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The Journal of Neuroscience, March 26, 2008, 28(13):3359-3373; doi:10.1523/JNEUROSCI.5247-07.2008
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Behavioral/Systems/Cognitive
Convergence between Lesion-Symptom Mapping and Functional Magnetic Resonance Imaging of Spatially Selective Attention in the Intact Brain
Pascal Molenberghs,1 Céline R. Gillebert,1 Ronald Peeters,2 andRik Vandenberghe1,3 1Cognitive Neurology Laboratory, Experimental Neurology Section, Katholieke Universiteit Leuven, and Departments of 2Radiology and 3Neurology, University Hospital Gasthuisberg, 3000 Leuven, Belgium
Correspondence should be addressed to Dr. Rik Vandenberghe, Neurology Department, University Hospital Gasthuisberg, Herestraat 49, 3000 Leuven, Belgium. Email: rik.vandenberghe{at}uz.kuleuven.ac.be
The parietal regions implicated in spatially selective attention differ between patient lesion studies and functional imaging of the intact brain. We aimed to resolve this discordance. In a voxel-based lesion-symptom mapping study in 20 ischemic stroke patients, we applied the same cognitive subtraction approach as in 23 healthy volunteers who underwent functional magnetic resonance imaging (fMRI) using identical tasks and stimuli. An instructive central cue directed attention to one visual quadrant. After a brief delay, a grating appeared in that quadrant together with an irrelevant grating in an uncued quadrant. Subjects had to discriminate the orientation of the grating in the cued quadrant. Patients with a right inferior parietal lesion were significantly more impaired during contralesional versus ipsilesional orienting when stimuli were bilateral and symmetrical than when stimuli occupied diagonally opposite quadrants or two quadrants within the same hemifield. In one area, the lesion-volume map overlapped with the activity map obtained in healthy volunteers: the lower bank of the middle third of the right intraparietal sulcus (IPS). In an additional 37 healthy fMRI subjects, we disentangled the effects of symmetry, bilaterality, and spatial configuration between stimuli on activity in the volume of overlap. Only the axis of configuration between stimuli had a significant effect, with highest activity when the configuration axis was horizontal. This constitutes converging evidence from patients and cognitively intact subjects that the lower bank of the middle third of the right IPS critically contributes to attentive selection between competing stimuli in a spatially anisotropic manner.
Key words: attention; neglect; extinction; fMRI; stroke; VLSM
Received July 16, 2007; revised Jan. 15, 2008; accepted Feb. 13, 2008.
Correspondence should be addressed to Dr. Rik Vandenberghe, Neurology Department, University Hospital Gasthuisberg, Herestraat 49, 3000 Leuven, Belgium. Email: rik.vandenberghe{at}uz.kuleuven.ac.be
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