Article

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.Westudied the ability of a well-documented patient (IG) with bilateral optic
ataxia to react to sudden target jumps by correcting ongoing reaches or by explicitly reporting the jump
direction. IG showed deficient reach corrections, especially for target jumps to the visual periphery, and
was similarly slow to discriminate the same jumps perceptually. Across six test conditions, in which
the retinal locations of target jumps were varied, her perceptual slowing mirrored her reaching deficit
precisely. These findings confirm perceptual impairments after dorsal stream lesions, and imply a shared
functional basis with the classical visuomotor symptoms of optic ataxia. Additionally, we show that the
online correction deficit is determined dually by the retinal location to which the reach must be diverted,
and the location to which it is initially directed.Wesuggest that this deficit, and its perceptual counterpart,
can be traced to a slowed contralesional orienting of attention in optic ataxia.

Langue : ANGLAIS