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Neural basis and recovery of spatial attention deficits in spatial neglect

Neural basis and recovery of spatial attention deficits in spatial neglect. Corbetta et al. Presented by: Vanessa Wong. Introduction to spatial neglect. Inability to pay attention to space Most common cause is stroke

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Neural basis and recovery of spatial attention deficits in spatial neglect

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  1. Neural basis and recovery of spatial attention deficits in spatial neglect Corbetta et al. Presented by: Vanessa Wong

  2. Introduction to spatial neglect • Inability to pay attention to space • Most common cause is stroke • Caused by focal injury to temporoparietal cortex or ventral frontal cortex • Damage in right hemisphere and neglects left side of space

  3. Two possible Theories • Local injury hypothesis • Injury to a brain area causes behaviour deficits that reflect local dysfunction of neurons at the site of injury • Distributed injury hypothesis • Lesion causes dysfunction in other nodes of a functional brain network, impairing processes other than those mediated by neurons at the site of injury

  4. Research question • Does the distributed injury hypothesis apply to spatial neglect? Hypothesis: Recovery is associated with a normalization of activity in attention networks

  5. Experiment • 11 participants (3 females, 8 males, M=60 years) • All with unilateral (right side) stroke with no damage to visual field areas and are representative of the most common lesion sites in neglect • All underwent standard rehabilitation for at least 3 months • Tested at acute(~4 weeks) and chronic (~39weeks) recovery stage

  6. fMRI

  7. Posner visual orienting task

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  10. Variables Independent • Valid cue or Invalid cue • Left or right visual field • Acute or chronic stage Dependent • Reaction time • Accuracy

  11. Results Significant recovery from acute to chronic stage • Decrease in rightward processing bias • Greater improvement in reaction time for left than right visual field targeting • Improvement in attentionalreorientating • Less reaction time and more hit rates in targeting invalid cues

  12. Discussion • Failed to support the local injury hypothesis • Supported the distributed injury hypothesis • Recovery correlates with reactivation and rebalancing of normal activity within network

  13. Limitations • Small sample size (N=11) • Even though all patients have clinical neglect, different areas of brain are damaged

  14. My opinion on the paper • Strengths • Brain scans and graphs • In depth description of brain regions • Clearly presented the results found • Well organized • Short and concise • Weakness • Little detail on the rehabilitation

  15. Future directions • The distributed impairment principle can likely be applicable to aphasia or sensory-motor deficits • Re-examination of localization of anatomical basis and functional information on specific neuropsychological disorders

  16. Corbetta, M., Kincade, M.J., Lewis, C., Znyder, A.Z. & Sapir, A. (2005). Neural basis and recovery of spatial attention deficits in spatial neglect. Nature Neuroscience, 8 (11), 1603-1610.

  17. Thank you! Any Questions?

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