title: Abnormalities of smooth eye and head movement control in Parkinson's disease.
abstract: The control of horizontal head and eye movements was examined in 13 nondemented patients with Parkinson's disease (PD) of mild to moderate severity. During pursuit of single-frequency sine waves, smooth component eye velocity was lower in the PD group at frequencies of 1.2 Hz and above; but the differences in overall eye displacement were even greater, indicating an impaired ability to generate catch-up saccades at high frequencies. A corresponding deficit in saccadic performance was observed during a high-frequency saccadic tracking task where predictive saccades of reduced gain and variable timing were generated. During pursuit of pseudo-random target motion with varying degrees of predictability, small differences in smooth component eye velocity were observed, but prediction was otherwise well preserved in the patient group. Vestibulo-ocular reflex (VOR) suppression was also normal during head-free pursuit. No major improvement in smooth pursuit gain could be attributed to drug treatment, based on a comparison of patient results before and after administration of levodopa.
authors.affiliation: MRC Human Movement and Balance Unit, Institute of Neurology, Queen Square, London, UK.
authors.forename: J A
authors.initials: JA
authors.lastname: Waterston
authors.forename: G R
authors.initials: GR
authors.lastname: Barnes
authors.forename: M A
authors.initials: MA
authors.lastname: Grealy
authors.forename: S
authors.initials: S
authors.lastname: Collins
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006257:Head / Q000503:physiopathology*; D006801:Humans; D007980:Levodopa / Q000494:pharmacology / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000187:drug effects*; D010300:Parkinson Disease / Q000188:drug therapy* / Q000503:physiopathology*; D011698:Pursuit, Smooth / Q000187:drug effects*; D011930:Reaction Time; D012027:Reflex, Vestibulo-Ocular / Q000187:drug effects; D012438:Saccades / Q000187:drug effects
chemical_list: D007980:Levodopa