title: Role of the prepositus hypoglossi nucleus on primary position upbeat nystagmus.
abstract: Electrolytical destruction of the floor of the fourth ventricle was performed on 10 cats in order to produce primary position upbeat nystagmus (PPUN). In 5 cats who had unilateral lesions of the floor of the fourth ventricle, PPUN was never seen. Two of the remaining 5 cats, who had bilateral lesions, showed PPUN. In 2 cats with PPUN, the oculomotor level of the caudal fourth ventricle, in order that PPUN may be developed, it is necessary that the prepositus hypoglossi nucleus (PH) be destroyed bilaterally. The present experiment suggests that bilateral PH lesions could result in a tonic imbalance for eye positions and eye movements of the vertical axis, resulting in a downward drift with a corrective saccade; PPUN.
authors.affiliation: Department of Otolaryngology, Yamagata University, School of Medicine, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Harada
authors.forename: I
authors.initials: I
authors.lastname: Kato
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
authors.forename: Y
authors.initials: Y
authors.lastname: Koike
mesh_terms: D000818:Animals; D001927:Brain Diseases / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D002415:Cats; D004585:Electrooculography; D005133:Eye Movements / Q000502:physiology; D007002:Hypoglossal Nerve / Q000473:pathology / Q000503:physiopathology*; D008526:Medulla Oblongata / Q000473:pathology / Q000503:physiopathology*; D017120:Nystagmus, Optokinetic / Q000502:physiology; D009759:Nystagmus, Pathologic / Q000209:etiology* / Q000503:physiopathology; D009847:Olivary Nucleus / Q000473:pathology / Q000503:physiopathology; D011149:Pons / Q000473:pathology / Q000503:physiopathology; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology; D012438:Saccades / Q000502:physiology; D014630:Vagus Nerve / Q000473:pathology / Q000503:physiopathology