RT Journal Article
SR Electronic
T1 Attention to One or Two Features in Left or Right Visual Field: A Positron Emission Tomography Study
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 3739
OP 3750
DO 10.1523/JNEUROSCI.17-10-03739.1997
VO 17
IS 10
A1 Rik Vandenberghe
A1 John Duncan
A1 Patrick Dupont
A1 Robert Ward
A1 Jean-Baptiste Poline
A1 Guy Bormans
A1 Johan Michiels
A1 Luc Mortelmans
A1 Guy A. Orban
YR 1997
UL http://www.jneurosci.org/content/17/10/3739.abstract
AB In human vision, two features of the same object can be identified concurrently without loss of accuracy. Performance declines, however, when the features belong to different objects in opposite visual fields. We hypothesized that different positron emission tomography activation patterns would reflect these behavioral results. We first delineated an attention network for single discriminations in left or right visual field and then compared this with the activation pattern when subjects divided attention over two features of a single object or over two objects in opposite hemifields. When subjects attended to a single feature, parietal, premotor, and anterior cingulate cortex were activated. These effects were strongest in the right hemisphere and were, remarkably, unaffected by the direction of attention. In contrast, direction of attention affected occipital and frontal activity: right occipital and left lateral frontal activity were higher with attention to the left, whereas right lateral frontal activity was higher with attention to the right. When subjects identified two features of the same object, parietal, premotor, and anterior cingulate activity was enhanced further, predominantly this time in the left hemisphere. Again, there was no direction sensitivity. Direction-sensitive activation of lateral frontal cortex also was increased. Finally, when subjects divided their attention over opposite hemifields, activity in the direction-sensitive occipital and frontal regions fell to a level midway between those seen during exclusively leftward or rightward attention. Thus, the behavioral efficiency with which we attend to multiple features of a single peripheral object is paralleled by enhanced activity in structures generally active during peripheral selective attention as well as in structures that depend on the specific direction of attention, most notably lateral frontal cortex. In addition, in the direction-sensitive regions, dividing attention over hemifields causes a compromise pattern between the extreme levels obtained during unilateral attention.