Motor resonance in Parkinson's disease:Effects of observed actions on behaviour

Poliakoff, E. and Bek, J. and Vogt, S. and Crawford, T. and Gowen, E. (2017) Motor resonance in Parkinson's disease:Effects of observed actions on behaviour. Movement Disorders, 32 (6). ISSN 0885-3185

Abstract

Objective: To investigate whether people with Parkinson's disease (PD) exhibit motor resonance from observed human actions. Background: Seeing another person move can influence one's own movements, a process which is relevant for both learning and social interaction. This motor resonance can be measured in the laboratory using visuomotor priming; the participant's movement (e.g. finger press) is influenced by whether the observed movement is compatible (e.g. downward finger movement) or incompatible (e.g. upward finger movement). Visuomotor priming in PD has been examined in two previous studies, but imitative compatibility effects (specific to human movement) have not been separated from stimulus-response compatibility effects (general directional movement). Methods: 23 participants with mild to moderate PD (63.5 ± 6.5 years; Hoehn & Yahr stage 2.0 ± .71) and 24 healthy older adults (68.3 ± 5.4 years) completed a visuomotor priming task. Participants pressed a key with their left hand when they saw a go-signal preceded by a task-irrelevant compatible or incompatible moving finger or non-biological shape (rectangle). By rotating the observed movement such that a downward finger/shape movement moved rightward on the screen, imitative compatibility was pitted against general directional stimulus-response compatibility (Gowen et al. 2016). Results: Both groups demonstrated imitative compatibility effects from the observed finger movement and there were no between group differences. However, response times in the incompatible movement condition positivity correlated with disease severity (UPDRS motor scale) in the PD group. Conclusions: Both people with PD and healthy older people demonstrated imitative compatibility, showing intact motor resonance that cannot be attributed to general stimulus-response compatibility effects. This is particularly relevant for the use of action observation as a therapy to facilitate movement. The findings also have implications for understanding social cognitive difficulties in PD; in particular the correlation suggests that imitative control might decline with disease progression. Previously presented at the British Neuropsychological Society Meeting (October 2016).