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Neurocognitive sequela of non-canonical sentence comprehension in chronic agrammatic aphasia: eye movement and fMRI correlates of behavioral recovery

Elena Barbieri1*, Jennifer E. Mack1, Brianne Chiappetta1, Eduardo Europa1 and Cynthia K. Thompson1, 2, 3
  • 1 Northwestern University, Department of Communication Sciences and Disorders, United States
  • 2 Northwestern University, United States
  • 3 Northwestern University, Department of Neurology, United States

Eye-tracking and other on-line studies indicate that neurotypical adults assign the role of Agent to the first participant encountered in sentences (i.e. ‘Agent-first’ strategy), which is revised in noncanonical sentences in which the Theme precedes the Agent [1,2]. According to neurocognitive models [3] and neuroimaging evidence in healthy people [4], accessing thematic roles and integrating them into the syntax activates a set of regions in the left hemisphere (LH), which includes the inferior frontal gyrus (IFG), the angular gyrus (AG) and the posterior middle/temporal gyri (pMTG/pSTG). This sentence processing network (SPN, [5]) is often damaged in people with agrammatic aphasia, who show impaired comprehension of noncanonical sentences, such as passivized structures, in off-line (behavioral) and on-line (eye-tracking) tasks [2]. The present study investigated the neurocognitive mechanisms underlying recovery of sentence comprehension in patients with agrammatic aphasia, to determine whether off-line behavioral recovery (1) affects on-line sentence processing strategies, as determined by eye movements, (2) is associated with recruitment of ipsilesional and/or contralesional neural tissue [6,7], and (3) relies on language-specific vs. domain-general networks [8]. Participants with chronic agrammatism were randomly assigned to receive a 3-month language treatment (N=13) focused on comprehension and production of passive sentences (Treatment of Underlying Forms, TUF [9]), or to serve as control participants (N=5). Prior to and following a 3-month treatment/control period, all participants’ comprehension and production of trained sentences, as well as untrained related and unrelated structures was tested. Participants also performed an eyetracking task evaluating on-line passive/active sentence processing, and an fMRI block-design, sentence-picture verification task, in which comprehension of active and passive sentences was alternated with a control condition (scrambled picture presented with reversed speech). Results showed significant pre-post changes in comprehension of trained structures and generalization to untrained related structures in the treatment group, but not in the control group (see Table 1). Significant changes in eye movement also were found for the treated (but not the control) participants, who showed patterns associated with thematic prediction and integration during passive sentence processing at post-treatment that were not evident prior to treatment. Participants in the treatment group also showed increased activation from pre- to post-treatment (i.e. upregulation) in regions homologous to the SPN in the right hemisphere (IFG), as well left hemisphere regions, i.e., the MFG and the SPL, which is part of the dorsal attention networks (DAN) (domain-general), and bilateral occipital regions (see Figure 1). Improved off-line and on-line comprehension were both positively correlated with upregulation in the right hemisphere within both the SPN and DAN regions, however, changes in eye movements were associated only with upregulation in RH homologues of the SPN. These findings indicate that – when the sentence processing network in the LH is disrupted – the RH is recruited to compensate for language deficits. Moreover, the study demonstrates that RH homologues of regions within the sentence processing network, rather than domain-general systems, support recovery of processes that are crucial for comprehension of non-canonical sentences.

Figure 1
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References

[1]. Kamide, Y., Scheepers, C., & Altmann, G.Y. (2003). Journal of Psycholinguistic Research, 32, 37-55
[2]. Mack, J.E., & Thompson, C.K. (2017). Journal of Speech, Language and Hearing Research, 60, 1299-1315.
[3]. Thompson, C.K., & Meltzer-Asscher, A. (2014). In A. Bachrach, I. Roy, & L. Stockall (Eds.), Structuring the Argument: Multidisciplinary research on verb argument structure (pp. 141-168). John Benjamins Publishing Company.
[4]. Mack, J.E., Meltzer-Asscher, A., Barbieri, E., & Thompson, C.K. (2013). Brain sciences, 3(3), 1198-1214.
[5]. Walenski, M., Europa, E., Caplan, D., & Thompson, C.K. (submitted). Human Brain Mapping.
[6]. Fridriksson, J., Richardson, J. D., Fillmore, P., & Cai, B. (2012). NeuroImage, 60(2), 854-863.
[7]. Kiran, S., Meier, E. L., Kapse, K. J., & Glynn, P. A. (2015). Frontiers in Human Neuroscience, 9.
[8]. Geranmayeh, F., Brownsett, S. L., & Wise, R. J. (2014). Brain, 137(10), 2632-2648.
[9]. Thompson, C.K., & Shapiro, L.P (2005). Aphasiology, 19(10-11), 1021-1036.

Keywords: agrammatism, neural plasticity, sentence processing, Language recovery, fMRI, Eye-tracking, treatment of underlying forms

Conference: Academy of Aphasia 56th Annual Meeting, Montreal, Canada, 21 Oct - 23 Oct, 2018.

Presentation Type: oral presentation

Topic: not eligible for a student prize

Citation: Barbieri E, Mack JE, Chiappetta B, Europa E and Thompson CK (2019). Neurocognitive sequela of non-canonical sentence comprehension in chronic agrammatic aphasia: eye movement and fMRI correlates of behavioral recovery. Conference Abstract: Academy of Aphasia 56th Annual Meeting. doi: 10.3389/conf.fnhum.2018.228.00023

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Received: 30 Apr 2018; Published Online: 22 Jan 2019.

* Correspondence: Dr. Elena Barbieri, Northwestern University, Department of Communication Sciences and Disorders, Evanston, ILLINOIS, 60208, United States, elena.barbieri@northwestern.edu