Key result
Combined HRV and neurofeedback modifies both trained and untrained EEG frequencies versus HRV alone.
Why the study?
It remained unclear whether participants can intentionally modify the power densities of specifically selected EEG frequencies during neurofeedback training.
Does a combination of HRV biofeedback and neurofeedback training selectively modify trained EEG frequencies compared to HRV biofeedback alone?
RCT (n=26)
Open-label
Randomized
No
Does a combination of HRV biofeedback and neurofeedback training selectively modify trained EEG frequencies compared to HRV biofeedback alone?
Neurofeedback training does not selectively modify only the targeted EEG frequencies, as untrained frequencies and different training modalities also induce EEG changes.
Questions assumptions of EEG frequency specificity in biofeedback; hypothesis-generating and should not yet change practice.
Neurofeedback (NFB) is an operant conditioning procedure whereby an individual learns to self-regulate the electrical activity of his/her brain. Initially developed as a treatment intervention for pathologies with underlying EEG dysfunctions, NFB is also used as a training tool to enhance specific cognitive states required in high-performance situations. The original idea behind the NFB training effect is that the changes should only be circumscribed to the trained EEG frequencies. The EEG frequencies which are not used as feedback frequencies should be independent and not affected by the neurofeedback training. Despite the success of sensorimotor rhythm NFB training in cognitive performance enhancement, it remains unclear whether all participants can intentionally modify the power densities of specifically selected electroencephalographic (EEG) frequencies. In the present study, participants were randomly assigned to either a control heart rate variability (HRV) biofeedback (HRV) training group or a combination of HRV biofeedback and neurofeedback (HRV/NFB) training group. This randomized mixed design experiment consisted of two introductory theoretical lessons and a training period of 6 weeks. We investigated the evolution of the different EEG frequency bands of our two experimental groups across and within session. All the participants exhibited EEG changes across and within session. However, within the HRV/NFB training group, untrained EEG frequencies have been significantly modified, unlike some of the trained frequencies. Moreover, EEG activity was modified in both the HRV group and the HRV/NFB groups. Hence, the EEG changes were not only circumscribed to the trained frequency bands or to the training modality.
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Dessy et al. (2020) conducted an RCT in Healthy (n=26). Combined heart rate variability biofeedback and neurofeedback (HRV/NFB) training vs. Heart rate variability (HRV) biofeedback training was evaluated on Changes in power densities of trained and untrained EEG frequency bands. Combined neurofeedback and heart rate variability biofeedback training modified both trained and untrained EEG frequencies, demonstrating that EEG changes are not circumscribed to the specifically trained frequency bands.
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