Visual attention may be voluntarily directed to particular locations or features (voluntary control), or it may be captured by salient stimuli, such as the abrupt appearance of a new perceptual object (stimulus-driven control). Most often, however, the deployment of attention is the result of a dynamic interplay between voluntary attentional control settings (e.g., based on prior knowledge about a target's location or color) and the degree to which stimuli in the visual scene match these voluntary control settings. Consequently, nontarget items in the scene that share a defining feature with the target of visual search can capture attention, a phenomenon termed contingent attentional capture. We used functional magnetic resonance imaging to show that attentional capture by target-colored distractors is accompanied by increased cortical activity in corresponding regions of retinotopically organized visual cortex. Concurrent activation in the temporoparietal junction and ventral frontal cortex suggests that these regions coordinate voluntary and stimulus-driven attentional control settings to determine which stimuli effectively compete for attention.

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The parietal lobe forms about 20% of the human cerebral cortex and is divided into two major regions, the somatosensory cortex and the posterior parietal cortex. Posterior parietal cortex, located at the junction of multiple sensory regions, projects to several cortical and subcortical areas and is engaged in a host of cognitive operations. One such operation is selective attention, the process where by the input is filtered and a subset of the information is selected for preferential processing. Recent neuroimaging and neuropsychological studies have provided a more fine-grained understanding of the relationship between brain and behavior in the domain of selective attention. anterior intraparietal sulcus CVA cerebrovascular accident DMS delayed match-to-sample fMRI functional magnetic resonance imaging IPL inferior parietal lobule SPL superior parietal lobule TPJ temporoparietal junction IntroductionParietal cortex, situated at the intersection of visual, auditory, and tactile cortices at the 'crossroads of the brain' [1], is 'association' or tertiary cortex. With its requisite connectivity to cortical and subcortical regions associated with motor responses, parietal cortex serves a crucial role in transforming sensory input into motor output. In the course of doing so, a host of cognitive computations are engaged including spatial representation and updating, attention, coordinate transformation, as well as abstract motor planning [2]. Although much progress has been made in demarcating fine-grained anatomical distinctions in parietal cortex and their functional correlates in nonhuman primates [2,3], this has not been possible in humans. In the past, neuropsychological studies in individuals with lesions have been somewhat helpful in this regard; however, in most cases, the lesions are diffuse, precluding definitive conclusions about the structural and functional aspects of human parietal cortex.With the advent of high-resolution functional neuroimaging, this mapping of anatomical areas is now possible. In addition, the development and accessibility of methods for detailed structural analysis of lesions has enabled a more fine-grained demarcation of the lesion site in braindamaged individuals, and, consequently, a more precise brain-behavior correlation. Here, we review the recent advances that suggest that the role of posterior parietal cortex in selective attention is more specific than was previously assumed. Parietal cortex and attentionSelective attention is the process whereby a subset of the input is selected preferentially for further processing. A primary focus of several recent neuroimaging investigations of attention has been to determine the anatomical locus within the parietal lobe that gives rise to the attentional biasing signal (i.e. the source) that ultimately initiates the sensory enhancement of the selected stimulus (i.e. the effect). The attentional biasing signal could potentially be generated in one of two ways: first, in a bottom-up or stimulus-driven manner (also referred to as 'attent...

Selective attention contributes to perceptual efficiency by modulating cortical activity according to task demands. Visual attention is controlled by activity in posterior parietal and superior frontal cortices, but little is known about the neural basis of attentional control within and between other sensory modalities. We examined human brain activity during attention shifts between vision and audition. Attention shifts from vision to audition caused increased activity in auditory cortex and decreased activity in visual cortex and vice versa, reflecting the effects of attention on sensory representations. Posterior parietal and superior prefrontal cortices exhibited transient increases in activity that were time locked to the initiation of voluntary attention shifts between vision and audition. These findings reveal that the attentional control functions of posterior parietal and superior prefrontal cortices are not limited to the visual domain but also include the control of crossmodal shifts of attention.

The human posterior parietal cortex (PPC) is widely believed to subserve visually guided spatial behavior, including the control of visual attention, eye movements, and reaching. To explore the generality of this function, we measured human brain activity using functional magnetic resonance imaging during spatial and nonspatial shifts of auditory attention. Both spatial and nonspatial shifts of auditory attention evoked transient activity in the medial superior parietal cortex. These results reveal that the PPC is not exclusively devoted to visuospatial behavior; similar regions within a dorsomedial subcompartment provide a domain-independent reconfiguration signal for the control of spatial and nonspatial attention in both visual and nonvisual modalities.