Observation and Imagery of Action in Parkinson's

Parkinson's disease is one of the most common neurodegenerative diseases, which profoundly affects movement. Typically, a person is slower to initiate movements and the movements themselves are of smaller size. The gold standard treatment is dopaminergic medication, which can be effective, but is also associated with debilitating side-effects as the disease progresses. Some basic cues are already used to aid movement in Parkinson's: for example, audible beats or counting can be used to mark out a rhythm which can aid walking. Visual cues, such as lines marked onto the ground can help promote walking, balance and prevent freezing (inability to move) in certain situations. However, these cues do not work with all types of movements nor in all situations (visual cues for example may not be available in public). Therefore, there is a need for alternative behavioural interventions to improve movement in people with Parkinson's.

This project investigates a potential strategy to trigger movements in people with Parkinson's. This capitalises on the fact that in healthy people observing another person moving (action observation; AO) or imagining oneself move (motor imagery; MI) involves some of the same brain areas used for planning and performing one's own movements. Therefore, these processes may provide a route to trigger movement in people with Parkinson's. Furthermore, recent findings in healthy young participants show that the effect on movement is stronger when AO and MI are combined (imagining oneself performing the action that one is observing) than for either process in isolation. While it has been hypothesised that AO+MI may be effective in interventions for Parkinson's, evidence is needed. Our lab recently published the first study that showed AO+MI can be effective in increasing movement size in people with Parkinson's. It is critical to replicate this finding and to further understand the underlying processes, and whether these may be altered in Parkinson's. Previous findings indicate that people with Parkinson's may rely more on visual processing during motor imagery as a compensatory mechanism. Therefore, further investigation of this is crucial in understanding how AO+MI can be used as an effective rehabilitative strategy, as well as to explore the effect of affording (graspable) objects and environmental context.

This project will use EEG (a methodology which allows us to analyse electrical signals emitted by the brain in response to different presented stimuli) to investigate the neural effects of AO+MI, combined with behavioural measures to assess the impact of these techniques on movement execution. This methodology will also be useful to examine participants' neural changes when observing affording objects. Additionally, VR will be used to explore the effect of environmental context on the effectiveness of AO+MI: for example, observing someone pick up a saucepan could have a different impact when that person is in a kitchen compared to a garden. For this project, people with Parkinson's will be recruited and compared to healthy older adults, as well as healthy younger adults, which will allow us to explore the effect of healthy ageing as well as that of Parkinson's.
The findings will increase our understanding of how perception and action are affected in Parkinson's, as well as informing the design of interventions to facilitate movement in Parkinson's. Indeed, the findings will inform the lab's application of AO+MI into home-based training of movements and dance interventions for people with Parkinson's.