Word order and Broca's region: evidence for a supra-syntactic perspective

It has often been suggested that the role of Broca's region in sentence comprehension can be explained with reference to general cognitive mechanisms (e.g. working memory, cognitive control). However, the (language-related) basis for such proposals is often restricted to findings on English. Here, we argue that an extension of the database to other languages can shed new light on the types of mechanisms that an adequate account of Broca's region should be equipped to deal with. This becomes most readily apparent in the domain of word order variations, which we examined in German verb-final sentences using event-related fMRI. Our results showed that activation in the pars opercularis--a core subregion of Broca's area--was not only modulated by the relative ordering of subject and object, but also by a further factor known to affect word order in a number of languages, namely referentiality. Notably, the finding provides the first demonstration of a word order-related activation difference within subject-initial sentences in this region. Additional parametric analyses using individual behavioral data as predictors further attest to the independence of the pars opercularis activation from: (a) sentence acceptability, and (b) difficulty in performing the experimental (judgment) task. We argue that these and related findings attest to the need for a processing mechanism that can manipulate predicate-independent, interacting and hierarchically structured relational representations during real time comprehension. These properties pose a challenge to existing accounts of pars opercularis function.