Prominence vs. aboutness in sequencing: A functional distinction within the left inferior frontal gyrus Ina Bornkessel-Schlesewsky a, * , Tanja Grewe b , Matthias Schlesewsky c a Department of Germanic Linguistics, University of Marburg, Marburg, Germany b Faculty of Health, Hochschule Fresenius University of Applied Sciences, Idstein, Germany c Department of English and Linguistics, Johannes Gutenberg-University, Mainz, Germany article info Article history: Available online xxxx Keywords: Syntactic processing fMRI Left inferior frontal gyrus Superior temporal gyrus Word order Sequencing Prominence Aboutness Information structure German abstract Prior research on the neural bases of syntactic comprehension suggests that activation in the left inferior frontal gyrus (lIFG) correlates with the processing of word order variations. However, there are inconsisten- cies with respect to the specific subregion within the IFG that is implicated by these findings: the pars operc- ularis or the pars triangularis. Here, we examined the hypothesis that the dissociation between pars opercularis and pars triangularis activation may reflect functional differences between clause-medial and clause-initial word order permutations, respectively. To this end, we directly compared clause-medial and clause-initial object-before-subject orders in German in a within-participants, event-related fMRI design. Our results showed increased activation for object-initial sentences in a bilateral network of frontal, temporal and subcortical regions. Within the lIFG, posterior and inferior subregions showed only a main effect of word order, whereas more anterior and superior subregions showed effects of word order and sen- tence type, with higher activation for sentences with an argument in the clause-initial position. These find- ings are interpreted as evidence for a functional gradation of sequence processing within the left IFG: posterior subportions correlate with argument prominence-based (local) aspects of sequencing, while ante- rior subportions correlate with aboutness-based aspects of sequencing, which are crucial in linking the cur- rent sentence to the wider discourse. This proposal appears compatible with more general hypotheses about information processing gradients in prefrontal cortex (Koechlin & Summerfield, 2007). Ó 2010 Elsevier Inc. All rights reserved. 1. Introduction During real time communication, language unfolds over time, and, as a result, language understanding must proceed in a sequen- tial manner. Hence, the order in which the words that make up a sen- tence occur crucially constrains the possible ways in which that sentence can be understood. In view of these considerations, it is not surprising that word order variations have played an exception- ally important role in investigations of the functional neuroanatomy of language processing. Over several languages (e.g. English, Ger- man, Hebrew and Japanese) and different sentence types (relative clauses, questions, declarative sentences), researchers have consis- tently observed increased activation in the left inferior frontal gyrus (lIFG) for sentences with object-before-subject orders in comparison to their subject-initial counterparts (e.g. Just, Carpenter, Keller, Eddy, & Thulborn, 1996; Stromswold, Caplan, Alpert, & Rauch, 1996; Bahlmann, Rodriguez-Fornells, Rotte, & Münte, 2007; Ben- Shachar, Hendler, Kahn, Ben-Bashat, & Grodzinsky, 2003; Ben- Shachar, Palti, & Grodzinsky, 2004; Caplan, Alpert, & Waters, 1998; Caplan, Alpert, Waters, & Olivieri, 2000; Constable et al., 2004; Cooke et al., 2001; Fiebach, Schlesewsky, Lohmann, von Cramon, & Frieder- ici, 2005; Fiebach, Vos, & Friederici, 2004; Friederici, Fiebach, Schlesewsky, Bornkessel, & von Cramon, 2006; Keller, Carpenter, & Just, 2001; Kinno, Kawamura, Shioda, & Sakai, 2008; Röder, Stock, Neville, Bien, & Rösler, 2002). 1 From these findings, it has been concluded that object-initial sentences are more complex to process, leading to measurably increased processing demands in healthy individuals and to comprehension deficits in patient populations (e.g. Caramazza & Zurif, 1976; Drai & Grodzinsky, 2006). 1.1. Prominence information and sequencing Recent research suggests that, rather than being primary to the activation of the lIFG, the relative ordering of subject vs. object is only a subcase of more general requirements concerning the 0093-934X/$ - see front matter Ó 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.bandl.2010.06.004 * Corresponding author. Address: Department of Germanic Linguistics, University of Marburg, Wilhelm-Roepke-Strasse 6A, 35032 Marburg, Germany. Fax: +49 (0) 6421 2824558. E-mail address: iboke@staff.uni-marburg.de (I. Bornkessel-Schlesewsky). 1 Object-initial orders have also been shown to engender different event-related potential (ERP) signatures to their subject-initial counterparts (e.g. Bornkessel, Fiebach, & Friederici, 2004; Felser, Clahsen, & Münte, 2003; Fiebach, Schlesewsky, & Friederici, 2002; Hagiwara, Soshi, Ishihara, & Imanaka, 2007; Matzke, Mai, Nager, Rüsseler, & Münte, 2002; Phillips, Kazanina, & Abada, 2005; Rösler, Pechmann, Streb, Röder, & Hennighausen, 1998; Ueno & Garnsey, 2008; Ueno & Kluender, 2003). Brain & Language xxx (2010) xxx–xxx Contents lists available at ScienceDirect Brain & Language journal homepage: www.elsevier.com/locate/b&l Please cite this article in press as: Bornkessel-Schlesewsky, I., et al. Prominence vs. aboutness in sequencing: A functional distinction within the left inferior frontal gyrus. Brain & Language (2010), doi:10.1016/j.bandl.2010.06.004