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NEURAL BASIS AND RECOVERY OF SPATIAL ATTENTION
DEFICITS IN SPATIAL NEGLECT
Presented by: Vanessa Wong
Corbetta et al.
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
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
RESEARCH QUESTION Does the distributed injury hypothesis apply to spatial neglect?
Hypothesis: Recovery is associated with a normalization of activity in attention networks
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
VARIABLESIndependent Valid cue or Invalid cue Left or right visual field Acute or chronic stage
Dependent Reaction time Accuracy
RESULTSSignificant 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
DISCUSSION Failed to support the local injury
hypothesis Supported the distributed injury
hypothesis Recovery correlates with reactivation
and rebalancing of normal activity within network
LIMITATIONS Small sample size (N=11) Even though all patients have clinical
neglect, different areas of brain are damaged
MY OPINION ON THE PAPER Strengths
Brain scans and graphs
In depth description of brain regions
Clearly presented the results found
Well organizedShort and concise
WeaknessLittle detail on the
rehabilitation
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
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.