Brain regions exhibiting neuroplasticity and reorganization associated with spontaneous recovery from stuttering and therapy-induced improvements.

Colored areas display key cortical brain structures and arrows illustrate fiber connections involved in stuttering and its remission. Notably, spontaneous recovery in children shows a subcortical-to-cortical structural neuroplasticity gradient [76,77,79], whereas therapy-driven improvement in adults reveals functional reorganization within and beyond the speech network [40,45,48,95–103]. Yellow areas indicate greater reorganization potential, while green areas indicate medium potential, and purple areas indicate lesser potential. The purple areas in the panel for children indicate brain structures where the volume reduction was negatively correlated with the severity of stuttering in children with persistent stuttering, while the growth rate did not change or even reversed in children with spontaneous recovery [77]. Noticeably, this is a simplified illustration; reorganization potential dependents on various factors and evidence levels vary for the individual brain regions. Abbreviations: Ac, nucleus accumbens; AF, arcuate fasciculus; aSTG, anterior superior temporal gyrus; Ca, caudate nucleus; Cb, cerebellum; CC, corpus callosum; dMC, dorsal primary motor cortex; dPMC, dorsal premotor cortex; FAT, frontal aslant tract, FO, frontal operculum; Gp, globus pallidus; IFG, inferior frontal gyrus; ILF, inferior longitudinal fasciculus; IFGorb, inferior frontal gyrus pars orbitalis; MT, motor tracts; pSTG, posterior superior temporal gyrus; PO, parietal operculum; Pu, putamen; SLF, superior longitudinal fasciculus; SMA, supplementary motor area, SMG, supramarginal gyrus; Th, thalamus; vMC, ventral primary motor cortex; vPMC, ventral premotor cortex.