Poster No:
855
Submission Type:
Late-Breaking Abstract Submission
Authors:
Daisuke Shimane1, Teppei Okano2, Chengmi Hu3, Masaki Takeda1,2
Institutions:
1Res. Cent. Brain Commun., Kochi Univ. of Tech., Kami, Kochi, Japan, 2Sch. Informatics, Kochi Univ. of Tech., Kami, Kochi, Japan, 3Grad. Sch. Eng., Kochi Univ. of Tech., Kami, Kochi, Japan
First Author:
Daisuke Shimane
Res. Cent. Brain Commun., Kochi Univ. of Tech.
Kami, Kochi, Japan
Co-Author(s):
Teppei Okano
Sch. Informatics, Kochi Univ. of Tech.
Kami, Kochi, Japan
Chengmi Hu
Grad. Sch. Eng., Kochi Univ. of Tech.
Kami, Kochi, Japan
Masaki Takeda
Res. Cent. Brain Commun., Kochi Univ. of Tech.|Sch. Informatics, Kochi Univ. of Tech.
Kami, Kochi, Japan|Kami, Kochi, Japan
Introduction:
Memory consolidation relies on the reactivation of past experiences during sleep. Previous studies have highlighted the critical role of the precise temporal interplay among neural oscillations during sleep-slow oscillations (SO), spindles, and ripples-in memory reactivation and consolidation (Klinzing et al., 2019).
In human research, studies on SO have been particularly active, with causal studies demonstrating that auditory or electrical stimulation can enhance memory consolidation (Ngo et al., 2013; Marshall et al., 2006). More recently, researchers have focused on the importance of phase-specific stimulation in neuromodulation. Studies have reported that closed-loop transcranial alternating current stimulation (tACS) synchronized with the phase of ongoing SO can enhance memory consolidation (Ketz et al., 2018). However, despite growing interest in the relationship between sleep and memory, the causal link between SO and memory consolidation remains incompletely understood. To address this, we applied closed-loop tACS in either in-phase or anti-phase with ongoing SO to investigate whether memory consolidation can be modulated in a phase-dependent manner.
Methods:
A total of 90 students participated (36 in the in-phase condition, 36 in the anti-phase condition, and 18 in the sham condition). The study included a memory encoding task, a pre-sleep memory test, a 90-minute nap, and a post-sleep memory test. Participants first learned pairwise associations between words and images. Then, they performed the memory tests before and after sleep. In these memory tests, the participants identified whether each presented word was old or new (i.e., recognition memory). If they identified a word as old, they were required to select the corresponding image (i.e., associative memory). During sleep, we applied 1 Hz tACS to the forehead, triggered in real time based on the phase of ongoing SO.
Results:
The results showed that associative memory performance after sleep was significantly higher in the in-phase condition than in the anti-phase condition (p < .01). The sham condition fell between the two, with a significant trend of in-phase > sham > anti-phase (p < .05). Additionally, the number of stimulations correlated positively with memory performance improvements in in-phase condition (p < .01). Interestingly, stimulation effects were observed only in associative memory, not in recognition memory (p = .41).
Conclusions:
These findings support the causal role of SO in memory consolidation and suggest that closed-loop tACS can modulate this process by manipulating phase alignment. The selective effect on associative memory-closely linked to sleep oscillations-is consistent with previous research (Schreiner et al., 2021; Tambini & D'Esposito, 2020), further reinforcing the validity of these results.
Brain Stimulation:
Non-invasive Electrical/tDCS/tACS/tRNS 2
Learning and Memory:
Long-Term Memory (Episodic and Semantic) 1
Keywords:
Electroencephaolography (EEG)
Memory
Sleep
Other - tACS
1|2Indicates the priority used for review
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Please indicate below if your study was a "resting state" or "task-activation” study.
Task-activation
Healthy subjects only or patients (note that patient studies may also involve healthy subjects):
Healthy subjects
Was this research conducted in the United States?
No
Were any human subjects research approved by the relevant Institutional Review Board or ethics panel?
NOTE: Any human subjects studies without IRB approval will be automatically rejected.
Yes
Were any animal research approved by the relevant IACUC or other animal research panel?
NOTE: Any animal studies without IACUC approval will be automatically rejected.
Not applicable
Please indicate which methods were used in your research:
EEG/ERP
Behavior
Other, Please specify
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tACS
Provide references using APA citation style.
Ketz, N., Jones, A. P., Bryant, N. B., Clark, V. P., & Pilly, P. K. (2018). Closed-loop slow-wave tACS improves sleep-dependent long-term memory generalization by modulating endogenous oscillations. Journal of Neuroscience, 38(33), 7314-7326.
Klinzing, J. G., Niethard, N., & Born, J. (2019). Mechanisms of systems memory consolidation during sleep. Nature Neuroscience, 22(10), 1598-1610.
Marshall, L., Helgadóttir, H., Mölle, M., & Born, J. (2006). Boosting slow oscillations during sleep potentiates memory. Nature, 444(7119), 610-613.
Ngo, H. V. V., Martinetz, T., Born, J., & Mölle, M. (2013). Auditory closed-loop stimulation of the sleep slow oscillation enhances memory. Neuron, 78(3), 545-553.
Schreiner, T., Petzka, M., Staudigl, T., & Staresina, B. P. (2021). Endogenous memory reactivation during sleep in humans is clocked by slow oscillation-spindle complexes. Nature Communications, 12(1), 3112.
Tambini, A., & D’Esposito, M. (2020). Causal contribution of awake post-encoding processes to episodic memory consolidation. Current Biology, 30(18), 3533-3543.
No