Neurofeedback Tunes Scale-Free Dynamics in Spontaneous Brain Activity.
Brain oscillations exhibit long-range temporal correlations (LRTCs), which reflect the regularity of their fluctuations: low values representing more random (decorrelated) while high values more persistent (correlated) dynamics. LRTCs constitute supporting evidence that the brain operates near criticality, a state where neuronal activities are balanced between order and randomness. Here, healthy adults used closed-loop brain training (neurofeedback, NFB) to reduce the amplitude of alpha oscillations, producing a significant increase in spontaneous LRTCs post-training. This effect was reproduced in patients with post-traumatic stress disorder, where abnormally random dynamics were reversed by NFB, correlating with significant improvements in hyperarousal. Notably, regions manifesting abnormally low LRTCs (i.e., excessive randomness) normalized toward healthy population levels, consistent with theoretical predictions about self-organized criticality. Hence, when exposed to appropriate training, spontaneous cortical activity reveals a residual capacity for "self-tuning" its own temporal complexity, despite manifesting the abnormal dynamics seen in individuals with psychiatric disorder. Lastly, we observed an inverse-U relationship between strength of LRTC and oscillation amplitude, suggesting a breakdown of long-range dependence at high/low synchronization extremes, in line with recent computational models. Together, our findings offer a broader mechanistic framework for motivating research and clinical applications of NFB, encompassing disorders with perturbed LRTCs.
Geneva Neuroscience Center, Department of Neuroscience, University of Geneva, CH-1202 Geneva, Switzerland.
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Ros
Department of Psychiatry, Western University, London N6A 5A5, Ontario, Canada.
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Frewen
Department of Medical Imaging, Lawson Health Research Institute, London N6C 2R5, Ontario, Canada.
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Théberge
Geneva Neuroscience Center, Department of Neuroscience, University of Geneva, CH-1202 Geneva, Switzerland.
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Michela
Department of Psychosomatic Medicine and Psychotherapy, Mannheim-Heidelberg University, 68159 Mannheim, Germany.
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Kluetsch
Brain and Trauma Foundation, CH-7000 Chur, Switzerland.
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Mueller
Brain and Trauma Foundation, CH-7000 Chur, Switzerland.
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Candrian
Directorate of Mental Health, Canadian Forces Health Services, Ottawa K1A 0K6, Canada.
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Jetly
Geneva Neuroscience Center, Department of Neuroscience, University of Geneva, CH-1202 Geneva, Switzerland.
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Vuilleumier
Department of Psychiatry, Western University, London N6A 5A5, Ontario, Canada.
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Lanius
D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D004569:Electroencephalography / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D009424:Nervous System Physiological Phenomena; D058765:Neurofeedback / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D013313:Stress Disorders, Post-Traumatic / Q000503:physiopathology; D055815:Young Adult
EEG; Hurst exponent; PTSD; alpha rhythm; criticality; long-range temporal correlations; neurofeedback; scale-free dynamics