fMRI results: normal subjects, intraparietal
The normal data for intraparietal sulcus are rather interesting: they show an activation ipsilateral to the attended hemifield, or contralateral to the unattended hemifield. In line with a couple of recent studies which have found that intraparietal sulcus activity varies as a function of the irrelevant information in the stimulus, we suggest that intraparietal sulcus is involved in active suppression of irrelevant stimuli.

In our paradigm, in which subjects are constantly anticipating another shift and attention therefore may not settle fully on one hemifield or the other, this process of late attentional suppression may act in a complementary role to early attentional selection: any input from the unattended field that manages to squeak through the early attentional gate is actively suppressed at this later stage.

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`fMRI Evidence for Generalised Arousal as a Substitute for Early Selection in Autism during Conditions of Shifting Visual Spatial Attention', Matthew Belmonte, 10 November 2001