A structural distance effect for backward anaphora in Broca's area: an fMRI study.

Accounts of the role of Broca's area in sentence comprehension range from specific syntactic operations to domain-general processes. The present study was designed to tease apart these two general accounts by measuring the BOLD response to two syntactically distinct long-distance dependencies that invoke abstractly similar predictive processes: backward anaphora and filler-gap dependencies. Previous research has observed distance effects in Broca's area for filler-gap dependencies, but not canonical anaphora, which has been interpreted in support of a syntactic movement account. However, filler-gap dependencies engage predictive mechanisms, resulting in active search for the gap, while canonical anaphora do not. Backward anaphora correct for this asymmetry as they engage a predictive mechanism that parallels the active search in filler-gap dependencies. The results revealed a distance effect in the pars triangularis of Broca's area for the backward anaphora condition, supporting a prediction-based role for this region rather than one for a particular syntactic operation.