7/13/2006

Imaging Lapses of Attention

A new Nature Neuroscience article by Weissman, Roberts, Visscher, and Woldorff uses fMRI to identify the neural activity during momentary lapses of attention. The researchers used a version of the local/global task, in which subjects must identify whether one of two letters is an S or and H. On each trial, the subject should either attend to the "global letter," which is made up of a bunch of "local letters," or to the local letters themselves. The target letter is changed on some trials, and repeated on others.

The researchers discovered that lapses of attention (identified through slowing of reaction time) can be predicted on the basis of prestimulus-onset activity reductions in anterior cingulate and right prefrontal regions. After stimulus onset, activity markedly increases in right inferior frontal gyrus, and right temporo-parietal junction. This activity is hypothesized to reflect stimulus-driven reoirenting of attention.

As one would expect, ACC showed greater activation during incongruent (where global & local letters lead to different judgments) than congruent trials, consistent with the emerging view that ACC is responsible for managing conflict and error detection.

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