Attentional control functions of human frontal and posterior parietal cortex

Evidence from studies of patients suffering from attentional deficits due to brain damage, functional brain imaging in healthy subjects, and physiology studies in monkeys suggests that attention-related modulatory signals are derived from higher-order areas in frontal cortex and posterior parietal cortex (PPC) and are transmitted via feedback projections to the visual system. Thus far, researchers have successfully identified many of the frontoparietal areas responsible for controlling visual attention in the human brain. This frontoparietal attentional control network most likely includes the frontal eye fields (FEF) and supplementary eye field (SEF) in frontal cortex and the superior parietal lobule (SPL) and portions of the intraparietal sulcus (IPS) in PPC. However, researchers have barely begun to characterize each area's individual contribution to attentional control.;The current set of studies extends previous knowledge of attentional control functions in the human brain, through functional magnetic resonance imaging (fMRI), psychophysical, and transcranial magnetic stimulation (TMS) techniques. In each of the studies, a memory-guided saccade task was used to identify several topographically organized areas in frontal and parietal cortex, whose locations overlap with known activations of the fronto-parietal attentional control network (Study 1). These topographic areas were then used to further subdivide the fronto-parietal attention activations into more discrete regions in individual subjects, and to independently investigate the attentional response properties of each individual area within the network, much like the region-of-interest approach regularly used to investigate visual cortex. The use of this technique has led to the development of a new model of visuospatial attentional control (Study 2; Szczepanski et al., 2010), the identification of the neural correlates for behavioral preference of attentional allocation across the visual field (Study 3), has provided preliminary evidence that topographic fronto-parietal cortex plays a causal role in spatial attentional behavior (Study 4), and has helped to further specify the effective and functional connectivity among areas that are involved in human spatial attentional control (Study 5). Taken together, these studies provide a more complete picture of how the spatial attentional control network operates as a whole in the human brain.