Structural neuroplasticity effects of singing in chronic aphasia

Abstract

Singing-based treatments of aphasia can improve language outcomes, but the neural benefits of group-based singing in aphasia are unknown. Here, we set out to determine the structural neuroplasticity changes underpinning group-based singing induced treatment effects in chronic aphasia. Twenty-eight patients with at least mild nonfluent post-stroke aphasia were randomized into two groups that received a 4-month multicomponent singing intervention (singing group) or standard care control group). High-resolution T1-images and multi-shell diffusion-weighted MRI data were collected in two time points (baseline / 5-month). Structural grey and white matter neuroplasticity changes were assessed using language network region-of-interest based voxel-based morphometry (VBM) and quantitative anisotropy based connectometry, and their associations to improved language outcomes (WAB Naming and Repetition) were evaluated. Connectometry analyses showed that the singing group enhanced structural white matter connectivity in the left arcuate fasciculus and corpus callosum as well as in the frontal aslant tract, superior longitudinal fasciculus, and corticostriatal tract bilaterally compared to the control group. Moreover, in VBM, the singing group showed grey matter volume increase in the left inferior frontal cortex (BA44) compared to the control group. The neuroplasticity effects in the left BA44, arcuate fasciculus, and frontal aslant tract correlated with improved naming abilities after the intervention. These findings suggest that in post-stroke aphasia group singing can bring about structural neuroplasticity changes in left frontal language areas and in bilateral language pathways, which underpin treatment-induced improvement in speech production.

Significance Statement Understanding the neural underpinnings of improved language outcomes in aphasia is vital. We utilize longitudinal neuroplasticity measures of both grey and white matter and evaluate their contribution to group-based singing treatment effects in chronic aphasia. The results show that singing intervention induced grey and white matter neuroplasticity changes in the left frontal language-related structures, but also in the right hemisphere (white matter), correlating with improved naming abilities. These results shine light on treatment-induced structural changes in chronic aphasia and improve our understanding of aphasia rehabilitation.