Does Occipital Alpha Neurofeedback Require Critical Branching to Causally Influence LTRCs and Deterministic ERPs?

Critical branching is a form of theoretical interaction between simple units, which, in the case of the human brain are assumed to be neuronal elements. Zhigalov, Kaplan, & Palva (Clin Neurophysiol 2016;127:2882–89) revealed that neurofeedback flash stimulation phase-locked to high-amplitude occipital alpha influences the stimulus-locked occipital alpha-band averages and the power scaling of long-range temporal correlations of alpha-band amplitude fluctuations. At first, it might seem that neurofeedback influenced critical branching alongside there being an interaction between ongoing neuronal activity and evoked responses. However, the causal relations between these neuronal Long Range Temporal Correlations, sustained attention, and any avalanche dynamics are called into question, as is Zhigalov et al.’s assertion that the neurofeedback flashes are unconsciously processed rather than capturing attention. Uncorrected concerns about false discovery rate and an objective mathematical error in the cited foundational work for Zhigalov et al.’s study are also raised. Without critical branching, an alternative set of illustrative mathematical principles offered a preliminary fit to the effects in the data, whereby neurofeedback influenced the deterministic contribution to single-trial flash-evoked event-related potentials separately from the neurofeedback flash-evoked gain in the amplitude of those oscillations. Accordingly, microbehaviours produced by the model’s separate principles of neurofeedback-related exponential occipital oscillatory alpha gain and deterministic event-related potential generation have macroscale consequences causally influencing the power-scaling of long-range temporal correlations.