Date of Award


Degree Type


Degree Name

Master of Arts (MA)



First Advisor

Bruce Crosson


The neuroanatomy of language cognition has an extensive history of scientific interest and inquiry. Over a century of behavioral lesion studies and decades of functional neuroimaging research have established the left hemisphere’s inferior frontal gyrus (IFG) as a critical region for speech and language processing. This region’s subcortical projections are thought to be instrumental for supporting and integrating the cognitive functions of the language network. However, only a subset of these projections have been shown to exist in humans, and structural evidence of pars orbitalis’ subcortical circuitry has been limited to non-human primates. This thesis demonstrates direct, intra-structural connectivity of each of the left IFG’s gyral regions with the thalamus and the putamen in humans, using high-angular, deterministic tractography. Novel processing and analysis methods elucidated evidence of predominantly segregated cortical circuits within the thalamus, and suggested the presence of parallel circuits for motor/language integration along the length of the putamen.