Lexical retrieval constrained by sound structure: the role of the left inferior frontal gyrus |
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Authors: | Sharp David J Scott Sophie K Cutler Anne Wise Richard J S |
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Institution: | aMRC Clinical Sciences Centre, Cyclotron Unit, Hammersmith Hospital, London W12 0NN, UK;bMax Planck Institute of Psycholinguistics, Nijmegen, The Netherlands |
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Abstract: | Positron emission tomography was used to investigate two competing hypotheses about the role of the left inferior frontal gyrus (IFG) in word generation. One proposes a domain-specific organization, with neural activation dependent on the type of information being processed, i.e., surface sound structure or semantic. The other proposes a process-specific organization, with activation dependent on processing demands, such as the amount of selection needed to decide between competing lexical alternatives. In a novel word retrieval task, word reconstruction (WR), subjects generated real words from heard non-words by the substitution of either a vowel or consonant. Both types of lexical retrieval, informed by sound structure alone, produced activation within anterior and posterior left IFG regions. Within these regions there was greater activity for consonant WR, which is more difficult and imposes greater processing demands. These results support a process-specific organization of the anterior left IFG. |
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Keywords: | PET Word retrieval Vowel Consonant Left inferior frontal gyrus Lexical Word generation |
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