The Neurofeedback is a special direction of biofeedback . The oldest form is EEG neurofeedback. Here, brain waveforms ( EEG waves) are analyzed by a computer in real time , broken down according to their frequency components and displayed on a computer screen. The frequency distribution determined in this way in the quantitative EEG , which is dependent on the state of attention or consciousness (for example, awake, asleep, attentive, relaxed, stressed), can be used for training (by means of feedback training). It is possible for the test person to achieve better self-regulation through feedback from their own brain wave pattern.
The effect of neurofeedback training is explained by what is known as operant conditioning . This is essentially a learning process that reinforces certain behavior. Because this takes place without consciousness, no conscious effort is required. In principle, every person can learn neurofeedback ( learning theory ).
The EEG signal serves as the basis for neurofeedback training. This is essentially determined by its strength (amplitude) and the number of vibrations (frequency of the individual frequency bands). For this purpose, the raw EEG signal, which is picked up by electrodes on the scalp, must first be sufficiently amplified.
The EEG amplifier forwards the signals directly to a computer, where they are processed by a special program for training purposes. This is done, for example, by breaking down the raw EEG into different wave components, the brain frequencies such as alpha , beta, delta, theta or gamma.
In this way, physiological processes that are otherwise hidden are made perceptible so that the body can receive feedback at all . Acoustic and / or optical feedback (for example music, noise, video clip or a computer animation ) is given by the computer when the EEG waves of the brain have a desired composition. This is done by continuously analyzing the signal, in which the computer program calculates trends in the deflections of the brain waves and compares them with a predetermined threshold value in fractions of a second. If thresholds are now undershot or exceeded to a certain desired extent, this brain activity is increased by means of a reward stimulus. See also positive reinforcement .
Model of neural dysregulation
There are a variety of models that can be associated with the development of symptoms. Theorists of neurofeedback training see the cause of many central nervous disorders in a dysregulation of cortical and subcortical structures, which can be globally divided into four cause classes. These are: overstimulation (overarousal), under-stimulation (underarousal), lack of inhibition (disinhibition) and instability. The aim is to positively influence symptoms by training down or training up certain wave components. There is no direct treatment of symptoms.
In 1898 Edward Lee Thorndike discovered the learning “law of action” and laid the foundation for the development of instrumental conditioning . In 1905 Ivan Petrovich Pavlov carried out the now famous experiments with a dog and thus discovered the concept of classical conditioning ( Pavlovian dog ).
In 1929, Hans Berger discovered electrical potential fluctuations at different frequencies on electrodes attached to the top of the skull and called the curves recorded by them " electroencephalograms ". In particular, the characteristics of the alpha waves in the EEG that he researched are still of great importance for neurofeedback therapists today.
In 1950, Neal E. Miller of Yale University got mice to train their heart rate (in a chosen preferred direction) by giving them a reward by stimulating the pleasure center in the brain. Later he also trained people in a similar way by training them using sounds that were perceived as pleasant or, if successful, rewarding them. In 1967, M. Barry Sterman published a study stating that he trained cats to modify their EEG waves. He later discovered by chance that cats trained in this way are resistant to epileptic seizures (which in untrained cats were triggered by contact with toxic fumes ( monomethylhydrazine )) and thus showed that EEG wave training can improve the abilities of the brain. In 1974, M. Barry Sterman stated in his first of five publications that epileptic seizures in humans can be brought under control by means of EEG wave training (SMR). From 1975 Joel Lubar researched EEG biofeedback first with regard to epilepsy and later on hyperactivity and ADHD.
In 1998, the Yonkers District Schools, New York added neurofeedback training to their curriculum. In 2006 the Italian national soccer team trained with neurofeedback.
Procedure (training protocols)
Before starting any treatment, it is important to first take a detailed anamnesis, diagnose and collect findings. The result provides the neurofeedback therapist with important information about the type of central nervous excitation the patient is dealing with. For example, poor sleep is often associated with (cortical) overexcitation, ADD (without hyperactivity) with (cortical) underexcitation. Migraines, various seizure disorders, but also tics are more related to unstable arousal. A so-called “symptom checklist” can then be used to determine which type is predominant. With this, however, only vague statements can be made about the frequency range in which there is too much or too little activity. Therefore, in addition to the purely symptom-oriented approach, the quantitative analysis of the EEG (QEEG) is also used. With the help of scientifically created databases, it is now possible to differentiate between normal and impaired brain function much more precisely. This in turn enables a more precise selection of suitable neurofeedback protocols.
