Résumé
Parkinson’s Disease (PD) impairs the physical execution of action sequences. As action sequences are integral to many daily activities, impaired action sequencing has significant functional implications. PD-related deficits in the processing of action representations may contribute to this impairment. One way to examine action representations is through motor imagery. This study investigated how PD affects motor imagery of sequential actions in terms of behaviour and oscillatory activity. Electroencephalographic (EEG) recordings were collected from 20 people with PD and 20 controls as they completed the Test of Ability in Movement Imagery (TAMI). The two groups did not differ in terms of age, sex, or cognitive status. EEG analysis focused on mu oscillations (8-14 Hz), as their suppression is proposed to represent activation of the sensorimotor network, and theta oscillations (3.5-7 Hz), which have been implicated in sensorimotor integration. Lower TAMI scores were observed in the PD group. While participants exhibited less mu oscillations during successful TAMI trials, the two groups did not differ in overall mu activity. The PD group exhibited more theta oscillations over the right temporo-occipital region, which may reflect increased activity in the extrastriate body area. The present findings suggest that impaired execution of action sequences in PD may stem in part from deficits related to action representations. Given the similar levels of sensorimotor network activation between groups, it is possible that this activation is less efficient in PD. This inefficiency may then lead people with PD to rely more on visual networks when imagining action sequences.
