ATTENTIONAL NETWORKS

Recent brain-imaging and neurophysiological data indicate that attenti on is neither a property of a single brain area, nor of the entire bra in. While attentional effects seem mediated by a relative amplificatio n of blood flow and electrical activity in the cortical areas processi ng the attended computation, the details of how this is done through e nhancement of attended or suppression of unattended items, or both, ap pear to depend on the task and brain-area studied. The origins of thes e amplification effects are to be found in specialized cortical areas of the frontal and parietal lobes that have been described as the ante rior and posterior attention systems. These results represent substant ial progress in the effort to determine how brain activity is regulate d through attention. While many philosophical and practical issues rem ain in developing an understanding of attentional regulation, the new tools available should provide the basis for progress.