Functional Specialization for Case processing and Phonotactics in LIFG: Improving tests for functional specialization?

Abstract

The left inferior frontal gyrus (LIFG) is a node in the language network associated with different linguistic processing tasks. A meta-analysis by Bookheimer (Bookheimer, 2002) suggests that there is functional specialization for different linguistic processing tasks as for example semantics, syntax and phonology in the LIFG. This has not been experimentally tested in a within subject experiment. To experimentally test whether there is functional specialization in the LIFG for different domains of linguistic processing we presented German sentences containing either a case violation (syntactic manipulation) or a phonotactically illegal German sound cluster (phonotactic manipulation) to 26 Gerrnan native speakers in an event-related fMRI experiment. Looking at three Rüls in the LIFG, the pars opercularis, the pars triangularis and the pars orbitalis, we found that both manipulations activated the pars opercularis and the pars triangularis. We further analyzed our data to test for functional specialization for phonotactic and syntax by comparing the coordinates of peaks of clusters activated by the two violations at the single subject level. We did not find significant differences between the coordinate values for syntactic and phonotactic manipulations. Our data does not support functional specialization in the LIFG for phonotactics and syntax.