tDCS Effects on Brain Plasticity in Aphasia Treatment

Brain Network Plasticity in Aphasic Patients Associated With Combined Speech Therapy and Transcranial Direct Current Stimulation

The efficacy of conventional speech therapy alone for aphasia recovery is inconclusive. The prospective study will monitor the effects of combined language therapy and tDCS through structural and functional MRI.

The efficacy of conventional speech therapy alone for aphasia recovery is inconclusive. The prospective study will monitor the effects of combined language therapy and tDCS through structural and functional MRI. This randomized, placebo-controlled, double-blinded pilot study will recruit ten chronic stroke patients with Broca's Aphasia randomly assigned either to sham or an anodal tDCS groups. Following speech and language assessment, all the participants will receive 20 minutes of individualized language therapy daily for ten days in two consecutive weeks. Simultaneously, the treatment group will receive 20 minutes of 2mA anodal HD-tDCS over the left IFG, while the sham group will receive the 30s of 2mA anodal HD-tDCS. Structural, resting state and task activated functional MRI will be performed. Data acquisition will be performed before, immediately after and two months after the treatment. Repeated measure ANOVA for changes in picture-naming accuracy and response time will be performed as a within-subject factor between sham and anodal tDCS. Pearson's correlation coefficient of left IFG and its homolog in the right hemisphere through Independent component analysis (ICA) of low-frequency fluctuations in resting-state and task activated state will be compared for functional connectivity analysis for IFG and other major languages hubs for oral language production between groups.

Five post-stroke patients will be allocated by the flip the coin method to the experimental group. Participants will receive anodal tDCS stimulation for 20 minutes

Five participants will be allocated by the flip coin method to the sham comparator group. Participants will receive the tDCS stimulation for the 30s

An anodal high-definition tDCS of 2 mA lasting for 20 minutes will be delivered to the left inferior frontal gyrus during speech therapy.

An anodal high-definition tDCS of 2 mA lasting for 30 seconds will be delivered to the left inferior frontal gyrus during speech therapy.

Picture-naming accuracy and response time for each stimuli will be determined perceptual and calculated using praat software

Mapping changes in functional connections of language networks, inter-hemispheric and intra-hemispheric regions of the brain.

Inclusion Criteria: History of a single unilateral left-hemispheric stroke, Right handedness Demonstrated features of Broca's Aphasia Cantonese speaker Comprehension sufficient to carry out tasks No history of other neurological diseases Exclusion Criteria: Aphasia due to reasons other than Stroke, Traumatic brain injury Bilateral or multiple brain lesions Wernicke's aphasia and other speech disorders, degenerative, psychiatric or metabolic disorders Deaf, blind, pregnant/ or preparing for pregnancy, cognitive issues, tattoos Have cochlear implants, pacemaker, surgical nails for bone fracture, artificial joints, dental braces, dentures Taking anti-depressant medications