement), and a third group did not perform any training (control group). The differences (i.e.the gain) between the
movement durations recorded before and after the training period was calculated, in addition, for the learning period,
the average duration and the best fitting were computed.

Results
The results showed a gain in duration for both the physical and mental training groups (Graph.1), whereas the control
group did not enhance his performance. However, even if both types of training (physical and mental) increased the
motor performance, the improvement was greater for the physical group than for the mental group. The learning curves
showed two different shapes (Graph.2). The best adjustment was obtained for exponential and linear fitting for the
group trained using physical and mental learning, respectively.

Discussion/conclusion
In agreement with others authors ([1],[2],[3]), it appears that mental practise improves the performance but not so
greatly as the physical one. What was novel in our study was that the shapes of the learning curves were differents:
exponential and linear for the physical group and the mental group, respectively. A possible explanation for this
difference in motor learning could be, that during mental practise, no movements are produced and no peripheral
feedbacks are available since the neural command is prepared but blocked. Conversely, during the physical practise, the
presence of peripheral feedbacks (visual and proprioceptive) allows the comparison between the desired movement and
that actually performed. Thus, the absence of peripheral feedbacks during mental training does not permit to take into
account the performance from previous trials since movement does not occur, and therefore it conduces to a partial
improvement of the performance ([4],[5]).

References
[1]. Lafleur MF et al.(2001), Neuroimage, 16, 142-157.
[2]. Yagüez L et al. (1998), Behavioural Brain Research, 102, 115-127.
[3]. Yue G & Cole KJ (1992), Journal of Neurophysiology,1114-1123.
[4]. Papaxanthis C et al.(2002), Experimental Brain Research, 143(4), 447-52.
[5]. Papaxanthis C et al.(2002), Behavioural Brain Research, 134(1-2), 209-215.

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