Neurofeedback

An analysis of existing practices and predictions for the future

Romke van der Meulen∗

June 24, 2011

Abstract

In this paper I survey the field of ‘neurofeedback’. Neurofeedback involves measuring brainwave patterns from a subject, processing the data and comparing it to a target value, andfeeding the results back to the subject. Typically, audio and visual feedback are used, andthe neural activity is measured using an EEG with two or three sensors. Neurofeedbackcan be used to inhibit or enhance brain waves, depending on the desired effect. Neurofeed-back has been used to train theta, alpha, beta, SMR waves and slow cortical potentials.Neurofeedback has notably been applied to the treatment of a number of disorders withmental components, such as ADHD, epilepsy and PTSD. Neurofeedback was first used inthe 1970s, and has been continually developed since. It is now becoming more acceptedas a viable treatment method. Neurofeedback has a number of advantages compared totraditional medical treatments: it is cheap, it has few side effects and it actively involvesthe patient in the treatment. As such, we can expect neurofeedback to become a widelyaccepted treatment method in the future.

Keywords: biofeedback, neurofeedback, therapy, EEG, QEEG

Introduction

Neurofeedback is a specific case of biofeedback. In biofeedback, biological data is recorded froma subject and fed back to this subject online, typically using both visual and audio feedback.The goal for the subject is to attain a particular state as often and for as long as possible. Thistraining is done continuously through several sessions, with the goal being that the subjectlearns to attain this state at will, without requiring feedback. This practice is used in therapy,for example by teaching people with hypertension to lower their own blood-pressure levels.

In neurofeedback, what is fed back to the subject is a measure of their brain activity.Typically, an EEG is measured and analyzed. According to the training goals, particular brainpatterns are selected and fed back to the subject. Typical neurofeedback training includesenhancing beta waves, alpha waves or alpha/gamma ratio. By training people to alter their brainpatterns, a range of ailments with distinct mental components may be treated. Neurofeedbackhas been applied to the treatment of Attention-Deficit/Hyperactivity Disorder (ADHD), Post-Traumatic Stress Disorder (PTSD), autism-spectrum disorders, epilepsy, and many others.

Neurofeedback was first explored and popularized by the work of Joe Kamiya in the 1960’s.He used early EEG measures to train people to induce a state of heightened alpha wave activity(Kamiya, 1971). Neurofeedback continued to develop, but was still a minor field in biofeedback.In 1993, several meetings were held to advance the field. Out of one of these, the precursor to

∗Student Human Machine Communications, Department of Artificial Intelligence, Rijksuniversiteit Groningen

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the International Society for Neurofeedback Research (www.isnr.org) was formed. At a meetingof the Association for Applied Psychophysiology and Biofeedback (www.aapb.org), the sectionof the organisation concerned with EEG grew to become the biggest section in the organisation.Neurofeedback is now becoming an established practice, in the United States in particular.

In this paper, I present a survey of the field of neurofeedback. I will in particular highlightneurofeedback practices, applications and effectiveness. Based on this, I will present an outlookon the future of neurofeedback research. To gather this information, I made a study of existingliterature. I also interviewed Drs. Roland Verment, a neurofeedback practitioner at Neurobicsin Groningen (www.neurobics.nl).

Methods

Neurofeedback setups consist of three components: a device for measuring brain activity, amathematical analysis of the data, and a method of feeding back the results to the subject.Many combinations of methods have been applied, but there are some standards that havebeen most widely used. A typical neurofeedback setup uses (Q)EEG measurements and presentsaudio and visual feedback.

A quantitative electroencephalogram (QEEG) is a measurement taken using an electrodecap with 19 electrodes. The subject’s brain activity is measured for an extended time, artifactsare removed from the signal, and the data is compared to normative data to identify obviousabnormalities. A QEEG may be used at the start of neurofeedback training, to aid the practi-tioner in identifying problems and designing a training regimen and during training to updateassessment (Hammond, 2006).

During a neurofeedback training session, two electrodes and an ear clip suffice to get brainwave readings for feedback. The signal is analyzed, the appropriate brain wave signal is isolatedand compared to the target value. The result is used to generate an audio and/or visual signal,which is fed back to the subject. (Hammond, 2006)

The type of feedback can vary greatly. There seems to be a consensus that for the bestresults, a combination of modalities, mostly visual and audio, should be used (Vernon et al.,2004, p. 65). Neurobics, for example, in one type of training, shows the subject a movie. Achime sounds whenever the subject maintains the target state for half a second, and the sizeof the movie projection varies with the proximity of the brain pattern to the target pattern.Another approach is to display a bar next to the movie, where the bar height is an indication ofthe current strength of the target brain pattern, and a line indicates the target height. Childrenseem to respond well to positive reinforcement and lots of it.

