Common and dissociable activation patterns associated with controlled semantic and phonological processing: Evidence from fMRI adaptation

Recent evidence suggests specialization of anterior left inferior prefrontal cortex (aLIPC; ∼BA 45/47) for controlled semantics and of posterior LIPC (pLIPC; ∼BA 44/6) for controlled phonology. However, the more automated phonological tasks commonly used raise the possibility that some of the typically extensive aLIPC activation during semantic tasks may relate to controlled language processing beyond the semantic domain. In the present study, an event-related fMRI adaptation paradigm was employed that used a standard controlled semantic task and a phonological task that also emphasized controlled processing. When compared with letter (baseline) processing, significant fMRI task and adaptation effects in the aLIPC and pLIPC regions (∼BA 45/47, ∼BA 44) were observed during both semantic and phonological processing, with aLIPC showing the strongest effects during semantic processing. A left frontal region (∼BA 6) showed task and relative adaptation effects preferential for phonological processing, and a left temporal region (∼BA 21) showed task and relative adaptation effects preferential for semantic processing. Our results demonstrate that aLIPC and pLIPC regions are involved in controlled processing across multiple language domains, arguing against a domain-specific LIPC model and for domain-preferentiality in left posterior frontal and temporal regions.