Although the effect of inhibitory repetitive transcranial magnetic stimulation (rTMS) for the treatment of non-fluent aphasia has been successfully explored, the exact mechanism associated with the neuroplasticity of this regimen remains unclear.

Twenty-two patients with sustained chronic non-fluent aphasia for more than 6 months after left hemispheric stroke were recruited for this randomized, sham-controlled, double-blind parallel study. Patients in the experimental group (n=11) received real 1Hz rTMS intervention over right (R) pars triangularis for 10 consecutive weekdays and were compared with the sham stimulation (n=11). All patients underwent resting-state functional magnetic resonance imaging (fMRI) and Concise Chinese Aphasia Test (CCAT) pre- and post-rTMS intervention.

After intervention, the experimental group exhibited significantly superior results in total CCAT score, expression, conversation and description subtests (P<0.05). After rTMS, fractional amplitude of low frequency fluctuations (fALFF) significantly more active in several cortical and subcortical areas including R superior temporal pole (BA 38), R superior temporal gyrus (BA 22), R middle frontal gyrus (BA 46), R insular cortex and R caudate nucleus. Moreover, the R caudate nucleus and R middle frontal gyrus were associated with the clinical language performance.

Inhibitory rTMS protocol may facilitate language recovery without compromising beneficial contralesional reorganization. Conversely, this regimen enhances the expression of newly organized areas for the improvement language performance in post-stroke non-fluent aphasic patients, particularly the caudate nucleus and middle frontal gyrus, likely through intercortical modulating mechanisms.