Time course of activating brain areas in generating verbal associations

Generating a use for a visual word in comparison with reading the word aloud activates frontal attention areas first (170 ms), a left lateral frontal area next (250 ms), and then a left temporo-parietal (Wernicke's) area (650 ms). A brief period of practice reduces these activations. If subjects are asked to respond to a word from the same practiced list by giving a novel use, the original activations reappear and are joined by activity similar in location and time to Wernicke's activation but in the right hemisphere. These findings demonstrate the time course of activations of neuroanatomical areas in word processing and indicate a role for the right hemisphere when semantic processing is more difficult, such as in generating a less frequent association in the presence of a highly practiced one.