ORIGINAL RESEARCH article
Front. Psychol.
Sec. Consciousness Research
This article is part of the Research TopicAdvances in Explainable Analysis Methods for Cognitive and Computational NeuroscienceView all 6 articles
Cross-Frequency Coupling Patterns During Oddball Processing in Disorders of Consciousness: A Delta-Gamma Predominance
Provisionally accepted
- 1School of Special Education and Rehabilitation, Binzhou Medical University - Yantai Campus, Yantai, China
- 2Department of Rehabilitation Medicine, Binzhou Medical University Hospital, Binzhou, China
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Abstract Background: Phase–amplitude coupling (PAC) between low- and high-frequency oscillations provides a candidate mechanism for integrating information across cortical networks. While PAC alterations have been reported in disorders of consciousness (DOC), the frequency specificity and task dependence of these changes remain poorly characterized. Objective: To systematically examine cross-frequency coupling patterns during auditory oddball processing in DOC patients and explore whether specific frequency combinations or frequency shifts are associated with different levels of consciousness. Methods: Sixty-two participants [20 healthy controls (HC), 21 minimally conscious state (MCS), 21 unresponsive wakefulness syndrome (UWS)] underwent EEG recording during an auditory oddball paradigm. PAC was quantified using the Kullback–Leibler modulation index across comprehensive frequency ranges (phase: 1–31 Hz; amplitude: 8–77 Hz) without strong a priori band assumptions. Group comparisons relied on non-parametric permutation testing and bootstrap confidence intervals. Results: Delta–gamma coupling (1–4 Hz phase) dominated across all groups, with delta–gamma PAC consistently and significantly exceeding theta–gamma, alpha–gamma and beta–gamma coupling (all p < 0.001). A descriptive trend towards a downshift in the peak coupled amplitude frequency was observed along the consciousness continuum, with median values in the gamma range for HC (39.5 Hz) and MCS patients (35.0 Hz) and in the high-beta range for UWS patients (23.0 Hz), but this trend did not reach statistical significance (Kruskal–Wallis, p = 0.329). Conversely, between-group differences in delta–gamma coupling strength were not significant (p = 0.218), in the context of marked inter-individual heterogeneity (CV = 0.67 in HC, 0.73 in MCS) that was paradoxically lowest in the UWS group (CV = 0.50).
Keywords: disorders of consciousness, phase-amplitude coupling, oddball paradigm, delta oscillations, Electroencephalography, task-specific oscillations
Received: 24 Sep 2025; Accepted: 19 Nov 2025.
Copyright: © 2025 Huang, Zhang, Li, Liu, Cui, Wang and Li. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Deqiang Wang, wdqbz@163.com
Wei Li, yishengliwei@163.com
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