Dissociation of 'on-line' and 'off-line' visuomotor control of the arm by focal lesions in the cerebellum and brainstem.
Visuomotor control of the arm was assessed in a single case study of a subject with focal lesions in the cerebellum and brainstem. A dissociation between 'on-line' and 'off-line' visuomotor control was revealed: impairments in 'on-line' visuomotor control included inaccuracy of tracking velocity, increase in spatial pointing variability and a delay in simple reaction time; whereas the patient was able to adapt to a gain change in 'off-line' visual feedback during a pointing task, and his adaptation was less affected than that of control subjects by trial-to-trial random fluctuations in 'off-line' visual feedback. We conclude that focal damage in the cerebellar peduncles may be principally responsible for this dissociation.
D000222:Adaptation, Physiological / Q000502:physiology; D001921:Brain / Q000473:pathology; D001933:Brain Stem / Q000503:physiopathology*; D002531:Cerebellum / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000175:diagnosis / Q000503:physiopathology*; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D012016:Reference Values