
Neurofeedback is a form of
biofeedback
Biofeedback is the technique of gaining greater awareness of many physiology, physiological functions of one's own body by using Electronics, electronic or other instruments, and with a goal of being able to Manipulation (psychology), manipulate ...
that uses electrical potentials in the brain to reinforce desired brain states through
operant conditioning
Operant conditioning, also called instrumental conditioning, is a learning process in which voluntary behaviors are modified by association with the addition (or removal) of reward or aversive stimuli. The frequency or duration of the behavior ma ...
. This process is non-invasive
neurotherapy
Neurotherapy is medical treatment that implements systemic targeted delivery of an energy stimulus or chemical agents to a specific neurological zone in the body to alter neuronal activity and stimulate neuroplasticity in a way that develops (or b ...
and typically collects brain activity data using
electroencephalography
Electroencephalography (EEG)
is a method to record an electrogram of the spontaneous electrical activity of the brain. The biosignal, bio signals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in ...
(EEG). Several neurofeedback protocols exist, with potential additional benefit from use of
quantitative electroencephalography
Quantitative electroencephalography (qEEG or QEEG) is a field concerned with the numerical analysis of electroencephalography (EEG) data and associated behavioral correlates.
Details
Techniques used in digital signal analysis are extended to t ...
(QEEG) or
functional magnetic resonance imaging
Functional magnetic resonance imaging or functional MRI (fMRI) measures brain activity by detecting changes associated with blood flow. This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area o ...
(fMRI) to localize and personalize treatment.
Related technologies include
functional near-infrared spectroscopy-mediated (fNIRS) neurofeedback,
hemoencephalography
Hemoencephalography (HEG) is a neurofeedback technique in the field of neurotherapy. Neurofeedback, a specific form of biofeedback, is based on the idea that human beings can consciously alter their brain function through training sessions in whic ...
biofeedback (HEG), and fMRI biofeedback.
Neurofeedback is
FDA
The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...
-cleared for
PTSD
Post-traumatic stress disorder (PTSD) is a mental disorder that develops from experiencing a traumatic event, such as sexual assault, domestic violence, child abuse, warfare and its associated traumas, natural disaster, traffic collision, ...
treatment, and training for ADHD and
major depressive disorder
Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive depression (mood), low mood, low self-esteem, and anhedonia, loss of interest or pleasure in normally ...
shows promising results. It has been shown to trigger positive behavioral outcomes, such as relieving symptoms related to psychiatric disorders or improving specific cognitive functions in healthy participants. These positive behavioral outcomes rely on brain plasticity mechanisms and the ability of subjects to learn throughout life.
History
In 1898,
Edward Thorndike
Edward Lee Thorndike ( – ) was an American psychologist who spent nearly his entire career at Teachers College, Columbia University. His work on comparative psychology and the learning process led to his " theory of connectionism" and helped ...
formulated the law of effect. In his work, he theorized that behavior is shaped by satisfying or discomforting consequences. This set the foundation for
operant conditioning
Operant conditioning, also called instrumental conditioning, is a learning process in which voluntary behaviors are modified by association with the addition (or removal) of reward or aversive stimuli. The frequency or duration of the behavior ma ...
.
In 1924, the German psychiatrist
Hans Berger
Hans Berger (21 May 1873 – 1 June 1941) was a German psychiatrist. He is best known as the inventor of electroencephalography (EEG) in 1924, which is a method used for recording the electrical activity of the brain, commonly described in terms ...
connected several electrodes to a patient's scalp and detected a small current by using a ballistic
galvanometer
A galvanometer is an electromechanical measuring instrument for electric current. Early galvanometers were uncalibrated, but improved versions, called ammeters, were calibrated and could measure the flow of current more precisely. Galvanomet ...
. In his subsequent studies, Berger analyzed EEGs qualitatively, but in 1932, G. Dietsch applied
Fourier analysis
In mathematics, Fourier analysis () is the study of the way general functions may be represented or approximated by sums of simpler trigonometric functions. Fourier analysis grew from the study of Fourier series, and is named after Joseph Fo ...
to seven EEG records and later became the first researcher to apply quantitative EEG (QEEG).
In 1950,
Neal E. Miller
Neal Elgar Miller (August 3, 1909 – March 23, 2002) was an American experimental psychologist. Described as an energetic man with a variety of interests, including physics, biology and writing, Miller entered the field of psychology to pursue ...
of Yale University was able to train mice to regulate their heartbeat frequency. Later on, he continued his work with humans, training them through auditory feedback.
The first study to demonstrate neurofeedback was reported by Joe Kamiya in 1962.
