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Sarah Shomstein, Fatma Uyar, Adam Greenberg, Marlene Behrmann; Sensory Processing with Varying Degrees of Attention: Lessons from Hemispatial Neglect. Journal of Vision 2013;13(9):286. doi: 10.1167/13.9.286.
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© ARVO (1962-2015); The Authors (2016-present)
Following right parietal lobe damage, patients with hemispatial neglect display impairments in attending to information on the left side of space. Recent theories suggest that this spatial attention deficit arises from structural/functional perturbation of the balance between the dorsal and ventral attentional networks. The consequence of the attentional imbalance on the sensory signals elicited in response to visual stimulation is not yet understood. Neglect offers a unique opportunity to examine direct consequences of attention on sensory processing by measuring behavioral and neural responses to a stimulus presented in the unaffected right side of space as compared to the same stimulus presented to the affected left side of space. Here, we compared neural signals elicited in response to the attended and neglected visual stimulation in patients with right parietal lobe lesions and intact occipital and temporal cortex. FMRI was used to localize four visual field locations in sensory regions V1-V4, FFA, and PPA. In addition, patients performed a fixation task while task-irrelevant images of faces and houses were presented in 4 locations. Univariate analysis showed greater difference between the preferred and non-preferred stimuli as one moves anteriorly from V1, V2, V3, V4, to PPA, and FFA, in left versus right hemisphere. The reduction of right hemisphere response to preferred stimuli was correlated with the severity of neglect. The signal integrity within the two hemispheres was tested separately with multivariate analysis. Category and location information in right hemisphere ROIs was lower as compared to the left hemisphere as evidenced by lower within-category cross correlation coefficients and classification accuracies. These results provide evidence that attention directly affects perceptual processing by improving the integrity of sensory responses elicited in visual cortex via magnifying the difference between the response to preferred and non-preferred stimuli.
Meeting abstract presented at VSS 2013
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