Modulating Phonological Short-Term Memory in Stroke Survivors With Aphasia Using Transcranial Alternating Current...

Area of Science:

• Neuroscience
• Neurology
• Speech and Language Pathology

Background:

• Short-term maintenance of phonological information is crucial for language processing.
• Phonological short-term memory (pSTM) is frequently impaired in stroke survivors with aphasia (SWA).
• Understanding and modulating brain activity in pSTM is vital for therapeutic interventions.

Purpose of the Study:

• To investigate the effects of theta transcranial alternating current stimulation (tACS) on pSTM in SWA.
• To determine if in-phase or anti-phase tACS can modulate brain oscillatory activity related to pSTM.
• To assess the potential of tACS as a non-invasive neuromodulation technique for aphasia rehabilitation.

Main Methods:

• A within-subject, single-blinded, sham-controlled pilot study involving 13 SWA.
• Participants received 20-minute sessions of theta-tACS (4-7 Hz) targeting left temporoparietal and inferior frontal regions under three conditions: in-phase, anti-phase, and sham.
• pSTM capacity was measured using an adaptive delayed match-to-sample task assessing the number of syllables maintained over a 5-second delay.

Main Results:

• A significant interaction between tACS condition and block indicated modulation of pSTM capacity.
• In-phase theta-tACS significantly increased pSTM capacity compared to both sham and anti-phase conditions during stimulation.
• Individual responses to tACS were variable, with approximately 60% of participants showing a positive effect.

Conclusions:

• In-phase theta-tACS demonstrates a positive impact on phonological short-term memory capacity in stroke survivors with aphasia.
• This finding supports the potential of tACS as a targeted neuromodulation strategy for enhancing cognitive functions in aphasia.
• Larger-scale studies are warranted to confirm these preliminary results and explore the long-term clinical efficacy of tACS.