Cerebral Cortex Advance Access originally published online on April 13, 2007
Cerebral Cortex 2008 18(1):114-125; doi:10.1093/cercor/bhm036
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Cortical Mechanisms for Shifting and Holding Visuospatial Attention
1 Department of Psychological and Brain Sciences, The Johns Hopkins University (JHU), Baltimore, MD, USA, 2 Department of Cognitive Sciences, University of California, Irvine, CA, USA, 3 Department of Psychology, University of California, Santa Barbara, CA, USA
Address correspondence to Todd Kelley, Department of Psychological and Brain Sciences, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA. Email: tkelley{at}jhu.edu.
Access to visual awareness is often determined by covert, voluntary deployments of visual attention. Voluntary orienting without eye movements requires decoupling attention from the locus of fixation, a shift to the desired location, and maintenance of attention at that location. We used event-related functional magnetic resonance imaging to dissociate these components while observers shifted attention among 3 streams of letters and digits, one located at fixation and 2 in the periphery. Compared with holding attention at the current location, shifting attention between the peripheral locations was associated with transient increases in neural activity in the superior parietal lobule (SPL) and frontal eye fields (FEF), as in previous studies. The supplementary eye fields and separate portions of SPL and FEF were more active for decoupling attention from fixation than for shifting attention to a new location. Large segments of precentral sulcus (PreCS) and posterior parietal cortex (PPC) were more active when attention was maintained in the periphery than when it was maintained at fixation. We conclude that distinct subcomponents of the dorsal frontoparietal network initiate redeployments of covert attention to new locations and disengage attention from fixation, while sustained activity in lateral regions of PPC and PreCS represents sustained states of peripheral attention.
Key Words: frontal eye fields (FEF) • functional magnetic resonance imaging (fMRI) • intraparietal sulcus (IPS) • posterior parietal cortex (PPC) • superior parietal lobule (SPL) • supplementary eye fields (SEF)
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