Here is the summary of the study with the title:
The Impact of Alpha-Neurofeedback Training on Gastric Slow Wave Activity and Heart Rate Variability in Humans
Background:
The study investigates the possibility of influencing gastric function through targeted neurofeedback training (EEG-NF). Previous research has shown a coupling between the alpha-band activity of the insula in the EEG and gastric slow wave (GSW) activity.
Methods:
- Design: Randomized crossover design with 20 healthy volunteers
- Interventions: Two sessions of different EEG neurofeedback training:
- Active training: increase in alpha activity in the left posterior insula (LPIns)
- Control training: increasing activity in the primary visual cortex (PVC)
- Data recording: EEG, electrogastrogram (EGG) to record gastric slow wave activity, ECG to record heart rate variability (HRV)
- Test after training: 5-minute water load test (5WLT)
Procedure
1. electrode placement for EEG neurofeedback training
- The EEG signals were recorded with a 21-channel cap in the 10/20 system.
- Neurofeedback training was performed using a specific electrode or a combination of electrodes that best represent the activity of the left posterior insula (LPIns).
- As a rule, a lead via P3, CP3 or T5/P7 (depending on the individual head model) is used to approximate LPIns activity, as these electrodes cover the nearest surface representations of the insula.
(comment not part of the study) - As the training aimed to increase alpha-band activity (8-12 Hz) in the LPIns, feedback was generated based on real-time EEG data from this region.
2. training protocol: real-time feedback for alpha neurofeedback
- During the 30-minute neurofeedback session, participants received auditory feedback when alpha activity in the target region (LPIns) increased above a threshold.
- Reward mechanism: An audio signal was triggered when alpha activity within the LPIns (based on the 10/20 electrodes) was enhanced.
- Comparison condition: In a control group, the primary visual cortex (Brodmann area 17, near Oz) was trained instead of the LPIns.
Summary:
- EEG recording via the 10/20 system with a 21-channel cap.
- Neurofeedback training presumably via P3, CP3 or P7/T5as these electrodes are closest to the left posterior insula.
(comment not part of the study) - Real-time audio feedback based on alpha-band activity (8-12 Hz) in these channels.
- Subsequent source localization with eLORETA to check whether the activation really took place in the LPIns.
Results:
- heart rate variability (HRV): Longer successful neurofeedback duration was associated with increased parasympathetic activation (RMSSD: r = 0.59; p = 0.005) and decreased stress response (SI: r = -0.59; p = 0.006).
- Gastric slow wave activity: There was a significant correlation between successful neurofeedback duration and the stability of gastric rhythmicity in the control training, but not in the LPIns group.
- EEG activity: Correlations were found between the successful duration of LPIns training and different EEG frequency bands in the insula (e.g. beta-band activity in the left and right anterior insula).
- Functional connectivity: Beta-band connectivity between LPIns and RAIns was negatively correlated (r = -0.54; p = 0.013), while gamma-band connectivity between LPIns and RPIns was positive (r = 0.46; p = 0.04).
Conclusion:
- EEG neurofeedback training of LPIns had significant effects on HRV, EEG activity and functional connectivity.
- Training efficiency should be given greater consideration in the future, especially the duration of successful neurofeedback training.
- The results suggest that targeted EEG neurofeedback training may be a non-invasive method to modulate the brain-gut axis and autonomic function.
- The study only examined the acute effects of alpha neurofeedback training on HRV. This means that the improvement in HRV was measured directly after the 30-minute training session, but no long-term study was carried out.
Mathew, J., Galacgac, J., Smith, M.L., Du, P. and Cakmak, Y.O. (2025), The Impact of Alpha-Neurofeedback Training on Gastric Slow Wave Activity and Heart Rate Variability in Humans. Neurogastroenterology & Motility e15009. https://doi.org/10.1111/nmo.15009
Can a long-term improvement in HRV be expected?
As this study only looked at the acute effects, no direct statement can be made about long-term effects. However, there is some evidence from neurofeedback research that suggests that regular training can lead to lasting improvements:
- Neuroplasticity & Repetitive Training:
- Neurofeedback can bring about lasting changes in neuronal networks through operant conditioning.
- Previous studies have shown that regular EEG neurofeedback (over several weeks) can bring about long-term changes in HRV.
- Mechanism: Improvement of vagus activity:
- Since alpha training in the left posterior insula (LPIns) is associated with higher parasympathetic activity and vagus tone, regular training could stabilize this effect.
- The insula is a central modulator of the autonomic nervous system, so a long-term increase in alpha activity could improve vagus function and thus HRV in the long term.
Recommendation for long-term effect:
Since this study only examined a single session, it would be useful to conduct future studies with a multi-week training program. Based on previous neurofeedback studies, 6 to 8 weeks of training (2-3 sessions per week) may be required to achieve a lasting improvement in HRV.
Dipl. Ing. Michael Schiffer MBA, 22-Feb-2025, Baden-Baden