Revisiting previously searched locations in visual neglect: role of right parietal and frontal lesions in misjudging old locations as new

Mannan, S. K. and Mort, D. J. and Hodgson, T. L. and Driver, J. and Kennard, C. and Husain, M. (2005) Revisiting previously searched locations in visual neglect: role of right parietal and frontal lesions in misjudging old locations as new. Journal of Cognitive Neuroscience, 17 (2). pp. 340-354. ISSN 0898-929X

Full content URL: http://dx.doi.org/10.1162/0898929053124983

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Abstract

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.

Keywords:adult, aged, article, attention, brain injury, brain region, clinical article, controlled study, eye movement, frontal cortex, human, image analysis, neuroimaging, nuclear magnetic resonance imaging, parietal lobe, pathophysiology, priority journal, right hemisphere, visual discrimination, visual stimulation, Adult, Aged, 80 and over, Brain Injuries, Brain Mapping, Eye Movements, Female, Frontal Lobe, Functional Laterality, Humans, Magnetic Resonance Imaging, Male, Middle Aged, Perceptual Disorders, Perceptual Masking, Photic Stimulation, Reaction Time
Subjects:C Biological Sciences > C850 Cognitive Psychology
Divisions:College of Social Science > School of Psychology
ID Code:10536
Deposited On:12 Jul 2013 15:07

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