title: Do brainstem omnipause neurons terminate saccades?
abstract: Saccade-generating burst neurons (BN) are inhibited by omnipause neurons (OPN), except during saccades. OPN activity pauses before saccade onset and resumes at the saccade end. Microstimulation of OPN stops saccades in mid-flight, which shows that OPN can end saccades. However, OPN pause duration does not correlate well with saccade duration, and saccades are normometric after OPN lesions. We tested whether OPN were responsible for stopping saccades both in late-onset Tay-Sachs, which causes premature saccadic termination, and in individuals with cerebellar hypermetria. We studied gaze shifts between two targets at different distances aligned on one eye, which consist of a disjunctive saccade followed by vergence. High-frequency conjugate oscillations during the vergence movements that followed saccades were present in all subjects studied, indicating OPN silence. Thus, mechanisms other than OPN discharge (e.g., cerebellar caudal fastigial nucleus-promoting inhibitory BN discharge) must contribute to saccade termination.
authors.affiliation: Department of Neurology Department of Ophthalmology, Mount Sinai School of Medicine, New York, New York 10029, USA. janet.rucker@mssm.edu
authors.forename: Janet C
authors.initials: JC
authors.lastname: Rucker
authors.forename: Sarah H
authors.initials: SH
authors.lastname: Ying
authors.forename: Willa
authors.initials: W
authors.lastname: Moore
authors.forename: Lance M
authors.initials: LM
authors.lastname: Optican
authors.forename: Jean
authors.initials: J
authors.lastname: Büttner-Ennever
authors.forename: Edward L
authors.initials: EL
authors.lastname: Keller
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Shapiro
authors.forename: R John
authors.initials: RJ
authors.lastname: Leigh
mesh_terms: D000328:Adult; D000818:Animals; D001933:Brain Stem / Q000033:anatomy & histology / Q000502:physiology* / Q000503:physiopathology; D016022:Case-Control Studies; D002524:Cerebellar Ataxia / Q000503:physiopathology; D005260:Female; D000882:Haplorhini; D006801:Humans; D008297:Male; D008875:Middle Aged; D015835:Ocular Motility Disorders / Q000209:etiology / Q000503:physiopathology; D010775:Photic Stimulation; D012438:Saccades / Q000502:physiology*; D011984:Sensory Receptor Cells / Q000502:physiology; D013661:Tay-Sachs Disease / Q000503:physiopathology; D055815:Young Adult