Behavioral studies of sentence comprehension suggest that processing long-distance dependencies is subject to interference effects when Noun Phrases (NP) similar to the dependency head intervene in the dependency. Neuroimaging studies converge in localizing such effects to Broca's area, showing that activity in Broca's area increases with the number of NP interveners crossed by a moved NP of the same type. To test if NP interference effects are modulated by adding an intervening clause boundary, which should by hypothesis increase the number of successive-cyclic movements, we conducted an fMRI study contrasting NP interveners with clausal (CP) interveners. Our design thus had two components: (I) the number of NP interveners crossed by movement was parametrically modulated; (II) CP-intervention was contrasted with NP-intervention. The number of NP interveners parametrically modulated a cluster straddling left BA44/45 of Broca's area, replicating earlier studies. Adding an intervening clause boundary did not significantly modulate the size of the NP interference effect in Broca's area. Yet, such an interaction effect was observed in the Superior Frontal Gyrus (SFG). Therefore, the involvement of Broca's area in processing syntactic movement is best captured by memory mechanisms affected by a grammatically instantiated type-identity (i.e., NP) intervention.
Bibliographical noteFunding Information:
Partial support for this project was provided by an Alexander von Humboldt Foundation Research Award (YG), SSHRC (standard grand #410-2009-0431), Canada Research Chairs (YG), the Edmond and Lily Safra Center for Brain Research (ELSC, to YG), European Research Council (ERC-2010-360 AdG20100407 awarded to AF) and the German Ministry of Education and Research (BMBF; Grant Nr. 01GW0773 AF).
Copyright © 2015 Santi, Friederici, Makuuchi and Grodzinsky.
- Broca's area
- syntactic processing
- working memory