title: Modulation of critical brain dynamics using closed-loop neurofeedback stimulation.
abstract: EEG long-range temporal correlations (LRTCs) are a significant for both human cognition and brain disorders, but beyond suppression by sensory disruption, there are little means for influencing them non-invasively. We hypothesized that LRTCs could be controlled by engaging intrinsic neuroregulation through closed-loop neurofeedback stimulation.
  
  
  
  We used a closed-loop-stimulation paradigm where supra-threshold α-waves trigger visual flash stimuli while the subject performs the standard eyes-closed resting-state task. As a "sham" control condition, we applied similar stimulus sequences without the neurofeedback.
  
  
  
  Over three sessions, a significant difference in the LRTCs of α-band oscillations (U=89, p<0.028, Wilcoxon rank sum test) and their scalp topography (T=-2.92, p<0.010, T-test) emerged between the neurofeedback and sham conditions so that the LRTCs were stronger during neurofeedback than sham. No changes (F=0.16, p>0.69, ANOVA test) in the scalp topography of α-band power were observed in either condition.
  
  
  
  This study provides proof-of-concept for that EEG LRTCs, and hence critical brain dynamics, can be modulated with closed-loop stimulation in an automatic, involuntary fashion. We suggest that this modulation is mediated by an excitation-inhibition balance change achieved by the closed-loop neuroregulation.
  
  
  
  Automatic LRTC modulation opens novel avenues for both examining the functional roles of brain criticality in healthy subjects and for developing novel therapeutic approaches for brain disorders associated with abnormal LRTCs.
authors.affiliation: Neuroscience Center, University of Helsinki, Helsinki 00014, Finland; Laboratory for Neurophysiology and Neuro-Computer Interfaces, Faculty of Biology, Lomonosov Moscow State University, Moscow 119991, Russia. Electronic address: alexander.zhigalov@helsinki.fi.
authors.forename: Alexander
authors.initials: A
authors.lastname: Zhigalov
authors.affiliation: Laboratory for Neurophysiology and Neuro-Computer Interfaces, Faculty of Biology, Lomonosov Moscow State University, Moscow 119991, Russia.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kaplan
authors.affiliation: Neuroscience Center, University of Helsinki, Helsinki 00014, Finland.
authors.forename: J Matias
authors.initials: JM
authors.lastname: Palva
mesh_terms: D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D058256:Brain Waves / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D058765:Neurofeedback; D010775:Photic Stimulation; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult
keywords: Closed-loop stimulation; Critical neuronal dynamics; Electroencephalography; Excitation–inhibition balance; Long-range temporal correlations