Attention Orienting System and Associated Disorders Neglect, Extinction and Balint’s Syndrome
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?
Orienting Spatial Attention Corbetta et al. (1993) – Subjects oriented attention according to a light moving in the visual field
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
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?
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)
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
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
Hemispatial Neglect E.g. line bisection task