Poster D61, Wednesday, August 21, 2019, 5:15 – 7:00 pm, Restaurant Hall
Grey and white matter structures associated with temporal aspects of speech: Are different genres supported by distinct brain networks?
Georgia Angelopoulou1, Dimitrios Kasselimis1,2, Michel Rijntjes3, Marco Reisert4, Dimitrios Tsolakopoulos1, Georgios Papageorgiou1, Anna-Maria Psaroba5, Christina Petrakou5, Maria Varkanitsa6, Georgios Velonakis7, Efstratios Karavasilis7, Dimitrios Kelekis7, Dionysios Goutsos8, Micheal Petrides9, Cornelius Weiller10, Constantin Potagas1;1Neuropsychology and Language Disorders Unit, 1st Neurology Department, Eginition Hospital, Faculty of Medicine, National and Kapodistrian University of Athens, 2Division of Psychiatry and Behavioral Sciences, School of Medicine, University of Crete, 3Department of Neurology and Neurophysiology, University Hospital Freiburg, 4Medical Physics, Department of Diagnostic Radiology, Faculty of Medicine, University Freiburg, 5Panteion University of Athens, 6Massachusetts General Hospital - Harvard Medical School, 7Radiology and Medical Imaging Research Unit, University of Athens, 8Department of Linguistics, School of Philosophy, National and Kapodistrian University of Athens, 9Montreal Neurological Institute, Department of Neurology and Neurosurgery and Department of Psychology, McGill University, 10Department of Neurology, University Medical Center, University of Freiburg
Introduction During the last decades, accumulating evidence from different disciplines indicates that there are quantitative and qualitative differences between narratives derived from various elicitation tasks in clinical populations, as well as healthy speakers (Armstrong, 2000; Efthymiopoulou et al., 2017). It has been argued that such discrepancies may reflect disparate cognitive demands and are possibly associated with discrete brain networks(. This study aims to investigate grey and white matter correlates of silent pauses, a measure thought to reflect speech planning and word retrieval, in two distinct narrative tasks, i.e. a picture description and a personal event narration in healthy individuals. Methods Sixty healthy participants, monolingual Greek speakers (27 males), 19-65 years old, with 6-24 years of education and no history of neurological or psychiatric disorders participated in the study. Narration tasks consisted of Cookie theft picture description and a personal medical event. Speech samples were recorded and then transcribed and silent pauses were annotated with ELAN software. Cortical surfaces from the 3D T1-weighted were reconstructed using the automated pipeline of FreeSurfer 6.0.0. (http://www.surfter.nmr.mgh.harvard.edu/). We run separate whole brain general linear models for pause frequency and duration for each narration task and three brain metrics (surface area, cortical thickness, grey matter volume). Monte Carlo simulations were used to correct all vertex-wise results at an individual vertex level of p < 0.05 (Hagler, Saygin, & Sereno, 2006). 30-directional DTI protocol was also acquired, and white matter fibers were reconstructed using the global tractography approach implemented in DTI&Fibertools (Reisert et al., 2011). Results Picture description: Whole brain GLMs revealed an inverse association between pause duration and surface area in two clusters (pars opercularis, p = 0.0002 and superior frontal gyrus, p = 0.0026). Pause duration was also negatively correlated with arcuate fasciculus mean FA (r= -0.348, p = 0.009) and positively correlated with arcuate fasciculus volume (r= 0.361, p = 0.006), while no significant correlation appeared for pause frequency. In all analyses, age, years of education and total duration of narratives were used as nuisance variables. Personal story: Whole brain analysis GLMs revealed a weak positive association between pause frequency and surface area in one cluster (superior parietal lobule, p=0.048). Pause duration was positively correlated with temporofrontal extreme capsule (tfEmC) mean FA (r=0.418, p=0.001). Additionally, pause frequency was negatively correlated with tfEmC volume (r= -0.342, p = 0.010) and positively correlated with tfEmC mean FA (r= 0.348, p = 0.009). In all analyses, age, years of education and total duration of narratives were used as nuisance variables. Discussion Our results clearly indicate a dissociation pattern regarding pauses’ grey and white matter structural correlates in the two narration genres. Pauses during picture description are associated with dorsal stream areas, while pauses during free narration are correlated with cortical and subcortical structures involved in the ventral stream (Saur et al., 2008). Overall, we argue that silent intervals during speech follow distinct patterns, depending on task types possibly reflecting different cognitive processing routes, which in turn may be supported by different brain networks.
Themes: Language Production, Meaning: Lexical Semantics
Method: Other