Zhiqing Deng¹ (), Ruixue Wang¹, Gexiu Wang¹, Yichong Zhang¹, Jie Gao¹, Can Wang¹, Chao Zheng¹, Fuying Zhu¹, Zina Li¹, Pengmin Qin^1,2, Qiuyou Xie^3,4, Juan Chen^1,2; ¹Center for the Study of Applied Psychology, Guangdong Key Laboratory of Mental Health and Cognitive Science, and the School of Psychology, South China Normal University, Guangzhou, Guangdong Province, 510631, China, ²Key Laboratory of Brain, Cognition and Education Sciences (South China Normal University), Ministry of Education, Guangzhou, Guangdong Province, 510631, China, ³Joint Center for Disorders of Consciousness, Department of Rehabilitation Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, 510220, China, ⁴School of Rehabilitation Sciences, Southern Medical University

Disorders of consciousness (DoC), mainly caused by traumatic brain injury, are typically with impairment in sensory processing. Among sensory modalities, vision is one of the most critical senses in humans. Accurate evaluation of the remaining vision function along the visual hierarchy from low-level visual features to high-level object recognition in DoC patients is crucial for their waking and rehabilitation. It is also challenging due to their limited ability to understand instructions and respond. Here, we proposed a method to rapidly evaluate DoC patients' visual function along the visual hierarchy at the bedside without participants' responses. A series of images were presented at 6 Hz (base frequency), with oddball stimuli presented following every four base stimuli (oddball frequency, 1.2 Hz) according to the fast periodic visual stimulation (FPVS) oddball paradigm while recording electroencephalographic signals. We observed electrophysiological response at 6 Hz in healthy controls, revealing their normal abilities to receive visual information. Oddball images generated an electrophysiological response at 1.2 Hz in healthy controls, revealing normal abilities to discriminate oddball stimuli from base stimuli. Unresponsive wakefulness syndrome/vegetative state (UWS/VS), minimally conscious state (MCS), and emergence from MCS (EMCS) retained the ability to receive visual information across almost all visual levels. However, UWS/VS primarily retained visual discrimination in low-level visual conditions, while MCS and EMCS demonstrated preserved discrimination in low-level, middle-level, and high-level visual conditions. Classification and prognosis results suggested that high-level visual functions were the strongest predictors of both current consciousness state and changes in consciousness state. These findings indicate that the FPVS oddball paradigm across various visual levels is a highly-sensitive, efficient, no-report tool for assessing visual processing in DoC patients, with high-level visual function indices predicting consciousness recovery. It advances our understanding of visual processing in DoC, offers insights for improving diagnostics, and guides patient awakening and rehabilitation strategies.

Acknowledgements: This work was supported by grants from the National Natural Science Foundation of China (No. 31970981 to JC, No. 82171174 and No. 82371184 to QX), the National Science and Technology Innovation 2030 Major Program (STI2030-Major Projects 2022ZD0204802 to JC), and the China Scholarship Council to JC.