Closed-Loop tACS Delivered during Slow-Wave Sleep Reduces Retroactive Interference on a Paired-Associates Learning...

Area of Science:

• Neuroscience
• Cognitive Psychology
• Sleep Science

Background:

• Previous research indicates closed-loop transcranial alternating current stimulation (CL-tACS) benefits memory consolidation during sleep.
• The current study investigates CL-tACS in a more challenging retroactive interference paired associates task (ri-PAT) paradigm.

Purpose of the Study:

• To evaluate the impact of CL-tACS, synchronized with slow-wave oscillations (SWO) during sleep, on memory performance within a retroactive interference paradigm.
• To determine if CL-tACS effects differ based on individual encoding strengths.

Main Methods:

• Thirty-one participants completed a paired associates task (PAT) before sleep.
• CL-tACS was applied over the dorsolateral prefrontal cortex (DLPFC) or mastoids during SWO.
• Memory recall was assessed the following morning after learning a new list to introduce retroactive interference.

Main Results:

• A significant effect of stimulation condition was observed, with verum CL-tACS reducing retroactive interference compared to sham stimulation (p=0.04297).
• A significant interaction between encoding strength and stimulation condition was found (p=0.03591).
• CL-tACS significantly benefited low-encoders (p=0.0066) but not high-encoders.

Conclusions:

• CL-tACS applied during sleep enhances protection against retroactive memory interference.
• The memory benefits of CL-tACS are most pronounced in individuals with lower encoding aptitude.