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The left intraparietal sulcus modulates the selection of low salient stimuli

Mevorach, Carmel and Shalev, Lilach and Allen, Harriet A. and Humphreys, Glyn W. (2009) The left intraparietal sulcus modulates the selection of low salient stimuli. Journal of cognitive neuroscience, 21 (2). pp. 303-15. ISSN 0898-929X

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URL of Published Version: http://www.mitpressjournals.org/doi/full/10.1162/jocn.2009.21044

Identification Number/DOI: 10.1162/jocn.2009.21044

Neuropsychological and functional imaging studies have suggested a general right hemisphere advantage for processing global visual information and a left hemisphere advantage for processing local information. In contrast, a recent transcranial magnetic stimulation study [Mevorach, C., Humphreys, G. W., & Shalev, L. Opposite biases in salience-based selection for the left and right posterior parietal cortex. Nature Neuroscience, 9, 740-742, 2006b] demonstrated that functional lateralization of selection in the parietal cortices on the basis of the relative salience of stimuli might provide an alternative explanation for previous results. In the present study, we applied a whole-brain analysis of the functional magnetic resonance signal when participants responded to either the local or the global levels of hierarchical figures. The task (respond to local or global) was crossed with the saliency of the target level (local salient, global salient) to provide, for the first time, a direct contrast between brain activation related to the stimulus level and that related to relative saliency. We found evidence for lateralization of salience-based selection but not for selection based on the level of processing. Activation along the left intraparietal sulcus (IPS) was found when a low saliency stimulus had to be selected irrespective of its level. A control task showed that this was not simply an effect of task difficulty. The data suggest a specific role for regions along the left IPS in salience-based selection, supporting the argument that previous reports of lateralized responses to local and global stimuli were contaminated by effects of saliency.

Type of Work:Article
Date:February 2009 (Publication)
School/Faculty:Colleges (2008 onwards) > College of Life & Environmental Sciences
Department:School of Psychology
Keywords:POSTERIOR PARIETAL CORTEX; TRANSCRANIAL MAGNETIC STIMULATION; VISUAL-ATTENTION; HEMISPHERIC ASYMMETRIES; SPATIAL-FREQUENCY; MOTOR ATTENTION; RHESUS-MONKEY; BRAIN IMAGES; FRONTAL-LOBE; FMRI
Subjects:RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry
BF Psychology
Institution:University of Birmingham
Copyright Holders:Massachusetts Institute of Technology
ID Code:687
Refereed:YES
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