UCSF

Parkinson’s disease is a highly prevalent, neurodegenerative movement disorder. Gait disturbances and postural instability, symptoms that produce the highest incidence of morbidity in individuals with PD, respond poorly to dopaminergic treatment. Further, the neural correlates underlying these disabilities are currently uncharacterized. It is essential to understand the non-dopaminergic pathways that break down in patients with PD, in order to develop a neuroprotective treatment for PD.

The TUG task is a clinical marker for PD. It integrates several motor components including gait speed, initiation of movement, and turning. In this study, an fMRI paradigm was developed in order to quantitatively evaluate neural correlates related to PD motor dysfunction, which could be directly compared to performance on the TUG task. fMRI brain activation patterns of the patient imagining themselves walking, imagining themselves turning in 360-degree circles and resting were compared in 11 patients with PD and in 11 age-matched controls. Motor performance on three physical tests - the TUG task, the ten-meter walk test and the timed 360-degree turn were also recorded. These motor metric results are correlated with fMRI activation strengths.

This study concluded that a neural correlate of the TUG task exists in blood oxygen level dependent, BOLD signal change in the premotor and primary motor area when imagining-turning compared to imagining-walking. When comparing patients with PD and controls, there were no detectable differences between the outcomes on the physical tasks, the TUG, 10-meter walk, or a 360-degree turn. Cortical activation in the SMA was localized in all subjects during motor imagery tasks. There were no significant differences between patients with PD and healthy controls relative to SMA ROI activation. However, individuals with PD had a significant increase in lateral occipital lobe activation when imagining-turning compared to imagining-walking. Assessing the relationship between postural instability and the corresponding functional brain areas has the potential to increase our understanding of the breakdown of motor control in patients with PD.