title: A hand and a field effect in on-line motor control in unilateral optic ataxia.
abstract: Patients with bilateral optic ataxia fail to show rapid perturbation-induced corrections during manual aiming movements. Based on this, it has been proposed that this pathology results from a disruption of processes of on-line motor control in the posterior parietal cortex (PPC). Here, we show that on-line motor control performance in a patient with unilateral optic ataxia is similar to that of pointing towards stationary targets in peripheral vision, showing the same combination of hand and field effects. We also show that in the patient, manual correction towards his ataxic field was possible only when a preceding saccade (100msec earlier) rapidly provides foveal information about the new target location. In control subjects, manual correction was often, but not necessarily preceded by a saccade. These results allow us to put forward a model of visuo-manual transformation, which involves updating of the reach plan based on the target-eye error, and rely upon two dissociated spatial representations (of the hand and of the target, respectively) within the PPC.
authors.affiliation: INSERM, U864, Espace et Action, avenue Lépine, Bron, France.
authors.forename: Annabelle
authors.initials: A
authors.lastname: Blangero
authors.forename: Valérie
authors.initials: V
authors.lastname: Gaveau
authors.forename: Jacques
authors.initials: J
authors.lastname: Luauté
authors.forename: Gilles
authors.initials: G
authors.lastname: Rode
authors.forename: Romeo
authors.initials: R
authors.lastname: Salemme
authors.forename: Marine
authors.initials: M
authors.lastname: Guinard
authors.forename: Dominique
authors.initials: D
authors.lastname: Boisson
authors.forename: Yves
authors.initials: Y
authors.lastname: Rossetti
authors.forename: Laure
authors.initials: L
authors.lastname: Pisella
mesh_terms: D000328:Adult; D001259:Ataxia / Q000209:etiology / Q000503:physiopathology*; D016022:Case-Control Studies; D002544:Cerebral Infarction / Q000150:complications / Q000503:physiopathology; D005128:Eye Diseases / Q000209:etiology / Q000503:physiopathology*; D005133:Eye Movements / Q000502:physiology*; D007839:Functional Laterality / Q000502:physiology*; D006225:Hand / Q000502:physiology; D006801:Humans; D008297:Male; D016555:Matched-Pair Analysis; D009068:Movement / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012016:Reference Values; D013028:Space Perception / Q000502:physiology; D014794:Visual Fields / Q000502:physiology