title: Pure optic ataxia and visual hemiagnosia - extending the dual visual hypothesis.
abstract: Goodale and Milner's two visual system hypothesis is an influential model for the understanding of the primate visual system. Lesions of either the ventral (occipito-temporal) or the dorsal (occipito-parietal) stream produce distinct and dissociated syndromes in humans: visual agnosia is typical for ventral damage, whereas optic ataxia (OA) for dorsal damage. We studied the case of a 59-year-old left-handed woman with a circumscribed lesion around the left posterior occipital sulcus, extending to the underlying white matter. Initially, she presented with a central visual field OA, which regressed to an OA to the right visual hemifield during the 3 months observation period. In addition, tachistoscopic experiments showed visual hemiagnosia to the right visual hemifield. In line with the findings of the neuropsychological experiments, the analysis of the structural MR data by means of a trackwise hodologic probabilistic approach revealed damage to the left superior longitudinal fasciculus and to the left inferior longitudinal fasciculus, indicating an impairment of both the dorsal and the ventral stream. The combination of OA and visual hemiagnosia in the same patient has never been previously described. The present case study thus provides further insights for the understanding of visual processing.
authors.affiliation: Department of Neurology, Inselspital, University Hospital Bern, Switzerland.|Perception and Eye Movement Laboratory, Departments of Neurology and Clinical Research, Inselspital, University Hospital Bern, University of Bern, Switzerland.
authors.forename: Jurka R
authors.identifier: http://orcid.org/0000-0002-8195-859X
authors.initials: JR
authors.lastname: Meichtry
authors.affiliation: Perception and Eye Movement Laboratory, Departments of Neurology and Clinical Research, Inselspital, University Hospital Bern, University of Bern, Switzerland.|Gerontechnology and Rehabilitation Group, ARTORG Center for Biomedical Engineering Research, University of Bern, Switzerland.
authors.forename: Dario
authors.initials: D
authors.lastname: Cazzoli
authors.affiliation: Department of Neurology, Inselspital, University Hospital Bern, Switzerland.
authors.forename: Silvia
authors.initials: S
authors.lastname: Chaves
authors.affiliation: Department of Neurology, Inselspital, University Hospital Bern, Switzerland.
authors.forename: Sebastian
authors.initials: S
authors.lastname: von Arx
authors.affiliation: Center of Neurology and Neurorehabilitation, State Hospital Luzern, Switzerland.
authors.forename: Tobias
authors.initials: T
authors.lastname: Pflugshaupt
authors.affiliation: Department of Neurology, Inselspital, University Hospital Bern, Switzerland.
authors.forename: Roger
authors.initials: R
authors.lastname: Kalla
authors.affiliation: Department of Neurology, Inselspital, University Hospital Bern, Switzerland.
authors.forename: Claudio L
authors.initials: CL
authors.lastname: Bassetti
authors.affiliation: Department of Neurology, Inselspital, University Hospital Bern, Switzerland.|Perception and Eye Movement Laboratory, Departments of Neurology and Clinical Research, Inselspital, University Hospital Bern, University of Bern, Switzerland.
authors.forename: Klemens
authors.initials: K
authors.lastname: Gutbrod
authors.affiliation: Department of Neurology, Inselspital, University Hospital Bern, Switzerland.|Perception and Eye Movement Laboratory, Departments of Neurology and Clinical Research, Inselspital, University Hospital Bern, University of Bern, Switzerland.|Gerontechnology and Rehabilitation Group, ARTORG Center for Biomedical Engineering Research, University of Bern, Switzerland.
authors.forename: René M
authors.initials: RM
authors.lastname: Müri
mesh_terms: D000377:Agnosia / Q000150:complications*; D001259:Ataxia / Q000150:complications*; D003072:Cognition Disorders / Q000209:etiology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009483:Neuropsychological Tests; D014796:Visual Perception / Q000502:physiology*
keywords: dorsal premotor cortex; inferior longitudinal fasciculus; medial intraparietal sulcus; optic ataxia; parieto-occipital junction; superior longitudinal fasciculus; visual agnosia