Xin-Yue Yang^1-4, Qing He⁵, Fang Fang^1-4,*; ¹School of Psychological and Cognitive Sciences and Beijing Key Laboratory of Behavior and Mental Health, Peking University, Beijing, China, ²Key Laboratory of Machine Perception, Ministry of Education, Peking University, Beijing, China, ³IDG/McGovern Institute for Brain Research, Peking University, Beijing, China, ⁴Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China, ⁵State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China

Understanding how newly encoded information is consolidated in visual perceptual learning (VPL) is significant in contemporary vision science. Consolidation can be manifested in different forms at different stages of VPL, among which the early consolidation post-initial training remains largely uncharted, with numerous aspects still unknown regarding neural mechanisms and potential interventions. In this study, we investigated whether repetitive visual stimulation (RVS), known for inducing LTP- or LTD-like effects on neural activities and measures of behavioral performance in a frequency-dependent manner, could be used to promote early consolidation of VPL and investigated the neuroelectrical activities supporting such effects. Forty-five participants were equally assigned to three groups with 10-Hz, 1-Hz, and 0-Hz (static) flickers. Participants underwent training on an orientation discrimination task (ODT), an RVS session, a four-hour break, and a post-test on ODT. In an ODT trial, participants fixated on a central fixation point, two embedded-in-noise Gabors with slightly different orientations successively appeared in the periphery, and the participants reported the rotation (clockwise or counter-clockwise) with a keypress. In RVS, a sinusoidal grating flicker was flashed at the corresponding frequency in the same location as the Gabor in ODT. During all tasks, we continuously monitored eye movement using a video-based eye tracker and recorded electroencephalogram (EEG) using 64-channel electrode caps. Results showed a decline in discrimination threshold with training in all three groups, indicating that learning had occurred. Ten-Hz flicker resulted in decreased threshold in the post-test, while 1-Hz flicker increased the threshold, and static flicker yielded no effect. The 10-Hz flicker-induced improvement was accompanied by a stronger N145 component of visually evoked potential (VEP) recorded in the contralateral occipito-parietal cortex in the post-test. Our findings suggest that VPL-involved neural traces exhibit plasticity in early consolidation, and 10-Hz RVS induces LTP-like activity in the visual areas, facilitating early consolidation of VPL.