| Description |
Parkinson disease (PD) is a progressive neurodegenerative disorder with selective damage of dopaminergic neurons within the Basal Ganglia (BG), leading to the most clearly recognized sequelae of motor deficits observed in PD. The BG have also been shown to be important during implicit motor sequence learning (IMSL), and individuals with BG lesions have demonstrated impairment in IMSL compared to healthy age matched controls. Additionally, individuals with PD are typically prescribed dopamine replacement or agonist medications, which have been found to reduce the observed movement deficits. However, it has been observed that dopamine addition may potentially impair IMSL. The primary purpose of this paper was to describe impairments in IMSL in individuals with PD, describe a neurobiological model for the observed deficits in IMSL, and to determine the impact of dopamine addition on acquisition performance and retention learning of repeated segments during a standing implicit continuous tracking task in individuals with PD. We hypothesized that IMSL would be impaired in individuals with PD on their usual dosage of dopamine. Secondarily, the impact of age, PD, and dopamine on sequence-specific integration was assessed, and it was hypothesized that there would be a graded deficit related to age, PD, and dopamine on sequencespecific integration. Finally, the relationship of spatial and temporal parameters within sequence learning was assessed as an exploratory aim. The results of this study supported an IMSL deficit primarily related to age and secondarily related to PD, but not dopamine replacement. Additionally, individuals with PD, regardless of medication, demonstrated impaired spatial integration compared to healthy young and elder participants. The type of task performed in this study was a demanding postural task compared to the traditional IMSL paradigms using the upper extremity and task difficulty could account for the lack of observed difference during acquisition. Longer time to practice the paradigm may be required to observe improved performance. Finally, although IMSL has been observed to be impaired in individuals with PD, a better understanding of the IMSL deficit related to the impact of medication and age during a standing motor task is warranted. |
