Efficiency of EEG-Guided Adaptive Neurostimulation Increases with the Optimization of the Parameters of Preliminary Resonant Scanning

Abstract

The development and improvement of closed-loop methods for non-invasive brain stimulation is an actual and rapidly developing area of neuroscience. An innovative version of this approach, in which a person is presented with audiovisual therapeutic stimulation, automatically modulated by the rhythmic components of his electroencephalogram (EEG), is EEG-guided adaptive neurostimulation. The present study aims to experimentally test the assumption that the effectiveness of EEG-guided adaptive neurostimulation can be increased by optimizing the parameters of preliminary resonance scanning, which consists of LED photostimulation with stepwise increasing frequency in the range of θ-, α-, and β EEG-rhythms. In order to test this assumption, we compared the effects of two types of resonance scanning, which differ in the step length of the gradually increasing frequency of LED photostimulation. The experiments involved two equal groups of university students in a state of exam stress. Before EEG-guided adaptive stimulation, one of the groups underwent resonance scanning with a short (3 s), and the other with a long (6 s) step of a gradual increase in the frequency of photostimulation. Changes in the EEG and psychophysiological parameters were analyzed under the influence of combined (resonance scanning plus EEG-guided adaptive neurostimulation) interventions relative to the initial level. It was found that only with a short (3 s) step of increasing the frequency of photostimulation, significant increases in the power of EEG-rhythms are observed, accompanied by significant changes in subjective indicators – a decrease in the number of errors in the word recognition test, a decrease in the level of emotional maladaptation, and an increase in well-being scores. The revealed positive effects are already observed after single therapeutic procedures due to the optimal conditions for the involvement of the resonant and integration mechanisms of the brain and the mechanisms of neuroplasticity in the processes of normalization of body functions. The developed combined approach to neurostimulation after additional experimental studies can be used in a wide range of rehabilitation procedures.