부산대학교 도서관

ABSTRACT: The basal ganglia are involved in the preferential selection and suppression of competing responses. Parkinsonʼs disease and Huntingtonʼs disease are 2 prototypical basal ganglia disorders that feature impaired inhibitory control, a function of poor conflict resolution. Previous saccadic studies showed that individuals with Parkinsonʼs disease experience difficulty suppressing unwanted ocular motor responses, whereas evidence for a similar difficulty in Huntingtonʼs disease is more equivocal. Relative to saccades, few research studies have examined inhibitory control processes in the context of an ongoing smooth pursuit task. In this study, we examined the ability of 16 patients with Parkinsonʼs disease and 12 patients with Huntingtonʼs disease to suppress automatic responses to irrelevant distracters that transiently appeared during the tracking of a moving visual stimulus. Compared with an equivalent number of age-matched controls, patients with Parkinsonʼs disease generated proportionately more saccades to distracter stimuli. This was particularly evident for distracters appearing far away from the target. Conversely, whereas individuals with early-stage Huntingtonʼs disease and healthy controls made a comparable number of errors toward distracter stimuli, those in a more advanced clinical stage demonstrated significantly poorer inhibitory control. The current findings in parkinsonian patients replicate those previously reported in the saccadic and manual response literature, demonstrating difficulty inhibiting a competing motor response. However, in Huntingtonʼs disease we demonstrate for the first time that inhibitory control declines in more advanced-disease stages. This suggests that ocular motility may provide a sensitive marker of clinical disease progression in Huntingtonʼs disease. © 2011 Movement Disorder Society