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Diffusion tractography reveals pervasive asymmetry of cerebral white matter tracts in the bottlenose dolphin (Tursiops truncatus)

TitleDiffusion tractography reveals pervasive asymmetry of cerebral white matter tracts in the bottlenose dolphin (Tursiops truncatus)
Publication TypeJournal Article
Year of Publication2018
AuthorsWright A.K, Theilmann R.J, Ridgway S.H, Scadeng M.
JournalBrain Structure & Function
Date Published2018/05
Type of ArticleArticle
ISBN Number1863-2653
Accession NumberWOS:000429200400008
KeywordsAnatomy & Morphology; Arcuate fasciculus; asymmetry; Bottlenose dolphin (Tursiops truncatus); brain; chimpanzee; conduction-velocity; continuous auditory vigilance; corpus-callosum; Diffusion tensor imaging (DTI); human brain; lagenorhynchus-obliquidens; language networks; magnetic-resonance images; Neurosciences & Neurology; sound production; Tractography; White matter

Brain enlargement is associated with concomitant growth of interneuronal distance, increased conduction time, and reduced neuronal interconnectivity. Recognition of these functional constraints led to the hypothesis that large-brained mammals should exhibit greater structural and functional brain lateralization. As a taxon with the largest brains in the animal kingdom, Cetacea provides a unique opportunity to examine asymmetries of brain structure and function. In the present study, diffusion tensor imaging and tractography were used to investigate cerebral white matter asymmetry in the bottlenose dolphin (Tursiops truncatus). Widespread white matter asymmetries were observed with the preponderance of tracts exhibiting leftward structural asymmetries. Leftward lateralization may reflect differential processing and execution of behaviorally variant sensory and motor functions by the cerebral hemispheres. The arcuate fasciculus, an association tract linked to human language evolution, was isolated and exhibited rightward asymmetry suggesting a right hemisphere bias for conspecific communication unlike that of most mammals. This study represents the first examination of cetacean white matter asymmetry and constitutes an important step toward understanding potential drivers of structural asymmetry and its role in underpinning functional and behavioral lateralization in cetaceans.

Short TitleBrain Struct. Funct.
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