COVARIATION OF SPECTRAL AND NONLINEAR EEG MEASURES WITH ALPHA BIOFEEDBACK (original) (raw)
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eneuro
Alpha rhythm (8-13 Hz) is linked to relaxed mental state in humans. Earlier reports have shown that individuals can increase their alpha power if provided with a valid feedback, compared to controls who are provided invalid feedback. However, these results remain controversial, partly because controls may be in a different behavioral state, making it difficult to directly compare their alpha power with the valid group. We here address this issue by using an experimental paradigm in which an invalid feedback is given on a fraction of trials, such that both valid and invalid conditions can be obtained from the same participant. Using electroencephalography (EEG), we recorded alpha power from the occipital area from 24 humans (nine females) and played a feedback tone which could be valid (tone frequency proportional to alpha power), invalid (tone sequence from a previous valid trial; participants were unaware of this condition), or neutral (constant tone frequency). We found that during eyes closed-state, neurofeedback did not enhance alpha activity beyond pre-trained state within the experimental duration, probably because of saturation of alpha rhythmicity. However, for participants whose alpha power decreased over time within a trial, valid feedback helped them to sustain alpha more than invalid feedback. Further, alpha increase showed a weak negative correlation with their self-reported attentional load but was uncorrelated with relaxation levels. Our results reconcile many conflicting reports in the neurofeedback literature, and show that even under most stringent control, valid neurofeedback can help participants who are otherwise unable to sustain their alpha activity.
Control of Alpha Rhythm (8–13 Hz) Using Neurofeedback
Journal of the Indian Institute of Science, 2017
Alpha is a prominent rhythm occurring between 8 and 13 Hz in brain signals that is often linked to a relaxed mental state. Some studies have shown that individuals can learn to control their own alpha rhythm if provided with a contingent feedback. However, investigations till date in alpha neurofeedback have provided contrasting views regarding the enhancement of alpha power. In this review, we discuss various aspects of this controversy and highlight some issues with past approaches of neurofeedback driven alpha enhancement. In particular, we discuss possible modifications in future investigations which would address some of the concerns.
Scientific Reports
Neurofeedback training (NFT) enables users to learn self-control of EEG activity of interest and then to create many benefits on cognitive function. A considerable number of nonresponders who fail to achieve successful NFT have often been reported in the within-session prediction. This study aimed to investigate successful EEG NFT of upregulation alpha activity in terms of trainability, independence, and between-session predictability validation. Forty-six participants completed 12 training sessions. Spectrotemporal analysis revealed the upregulation success on brain activity of 8–12 Hz exclusively to demonstrate trainability and independence of alpha NFT. Three learning indices of between-session changes exhibited significant correlations with eyes-closed resting state (ECRS) alpha amplitude before the training exclusively. Through a stepwise linear discriminant analysis, the prediction model of ECRS’s alpha frequency band amplitude exhibited the best accuracy (89.1%) validation re...
Mapping of Changes in EEG Spectrum Power during a Session of Biofeedback Training of the 1 Rhythm
Human Physiology, 2000
Changes in EEG spectrum power from 19 electrode sites were studied in 19 children with attention disorders during one session of EEG-biofeedback (EEG-BFB). EEG-BFB was aimed at increasing the relative power of the β 1 rhythm (15-18 Hz) in sites Fz-C 3 with a bipolar electrode assembly. Comparison of the EEG spectrum powers at relaxation versus training periods in one BFB session revealed significant changes in the left parasagittal frontoparietal area (F 3 , Fz , C 3 , C 4 , P 3).
Comparison of Visual and Auditory Modalities for Upper-Alpha EEG-Neurofeedback
2019 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), 2019
Electroencephalography (EEG) neurofeedback (NF) training has been shown to produce long-lasting effects on the improvement of cognitive function as well as the normalization of aberrant brain activity in disease. However, the impact of the sensory modality used as the NF reinforcement signal on training effectiveness has not been systematically investigated. In this work, an EEG-based NFtraining system was developed targeting the individual upperalpha (UA) band and using either a visual or an auditory reinforcement signal, so as to compare the effects of the two sensory modalities. Sixteen healthy volunteers were randomly assigned to the Visual or Auditory group, where a radiusvarying sphere or a volume-varying sound, respectively, reflected the relative amplitude of UA measured at EEG electrode Cz. Each participant underwent a total of four NF sessions, of approximately 40 min each, on consecutive days. Both groups showed significant increases in UA at Cz within sessions, and also across sessions. Effects subsequent to NF training were also found beyond the target frequency UA and scalp location Cz, namely in the lower-alpha and theta bands and in posterior brain regions, respectively. Only small differences were found on the EEG between the Visual and Auditory groups, suggesting that auditory reinforcement signals may be as effective as the more commonly used visual signals. The use of auditory NF may potentiate training protocols conducted under mobile conditions, which are now possible due to the increasing availability of wireless EEG systems.
An Exploratory Study of Training Intensity in EEG Neurofeedback
2021
Neurofeedback training has shown benefits in clinical treatment and behavioral performance enhancement. Despite the wide range of applications, no consensus has been reached about the optimal training schedule. In this work, an EEG neurofeedback practical experiment was conducted aimed at investigating the effects of training intensity on the enhancement of the amplitude in the individual upper alpha band. We designed INTENSIVE and SPARSE training modalities, which differed regarding three essential aspects of training intensity: the number of sessions, the duration of a session, and the interval between sessions. Nine participants in the INTENSIVE group completed 4 sessions with 37.5 minutes each during consecutive days, while nine participants in the SPARSE group performed 6 sessions of 25 minutes spread over approximately 3 weeks. As a result, regarding the short-term effects, the upper alpha band amplitude change within sessions did not significantly differ between the two group...
Journal of Medical and Bioengineering, 2015
This document is the result of a research project called design and implementation of a prototype EEG Neurofeedback for control and stimulation of alpha wave, where, Neurofeedback is identifier as a therapeutic technique that was development by the Chicago University, to reduce conditions such as stress, insomnia, physical exhaustion, and hallucinogens dependence. In the design and implementation of real-time Neurofeedback, were used instrumentation amplifiers (INA 128), and low-pass active filters, aiming to detect the alpha wave; which is in low frequency ranges, for analog operation was also used, the TL 084 amplifier and FPGA card, the module pmodAD1 with 12 bits of resolution, and the visualization is presented in a 7 inch VGA screen with a resolution of 640x480 pixels, and for recording the EEG signal was used cup electrodes. The prototype (Neurofeedback) is distinguished by features such as: Easy, Integrated viewing screen, rechargeable batteries, feedback and binaural sound with low cost compared with commercial Neurofeedback, allowing reducing the effects of stress and many symptoms more.