Abstract: Semantic unification, the process that combines word-level semantics into an overall meaning representation of an utterance, is a crucial aspect of language comprehension. Although many brain imaging studies using fMRI and MEG techniques have associated left inferior frontal gyrus (LIFG) and posterior temporal regions with semantic unification, there are also contradictory findings and alternative explanations attributing the observed LIFG activation to other processes such as controlled semantic retrieval and general selection. Based on review of the present empirical evidence and theoretical arguments, future directions are suggested to reveal the mechanism of semantic unification and its underlying neural substrates.

Key words: sentence comprehension, semantic unification, left inferior frontal gyrus