Poster Session D, Monday, March 25, 8:00 – 10:00 am, Pacific Concourse
Genetic topology of the language network
Roeland Hancock1; 1University of Connecticut
Genetic correlation (rG) describes the proportion of covariance between two phenotypes attributable to shared genetic factors. rG analysis was applied to functional activation (beta) values from the narrative comprehension fMRI task (Binder 2011) of the preprocessed Human Connectome Project (HCP) young adult data (Barch et al., 2013). The twin-based sample was split into test and validation samples (approximately 120 monozygotic and 120 dizygotic pairs per split) to verify the reliability of clusters. Genetic correlations were estimated between each vertex within left inferior frontal cortex (IFC; including BA44, BA45, BA47 and FOP) and every other vertex in the left hemisphere using a bivariate additive-environmental model to obtain a measure of genetic similarity between each vertex in the IFC. The genetic similarity matrix was used to partition the IFC, resulting in 4 clusters. A cluster spanning BA44/45 largely reproduced current models of dorsal stream language architecture, with significant genetic correlation between IFG, posterior STS, perisylvian cortex and angular gyrus. A cluster spanning inferior BA45 and posterior BA47 was suggestive of a ventral language stream, having significant genetic correlations with middle temporal gyrus/TE2. These results provide novel confirmation of current understanding of language networks, showing that a broad dorsal/ventral stream distinction is also supported by genetic differentiation of the two streams. In contrast, there was no evidence for genetic similarity between the IFC and the aTL. This suggests that aTL language functions may be mediated by genetic factors distinct from those that shape function in the majority of the language network.
Topic Area: LANGUAGE: Syntax