Observation and imitation of object-directed hand movements in Parkinson’s disease

Bek, Judith and Gowen, Emma and Vogt, Stefan and Crawford, Trevor and Poliakoff, Ellen (2023) Observation and imitation of object-directed hand movements in Parkinson’s disease. Scientific Reports. ISSN 2045-2322 (In Press)

Text (Object directed imitation PD Bek et al accepted 13_09_23 manuscript)
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Abstract

Action observation and imitation may facilitate movement in Parkinson’s disease (PD). People with PD have been found to imitate intransitive actions similarly to neurologically healthy older adults, but their imitation of object-directed hand movements has not been investigated using kinematic measures. The present study examined observation and imitation of object-directed hand movements in 18 participants with PD compared to 21 neurologically healthy age-matched control participants. Participants observed and immediately imitated sequences showing a human hand reaching for and transferring an object between horizontal positions. Both groups significantly modulated the vertical amplitude of their finger movements, showing higher movements when imitating elevated compared to direct trajectories. Movements were lower in vertical amplitude and higher in velocity when imitating the reaching segment than the transfer segment. Eye-tracking revealed that controls made smaller saccades when observing predictable than unpredictable elevated movements, but no effects of predictability on eye movements were found for the PD group. This study provides quantitative evidence that people with mild to moderate PD can imitate object-directed hand movement kinematics, although their prediction of such movements may be reduced. These findings suggest that interventions targeting object-directed actions may capitalize on the ability of people with PD to imitate movement kinematics.