Anatomy of the Persisylvian language pathways in the living human brian

: A diffusion tensor imaging approach.

Abstract

Language is a unique human ability influenced by genetic, cultural and social factors. Decades of research in the field have identified those brain networks that have made the development of language in humans possible. This PhD thesis introduces three studies that aim to explore the anatomy of the perisylvian
language pathways (three segments of the arcuate fasciculus) both in healthy and pathological condition, using dffusion tensor imaging tractography. First study examined typical developmental trajectories of the perisylvian language network in a normative data of 101 subjects (age range: 9-49 years). After observing
how these pathways mature across life span, second study investigated how these are influenced by genes and environment in a sample of 43 adult twin pairs (26 monozygotic and 17 dizygotic pairs). The results showed that perisylvian language pathways exhibit distinct maturational patterns and vary in respect to
genetic control that guides this process. Familial effects played an important role for those tracts that lateralised early in life (frontal lobe connections), whereas those tracts that continue to remodel throughout adolescence (temporo-parietal connections) were driven more by unique environmental effects. While the
first two studies explored anatomy of perisylvian language pathways in healthy population, third study examined neural correlates in a pathological condition that affects language processing. This study included 61 adults with autism spectrum disorder and 61 matched neurotypical controls. Localised abnormalities were
identified in the left perisylvian language pathways in people with autism spectrum disorder and an association was found between these white matter abnormalities and severity of past language deficits. In conclusion, these findings may be important to furthering our knowledge of the anatomy of the perisylvian language pathways in healthy population. Also, they may facilitate our understanding of possible biological mechanisms that underpin language dysfunction in psychiatric disorders, and lead to new approaches for early diagnosis and treatment.

Date of Award	1 May 2013
Original language	English
Awarding Institution	King's College London
Supervisor	Steven Williams (Supervisor) & Declan Murphy (Supervisor)