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Attention Orienting System and Associated Disorders

Attention Orienting System and Associated Disorders. Neglect, Extinction and Balint’s Syndrome. Orienting Spatial Attention. Corbetta et al. (1993) Subjects oriented attention according to a light moving in the visual field. Orienting Spatial Attention. Results:

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Attention Orienting System and Associated Disorders

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  1. Attention Orienting System and Associated Disorders Neglect, Extinction and Balint’s Syndrome

  2. Orienting Spatial Attention • Corbetta et al. (1993) • Subjects oriented attention according to a light moving in the visual field

  3. Orienting Spatial Attention • Results: • Parietal and Pre-motor areas were activated by attention tracking task • Hemisphere of activation depended on which visual field attention was being shifted in

  4. Orienting Spatial Attention • Corbetta et al (1993) confounded stimulus w/ orienting • Hopfinger et al. (2000) used event-related fMRI to identify top-down orienting processes (distinct from stimulus-driven processes) • Cue-target paradigm using arrows • What is the brain activity caused by the cue?

  5. Orienting Spatial Attention • Result: • Cue-related activations indicate a distributed network that mediates voluntary orienting • Network includes mainly frontal and parietal structures, mainly on the left side (keep this in mind for discussing neglect)

  6. Orienting Spatial Attention • Result: • Directly contrasting cue vs. target reveals an attention orienting network distinct from a target processing network Cue activity > Target activity Target activity > Cue activity

  7. Hemispatial Neglect • Unilateral lesion to Parietal or Temporo-Parietal Junction • Patients present with vision problems, but are not “blind” • Rather, they fail to apprehend (and interact appropriately with) stimuli in the contralesional field

  8. Hemispatial Neglect • E.g. line bisection task

  9. Hemispatial Neglect • E.g. reproducing visual forms

  10. Investigation of Neglect with Cue-Target Paradigm • Posner et al. (late 1970s) used a cue-target paradigm • Parietal Lobe patients are profoundly impaired only when invalidly cued to attended to the ipsilesional (good) side

  11. Extinction • Extinction is a more complicated aspect of neglect • Patients fail to apprehend objects in the contralesional field when stimuli are present in the ipsilesional field

  12. Balint’s Syndrome • Bilateral parietal lesions • Patients fail to apprehend all but one of simultaneously presented objects at the same location • Condition is object-based, not location-based • Multi-colored dots are properly seen if they are connected by lines

  13. Balint’s Syndrome

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