Grey matter microstructural differencesin developmental stuttering

Abstract

Theoretical accounts of developmental stuttering implicate dysfunctional cortico-striatal-thalamo-cortical motor loops through the putamen, but empirical evidence of these proposed differences is currently limited. Conventional MRI data has been used in people who stutter to measure the size or volume of grey matter structures, cortical thickness,and diffusion properties of white matter fibre tracts. Quantitative mapping of brain tissue can reveal detailed maps of microstructural properties of brain tissue in both grey and white matter, but has not yet been assessed in people who stutter. Analysis of these quantitative maps in 41 people who stutter and 32 matched controls revealed significant group differences in maps of R2*, indicative of higher iron content in people who stutter than controls in left cortical regions important for speech motor control and the left putamen. Higheriron levels in brain tissuein people who stutter may be a markerof elevated dopamine levels or lysosomal dysfunction. This study represents the first use of these quantitative measures in developmental stuttering and provides new evidence of structural differences.