Agenesis of the corpus callosum is the lack of the development of the corpus callosum. This condition can lead to impairments in language processing, epilepsy, and emotion and social functioning, but many individuals with this condition do not show any of these impairments. The present study investigated the connectivity of language and sensorimotor networks within an individual with agenesis of the corpus callosum using resting-state fMRI. The individual’s results were compared to those of neurotypical control subjects. It was hypothesized that the overall interhemispheric functional connectivity would be less than that of a control group in bilateral language networks, but the intrahemispheric connectivity, particularly within the sensorimotor network, would show greater functional connectivity. The results revealed significantly weaker functional connectivity in the individual with agenesis of the corpus callosum within the right ventral stream compared to the control group. There were no other significant inter or intrahemispheric differences in the functional connectivity of the language and sensorimotor networks. These findings lead us to conclude that the right hemisphere’s ventral stream perhaps relies upon connections with the left hemisphere’s language networks to maintain its typical functionality. The results of this study support the idea that, in the case of corpus callosum agenesis, the right language network may contribute differently to language processes than in neurotypical controls.

The distinctions between the neural resources supporting speech and music comprehension have long been studied using contexts like aphasia and amusia, and neuroimaging in control subjects. While many models have emerged to describe the different networks uniquely recruited in response to speech and music stimuli, there are still many questions, especially regarding left-hemispheric strokes that disrupt typical speech-processing brain networks, and how musical training might affect the brain networks recruited for speech after a stroke. Thus, our study aims to explore some questions related to the above topics. We collected task-based functional MRI data from 12 subjects who previously experienced a left-hemispheric stroke. Subjects listened to blocks of spoken sentences and novel piano melodies during scanning to examine the differences in brain activations in response to speech and music. We hypothesized that speech stimuli would activate right frontal regions, and music stimuli would activate the right superior temporal regions more than speech (both findings not seen in previous studies of control subjects), as a result of functional changes in the brain, following the left-hemispheric stroke and particularly the loss of functionality in the left temporal lobe. We also hypothesized that the music stimuli would cause a stronger activation in right temporal cortex for participants who have had musical training than those who have not. Our results indicate that speech stimuli compared to rest activated the anterior superior temporal gyrus bilaterally and activated the right inferior frontal lobe. Music stimuli compared to rest did not activate the brain bilaterally, but rather only activated the right middle temporal gyrus. When the group analysis was performed with music experience as a covariate, we found that musical training did not affect activations to music stimuli specifically, but there was greater right hemisphere activation in several regions in response to speech stimuli as a function of more years of musical training. The results of the study agree with our hypotheses regarding the functional changes in the brain, but they conflict with our hypothesis about musical expertise. Overall, the study has generated interesting starting points for further explorations of how musical neural resources may be recruited for speech processing after damage to typical language networks.