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Complementary hemispheric lateralization of language and social processing in left-handers
Poster Session B, Friday, September 12, 4:30 - 6:00 pm, Field House
Cristina Cano Melle1, María Baena Pérez1, José María García Yagüe1, Esteban Villar Rodriguez1, Cesar Avila1; 1universidad Jaume I
One of the oldest findings in human neuroscience is that some cognitive functions are lateralized, predominantly processed in one cerebral hemisphere or in both(Ocklenburg & Güntürkün, 2024). Recent research (Rajimehr et al., 2022) suggest acomplementary hemispheric lateralization for language (typically left-lateralized) and socialprocessing (typically right-lateralized). Here, we extend this line of research by examining these cognitive processes in a sample of left-handed individuals with typical and atypical language lateralization. Using Glasser multimodal cortical parcellation, we assess functional asymmetry in language and social networks. Following the framework proposed by Rajimehr et al. (2022) and the causal hypothesis (Kosslyn, 1987; Hellige, 1990), we hypothesize that individuals with atypical language lateralization will exhibit reversed lateralization patterns. A total of 97 left-handed individuals participated (62 with typical and 35 with atypical language lateralization). Language lateralization was calculated using the LI toolbox from an fMRI verb-generation task. Additionally, participants performed two fMRI tasks adapted from Human Connectome Project task: a) Auditory language task, in which participants listened to adapted fables; b) Social task, in which they watched short videos and indicated whether the scenes depicted social interactions or not. Activations were segmented using Glasser’s multimodal cortical parcellation atlas, focusing on language-related regions and their contralateral homologues. Lateralization patterns were statistically assessed through repeated-measures analyses, comparing the LI values across tasks (language vs. social) and between groups (typical vs. atypical lateralization of language), applying multiple-comparison corrections. Analyses were conducted using SPM12 and SPSS software. Significant hemispheric asymmetries were observed in región such as STSa (F(1,91)=6.71; P= 0.011), PGi (F(1,91)=24.46; P<0.001), PSL (F(1,91) = 14.98; P<.001), Broca (F(1,91)=12.55; P<0.001) and SFL (F(1,91)=3.41; P= 0.068). For language task, the atypical group showed a right lateralization and the typical group a left lateralization in STSa (P<.001), PGi (P <.001), PSL (P <.001), Broca (P <.001) and SFL (P<.001). In the social task, marginal differences were observed only in PGi (p = 0.026) and a trend in SFL (p = 0.075), where the typical group showed right hemisphere lateralization, while the atypical group exhibited reduced lateralization compared to the language task. Our results largely support the regions proposed by Rajimehr et al. (2022) as key language- related areas, as most showed functional lateralization consistent with typical or atypical profiles, defined through a verb-generation task. However, only one region the inferior parietal gyrus exhibited a possible pattern of complementary lateralization across language and social tasks depending on the type of lateralization. This suggests that, although language regions are also engaged during social processing, not all of them clearly reflect the dual hemispheric organization proposed in the previous study.
Topic Areas: Language Development/Acquisition, Language Production