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Alpha Coherence and Asymmetry Neurofeedback for Emotional Regulation

Updated: Jan 18


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Open-Access Articles on Neurofeedback for Emotional Regulation


Dehghani, A., Soltanian-Zadeh, H., & Hossein-Zadeh, G. A. (2023). Probing fMRI brain connectivity and activity changes during emotion regulation by EEG neurofeedback. Frontiers in Human Neuroscience, 16, 988890. https://doi.org/10.3389/fnhum.2022.988890 Dehghani, A., Soltanian-Zadeh, H., & Hossein-Zadeh, G. A. (2023). Neural modulation enhancement using connectivity-based EEG neurofeedback with simultaneous fMRI for emotion regulation. NeuroImage, 279, 120320. https://doi.org/10.1016/j.neuroimage.2023.120320

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What is the science?


Clinical depression is associated with less activation of the left frontal lobe than the right. Since alpha is an "idling frequency," this asymmetry is seen when the alpha amplitude is greater in the left (F3) than in the right frontal lobe (F4). The goal of alpha asymmetry neurofeedback for depression is to correct this imbalance, decreasing left frontal alpha with respect to right frontal alpha. Successful neurofeedback training increases the activation of the left hemisphere with respect to the right.


What is the takeaway?


A pair of high-quality research studies from Dartmouth University show positive results from frontal alpha asymmetry neurofeedback and frontal alpha coherence neurofeedback in a randomized, sham-controlled study, with significant positive changes in EEG, fMRI, and psychometric measures. Increasing alpha coherence between F3 and F4 produced significantly better results than F3-F4 alpha asymmetry training, which was better than the sham control group results. These results may be used for planning neurofeedback for mental disorders.



How did they do it?

In the first study, Amin Dehgahni (2023a) and his team randomly assigned healthy male subjects to either sham neurofeedback or alpha asymmetry neurofeedback at F3 and F4. They simultaneously recorded the EEG and fMRI during valid and sham neurofeedback, with additional pre-training and post-training psychometric measures.

All subjects engaged in a training paradigm that used a happiness-inducing method involving recalling positive autobiographical memories. The training was presented in 10 runs of 130 seconds each. Each run consisted of a 10-second “rest” period followed by a 60-second “view” period for subjects to look at pictures relevant to their positive memories, and then by 60 seconds of alpha asymmetry neurofeedback when the subject viewed similar positive pictures while attempting to increase feedback. Institutional ethics review approved withholding information about the random nature of feedback used for the sham EEG biofeedback condition.

The researchers recruited another sample of healthy male subjects for the second study. The measurement and training were identical to the first study, but the training in this second study provided EEG biofeedback for increasing alpha band coherence between F3 and F4. The session procedure was identical to the first study, allowing the researchers to compare coherence training, asymmetry training, and sham feedback.



What did they find?

In the first study, significant fMRI and functional connectivity increases were found only in the group that received alpha asymmetry training. Activation and connectivity increases were consistent with cortical and subcortical structures and their connections as proposed by a well-supported model of emotional regulation relevant to depression, PTSD, and anxiety. In addition to producing larger F4-F3 alpha asymmetry increases during EEG biofeedback compared to the rest or view training elements, the asymmetry training group also showed larger asymmetry changes than the sham group. The fMRI BOLD signal for the left orbitofrontal cortex, the left amygdala, and the left insula increased more in the asymmetry training group.


The EEG and fMRI BOLD changes were not merely due to viewing positive imagery or recalling positive autobiographical memories because of the larger changes during EEG biofeedback than during the "view" or "rest" elements. Greater synchronization between brain areas during EEG biofeedback was shown by increases increased functional connectivity between the following regions: the right dorsomedial prefrontal cortex and right insula, right thalamus and right amygdala, left dorsomedial prefrontal cortex and left ventral striatum, left thalamus and left insula, and left thalamus and left amygdala. Psychometric assessment showed positive changes on two of the four measures only for the EEG biofeedback group. The second study used a new group of healthy subjects who received EEG biofeedback to increase alpha band connectivity between F3 and F4, and compared their results to those of the alpha asymmetry and sham EEG biofeedback groups of the first study. Results showed that connectivity training improved the fMRI BOLD signal and connectivity in emotional regulation regions such as the amygdala, thalamus, insula, and prefrontal cortical regions. The regions of increased signal and connectivity seen in the first study were more influenced by connectivity than asymmetry training, particularly the thalamus and prefrontal regions. Further, connectivity training resulted in more wide-ranging functional connectivity than asymmetry training. For connectivity and asymmetry training, connectivity increases were the largest between the right dorsomedial prefrontal cortex and the right insula.

Additionally, connectivity training had a beneficial effect on EEG frontal asymmetry that exceeded that seen in asymmetry training and the sham control group. Both connectivity and asymmetry training increased EEG coherence between F3 and F4 and several other sites. Psychometric measures showed better pre-post improvement following the connectivity training condition than the asymmetry or sham conditions.



What is the impact?


This pair of studies provides further credible support for the effectiveness of EEG neurofeedback based on its strong research design, use of randomization and sham control group, relatively large sample size (N = 42), its demonstration of training effects on EEG and fMRI signals, and self-reported changes in emotion. Training of increases in frontal alpha coherence between F3 and F4 was superior to frontal alpha asymmetry training at F3 and F4, which was significantly better than the sham control treatment. Relatively simple neurofeedback using frontal asymmetry or coherence training is a method that most neurofeedback providers can offer, expecting that it beneficially affects neuroplasticity in cortical, limbic, and subcortical regions of interest and their connections. Experimental investigation of such two-channel training methods compared to 19-channel EEG training of entire brain networks remains to be carried out.


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