Your brain is made of neurons which transmit information to one another through the release of neurotransmitters, chemical messengers which excite or inhibit target neurons. Whether a neuron is stimulated or inhibited depends on how neurotransmitters alter the electrical potential of that neuron. A depolarization, or positive change in electrical potential of a neuron causes the neuron to fire and communicate with subsequent neurons.
Changes in electrical potential can be recorded by an EEG apparatus which models the timing of neuronal firing through electrical waves. Neural discharges are recorded in Hertz, which is the amount of cycles of firing per second. Different types of brain wave ranges are recorded in neurofeedback, with all types of waves simultaneously occurring: these include delta, theta, alpha, beta, beta 1, beta 2, and gamma waves. These various waves are compared between the left and right hemispheres as well as anterior and posterior regions of the brain to determine relative normalcy.
When the brain functions normally, waves synchronize with each other and remain in healthy ranges of amplitude and frequency. A dysfunctional brain may show ranges which are too low or high. Adverse influences, such as stress, can disturb neuronal firing loops which usually contribute to healthy brain function and cause changes in brain wave generation. Neurofeedback can restore the stability of these neuronal circuits, augment neural cohesiveness, and eventually stimulate the formation of new circuits. Neurofeedback has been found to be effective in treating ADHD, depression, anxiety, and many other psychiatric illnesses.
(Markiewcz, 2017) – https://pubmed.ncbi.nlm.nih.gov/29432505/