How Neuroptimal works
You rest comfortably with five electrodes on your head and you have nothing to do but listen to music and let your thoughts float free. If you fall asleep, no problem, it works just as well! Indeed, everything happens on an unconscious level without requiring any active participation. It is also important that you do not try to observe your thoughts, are not checking your phone and do not try to control anything during the process.
Every 4 milliseconds (256 times a second), the sensors collect information relating to the electrical operation of each brain hemisphere for eight groups of frequencies. The numbers are crunched to compare the data obtained each time with the average of the four previous intervals (i.e. the previous 16 ms). If a sudden and rapid change (rising or falling) in activity, known as turbulence, is observed, a signal is sent to tell the brain about it. This signal is nothing more than a pause in the sound (or music) playing throughout the session. This signal does not require anything of circuits that are changing their activity, but the very brief interruption of the sound is received as an important signal and is an opportunity for the brain (at the site of the turbulence) to modify its function or the routes it uses to communicate with the adjacent neural circuits. This works by strengthening adjacent synapses.
It would therefore be true to say that Neurofeedback helps the brain to repair or regulate itself.
For more information on this subject, please see the chapter entitled "Communication entre neurones" in the book (in French) by Corinne Fournier and Pierre Bohn "Neurofeedback dynamique".