Impaired attentional selection following lesions to human pulvinar: evidence for homology between human and monkey - PubMed (original) (raw)

Clinical Trial

. 2009 Mar 10;106(10):4054-9.

doi: 10.1073/pnas.0810086106. Epub 2009 Feb 23.

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Clinical Trial

Impaired attentional selection following lesions to human pulvinar: evidence for homology between human and monkey

Jacqueline C Snow et al. Proc Natl Acad Sci U S A. 2009.

Abstract

We examined the contributions of the human pulvinar to goal directed selection of visual targets in 3 patients with chronic, unilateral lesions involving topographic maps in the ventral pulvinar. Observers completed 2 psychophysical tasks in which they discriminated the orientation of a lateralized target grating in the presence of vertically-aligned distracters. In experiment 1, where distracter contrast was varied while target contrast remained constant, the patients' contralesional contrast thresholds for discriminating the orientation of grating stimuli were elevated only when the task required selection of a visual target in the face of competition from a salient distracter. Attentional selectivity was restored in the patients in experiment 2 where target contrast was varied while distracter contrast remained constant. These observations provide the first evidence that the human pulvinar plays a necessary role in modulating physical saliency in attentional selection, and supports a homology in global pulvinar structure between humans and monkey.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.

Fig. 1.

Effects of distracters on grating orientation discrimination. (A) Example display sequence used in the orientation discrimination task. Observers fixated a central point throughout all trials. Lateralized target gratings appeared with/without distractor discs (shown here with distracters). Stimuli appeared briefly within the left or right visual field. observers were required to discriminate whether the grating was tilted to the left or right of vertical. In experiment 1, target orientation thresholds for each observer were calculated at 4 levels of distractor disk contrast (−50%, 0%, +50%, 80%). Distractor contrast was manipulated by changing disk luminance relative to the background (see Methods). (B) Orientation discrimination performance as a function of distracter contrast for pulvinar-lesioned patients and controls. Data represent mean (SE) change in orientation threshold from baseline. Data points in each graph are averages based on 4–6 thresholds. Performance in the “zero-contrast” distracter condition (baseline) is indicated by the dotted line. Examples of the 4 distractor conditions are illustrated above the graph. Open squares, patients; filled squares, controls. (C) Mean (SE) change in orientation threshold from baseline plotted separately for patients D.G. (Top), C.R. (Middle), and T.N. (Bottom). Data are plotted separately for targets appearing within the contralesional (filled squares) and ipsilesional (open squares) fields.

Fig. 2.

Fig. 2.

Mean (SE) target grating orientation thresholds for each patient as a function of target contrast in experiment 2. (Upper) Patient D.G. (Lower) Patient C.R. Target orientation thresholds for each observer were measured with a low-contrast target grating that appeared alone (“T-only” condition), or in the presence of low-contrast distracters (“T and D” condition). In the remaining conditions distracter contrast was held constant while target grating contrast increased by 5% (T 5%) and 40% (T 40%) relative to the no-distracter (T-only) condition. Grating contrast was manipulated by changing the contrast between dark and light stripes (see Methods). Examples of the 4 target/distractor contrast conditions in experiment 2 are illustrated above the graph. Data points are averages based on 4–8 thresholds. Data are plotted separately for targets appearing within the contralesional (filled squares) and ipsilesional (open squares) fields.

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