Not much hardware is actually involved: a simple EEG clip and amplifier, and a computer.Neurobics has in some instances tried letting subjects perform training sessions at home, super-vised over the internet. Drs. Verment reports mixed results: is some instances, home trainingcan be a positive influence, but in many cases the subject cannot relax and focus on the trainingas well at home, with numerous distractions, as in the specially designed facilities at Neurobics.

Interestingly, Cortoos et al. (2010) did a study where patients with primary insomnia usedneurofeedback training at home two or three times a week over an eight week period. The groupwhose neurofeedback training focused on inhibition of theta and high beta, as well as enhancedSMR, showed a signicant increase in total sleep time. Of several groups in the experiment,only the group that did neurofeedback training at home showed an increase in subjective sleepmeasures.

The brain pattern to train, and the target value of the signal, are parameters of the trainingsession. The practitioner determines these based on the subjects problems/goals, and on theQEEG results. When the desired result is a calm state, slow brain waves such as theta or alpha

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may be trained. If greater focus is desired, beta wave training is more appropriate. Goals maybe set to absolute values for some brain wave frequency, but may also aim at altering the ratioof certain types of brain wave, e.g. the ratio of theta to alpha. The assignment of brain wavetypes to frequency bands is usually fixed, but some research has suggested that these should bedetermined individually for optimal results, though this remains to be proven (Vernon et al.,2004).

The duration of each training session, and the frequency of sessions, are also free parameters.A typical session at Neurobics lasts for 40-50 minutes, once a week. According to Drs. Verment,positive effects outside the training session manifest quickly, often after only 5 to 10 sessions.Subjects often report feeling different mentally after even the first session.

In recent years, some alternatives to EEG as the measurement for neurofeedback haveemerged. Yoo and Jolesz made a pilot study of using fMRI in neurofeedback (Yoo and Jolesz,2002). They trained several subjects to move muscles in their hand to produce a target levelof cortical activity. Although fMRI had a significantly lower temporal resolution compared toEEG (data was only fed back to the subjects after a one minute block), they theorized thatthe increased spatial resolution means that this method might be successfully applied to aid inmotor functional rehabilitation after neurological damage.

Johnston et al. (2010) show a more recent application of fMRI to neurofeedback. Theytrained thirteen participants to increase activity in a target area on demand. First they showedthe participants emotionally negatively affective pictures, to determine the individual’s emotionnetwork in stead of relying on anatomically defined areas. The participants were then instructedto increase activity in the target area, alternated with rest periods. A thermometer, updatedat 2s intervals, represented activity in the target area. The participants spent an average of14 minutes in this feedback training. Participants were told to find their own mental strategyto increase activity, most chose negative emotional memories. They found that participantswere quickly able to increase activity in the target area. By using mental imagery, activity alsoincreased in areas outside the target, but no significant activation increases were found outsidethe target across runs.

Another recent development is an interest in the application of electromagnetic tomography,or inverse EEG. This involves analyzing the EEG signal on multiple places on the scalp toreconstruct activity at a specific location in the brain. Congedo et al. published a study inwhich they used 19 electrodes placed according to the 10-20 system to enhance the beta toalpha ratio in the Anterior Cingulate of six undergraduate students, which they claim to be thefirst application of inverse EEG to neurofeedback (Congedo et al., 2004). Drs. Verment tellsme interest in this method has grown in recent years, but the additional benefit remains to beproven.

There are a number of free parameters in setting up a neurofeedback training regimen.Unfortunately, though there have been a large number of publications on individual clinicaltrials, there has been very little systematic research into the influence of each parameter on theend result, and what the optimal approach would be. Vernon et al. (2004), in their comparativestudy of papers on the treatment of ADHD, have given a number of points for future research,and also conclude that research of this kind is required but lacking. Drs. Verment also indicateda lack of this type of research, which is unlikely to be done by commercial practitioners as suchresearch would entail giving suboptimal training to paying customers. As long as this researchis not done, aside from some established practices, neurofeedback practitioners have to findoptimal treatment procedures for themselves.

