How left inferior frontal cortex participates in syntactic processing: Evidence from aphasia☆

Abstract

We report on three experiments that provide a real-time processing perspective on the poor comprehension of Broca's aphasic patients for non-canonically structured sentences. In the first experiment we presented sentences (via a Cross Modal Lexical Priming (CMLP) paradigm) to Broca's patients at a normal rate of speech. Unlike the pattern found with unimpaired control participants, we observed a general slowing of lexical activation and a concomitant delay in the formation of syntactic dependencies involving "moved" constituents and empty elements. Our second experiment presented these same sentences at a slower rate of speech. In this circumstance, Broca's patients formed syntactic dependencies as soon as they were structurally licensed (again, a different pattern from that demonstrated by the unimpaired control group). The third experiment used a sentence-picture matching paradigm to chart Broca's comprehension for non-canonically structured sentences (presented at both normal and slow rates). Here we observed significantly better scores in the slow rate condition. We discuss these findings in terms of the functional commitment of the left anterior cortical region implicated in Broca's aphasia and conclude that this region is crucially involved in the formation of syntactically-governed dependency relations, not because it supports knowledge of syntactic dependencies, but rather because it supports the real-time implementation of these specific representations by sustaining, at the least, a lexical activation rise-time parameter.

Aging and syntactic representations: Evidence of preserved syntactic priming and lexical boost.

“…Therefore, one way to explain both our finding and that of previous aging syntax research is that, whereas underlying syntactic representations do not change with age, the ability to access the representations of complex syntactic structures in unsupported (i.e., unprimed) situations does decline in old age. This explanation draws parallels with a debate in the aphasia literature, specifically whether aphasia results in a complete degradation of syntactic knowledge (Grodzinsky, 1984(Grodzinsky, , 2000 or just a loss of rapid access to the relevant syntactic knowledge (Burkhardt, Avrutin, Piñango, & Ruigendijk, 2008;Love, Swinney, Walenski, & Zurif, 2008). Indeed, there is evidence that syntactic priming is maintained in aphasics despite profound impairments in language production and comprehension (Hartsuiker & Kolk, 1998;Verreyt et al, 2013).…”

Sentence comprehension disorders in aphasia: The concept of chance performance revisited

“…Such an absence of priming effects restricted to Broca's aphasia was originally interpreted as consistent with the hypothesis of deleted traces (TDH) and impaired syntactic processing. Later studies, however, demonstrated that, although reactivation of the antecedent of the trace may be absent at the trace/gap-site, the effect can still be observed in Broca's aphasia, although in a delayed fashion at later points in the sentence (Burkhardt, Pinango, & Wong, 2003;Love, Swinney, Walenski, & Zurif, 2008;Love, Swinney, & Zurif, 2001). Interestingly, gap-filling effects similar to those of unimpaired listeners can still be found in Broca's aphasia when sentences are presented with a slower-than-normal speech rate and, therefore, with a gap-site that is longer lasting (Love et al, 2008).…”

Comprehension and production of movement-derived sentences by Russian speakers with agrammatic aphasia

“…This impairment is typically associated with lesions that include Broca's area (left IFG, including Brodmann areas 44 and 45) (e.g., Alexander, Naeser, & Palumbo, 1990;Zurif, 1995). The left IFG has been consistently linked to syntactic processing, across a wide range of approaches and methods (Berndt & Caramazza, 1980;Caplan, Alpert, & Waters, 1998Constable et al, 2004;Damasio & Damasio, 1989;Dapretto & Bookheimer, 1999;Embick, Marantz, Miyashita, O'Neil, & Sakai, 2000;Friedmann & Shapiro, 2003;Grodzinsky, 2000Grodzinsky, , 2006Love, Swinney, Walenski, & Zurif, 2008;Luke, Liu, Wai, Wan, & Tan, 2002;Stromswold, Caplan, Alpert, & Rauch, 1996;Swinney & Zurif, 1995;Zurif, 1995). Specifically, brain imaging studies have reported consistent activations in Broca's area in response to sentences that are derived by syntactic movement, such as relative clauses and topicalization, structures that have been tested in the current study as well, and which load onto the CP layer (Ben-Shachar, Hendler, Kahn, Ben-Bashat, & Grodzinsky, 2003;Ben-Shachar, Palti, & Grodzinsky, 2004;Constable et al, 2004;Grodzinsky & Friederici, 2006;Grodzinsky & Santi, 2008;Just, Carpenter, Keller, Eddy, & Thulborn, 1996;Stromswold et al, 1996).…”