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

2. Intracranial Recordings of Attentional Selection Conclusion: – Attentional selection of locations and/or objects has physiological correlates and consequences How does attention get to where it needs to go?

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

4. 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

5. 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?

6. 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)

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

8. 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

9. Hemispatial Neglect E.g. line bisection task