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Applications

Neurofeedback has been applied to a wide range of disorders, and also to enhancing performancein healthy individuals. The ISNR website (www.isnr.org) holds links to studies in a numberof applications. I will list and evaluate a number of these applications here. This is not anexhaustive list: over the last few decades, neurofeedback has been applied to a great number ofuses.

ADHD

One of the most frequent applications of neurofeedback is in the treatment of ADHD. CommonADHD treatments using neurofeedback include inhibiting theta waves and enhancing SMR orlow-beta waves. (Vernon et al., 2004)

Theta waves (4-8 Hz) are one of the slower brain waves, associated with relaxation and lowarousal. ADHD patients typically show an excess of theta waves, and the training to inhibittheta is common to most ADHD treatments. The cause of this excess theta activity is unclear,but under arousal and developmental deficiencies have been implicated.

The SMR pattern (12-15 Hz) is related to inhibition of motor movements. An increase inthis type of activity translates into an increased sense of calm. Therefore, training to enhanceSMR is given to ADHD patients where hyperactivity/impulsiveness is one of the symptoms.

Low-beta (15-20 Hz) training was first given to ADHD patients because QEEG resultsshowed patients to have a lower level of this activity. Also, low-beta has been linked by anumber of researchers to mental activities related to (maintained) focus and attention. Trainingto enhance low-beta activity may therefore be most beneficial for ADHD patients where lowattention and/or low arousal are the primary symptoms.

Epilepsy

Since epilepsy is a disorder arising from uncontrolled brain activity, neurofeedback is ideallysuited to help patients get the condition under control. This is why epilepsy was one of thefirst disorders to be treated with neurofeedback. Monderer et al. (2002) reviewed thirty yearsworth of research on the use of neurofeedback training to treat epilepsy. They intended todo a meta-review of all results, but found insufficient rigorously controlled studies to produceaccurate results. They instead reviewed existing research more informally. They found twomajor training procedures that have been applied to epilepsy: inhibition of negative SCP andenhanced SMR.

Epilepsy has been linked to large oscillations in the Slow Cortical Potential (SCP). Positiveshifts are linked to relaxation, negative shifts with higher arousal and increased cortical activity.Therefore much research has focused on training patients to suppress negative SCP, hoping thatthereby the patient can learn to inhibit seizures. Monderer et al. reviewed a number of studiesthat showed significant benefits in patients thus trained: many had decreased seizure frequencies,while others even became seizure free. Unfortunately, a number of patients failed to respond tothe training. Elbert et al. (1980) suggested that factors such as increased age, stress and lackof motivation may be responsible.

Training for enhanced SMR has been studied by a number of researchers since the 1970s.Few controlled studies were done, but a number of clinical trials were published. Many showedpositive results, with seizure frequency being reduced even after training has ended.

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Alpha/theta training

Alpha (8-12 Hz) and theta (4-8 Hz) brain waves are connected to rest and relaxation. Neuro-feedback training to enhance these patterns can help a subject reach a relaxed state. A numberof conditions can be treated by such training. Alpha/theta training has been applied, amongothers, to alcoholism, stress, depression, PTSD and schizophrenia.

Peniston and Kulkosky from Colorado have researched a number of applications of al-pha/theta training, including the treatment of alcoholism (Peniston and Kulkosky, 1990). Saxbyand Peniston (1995) applied the same training method to the treatment of 14 alcoholics withdepressive symptoms. They obtained behavioural measurements both before and after thetraining, and during a 21 month follow-up. They found significant decreases in depressive andalcoholic symptoms, even at the 21 month follow-up. They did not obtain EEG measures to ver-ify altered brain wave patterns in the subjects, a shortcoming common to many neurofeedbackstudies: more on this later.

One of the most successful applications of alpha/theta training has been in the treatmentof Post-Traumatic Stress Disorder (PTSD). Peniston and Kulkosky (1991) compared the re-sults of alpha/theta training to a traditional medical control group. They obtained behaviouralmeasures after the training and at a thirty month follow-up. They found that patients re-ceiving alpha/theta training showed decreased scores for a number of depressive symptoms,while the control group only showed a decrease on the scale labelled schizophrenia. All four-teen alpha/theta training subjects who took psychotropic medication reduced their dosage aftertreatment, while only one of thirteen subjects in the control group did. At the thirty monthfollow-up, all fourteen subjects in the control group had relapsed, while of the fifteen trainingsubjects, only three had relapsed. This study did not have enough rigorous control for reliablescientific conclusions: the only measurements were behavioural data, and it was not establishedthat this was due to altered brain wave patterns. However, these results did prove so promisingthat research into this type of treatment has continued since.

