friedreich’s ataxia (frda) is a rare autosomal recessive spinocerebellar ataxia which in the majority of cases is associated with a gaa-trinucleotide repeat expansion in the first intron of frataxin gene located on chromosome 9. the clinical features include progressive gait and limb ataxia, cerebellar dysarthria, neuropathy, optic atrophy, and loss of vibration and proprioception. ataxia with ...

Optic ataxia and visual agnosia have been proposed to constitute a double dissociation which provides the main argument for the assimilation of the anatomical distinction between a dorsal and a ventral visual stream to the functional distinction between perception and action. In the present review, we argue that insufficient evidence has been collected to argue for this double dissociation. Sev...

Optic ataxia, following dorsal stream lesions, is characterised by impaired visuomotor guidance. Recent studies have found concurrent perceptual deficits, but it is unclear whether these are functionally related to the visuomotor symptoms. We studied the ability of a well-documented patient (IG) with bilateral optic ataxia to react to sudden target jumps by correcting ongoing reaches or by expl...

The classic definition of 'pure' optic ataxia suggests that these patients' visuomotor impairments are independent of perceptual or attentional deficits. More recent work suggests that some patients with optic ataxia also have difficulty attending to targets in their ataxic field. Thus, an important question is whether these attentional deficits might be related to the well-known problems in vi...

After coronary by-pass surgery, a 47 year old, right-handed man developed Gerstmann's syndrome, a visual-spatial perceptual deficit, and a gross impairment of movememt under visual guidance ("optic ataxia"). Visual fields and extraocular movements were intact; he had a left hemiparesis. The EMIscan showed three lesions: a left parietal-occipital lesion; a posterior callosal lesion, and a right ...

Optic ataxia is considered to be a specific visuo-manual guidance deficit, which combines pointing errors due to the use of the contralesional hand ("hand effect") and to the presentation of the visual target in the contralesional field ("field effect"). The nature of the hand effect has not been identified. The field effect is acknowledged as an impaired spatial integration of visual target lo...

Twenty patients are described with a distinctive clinical syndrome characterised by progressive cerebellar ataxia developing within the first two decades. This is associated with dysarthria, pyramidal signs in the limbs, normal or increased knee jerks and upper limb reflexes and in some instances sensory loss. Inheritance is probably autosomal recessive in the majority, if not all, of the cases...