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Jacqueline Snow, Harriet Allen, Robert Rafal, Glyn Humphreys; Impaired attentional selectivity following lesions to human pulvinar. Journal of Vision 2007;7(9):785. doi: 10.1167/7.9.785.
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Relatively little is currently known about the functional role of the pulvinar nucleus of the thalamus, particularly in humans. From an anatomical and functional perspective, the pulvinar is well placed to play a critical role in selective attention. In non-human primates, the pulvinar shows strong connections with brain areas known to be involved in coding visual salience, including the parietal and frontal lobes. In addition, bidirectional connections between the pulvinar and consecutive topographically organized maps in striate and extrastriate cortex suggest a critical role for this structure in co-ordinating activity across different brain areas. The current study examined the possible role of the human pulvinar in filtering out competing salient visual distractors. We tested a group of three neuropsychological patients with circumscribed unilateral pulvinar lesions and a group of healthy age-matched controls using a sensitive psychophysics task. Observers were required to discriminate the orientation of a covertly attended target grating that appeared to the left or right of fixation. The target was flanked above and below by distractor discs of increasing contrast. As in previous studies, distractor contrast had little effect on orientation sensitivity for healthy controls. For patients with lesions to the ventral pulvinar, however, increasing distractor contrast impaired orientation sensitivity. Interestingly, distractors impaired orientation sensitivity in both the contralesional and ipsilesional fields. These findings are consistent with previous suggestions that the pulvinar plays a key role in selective attention, particularly in representing target salience and filtering of distractors across the visual field.
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