Address for correspondence: mkb4@Cornell.edu

ABSTRACT: Although the effects of static allocations of visual spatial attention have been investigated using event-related potentials, most studies of shifts in visual spatial attention have been limited to behavioural measures. This study applied electroencephalographic measures to shifts in visual spatial attention in an effort to elucidate the time courses of such shifts. Using a custom-developed steady-state evoked potential analysis system, we analysed amplitude changes in phase-locked and non-phase-locked EEG responses to rapid, periodic visual stimulation during a behavioural task that required rapid, repetitive shifts in visual spatial attention. This analysis revealed a transient increase in phase-locked amplitude, in the interval 0-300ms post-stimulus, contralateral to the visual hemifield in which an attended target appeared. The magnitude of this increase varied with the length of the interval since the previous shift. In addition, by about 600ms post-stimulus, phase-locked amplitude increased in the hemisphere contralateral to the newly attended visual hemifield and decreased in the ipsilateral hemisphere. In the case of long inter-target intervals, phase-locked amplitude increased in the right hemisphere regardless of the laterality of the target. Non-phase-locked amplitude exhibited a complementary pattern of modulation: it decreased contralaterally to the newly attended visual hemifield and increased ipsilaterally. These components may be electrophysiological concomitants of both transient and long-lasting alterations in neural function that implement shifts in visual spatial attention. In particular, we suggest that they may reflect orienting to a target stimulus, and reorienting to a cued location.

• Introduction
• Methods
• Results
• Discussion
• Acknowledgements
• References

CITED IN PUBLICATIONS BY OTHERS:

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CITED IN MY OTHER PUBLICATIONS:

1. Belmonte MK, Yurgelun-Todd DA. Anatomic dissociation of selective and suppressive processes in visual attention. NeuroImage 19(1):180-189 (May 2003).
2. Belmonte MK, Yurgelun-Todd DA. Functional anatomy of impaired selective attention and compensatory processing in autism. Cognitive Brain Research 17(3):651-664 (October 2003).