Document Detail

Revisiting previously searched locations in visual neglect: role of right parietal and frontal lesions in misjudging old locations as new.
MedLine Citation:
PMID:  15811244     Owner:  NLM     Status:  MEDLINE    
Right-hemisphere patients with left neglect often demonstrate abnormal visual search, re-examining stimuli to the right while ignoring those to the left. But re-fixations alone do not reveal if patients misjudge whether they have searched a location before. Here, we not only tracked the eye movements of 16 neglect patients during search, but also asked them to click a response button only when they judged they were fixating a target for the very first time. ''Re-clicking'' on previously found targets would indicate that patients erroneously respond to these as new discoveries. Lesions were mapped with high-resolution MRI. Neglect patients with damage involving the right intraparietal sulcus or right inferior frontal lobe ''re-clicked'' on previously found targets on the right at a pathological rate, whereas those with medial occipito-temporal lesions did not. For the intraparietal sulcus patients, the probability of erroneous re-clicks on an old target increased with time since first discovering it; whereas for frontal patients it was independent of search time, suggesting different underlying mechanisms in these two types of patient. Re-click deficits correlated with degree of leftward neglect, mainly due to both being severe in intraparietal cases. These results demonstrate that misjudging previously searched locations for new ones can contribute to pathological search in neglect, with potentially different mechanisms being involved in intraparietal versus inferior frontal patients. When combined with a spatial bias to the right, such deficits might explain why many neglect patients often re-examine rightward locations, at the expense of items to their left.
Sabira K Mannan; Dominic J Mort; Tim L Hodgson; Jon Driver; Christopher Kennard; Masud Husain
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of cognitive neuroscience     Volume:  17     ISSN:  0898-929X     ISO Abbreviation:  J Cogn Neurosci     Publication Date:  2005 Feb 
Date Detail:
Created Date:  2005-04-06     Completed Date:  2005-05-27     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8910747     Medline TA:  J Cogn Neurosci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  340-54     Citation Subset:  IM    
Division of Neuroscience and Psychological Medicine, Imperial College London, London, UK.
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MeSH Terms
Aged, 80 and over
Attention / physiology*
Brain Injuries / physiopathology*
Brain Mapping
Eye Movements / physiology
Frontal Lobe / pathology,  physiopathology*
Functional Laterality / physiology
Magnetic Resonance Imaging
Middle Aged
Parietal Lobe / pathology,  physiopathology*
Perceptual Disorders / physiopathology*
Perceptual Masking / physiology
Photic Stimulation / methods
Reaction Time / physiology
Erratum In:
J Cogn Neurosci. 2005 Oct;17(10):table of contents

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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