Session-dependent effects of 6-Hz frontoparietal tACS on visuospatial working-memory accuracy

Area of Science:

• Neuroscience
• Cognitive Psychology

Background:

• Visuospatial working memory (VSWM) relies on fronto-parietal networks and neural oscillations, particularly in the theta band (4-8Hz).
• Non-invasive neuromodulation, such as transcranial alternating current stimulation (tACS), offers a potential method to enhance cognitive functions by entraining neural oscillations.

Purpose of the Study:

• To investigate the impact of 6Hz theta-frequency tACS applied to the left fronto-parietal network (F3/P3) on VSWM performance.
• To compare the effects of in-phase and anti-phase tACS, transcranial random noise stimulation (tRNS), and no stimulation.

Main Methods:

• A within-subjects design was employed with participants undergoing four stimulation conditions: in-phase tACS, anti-phase tACS, tRNS, and no stimulation.
• VSWM was assessed using the Corsi Block Tapping Task.
• Data were analyzed using linear mixed-effects modeling.

Main Results:

• Both in-phase and anti-phase theta tACS led to significantly higher accuracy compared to the no-stimulation condition.
• The effects of tACS on accuracy were most pronounced during the initial session and decreased with subsequent sessions.
• No significant effects of tACS or tRNS were observed on response speed.
• The tRNS condition did not yield statistically significant differences in performance compared to no stimulation.

Conclusions:

• Frontoparietal theta tACS can modulate VSWM accuracy, particularly in the early stages of task engagement.
• The findings suggest that theta tACS may enhance cognitive performance, but a clear advantage of anti-phase over in-phase stimulation was not demonstrated.
• Further research is needed to explore the temporal dynamics and optimal parameters for tACS in cognitive enhancement.