Objective: To explore the effect induced by the observation of a grasping movement, inserted in different emotional contexts, on cortico-spinal excitability, in healthy people and in patients with Parkinson’s disease, with and without freezing of gait (FOG).

Background: The activation of the “mirror neuron system”, that serves for action comprehension and prediction, requires a high level codification triggered not only by components of motor behavior, but also by the environment where the action is embedded. In healthy subjects, cortical excitability increases when subjects observe a grasping movement inserted in a disgusting context, compared to a sad or a neutral context. Parkinson’s disease (PD) causes deficits in the motor system due to dysfunctions in basal ganglia circuitry and nigro-striatal pathways. The dysfunction affects not only motor phenomena, but involves non-motor features, such as cognition and emotions. The hypothesis is that the dynamic balance of dopaminergic stimulation exerted via these competing, yet complementary, pathways (motor, cognitive and limbic loops) is central in determining behavioural outcomes, like the phenomenon of FOG.

Method: 23 PD patients and 24 healthy age-matched controls were recruited. Cortico-spinal excitability was recorded by means of transcranial magnetic stimulation while participants were watching the same grasping movement embedded in contexts eliciting disgust, sadness and a neutral context.

Results: In healthy subjects a greater increase of cortical excitability was present only during the observation of the hand moving in a digusting context, with respect to a context eliciting sadness (p= 0.003) or a neutral one (p=0.001). Regarding subjects with Parkinson’s disease, an increase in cortical excitability emerged only in patients without FOG and only during the observation of the video in the sadness context, compared to baseline (landscape video) (p= 0.044). For the other videos and in patients with FOG no differences emerged, meaning that changes in motor resonance were not observed.

Conclusion: In patients with FOG, neural impairment is more widespread and circuits involved in emotion recognition and their connection with motor system are so impaired that nor simple action observation neither emotional contexts are able to induce any kind of motor resonance.

« Back to MDS Virtual Congress 2021

MDS Abstracts - https://www.mdsabstracts.org/abstract/does-the-observation-of-an-action-inserted-in-an-emotion-enriched-context-influence-cortical-excitability-in-patients-with-parkinsons-disease/