The time-course and spatial distribution of brain activity associated with sentence processing Jonathan Brennan a, ⁎, Liina Pylkkänen b, c a Department of Radiology, The Children's Hospital of Philadelphia, USA b Department of Linguistics, New York University, USA c Department of Psychology, New York University, USA abstract article info Article history: Received 24 June 2010 Revised 29 December 2011 Accepted 2 January 2012 Available online 9 January 2012 Keywords: MEG Language comprehension Sentence processing aTL vmPFC LIFG Sentence comprehension involves a host of highly interrelated processes, including syntactic parsing, seman- tic composition, and pragmatic inferencing. In neuroimaging, a primary paradigm for examining the brain bases of sentence processing has been to compare brain activity elicited by sentences versus unstructured lists of words. These studies commonly find an effect of increased activity for sentences in the anterior tem- poral lobes (aTL). Together with neuropsychological data, these findings have motivated the hypothesis that the aTL is engaged in sentence level combinatorics. Combinatoric processing during language comprehen- sion, however, occurs within tens and hundreds of milliseconds, i.e., at a time-scale much faster than the tem- poral resolution of hemodynamic measures. Here, we examined the time-course of sentence-level processing using magnetoencephalography (MEG) to better understand the temporal profile of activation in this com- mon paradigm and to test a key prediction of the combinatoric hypothesis: because sentences are interpreted incrementally, word-by-word, activity associated with basic linguistic combinatorics should be time-locked to word-presentation. Our results reveal increased anterior temporal activity for sentences compared to word lists beginning approximately 250 ms after word onset. We also observed increased activation in a net- work of other brain areas, extending across posterior temporal, inferior frontal, and ventral medial areas. These findings confirm a key prediction of the combinatoric hypothesis for the aTL and further elucidate the spatio-temporal characteristics of sentence-level computations in the brain. © 2012 Elsevier Inc. All rights reserved. Introduction A broad neuroimaging literature has sought to identify neural ac- tivity associated with the cognitive operations engaged during the processing of sentences. A primary experimental design that has been used in this literature compares brain activity elicited when sub- jects read or listen to sentences to that observed for lists of words (Friederici et al., 2000; Humphries et al., 2005, 2006; Jobard et al., 2007; Mazoyer et al., 1993; Rogalsky and Hickok, 2009; Snijders et al., 2009; Stowe et al., 1998; Vandenberghe et al., 2002; Xu et al., 2005). This contrast has the desirable property that both conditions are likely to require an equivalent degree of word-level processing, but only the sentences are assumed to require processing associated with building and comprehending sentence structure. In this comparison, sentence- processing commonly leads to increased activity in the anterior temporal lobe (aTL; see e.g. Rogalsky and Hickok, 2009; Stowe et al., 2005 for discussion), a finding consistent across both the auditory (Friederici et al., 2000; Humphries et al., 2005, 2006; Jobard et al., 2007; Mazoyer et al., 1993; Rogalsky and Hickok, 2009) and visual (Jobard et al., 2007; Stowe et al., 1998; Vandenberghe et al., 2002) modalities. The majority of these studies report bilateral activation, with a stronger effect in the left hemisphere, while a subset have reported just a left-lateralized effect (Humphries et al., 2006; Vandenberghe et al., 2002). Sentence processing is, of course, a complicated and multi-faceted task that is comprised of a host of separate computations, including the construction of sentence structure (syntactic parsing), the com- position of complex meaning (semantic composition), the establish- ment of long distance dependencies, the determination of reference, and the drawing of pragmatic inferences. Thus, the cognitive opera- tions involved in sentence processing differ substantially from those engaged by lists of words. While the functional role of the aTL is, ac- cordingly, under-determined by the results from the sentence vs. word list comparison, the neuroimaging results together with defi- cit/lesion studies (Dronkers et al., 1994, 2004) have lead to hypothe- ses linking the aTL with aspects of linguistic composition (Pallier et al., 2011; Snijders et al., 2009), perhaps syntactic structure building (Grodzinsky and Friederici, 2006; Humphries et al., 2006), or incre- mental semantic composition (Stowe et al., 2005; Vandenberghe et al., 2002). A connection between this region and basic combinatory NeuroImage 60 (2012) 1139–1148 ⁎ Corresponding author at: Radiology Department, The Children's Hospital of Philadelphia, Wood Building, Second Floor, Suite 2115, 34th Street and Civic Center Blvd., Philadelphia, PA, 19104, USA. E-mail address: Brennanj3@email.chop.edu (J. Brennan). 1053-8119/$ – see front matter © 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.neuroimage.2012.01.030 Contents lists available at SciVerse ScienceDirect NeuroImage journal homepage: www.elsevier.com/locate/ynimg