Investigating the possibilities of dual-tACS by stimulating two frequencies simultaneously
Poster No:
24
Submission Type:
Abstract Submission
Authors:
Jeonghui Kim1, Nuri On2, Chany Lee3, Do-Won Kim4
Institutions:
1CHONNAM NATIONAL UNIVERSITY, Yeosu, Jeollanamdo, 2CHONNAM NATIONAL UNIVERSITY, Yeosu City, Jeollanam-do, 3Korea Brain Research Institute, Daegu, Korea, Republic of, 4Chonnam National University, Yeosu, Jeollanam-do
First Author:
Co-Author(s):
Introduction:
The steady-state visual evoked potential-based brain-computer interface (SSVEP-BCI) enables fast and reliable real-time interaction by utilizing electroencephalogram (EEG) responses synchronized with visual stimuli. However, the application of SSVEP-BCI is constrained by "SSVEP illiteracy", who show little or no response to flickering stimuli. Recent research suggests that transcranial electrical stimulation (tES) is a promising approach to enhance SSVEP responses in individuals with SSVEP illiteracy. Our research found that transcranial direct current stimulation (tDCS) enhances SSVEP responses, especially at low signal-to-noise ratio (SNR) frequencies (Kim, 2019). Additionally, frequency-specific transcranial alternating current stimulation (tACS) improves SSVEP responses using personalized low-SNR frequencies (Kim, 2023). but it was limited to stimulating one frequency at a time. This study explores dual-frequency tACS (df-tACS) as a novel stimulation method for concurrently stimulating multiple frequencies.
Methods:
The experiment involved 7 participants (5 males, age: 24.42 ± 2.19). Each participant received a 5 seconds of flickering checkboard stimuli with six randomly presented frequencies, each repeated 10 times. Based on the SSVEP response of each frequency, we superimposed two sine waves with distinct frequencies that showed the lowest SNR value of the SSVEP response. tACS stimulation was given using electrodes attached to Oz and Cz for 20 min. After tACS, the same experiment was repeated to observe changes in SSVEP response. All EEG recordings and tACS used a battery-driven current stimulator (Starstim R32, NeuroElectrics, Barcelona, Spain). All participants signed a written consent that was approved by the Institutional Review Board (IRB) of Chonnam National University prior to their participation in the study (IRB No. 1040198-210708-HR-103-03).
Results:
The frequency with the lowest SNR (f_stim1) showed a significant increase from pre-stimulation (0.818 ± 0.057) to post-stimulation (1.071 ± 0.069). Similarly, the second lowest SNR frequency (f_stim2) also increased significantly from pre-stimulation (0.901 ± 0.076) to post-stimulation (1.073 ± 0.091). However, there was a significant decrease at non-stimulated frequencies (fnon-stim). Absolute power results indicated a significant interaction effect between stimulation time and stimulation condition, but subsequent post hoc analysis did not reveal any significant differences. [Figure 1]
·Changes in (a) SNR and (b) absolute power according to each tACS stimulation condition
Conclusions:
In this study, we proposed a novel stimulation method capable of stimulating multiple frequencies simultaneously. We demonstrated that this approach significantly enhances the SNR of SSVEP responses, which can improve the classification accuracy of the BCI system for individuals with SSVEP illiteracy. Additionally, by applying dual-frequency stimulation, it is possible to target different brain regions with distinct frequencies or stimulate the same region with multiple frequencies. This technique is expected to enable more efficient modulation of brain functions, opening new avenues for advanced neurostimulation applications.
Brain Stimulation:
Non-invasive Electrical/tDCS/tACS/tRNS 1
Novel Imaging Acquisition Methods:
EEG 2
Keywords:
Electroencephaolography (EEG)
Other - steady-state visual evoked potential (SSVEP); dual-frequency transcranial alternating current stimulation (df-tACS); signal-to-noise ratio (SNR); visual cortex
1|2Indicates the priority used for review
Abstract Information
By submitting your proposal, you grant permission for the Organization for Human Brain Mapping (OHBM) to distribute your work in any format, including video, audio print and electronic text through OHBM OnDemand, social media channels, the OHBM website, or other electronic publications and media.
The Open Science Special Interest Group (OSSIG) is introducing a reproducibility challenge for OHBM 2025. This new initiative aims to enhance the reproducibility of scientific results and foster collaborations between labs. Teams will consist of a “source” party and a “reproducing” party, and will be evaluated on the success of their replication, the openness of the source work, and additional deliverables. Click here for more information. Propose your OHBM abstract(s) as source work for future OHBM meetings by selecting one of the following options:
Please indicate below if your study was a "resting state" or "task-activation” study.
Healthy subjects only or patients (note that patient studies may also involve healthy subjects):
Was this research conducted in the United States?
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.
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.
Please indicate which methods were used in your research:
Provide references using APA citation style.
Kim, J. and Kim, D.-W. (2023) "tACS modulates neural activity at specific frequency in SSVEP". 45th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2023.07.24-27, Syndey, Australia.