Transient neural activity in human parietal cortex during spatial attention shifts

Abstract

Observers viewing a complex visual scene selectively attend to relevant locations or objects and ignore irrelevant ones. Selective attention to an object enhances its neural representation in extrastriate cortex, compared with those of unattended objects, via top-down attentional control signals. The posterior parietal cortex is centrally involved in this control of spatial attention. We examined brain activity during attention shifts using rapid, event-related fMRI of human observers as they covertly shifted attention between two peripheral spatial locations. Activation in extrastriate cortex increased after a shift of attention to the contralateral visual field and remained high during sustained contralateral attention. The time course of activity was substantially different in posterior parietal cortex, where transient increases in activation accompanied shifts of attention in either direction. This result suggests that activation of the parietal cortex is associated with a discrete signal to shift spatial attention, and is not the source of a signal to continuously maintain the current attentive state.

Selective and interactive neural correlates of visual dimension changes and response changes

“…Dimension changes further elicited activation along the descending and horizontal segments of the intraparietal sulcus, whereas response changes led to activation in its ascending segment. This distribution is in good agreement with studies of visual attention shifts, both between locations and between features, which have consistently reported activation along the horizontal segment of the intraparietal sulcus (Corbetta et al, 1998;Gitelman et al, 1999;Lepsien and Pollmann, 2002;Liu et al, 2003;Pollmann and von Cramon, 2000;Pollmann et al, 2000b;Weidner et al, 2002;Yantis et al, 2003), and with studies of prehensile movements (Binkofski et al, 1998(Binkofski et al, , 1999; and it is consistent with studies of motor attention (Rushworth et al, 2001), which have reported activation along the ascending segment of the intraparietal sulcus and functional deficits following natural lesions or transcranial magnetic stimulation of this segment.…”

Neural Mechanisms of Selective Auditory Attention in Rats (Dissertation)

“…Similar parietal and frontal regions also showed sustained increase of activity in a study that requires subjects to covertly track a small dot appearing at different locations in the visual periphery (Beauchamp et al, 2001). In an object-based visual attention task, transient activity during shifts of attention between objects were found in frontal and superior parietal regions (Serences et al, 2004); functionally similar parietal areas were also found in previous studies of spatial attention shifts (Vandenberghe et al, 2001;Yantis et al, 2002). Since the demand for attention shifting and maintenance of attention differs from task to task, it's possible that parietal and frontal regions engage in both the initiation and the maintenance of attention depending on the task demand.…”

Distinct neural networks for target feature versus dimension changes in visual search, as revealed by EEG and fMRI

“…Previous fMRI studies on dimension changes found significant activation of multiple posterior brain areas (e.g., Pollmann et al, 2000: fusiform gyrus, lateral occipital gyrus, superior/middle temporal gyrus, SPL and precuneus; Pollmann et al, 2006: IPS, fusiform gyrus, striate/peristriate cortex and posterior putamen/claustrum) that have been implicated in early attentional processes (Corbetta et al, 1993(Corbetta et al, , 1995(Corbetta et al, , 2000Corbetta & Shulman, 1999;Kelley et al, 2008;Macaluso et al, 2000;Nobre et al, 1997, Vandenberghe et al, 2000Yantis et al, 2002). Hence, it was concluded that dimension changes interfere with attention shifts to the target.…”