Bio- and neurofeedback applications in stress regulation

Abstract

Chronically being stressed has a negative impact on health. Stress occurs when homeostasis in the body becomes disrupted. To bring the body back into a homeostatic state, a stress response is initiated. The stress response activates the autonomic nervous system and the hypothalamic-pituitary-adrenal axis. Several biological parameters (EDA, heart rate, respiration rate) represent stress in the body. Biofeedback makes use of these parameters to decrease the amount of stress individuals perceive. By measuring the parameters reflecting stress and feeding these back to the individual, the brain should learn that some behaviours or thoughts are rewarding and therefore should be executed more often. Studies showed that this procedure works in decreasing the amount of stress in healthy people and PTSD patients. Especially the dorsolateral, prefrontal, anterior cingulate and parietal cortices, amygdala and basal ganglia increase activation after biofeedback relaxation training sessions. Neurofeedback makes use of the EEG signal which consists of four main frequency bands, namely delta, theta, alpha and beta. Theta and alpha waves are related with relaxation and therefore these waves are often used in neurofeedback sessions aiming to increase relaxation. By feeding back the theta and alpha wave level in the EEG signal; the brain should learn how to permanently increase the amount of these waves. Studies showed that alpha theta neurofeedback training can increase relaxation, but a disadvantage is that these studies have a lot of limitations. In the future these limitations, such as a lack of control groups, have to be solved to get more powerful results. Based on the evidence provided by the current studies, biofeedback seems to be more effective in decreasing stress levels than neurofeedback.