Kamiya's experiment had two parts: In the first part, a subject was asked to keep their eyes closed, and when a tone sounded, to say whether they were experiencing
alpha wave
Alpha waves, or the alpha rhythm, are neural oscillations in the frequency range of 8–12 Hz likely originating from the synchronous and coherent ( in phase or constructive) neocortical neuronal electrical activity possibly involving thala ...
s. Initially, the subject would guess correctly about fifty percent of the time, but some subjects would eventually develop the ability to better distinguish between states.
M. Barry Sterman trained cats to modify their EEG patterns to exhibit more of the so-called
sensorimotor rhythm
The sensorimotor rhythm (SMR) is a brain wave. It is an oscillatory idle rhythm of synchronized electric brain activity. It appears in spindles in recordings of EEG, MEG, and ECoG over the sensorimotor cortex. For most individuals, the freq ...
(SMR). He published this research in 1967. Sterman subsequently discovered that the SMR-trained cats were much more resistant to
epileptic seizures
A seizure is a sudden, brief disruption of brain activity caused by abnormal, excessive, or synchronous neuronal firing. Depending on the regions of the brain involved, seizures can lead to changes in movement, sensation, behavior, awareness, o ...
after exposure to the convulsant chemical
monomethylhydrazine
Monomethylhydrazine (MMH) is a highly toxic, volatile hydrazine derivative with the chemical formula . It is used as a rocket propellant in bipropellant rocket engines because it is hypergolic with various oxidizers such as nitrogen tetroxide () ...
than non-trained cats. In 1971, he reported similar improvements with an epileptic patient whose seizures could be controlled through SMR training.
Joel Lubar contributed to the research of EEG biofeedback, starting with epilepsy and later with hyperactivity and
ADHD
Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterised by symptoms of inattention, hyperactivity, impulsivity, and emotional dysregulation that are excessive and pervasive, impairing in multiple ...
.
Ming-Yang Cheng was instrumental in advancing research on EEG neurofeedback, specifically targeting enhancements in SMR power among skilled golfers.
Neuroplasticity
In 2010, a study provided some evidence of
neuroplastic changes occurring after brainwave training. In this study, half an hour of voluntary control of brain rhythms led to a lasting shift in cortical excitability and intracortical function.
The authors observed that the cortical response to
transcranial magnetic stimulation
Transcranial magnetic stimulation (TMS) is a noninvasive neurostimulation technique in which a changing magnetic field is used to induce an electric current in a targeted area of the brain through electromagnetic induction. A device called a st ...
(TMS) was significantly enhanced after neurofeedback, persisted for at least twenty minutes, and was correlated with an EEG time-course indicative of
activity-dependent plasticity
Activity-dependent plasticity is a form of functional and structural neuroplasticity that arises from the use of cognitive functions and personal experience. Hence, it is the biological basis for learning and the formation of new memory, memories. ...
Types of neurofeedback
The term neurofeedback is not legally protected. There are various approaches that give feedback about neuronal activity, and as such are referred to as "neurofeedback" by their respective operators. Distinctions can be made on several levels. The first takes into account which technology is being used (EEG,
fMRI, fNIRS, HEG). Nonetheless, further distinctions are crucial even within the realm of EEG neurofeedback, as different methodologies of analysis can be chosen, some of which are backed up by a higher number of peer-reviewed studies, whereas for others, scientific literature is scarce, and explanatory models are entirely missing.
Despite these differences, a common denominator can be found in the requirement of providing feedback. Usually, feedback is provided by auditory or visual input. While original feedback was provided by sounding tones according to neurological activity, many new ways have been found. It is possible to listen to music or podcasts where the volume is controlled as feedback, for example. Often, visual feedback is used in the form of animations on a TV screen. Visual feedback can also be provided in combination with videos and films, or even during reading tasks where the brightness of the screen represents the direct feedback. Simple games can also be used, where the game itself is controlled by the brain activity. Recent developments have tried to incorporate virtual reality (VR), and controllers can already be used for more involved engagement with the feedback.
EEG neurofeedback
Frequency band / amplitude training
Amplitude training, or frequency band training (used synonymously), is the method with the largest body of scientific literature; it also represents the original method of EEG neurofeedback.
The EEG signal is analyzed with respect to its frequency spectrum, split into the common frequency bands used in EEG
neuroscience
Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions, and its disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, ...
(delta, theta, alpha, beta, gamma). The activity involves training the amplitude of a certain frequency band on a defined location on the scalp to higher or lower values.
Depending on the training goal (for example, increasing attention and focus, reaching a calm state, reducing epileptic seizures,
etc.), the electrodes have to be placed in different positions. Additionally, the trained frequency bands and the training directions (to higher or lower amplitudes) might vary according to the training goal.
