Right hemisphere contribution to metaphor processing in healthy subjects

We studied fourteen healthy volunteers who had previously been found left hemispheric language dominant in a word generation task [6]. To test for figurative language functions, subjects had to judge whether an acoustically presented sentence was a plausible metaphor or not. In addition, a literal sentence task was administered to control for activation related to semantic and syntactic analysis and auditory attention processes (Fig.2). Thirty-two epochs of 60 seconds were recorded in total. Odd epochs contained the literal sentence tasks, even epochs the metaphoric sentence tasks. Both tasks were practised prior to recording. While subjects were working on the tasks, we measured and recorded the cerebral blood flow velocity simultaneously in the left and right middle cerebral artery using transcranial Doppler ultrasonography (Fig.1). We compared the relative cerebral perfusion changes for the left and the right hemisphere during the two tasks. We conclude that, in healthy subjects with the typical left hemispheric language dominance, the processing of figurativ