The effect of infra slow frequency neurofeedback on quantitative electroencephalogram and autonomic nervous system function in adults with anxiety and related diseases

Abstract

Over the last decade it has been observed in clinical practice that Infra Slow Frequency (ISF) training alters clients physiological state during training. Peripheral body temperature, pupil size and breathe rate are a few examples of autonomic nervous system (ANS) responses regularly observed during ISF neurofeedback training. ISF electroencephalographic (EEG) biofeedback focusses on the low energy signals produced by the brain. This includes frequencies of less than 0.1 Hz. Evidence suggests that these slow oscillations play a role in synchronizing faster activity and modulates cortical excitability. The origins of these slow oscillations are not yet well understood but studies have indicated the involvement of the thalamus and other subcortical structures. The ANS is an important role player in maintaining sympathetic-parasympathetic and cardiovascular homeostasis. It includes vagal cholinergic and sympathetic noradrenergic nerves that supply the heart and sympathetic noradrenergic nerves that enmesh arterioles. Therefore, clinicians and researchers have long sought valid, non-invasive, quantitative means to identify patho-physiologically relevant abnormalities of these systems. Heart Rate Variability (HRV) is one of the most well-known measurements. There is increasing research pointing to the clinical application of HRV in training and exercise due to its apparent result in strengthening sympathetic-parasympathetic balance. Achieving an increased HRV while doing ISF training should be a good indicator of firstly reaching a clients’ Optimum Frequency (OF) and secondly achieving a sympathetic-parasympathetic balance. This study hypothesizes that ISF training has a measurable physiological effect on an individual by measuring certain autonomic functions viz. HRV, muscle tension, skin temperature, skin conductance, heart rate, respiration rate and blood pressure. Also, to demonstrate how ISF training impacts the resting state EEG. Methods Thirty adults between the ages of 18 and 55 with primarily anxiety will receive a Quantitative Electroencephalogram (QEEG) to get a baseline value before training. The participants will then receive ISF neurofeedback training for 10 sessions while continuous monitoring of ANS changes will be done to determine if there are measurable changes. After 10 sessions we will repeat a QEEG to determine what changes occurred. The same process will be completed for a control group. The control group will receive one channel power training where Theta and High Beta activity will be inhibited at 3-7 Hz and 22-30 Hz respectively and Lo Beta 12-15 Hz activity enhanced at the C4 location on the head. Results Significant changes were seen in the skin conductance (p<0.0001), electromyography (p=0.01), very low frequency and low frequency of HRV (p=0.004 and p=0.05) and blood pressure (systolic change p=0.049; diastolic less significant p=0.083). Changes are also noted in heart rate (p=0.22), and blood volume pulse amplitude (p=0.25). These are less significant but do indicate change. In the heart rate and blood pressure a large change is noted in the standard deviation indicating a non-linear change and regression towards the mean. No significant changes were seen in the control group. Conclusion The study demonstrated that autonomic functions are affected by ISF neurofeedback training and that changes occur in the resting state EEG of participants trained.