Action Observation and Motor Imagery as a Treatment in Patients with Parkinson's Disease

Abstract

Action observation (AO) and motor imagery (MI) has emerged as promising tool for physiotherapy intervention in Parkinson's disease (PD). This narrative review summarizes why, how, and when applying AO and MI training in individual with PD. We report the neural underpinning of AO and MI and their effects on motor learning. We examine the characteristics and the current evidence regarding the effectiveness of physiotherapy interventions and we provide suggestions about their implementation with technologies. Neurophysiological data suggest a substantial correct activation of brain networks underlying AO and MI in people with PD, although the occurrence of compensatory mechanisms has been documented. Regarding the efficacy of training, in general evidence indicates that both these techniques improve mobility and functional activities in PD. However, these findings should be interpreted with caution due to variety of the study designs, training characteristics, and the modalities in which AO and MI were applied. Finally, results on long-term effects are still uncertain. Several elements should be considered to optimize the use of AO and MI in clinical setting, such as the selection of the task, the imagery or the video perspectives, the modalities of training. However, a comprehensive individual assessment, including motor and cognitive abilities, is essential to select which between AO and MI suite the best to each PD patients. Much unrealized potential exists for the use AO and MI training to provide personalized intervention aimed at fostering motor learning in both the clinic and home setting.

Keywords: Parkinson’s disease; action observation; mirror neuron system; motor imagery; physiotherapy; training.

Fig. 1

A) Depiction of AO and MI networks in human brain. AO task predominantly activates premotor and motor regions (Premotor cortex (PMC), supplementary motor area (SMA), pre-SMA and M1 (green)), parietal areas, (parietal lobule (PL) and intraparietal areas (purple)) and visual areas (red). MI task activates regions including PMC, SMA, pre-SMA and M1 (green), PL and intraparietal area (purple). Visual imagery shows activity in visual areas (red) and kinesthetic MI in the primary somatosensory area (orange). Additionally, the dorsolateral prefrontal cortex (DLPFC) is consistently recruited during Motor Imagery task (yellow). Both cerebellum (light blue) and basal ganglia (blue) are activated during AO and MI. B) Cartoon of consecutive and concurrent training modalities.