Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale
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Comparative Study
Corticomotor facilitation associated with observation, imagery and imitation of hand actions: a comparative study in young and old adults.
In the present report, we extent our previous findings (Clark et al. in Neuropsychologia 42:105-122, 2004) on corticomotor facilitation associated with covert (observation and imagery) and overt execution (action imitation) of hand actions to better delineate the selectivity of the effect in the context of an object-oriented action. A second aim was to examine whether the pattern of facilitation would be affected by age. Corticomotor facilitation was determined in two groups of participants (young n = 21, 24 +/- 2 years; old n = 19, 62 +/- 6 years) by monitoring changes in the amplitude and latency of motor evoked potentials (MEPs) elicited in hand muscles by transcranial magnetic stimulation. ⋯ Taken together, these results further corroborate the notion that the corticomotor system is selectively active when actions are covertly executed through internal simulation triggered by observation or by motor imagery, as proposed by Jeannerod (Neuroimage 14:S103-S109, 2001). With aging, the ability to produce corticomotor facilitation in association with covert action execution appears to be largely preserved, although there seems to be a loss in selectivity. This lack of selectivity may, in turn, reflect age-related alterations in the function of the corticospinal system, which may impair the ability to individuate finger movements either in the covert or overt stage of action execution.