Virtual lesions and the not-so-modular brain.

Because lesions usually affect contiguous areas of the brain, cognitive neuropsychology has generally posited modularity of brain function, assuming that specific regions of the brain have specific dedicated functions. However, a review of 36 published functional neuroimaging studies suggests that functions are distributed over multiple regions. Or, in other words, specific brain regions are usually multifunctional. By a technique of "virtual lesions," I measure the contribution that regions of the brain make to tasks imaged in 36 PET experiments, and propose a new and more detailed interlink between neuropsychology and functional neuroimaging.