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The neural underpinnings of time comprehension: evidence from 85 left-hemisphere stroke survivors
Poster Session C, Friday, October 25, 4:30 - 6:00 pm, Great Hall 3 and 4
Nicoletta Biondo1,2, Maria V. Ivanova2, Alexis L. Pracar2, Juliana Baldo3, Nina F. Dronkers2,4; 1BCBL, Spain, 2UC Berkeley, USA, 3VA Northern California Health Care System, Martinez (CA), USA, 4UC Davis, USA
People with post-stroke aphasia often struggle to convey temporal information through language. Many studies have focused on the inability of producing correctly inflected verbs (in sentences such as e.g., Tomorrow night the lady … will go to the movies), but time comprehension can also be impaired (e.g., Wenzlaff & Clahsen, 2004; Clahsen & Ali, 2009; Faroqi-Shah & Dickey, 2009; Jonkers & de Bruin, 2009). Crucially, previous studies have investigated time comprehension impairment just behaviorally, by grouping small cohorts of patients based on aphasia type. In this study, we conducted lesion-symptom mapping (LSM) and indirect structural disconnection analyses focusing on the time comprehension abilities of 85 left-hemisphere stroke survivors. To our knowledge, no lesion-symptom mapping study has ever investigated time comprehension. However, based on previous fMRI studies on the comprehension of inflected verb forms by unimpaired individuals (e.g., Tyler et al., 2005; Wright et al., 2011) we expected parts of the left temporal (superior and temporal gyri, MTG and STG) to be involved during time comprehension. Time comprehension abilities were assessed through specific subtests of the CYCLE-R test (Curtiss & Yamada, 1988). In the subtests, participants heard sentences that included a past, present, or future tense verb phrase (e.g., The boy will pour the juice) and had to select the matching picture among 3 line drawings depicting past, present, and future actions (e.g., a boy about to pour juice in a glass; a boy pouring juice; a boy done pouring juice). Neural correlates of successful time comprehension were assessed using univariate LSM with lesion size, age, education, and time post-stroke as covariates (Ivanova et al., 2021). The role of white matter integrity was assessed through correlation analyses (Bonferroni-corrected alpha = 0.0038) between performance in the behavioral test and tract-level disconnection severities calculated via Indirect Structural Disconnection Mapping (Lesion Quantification Toolkit, Griffis et al., 2021). Results of the LSM analysis identified the left mid to posterior MTG and posterior superior temporal sulcus (STS) as crucial for successful time comprehension. Correlation analyses showed that time comprehension was affected by the disconnection of the inferior longitudinal fasciculus in the left hemisphere and corpus callosum (posterior division). Findings from this study provide novel evidence on successful time comprehension relying primarily on spared left posterior temporal regions (STS, MTG) and underlying white matter pathways. These findings also support accounts proposing the involvement of the STS for the processing of complex phenomena such as syntactic ambiguity or anaphora resolutions (e.g., Matchin & Hickock, 2020; Hagoort, 2013) that, similarly to time processing, lie at the interface between syntax and semantics.
Topic Areas: Disorders: Acquired, Syntax and Combinatorial Semantics