Asymmetries between dominant and non-dominant hands in real and imagined motor task performance

Motor imagery is a dynamic state in which an individual mentally simulates the performance of a specific motor action or motor task. Recent behavioura l and neuroimaging evidence suggests that the same neurocognitive networks control real and imagined movements. This hypothesis was tested by investig ating whether motor asymmetries related to cerebral dominance also occurred for imagined movements. Fifty subjects performed the visually guided point ing task of Sirigu et al. [Sirigu, A., Duhamel, J.., Cohen, L., Pillon, B., Dubois, B. and Agid, Y., The mental representation of hand movements after parietal cortex damage. Science, 1996, 273, 1564-1567.] using their domina nt and non-dominant hands. Analysis of group data indicated that both rear and imagined movement conformed to Fitts' law. Analysis of individual data indicated that asymmetries arising from motor dominance in real movements a lso occurred for imagined movements. However, the relative slowing and erro r associated with the non-dominant hand was greater for imagined movements than for real movements. These asymmetries support the hypothesis that real and imagined movements are represented within the same neurocognitive netw orks but suggest that asymmetries in performance related to handedness are greater for imagined movements. In addition, while the visually guided poin ting task provides a useful test of the ability to make imagined movements, asymmetries in the speed and reliability of imagined performance are signi ficantly greater than those for real performance. (C) 1999 Elsevier Science Ltd. All rights reserved.