Bolea (2010) describes the author’s experience with the application of neurofeedback therapyto the treatment of schizophrenia. It describes one severe case which the author claims isrepresentative of 70 schizophrenia patient he has likewise treated. Training included, amongothers, enhanced alpha and decreased beta activity. This patients, like many of the other70, had been classified as ‘hopeless’ after a range of therapies had been attempted. After aneurofeedback treatment of over a year, results were so good that the patient could resumeliving in the community.

Performance

Neurofeedback is not only applicable to therapeutic settings. Research has also been doneinto neurofeedback as a method of increasing performance in healthy subjects. Vernon (2005)reviewed a number of studies on this subject, categorized into training to enhance sports perfor-mance, cognitive performance or artistic performance. Some of the studies included applicationof neurofeedback to the enhancement of archery, athletics, dance, creativity, learning, memoryand musical ability. The reviewed studies included theta, alpha, alpha/theta and beta training.

Unfortunately, Vernon found that most studies were not rigorous enough to warrant strongconclusions. Some studies measured post-training brainwave patterns, but found no significantchange. Others obtained only post-training behavioural measurements, and some of these stud-ies also found no significant change. None of the studies was rigorously performed: of thosefew where there was a control group, the control group did not receive equivalent attention ortraining as the experimental group. Some did not have a control group at all. In fact, Vernonconcluded that based on the reviewed material, the applicability of neurofeedback training to

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performance enhancement was equivocal. However, the reviewed studies did show enough of aninteresting trend to warrant further research.

Effectiveness

Until recently, though neurofeedback had already been successfully applied to a number ofindividual cases, there was little scientific proof to conclude that neurofeedback was a viabletreatment, with significant benefits. Vernon et al. (2004) concluded that on the matter of thetreatment of ADHD, there had been a number of published clinical trials, but most of thesefailed to control for a number of factors, or to show that beside an alleviation of symptoms,there was also a measured, persistent change in brain wave activity, so that the success of thetreatment might just as well have been attributed to uncontrolled factors. In another review(Vernon, 2005), Vernon concluded that published studies on the effects of neurofeedback trainingto enhance performance in healthy individuals, there was also a lack of conclusive evidence dueto inadequate control, low number of subjects and insufficient data on the persistence of thealtered brain activity. He recommended future studies use better control groups, pre- andpost-training EEG baselines to check for altered neural activity, pre- and post- measures ofbehaviour, and correlation of changes in EEG to altered behaviour.

Fortunately, in recent years there has been a new focus on this shortcoming, and largerandomised controlled trials are now being held. Gevensleben and et al. (2009) did a study on102 children with ADHD, distributed over a test and control group, where the control groupreceived a carefully constructed placebo training designed to match the neurofeedback trainingas much as possible. Behavioural measures were obtained pre-, during and post-training, thoughpost-training EEG data was not provided, failing some of Vernon’s recommendations. Theirstudy did find a significant improvement in behavioural measures for the test group comparedto the control group, which might prove conclusively that neurofeedback is a viable treatmentfor ADHD.

Drs. Verment tells me that neurofeedback is recently becoming well accepted in manylarge Dutch organisations. Many medical insurance companies finance neurofeedback trainingin their extended packages, though official rulings prohibit them from offering it in their ba-sic coverages plans. Insurance companies view the treatment very favourably, due to its lowcost (EEG/processing equipment, space and man hours) and good results with disorders thatnormally require years of traditional treatment.

There are also a number of other reasons why neurofeedback is considered a good alternativeto traditional treatments. It actively involves the patient with his or her treatment, increasingmotivation and success rates. It makes use of the human bodies own abilities to cure disorders,in stead of relying on foreign elements such as medication. Also, unlike medication, there arelittle to no negative side effects in neurofeedback training. In fact, experience has shown thatsubjects not only decrease symptoms but also gain a relaxed or focused mind-set and a senseof well-being.

Besides therapeutic uses, neurofeedback has also been applied to neurological research.Keizer et al. (2010), for example, used neurofeedback to train two groups in a double-blindexperiment. One group was trained for enhanced gamma band (36-44 Hz) activity, one forenhanced beta band (12-20 Hz) activity. The goal was to determine how the change in eachband would affect short-term and longer-term feature binding related to long term memory.The gamma band group was able to increase frontal and occipital gamma activity, while thebeta band group got increased synchrony in the beta band between frontal and occipital ar-eas. Enhanced gamma activity led to “a greater exibility in handling integrated informationin short-term and long-term memory”, while increased coordination in beta activity led to “fa-

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cilitation of familiarity-based processes”. Keizer et al. concluded that neurofeedback can be apowerful tool in research, especially into the functional role of neural synchrony, which is oneof the primary causes of EEG brain wave patterns.

