Spectral peak analysis and intrinsic neural timescales as markers for the state of consciousness

• Published in: NeuroImage clinical 2024-01, Vol.44, p.103698, Article 103698
• Main Authors: Espinosa, Ezequiel Pablo, Zang, Di, Buccellato, Andrea, Qi, Zengxin, Wu, Xuehai, Abbasi, Samira, Catal, Yasir, Lechner, Stephan, Zilio, Federico, Northoff, Georg
• Format: Article
• Language: English
• Subjects: Adult; Aged; Alpha peak; Alpha Rhythm - physiology; Brain - physiopathology; Consciousness - physiology; Consciousness Disorders - diagnosis; Consciousness Disorders - physiopathology; Diagnosis; Disorders of consciousness; EEG; Electroencephalography - methods; Female; Humans; Intrinsic neural timescales; Male; Middle Aged; Regular; Young Adult
• ISSN: 2213-1582; 2213-1582
• DOI: 10.1016/j.nicl.2024.103698

•Intrinsic Neural Timescales (INTs) are prolonged in patients with disorders of consciousness (DOC) compared to controls.•Alpha frequency power peaks are prominent in healthy EEGs but uncommon and diminished in DOC patients.•Peak analysis quantifies the reduction in alpha peaks in DOC patients relative to controls.•Prolonged INTs and reduced alpha peaks may serve as biomarkers for consciousness assessment. Resting state EEG in patients with disorders of consciousness (DOC) is characterized by an increase of power in the delta frequency band and a concurrent decrease in the alpha range, equivalent to a weakening or disappearance of the alpha peak. Prolongation of Intrinsic Neural Timescales (INTs) is also associated with DOCs. Together, this raises the question whether the decreased alpha peak relates to the prolonged INTs and, importantly, how that can be used for diagnosing the state of consciousness in DOC individuals. Analyzing resting state EEG recordings from both healthy subjects and DOC patients, we measure INTs through autocorrelation window (ACW) and utilize peak analysis to quantify the weakening of the alpha peak. First, we replicate previous findings of prolonged ACW in DOC patients. We then identify significantly lower alpha peak measures in DOC compared to controls. Interestingly, spectral peaks shift from the alpha to the theta range in several DOC subjects while such change is absent in healthy controls. Next, our study reveals a close relationship between ACW and alpha peak in both healthy and DOC subjects, a correlation that holds for theta peaks in DOC. Further, the prolonged ACW correlates with the state of consciousness, as quantified by the Coma Recovery Scale-Revised (CRS-R), and mediates the relationship between theta peak and CRS-R. Finally, through split analyses and machine learning, we show that ACW and alpha peak measures conjointly distinguish healthy controls and DOC patients with high accuracy (95.5%). In conclusion, we demonstrate that the prolongation of ACW, together with spectral peak measures, holds promise to serve as additional EEG biomarkers for diagnosing the state of consciousness in DOC subjects.