The neurobiology of agrammatic sentence comprehension: A lesion study

Corianne Reddy, Arianna N. LaCroix, Kuan Hua Chen, Steven W. Anderson, Hanna Damasio, Tracy Love, Gregory Hickok

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    Abstract

    Broca’s area has long been implicated in sentence comprehension. Damage to this region is thought to be the central source of “agrammatic comprehension” in which performance is substantially worse (and near chance) on sentences with noncanonical word orders compared with canonical word order sentences (in English). This claim is supported by functional neuroimaging studies demonstrating greater activation in Broca’s area for noncanonical versus canonical sentences. However, functional neuroimaging studies also have frequently implicated the anterior temporal lobe (ATL) in sentence processing more broadly, and recent lesion-symptom mapping studies have implicated the ATL and mid temporal regions in agrammatic comprehension. This study investigates these seemingly conflicting findings in 66 left-hemisphere patients with chronic focal cerebral damage. Patients completed two sentence comprehension measures, sentence-picture matching and plausibility judgments. Patients with damage including Broca’s area (but excluding the temporal lobe; n = 11) on average did not exhibit the expected agrammatic comprehension pattern-for example, their performance was >80% on noncanonical sentences in the sentence-picture matching task. Patients with ATL damage (n = 18) also did not exhibit an agrammatic comprehension pattern. Across our entire patient sample, the lesions of patients with agrammatic comprehension patterns in either task had maximal overlap in posterior superior temporal and inferior parietal regions. Using voxel-based lesion-symptom mapping, we find that lower performances on canonical and noncanonical sentences in each task are both associated with damage to a large left superior temporal-inferior parietal network including portions of the ATL, but not Broca’s area. Notably, however, response bias in plausibility judgments was significantly associated with damage to inferior frontal cortex, including gray and white matter in Broca’s area, suggesting that the contribution of Broca’s area to sentence comprehension may be related to task-related cognitive demands.

    Original languageEnglish (US)
    Pages (from-to)234-255
    Number of pages22
    JournalJournal of Cognitive Neuroscience
    Volume30
    Issue number2
    DOIs
    StatePublished - Feb 1 2018

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    ASJC Scopus subject areas

    • Cognitive Neuroscience

    Cite this

    Reddy, C., LaCroix, A. N., Chen, K. H., Anderson, S. W., Damasio, H., Love, T., & Hickok, G. (2018). The neurobiology of agrammatic sentence comprehension: A lesion study. Journal of Cognitive Neuroscience, 30(2), 234-255. https://doi.org/10.1162/jocn_a_01200