Conclusion

In this paper, I have surveyed the research area of neurofeedback. Neurofeedback consists ofmeasuring brain activity, typically using EEG data, processing these measures, comparing themto target values and feeding the results back to the subject. The subject then learns to controlhis or her own brain waves, to positive and persistent effect.

Neurofeedback has been around for 40 years, and is starting to become accepted as a viablealternative treatment to a range of disorders with mental components, including but not limitedto the treatment of ADHD, alcoholism, autism, depression, epilepsy, PTSD and stress, and hasalso been applied to the enhancement of performance in healthy individuals. The effectiveness ofneurofeedback has recently been more and more well established, with rigorous control studiesproving the beneficial effects of neurofeedback in a number of applications.

Neurofeedback has a number of advantages over traditional medical practices: it is cheap,has few side effects and actively employs the patient into using their natural processes to treatdisorders. Neurofeedback will likely continue to grow in the public consciousness, and becomean established therapeutic practice.

References

Bolea, A. S. (2010). Neurofeedback treatment of chronic inpatient schizophrenia. Journal ofNeurotherapy, 14:47–54.

Congedo, M., Lubar, J. F., and Joffe, D. (2004). Low-resolution electromagnetic tomogra-phy neurofeedback. IEEE Transactions on Neural Systems and Rehabilitation Engineering,12(4):387 – 397.

Cortoos, A., Valck, E. D., Arns, M., Breteler, M. H. M., and Cluydts, R. (2010). An exploratorystudy on the effects of tele-neurofeedback and tele-biofeedback on objective and subjectivesleep in patients with primary insomnia. Applied Psychophysiolical Biofeedback, 35:125–134.

Elbert, T., Rockstroh, B., Lutzenbergera, W., and Birbaumer, N. (1980). Biofeedback of slowcortical potentials. i. Electroencephalography and Clinical Neurophysiology, 48(3):293 – 301.

Gevensleben, H. and et al. (2009). Is neurofeedback an efficacious treatment for adhd? arandomised controlled clinical trial. Journal of Child Psychology and Psychiatry, 50(7):780–789.

Hammond, D. C. (2006). What is neurofeedback? Journal of Neurotherapy, 10(4):25–36.

Johnston, S., Boehm, S., Healy, D.and Goebel, R., and Linden, D. (2010). Neurofeedback: Apromising tool for the self-regulation of emotion networks. NeuroImage, 49:1066–1072.

Kamiya, J. (1971). Operant control of the eeg alpha rhythm and some of its reported effects onconsciousness. Biofeedback and Self-Control: an Aldine Reader on the Regulation of BodilyProcesses and Consciousness.

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Keizer, A. W., Verment, R. S., and Hommel, B. (2010). Enhancing cognitive control throughneurofeedback: A role of gamma-band activity in managing episodic retrieval. NeuroImage,49:3404–3413.

Monderer, R. S., Harrison, D. M., and Haut, S. R. (2002). Neurofeedback and epilepsy. Epilepsy& Behavior, 3:214–218.

Peniston, E. G. and Kulkosky, P. J. (1990). Alcoholic personality and alpha-theta brainwavetraining. Medical Psychotherapy, 3:37–55.

Peniston, E. G. and Kulkosky, P. J. (1991). Alpha-theta brainwave neuro-feedback for vietnamveterans with combat-related post-traumatic stress disorder. Medical Psychotherapy, 4:47–60.

Saxby, E. and Peniston, E. G. (1995). Alpha-theta brainwave neurofeedback training: An effec-tive treatment for male and female alcholics with depressive symptoms. Journal of ClinicalPsychology, 51(5):685–693.

Vernon, D., Frick, A., and Gruzelier, J. (2004). Neurofeedback as a treatment for adhd:A methodological review with implications for future research. Journal of Neurotherapy,8(2):53–82.

Vernon, D. J. (2005). Can neurofeedback training enhance performance? an evaluation of theevidence with implications for future research. Applied Psychophysiology and Biofeedback,30(4):347–364.

Yoo, S.-S. and Jolesz, F. A. (2002). Functional mri for neurofeedback: feasibility study on ahand motor task. Neuroreport, 13(11):1377 – 1381.

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