Corbetta et al. Presented by: Vanessa Wong 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 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 Does the distributed injury hypothesis apply to spatial neglect? Hypothesis: Recovery is associated with a normalization of activity in attention networks 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 fMRI * * Independent Valid cue or Invalid cue Left or right visual field Acute or chronic stage Dependent Reaction time Accuracy 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 attentional reorientating Less reaction time and more hit rates in targeting invalid cues Failed to support the local injury hypothesis Supported the distributed injury hypothesis Recovery correlates with reactivation and rebalancing of normal activity within network Small sample size (N=11) Even though all patients have clinical neglect, different areas of brain are damaged 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 The distributed impairment principle can likely be applicable to aphasia or sensorymotor deficits Re-examination of localization of anatomical basis and functional information on specific neuropsychological disorders 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.