Amplitude training and frequency band training
The voltage that occurs in the EEG is greater, the more nerve cells locally “fire” synchronously. With neurofeedback amplitude training, local synchronicities are ultimately trained in the brain. In this case, increased synchronicity does not necessarily have to be desired; the achievement of a lower amplitude, i.e. less synchronicity, is often confirmed with positive feedback. Furthermore, several conditions are often trained at the same time. So there is only positive feedback for the test person if, for example, he achieves a higher amplitude in one frequency range and at the same time a lower amplitude in another frequency range. This means that the composition of the entire EEG of a test person can be addressed in a more targeted manner.
This means: EEG wave components (frequency ranges) that are known to be beneficial are rewarded when they occur, such as SMR (sensorimotor rhythm) and beta. Frequency band amplitudes that are known to be less beneficial (such as low theta - typical for lack of concentration - and high beta stress, hectic thought processes) are suppressed or, in this case, rewarded when the amplitude is reduced. Neurofeedback works exclusively with rewarding feedback. Neurofeedback is therefore also used in competitive sports in order to be able to reliably hit sports with high balance components and steady hands (e.g. shooting , archery , biathlon ).
Z-score method or Z-score training
The basic idea here is based on EEG databases. An EEG database contains EEG values of a normal healthy population determined according to scientific criteria with regard to amplitude, coherence, asymmetry and phase.
Training of connectivity of the EEG
Neurofeedback can also train the coherence of the signals from two electrode positions or brain regions in a selected frequency band. Coherence is a measure of the interaction between different localities in the cerebral cortex. For example, the coherence between the Broca area and the Wernicke center is crucial for language skills. Too much or too little cooperation can manifest itself in language disorders, for example. The coherence has a value range from 0 to +1 (in practice also sometimes referred to as 0 to 100%). In coherence training, this value is trained towards a specific target value so that it should, for example, reach the measured value of a healthy reference population group.
In SCP training, the value of the direct voltage component (so-called slow cortical potential , SCP) is trained. This type of neurofeedback is particularly due to the research work of the group around Niels Birbaumer . Slow cortical potentials play among others a major role in the so-called brain-computer interfaces ( Brain-Computer Interfaces BCI), plays a leading role in the research and development of Birbaumer.
Further variants of neurofeedback
Bipolar training, Z-value-based training (Z-score training), LENS (Low Energy Neurofeedback System from Len Ochs), Alpha-Theta training, Loreta-Neurofeedback (Low Resolution Electromagnetic Tomography) (3-D).
Areas of application
Medical / therapeutic
- Anxiety disorders
- Attention Deficit / Hyperactivity Disorder
- Learning disorders such as dyslexia and dyscalculia
- Migraines and headaches
- sleep disorders
- Tic disorder, Tourette syndrome
Health promotion and prevention (diagnosis-free application)
- Training to cope with and reduce stress
- Maintaining mental flexibility in old age
Education, socialization and school context
- Training to improve school performance (increase so-called performance IQ)
- Training "juvenile delinquents" (compensation of instability)
Maintaining professional performance and achieving top mental performance
- Training of professionals with high stress levels (e.g. military pilots)
- Improving the artistic performance of musicians
Criticism of the medical application
The US FDA (Food and Drug Administration) permits neurofeedback for relaxation training, but not for any other application.
In 2015, an international scientific publication was published in which it is assumed that the advantages of therapeutic EEG neurofeedback result from placebo effects and that the effectiveness in the treatment of mental disorders is controversial.
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- Child and adolescent psychiatric clinics of North America , MEDLINE Abbr: Child Adolesc Psychiatr Clin N Am, NLM ID: 9313451 Scientific journal which provides reviews of the state of research. In the January 2005 issue, which deals with the topic of 'Emerging Interventions', six out of ten articles are devoted to the topic of neurofeedback.
- Journal of Neurotherapy. The journal of the International Society for Neurofeedback & Research.
- Scientific work on neurofeedback
- Dissertation on Neurofeedback (PDF)
- Biofeedback Certification International Alliance, BCIA - Organization which certifies neurofeedback therapists internationally
- Journal of Neurotherapy website
- Website of the Neurofeedback Network
- The OpenEEG project
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