Identification of beta burst patterns underlying simultaneous transcranial alternating current stimulation

Abstract

Abstract Introduction: Beta bursts represent transient high-power brain waves within the beta frequency band. Previous studies have reported that beta bursts are closely associated with motor function [1]. Moreover, transcranial alternating current stimulation (tACS), a non-invasive brain stimulation technique, has been reported to be able to improve motor performance [2]. However, how tACS modulate beta burst patterns is still unclear. Therefore, the objective of the present study is to investigate changes in beta burst patterns underlying simultaneously applied tACS. Method: The dataset we used was provided by Dr. Noury from University of Tuebingen [3]. We used EEG recordings underlying 62Hz tACS for data analysis. To extract beta burst, we first band-pass filtered the EEG data within the beta frequency band (13 – 30Hz). Then, 75 percent of the average envelope of EEG signals under the sham stimulation condition was used as the threshold for burst detection. Finally, three recording electrodes covering the right motor cortex area and three burst features were analyzed to investigate the modulatory effects of gamma band tACS on beta burst patterns: burst number per trial, burst duration and burst amplitude. Results: During 62Hz tACS, more bursts along with larger burst amplitude were detected compared to the sham group (Figure 1A & C). However, duration of burst was reduced by 62Hz tACS (Figure 1B). Conclusion: In the present study, we investigated the changes in burst patterns underlying simultaneous 62Hz tACS. We showed that gamma band tACS can induced more bursts with larger amplitudes, though these bursts tend to be of shorter duration. This may imply that gamma tACS can excite more neurons to the firing state with larger spikes. Keywords: tACS, EEG, Beta burst, Motor function