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Understanding and combining words during sentence comprehension in primary progressive aphasia

Jennifer E. Mack1*, M.-Marsel Mesulam1 and Cynthia K. Thompson1
  • 1 Northwestern University, United States

Purpose. Sentence comprehension involves accessing words and integrating them into syntactic and semantic units (e.g., verb-argument integration). Impaired word comprehension is a defining feature of the semantic subtype of PPA (PPA-S) and contributes to impaired sentence comprehension (Gorno-Tempini et al., 2011). However, little work has addressed whether integration of word meanings is impaired in PPA-S. In contrast, the agrammatic (PPA-G) and logopenic (PPA-L) subtypes are associated with relatively preserved word comprehension, and sentence-level impairments have been attributed, respectively, to impaired grammatical processing and working memory (Thompson & Mack, 2014; Wilson, Galantucci, Tartaglia, & Gorno-Tempini, 2012). However, it is not known whether deficits in higher-level word integration processes (e.g., prediction) are present in these subtypes. Thus, the present study examined the processes supporting online verb-argument integration in PPA. Methods. 28 individuals with PPA (12 PPA-G, 10 PPA-L, 6 PPA-S) and 15 unimpaired older adults participated in four eyetracking experiments, in which they viewed arrays of four object pictures. Non-linguistic experiment. A circle appeared around one picture and latencies of eye movements to that picture were measured. Lexical access. Participants heard a noun and clicked on the matching picture. Verb-based integration. Participants heard sentences with restrictive verbs, semantically compatible with only one object, and unrestrictive verbs, compatible with all four objects. After sentence end, participants performed a picture-word verification task. Verb-based prediction. Participants heard sentence fragments with restrictive verbs and clicked on a picture to complete the sentence. Mixed-effects regression was used for data analyses. Results. Non-linguistic experiment. Accuracy was at ceiling and eye movement latencies did not differ significantly between healthy controls and any PPA subtype (Fig. A). Lexical access. Accuracy was significantly greater in all groups compared to PPA-S, and in controls compared to PPA-G. Eye movement data (Fig. B) indicated lexical access delays in all PPA groups (most severe in PPA-S). Verb-based integration. Impaired accuracy and lexical access delays (Fig. C) were observed in PPA-G and PPA-S (most severe in PPA-S). In addition, listeners with PPA-S showed a rapidly-decaying effect of verb meaning. Verb-based prediction. Impaired accuracy and predictive eye movements (Fig. D) were observed in PPA-G, but not in the other PPA groups. Discussion. The PPA-S group showed reduced accuracy and speed of lexical access (cf. Seckin et al. (2016)), and deficits in verb-argument integration (i.e., rapidly decaying verb effects). The slow rise and rapid decay of lexical information may affect linguistic integration processes in PPA-S. The PPA-G group showed mild impairments in lexical access accuracy and speed, both in single-word and sentence contexts. However, this group evinced a marked impairment in verb-based prediction, consistent with previous findings from stroke-induced agrammatism (Mack et al., 2013). The PPA-L group also showed a mild impairment in lexical access latency (but not accuracy). These effects were evident only in the single-word task, consistent with the view that sentence comprehension impairments in PPA-L are not lexically-based (e.g., working memory accounts). Given the comparable performance observed across groups in the non-linguistic experiment, these results cannot be attributed to differences in eye movement control.

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Acknowledgements

This research was supported by the NIH: R01-DC008552 (Mesulam), R01-DC001948 (Thompson), and P50-DC012283 (Thompson). The authors would like to thank the research participants, families, and caregivers, as well as Sarah Chandler and Stephanie Gutierrez for assistance with data collection and analysis.

References

Gorno-Tempini, M. L., Hillis, A. E., Weintraub, S., Kertesz, A., Mendez, M., Cappa, S. F., . . . Grossman, M. (2011). Classification of primary progressive aphasia and its variants. Neurology, 76(11), 1006-1014.
Mack, J. E., Ji, W., & Thompson, C. K. (2013). Effects of verb meaning on lexical integration in agrammatic aphasia: Evidence from eyetracking. Journal of Neurolinguistics, 26(6), 619-636.
Piñango, M. M., & Zurif, E. (2001). Semantic operations in aphasic comprehension: Implications for the cortical organization of language. Brain and Language, 79, 297-308.
Seckin, M., Mesulam, M. M., Voss, J. L., Huang, W., Rogalski, E. J., & Hurley, R. S. (2016). Am I looking at a cat or a dog? Gaze in the semantic variant of primary progressive aphasia is subject to excessive taxonomic capture. Journal of Neurolinguistics, 37, 68-81.
Thompson, C. K., & Mack, J. E. (2014). Grammatical impairments in PPA. Aphasiology, 28(8-9), 1018-1037.
Wilson, S. M., Galantucci, S., Tartaglia, M. C., & Gorno-Tempini, M. L. (2012). The neural basis of syntactic deficits in primary progressive aphasia. Brain and Language, 122(3), 190-198.

Keywords: Aphasia, Aphasia, Primary Progressive, sentence processing, Word Processing, Eye-tracking

Conference: Academy of Aphasia 55th Annual Meeting , Baltimore, United States, 5 Nov - 7 Nov, 2017.

Presentation Type: poster or oral

Topic: General Submission

Citation: Mack JE, Mesulam M and Thompson CK (2019). Understanding and combining words during sentence comprehension in primary progressive aphasia. Conference Abstract: Academy of Aphasia 55th Annual Meeting . doi: 10.3389/conf.fnhum.2017.223.00011

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Received: 27 Apr 2017; Published Online: 25 Jan 2019.

* Correspondence: Dr. Jennifer E Mack, Northwestern University, Evanston, IL, United States, jemack@umass.edu