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Christopher Striemer, Annabelle Blangero, Yves Rossetti, Laure Pisella, James Danckert; Attention for action? Examining the link between attention and visuomotor control deficits in a patient with optic ataxia. Journal of Vision 2008;8(6):51. doi: https://doi.org/10.1167/8.6.51.
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Lesions to the superior parietal lobe (SPL), including the intraparietal sulcus (IPS), commonly lead to optic ataxia (OA) - a disorder in which patients have difficulty reaching to objects under visual guidance. These visuomotor impairments are usually restricted to peripheral vision and spare central vision. Importantly, the classic definition of ‘pure’ OA suggests that these visuomotor impairments occur independently from any perceptual or attentional deficits (which, if present, were thought to be related to Balint-Holmes syndrome). However, more recent work from our group suggests that some patients with OA have difficulty orienting and reorienting attention towards their ataxic visual field. Thus, an important question is whether these attentional deficits might be related to the well known problems in visuomotor control evident in these patients. That is, these patients may be inaccurate when reaching towards peripheral targets because they are not able to adequately attend to peripheral locations. To investigate this question we had control participants (N=5) and CF, a patient with OA in his left visual field, perform tasks that required them to either detect, or reach towards, a target presented in either central, or peripheral vision. CF was impaired in both the detection and the reaching tasks compared to controls. Specifically, CF was much slower to detect the presence of targets in his ataxic (left) visual field, and he was very inaccurate when reaching towards those same targets. Interestingly, although CF was obviously impaired relative to controls in both tasks, there was no correlation between his attentional and his visuomotor impairments. Since the motor response in each task was carried out using the same effector (right, ipsilesional hand) it suggests that although SPL/IPS lesions may impair both attention and visuomotor control, these deficits may arise from damage to independent mechanisms.
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