Optic ataxia is defined as a spatial impairment of visually guided reaching, but it is typically accompanied by other visuomotor difficulties, notably a failure to scale the handgrip appropriately while reaching to grasp an object. This impaired grasping might reflect a primary visuomotor deficit, or it might be a secondary effect arising from the spatial uncertainty associated with poor reachi...

The spinocerebellar ataxias, like all neurodegenerative diseases, lack objective disease- and stage-specific biomarkers. Based on reports of clinically evident optic disc atrophy or retinal disease in some ataxia patients, and the discovery that pre-symptomatic retinal thinning occurs in other neurologic diseases such as multiple sclerosis, we tested the hypothesis that subclinical neuronal or ...

Interaction with visual objects in the environment requires an accurate correspondence between visual space and its internal representation within the brain. Many clinical conditions involve some impairment in visuo-motor control and the errors created by the lesion of a specific brain region are neither random nor uninformative. Modern approaches to studying the neuropsychology of action requi...

The posterior parietal cortex (PPC) is thought to play an important role in the sensorimotor transformations associated with reaching movements. In humans, damage to the PPC, particularly bilateral lesions, leads to impairments of visually guided reaching movements (optic ataxia). Recent accounts of optic ataxia based upon electrophysiological recordings in monkeys have proposed that this disor...

The dorsal stream of visual information processing connecting V1 to the parietal cortex is thought to provide a fast control of visually guided reaching. Important for this assumption was the observation that in both the monkey and the human, parietal lesions may provoke disturbance of visually goal-directed hand movements. In the human, severe misreaching termed 'optic ataxia' has been ascribe...

Posterior Cortical Atrophy (PCA) is a rare clinical syndrome characterized by the predominance of higher-order visual disturbances such as optic ataxia, a characteristic of Balint's syndrome. Deficits result from progressive neurodegeneration of occipito-temporal and occipito-parietal cortices. The current study sought to explore the visuomotor functioning of four individuals with PCA by testin...

The authors report a clinical review of 16 childhood cases with early-onset cerebellar ataxia with retained tendon reflexes. The preservation of tendon reflexes distinguishes this disorder from Friedreich's ataxia. The mean age of onset of symptoms was 7.1 years. The main presenting symptom was abnormal gait (100%). Ataxia of gait and limbs and normal or increased tendon reflexes were found in ...