Enhancement of Facilitation Training for Aphasia by Transcranial Direct Current Stimulation

Area of Science:

• Neuroscience
• Speech and Language Therapy
• Rehabilitation Medicine

Background:

• Aphasia, a language disorder common after stroke, significantly impacts communication and quality of life.
• Current therapies for chronic post-stroke aphasia have limited efficacy, necessitating novel treatment approaches.
• Transcranial direct current stimulation (tDCS) shows potential for modulating neural activity and enhancing cognitive functions.

Purpose of the Study:

• To investigate the efficacy of combining tablet-based language training with anodal transcranial direct current stimulation (tDCS) over the left inferior frontal cortex for improving naming and sentence production in chronic post-stroke aphasia.
• To determine if tDCS enhances a deblocking effect during language tasks, leading to improved performance in subsequent naming and sentence production.
• To compare the effects of active tDCS versus sham stimulation when integrated with language training.

Main Methods:

• Six participants with chronic post-stroke aphasia underwent a tablet-based language training program involving naming and sentence production tasks.
• A deblocking method was employed, where participants performed an intact modality task (spoken-word picture-matching) immediately before impaired modality tasks.
• Two conditions were tested: anodal tDCS over the left inferior frontal cortex and sham stimulation, delivered on non-consecutive days.

Main Results:

• Participants showed significantly greater improvements in naming and sentence production 2 weeks after training with active tDCS compared to sham stimulation.
• The accuracy rate for naming was significantly higher in the tDCS condition than in the sham condition for both trained and untrained words.
• Significant improvements in producing related words and sentences for untrained words were observed post-tDCS, unlike in the sham condition.

Conclusions:

• Combining anodal transcranial direct current stimulation (tDCS) with tablet-based language training on non-consecutive days is an effective strategy for enhancing naming and sentence production in chronic post-stroke aphasia.
• The findings support the hypothesis that tDCS facilitates a deblocking effect, leading to improved language performance.
• This approach offers a promising non-invasive neuromodulation technique for aphasia rehabilitation.