Poster B11, Tuesday, August 20, 2019, 3:15 – 5:00 pm, Restaurant Hall
The effect of left and right hemisphere lesions on discourse production
Dimitrios Tsolakopoulos1, Georgia Angelopoulou1, Georgios Papageorgiou1, Krystalli Gryllou1, Sofia Vassilopoulou2, Dionysios Goutsos3, Dimitrios Kasselimis1,4, Constantin Potagas1;1Neuropsychology and Language Disorders Unit, 1st Neurology Department, Eginition Hospital, Faculty of Medicine, National and Kapodistrian University of Athens, 2Stroke Unit, 1st Neurology Department, Eginition Hospital, Faculty of Medicine, National and Kapodistrian University of Athens, 3Department of Linguistics, School of Philosophy, National and Kapodistrian University of Athens, 4Division of Psychiatry and Behavioral Sciences, School of Medicine, University of Crete
Introduction Data derived from functional brain imaging (Troiani et al., 2008) and lesion studies (Ulatowska, North, & Macaluso-Haynes, 1981) strongly suggest that the left hemisphere is involved in including discourse production. Nevertheless, the right hemisphere is shown to be also involved in language, especially when it comes to discourse production (Alexandrou, Saarinen, Mäkelä, Kujala, & Salmelin, 2017). Contemporary lesion studies seem to be in accordance with this notion, by highlighting deficits related to the macrostructure of discourse production, after right hemisphere damage (Bartels-Tobin & Hinckley, 2005; Marini, 2012). In order to further investigate this issue, we attempted to assess possible deficits in discourse production in two groups of post-stroke patients: individuals with right hemisphere damage and left-lateralized lesions resulting in aphasia. Methods 10 patients (3 women) with aphasia due to left hemisphere stroke (LHS), 9 patients with right hemisphere stroke (5 women) (RHS) and 10 healthy participants, were recruited for the study. Patients with aphasia were recruited on the basis of a minimum speech rate criterion (≥50 words per minute) All participants were native Greek speakers. The groups were matched for age and formal years of schooling. Cookie Theft picture from the Boston Diagnostic Aphasia Examination was used to elicit speech samples. Speech samples were then transcribed and evaluated with regard to semantic content. The evaluation of the main concepts of discourse was based on methodology previously reported by Nicholas & Brookshire (1995). In particular, the picture corresponded to seven Content Units (CU). Each CU was marked as AC (accurate), AI (accurate incomplete), IN (incomplete), or AB (Absent). Results An Analysis of Variance showed significant differences between the two groups with regard to AC; F(2,26)=4.601, p=.019, η_p^2=.261. Post-hoc pairwise comparisons using Scheffe revealed significant differences between controls and LHS (p=.019), but not between LHS and RHS (p=.371) or controls and RHS (p=.332). It should be however noted that RHS demonstrated lower performance than controls and were superior to LHS. ANOVAs with AI, IN, and AB as dependent variables did not yield significant results. Conclusions As expected, our results show a clear-cut negative effect of left brain damage on the macrostructure of discourse production. Interestingly, individuals with RHS were superior to LHS patients, but demonstrated lower performance compared to controls. However, in contrast with recent studies, the difference between controls and RHS failed to reach significance. This could be attributed either to small sample or to the fact that description of the Cookie Theft Picture poses low demands in terms of cognitive load. In the latter case, RHS patients could face difficulties in organizing semantic aspects in order to provide a coherent narrative, but those are revealed only when the task is of increased complexity, and thus more demanding. Associations with lesion sites are also discussed.
Themes: Disorders: Acquired, Language Production
Method: Behavioral