Thus, EEG wave components that are expected to be beneficial to the training goal are rewarded with positive feedback when appearing and/or increasing in amplitude. Frequency band amplitudes that are expected to be hindering are trained downwards by reinforcement through the feedback.
As an example, considering ADHD, this would result in training low-beta or mid-beta frequencies in the central-to-frontal lobe to increase in amplitude, while simultaneously trying to reduce theta and high-beta amplitudes in the same region of the brain.
In the sports domain, SMR training has garnered attention, with a substantial body of research suggesting that enhancing it could improve performance. This improvement is particularly evident after multiple training sessions
designed to enhance motor skills critical for precise movements. Such precision is required in various sports activities, including
golf putting,
soccer free kicks, and basketball
free throw
In basketball, free throws or foul shots are unopposed attempts to score points by shooting from behind the free-throw line (informally known as the foul line or the charity stripe), a line situated at the end of the restricted area. Free throws ...
s.
SCP training
For SCP (slow cortical potentials) training, one trains the DC voltage component of the EEG signal. The application of this type of EEG neurofeedback training was mostly endorsed by research done by Niels Birbaumer and his group. The most common symptom base for SCP training is ADHD, whereas SCPs also find their application in brain-computer interfaces.
LORETA (low resolution electromagnetic tomography analysis) training
Normal EEG signals are restricted to the surface of the scalp. Using a high number of electrodes (19 or more), the source of certain electrical events can be localized. Similar to a tomography that renders a 3D image out of many 2D images, the many EEG channels are used to create LORETA images that represent in 3D the electrical activity distribution within the brain. The LORETA method can be used in combination with MRI to merge structural and functional activities. It is able to provide even better temporal resolution than PET or fMRI. For the application with live neurofeedback, however, 19-channel neurofeedback and LORETA has limited scientific evidence, and until now, shows no benefit over traditional 1- or 2-channel neurofeedback.
Effectiveness
Neurofeedback is
FDA
The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...
-cleared for
PTSD
Post-traumatic stress disorder (PTSD) is a mental disorder that develops from experiencing a traumatic event, such as sexual assault, domestic violence, child abuse, warfare and its associated traumas, natural disaster, traffic collision, ...
treatment. A 2023 systematic review and meta-analysis of ten clinical trials found that electroencephalographic neurofeedback significantly reduces PTSD symptoms, with a 79.3% remission rate compared to 24.4% in control groups, and suggests that improvements are associated with neurophysiological changes in brain activity.
Neurofeedback training for ADHD shows promising results, with some protocols offering better outcomes, though its efficacy remains controversial and requires further research to determine the best approach. A meta-analysis of 22 studies found that neurofeedback significantly improves depressive symptoms, neurophysiological outcomes, and neuropsychological function in individuals with major depressive disorders, with longer interventions enhancing psychological outcomes and shorter sessions benefiting neurophysiological measures.
There is ongoing discussion about the effect size of neurofeedback in the scientific literature. As neurofeedback is explained mostly based on the model of operant conditioning, the sensitivity of the feedback (the difficulty to receive a reward) also plays a role. It has been shown that the desired conditioning can be reversed if threshold values are set too low. Other publications have not found any effect of neurofeedback, apart from placebo, when using automatic thresholds that update every thirty seconds in order to maintain a constant success rate of 80%.
See also
*
Brainwave synchronization
Brainwave entrainment, also referred to as brainwave synchronization or neural entrainment, refers to the observation that brainwaves (large-scale electrical oscillations in the brain) will naturally synchronize to the rhythm of periodic external ...
*
Decoded neurofeedback
Decoded Neurofeedback (DecNef) is the process of inducing knowledge in a subject by increasing neural activation in predetermined regions in the brain, such as the visual cortex. This is achieved by measuring neural activity in these regions via fu ...
*
Mind machine
A mind machine (aka ''brain machine'' or ''light and sound machine'') uses pulsing rhythmic sound, flashing light, or a combination of these. Mind machines can Induced activity, induce deep states of relaxation or concentration.
The process app ...
*
Neuromodulation
Neuromodulation is the physiological process by which a given neuron uses one or more chemicals to regulate diverse populations of neurons. Neuromodulators typically bind to metabotropic, G-protein coupled receptors (GPCRs) to initiate a sec ...
References
Further reading
*
*
*
External links
BBC article about neurofeedback improving the performance of musicians*
{{Authority control
Devices to alter consciousness
Medical tests
Electroencephalography
Evoked potentials
Neurotechnology
Behaviorism
Attention deficit hyperactivity disorder management
Alternative medical systems
Naturopathy
Neuropsychology