Overview of Neurofeedback Mechanisms:
Setting the Agenda for Research
by Siegfried Othmer, Ph.D.
Chief Scientist, The EEG Institute
October, 2003 (Edited July, 2007)
In the following, references cover not only applications of Neurofeedback but also mechanisms of brain self-regulation that underlie EEG Feedback (Neurofeedback).
Application areas include in particular Attention Deficit Disorder, the Anxiety-Depression spectrum, seizures and addictions. We feature the key papers in the important application areas, as well as early papers that highlight emerging applications: the disruptive behavior disorders such as Oppositional-Defiant Disorder and Conduct Disorder; the Autism Spectrum and Asperger’s; Bipolar Disorder; Specific Learning Disabilities, including Dyslexia; sleep disorders; Traumatic Brain Injury and Stroke; Post-Traumatic Stress Disorder; women’s issues such as PMS and menopause; issues of aging such as Parkinsonism and dementia, and Age-Related Cognitive Decline; and, finally, pain syndromes such as migraine, as well as the management of chronic pain.
Neuro-Regulation in the Bio-Electrical Domain
Other references deal with the brain mechanisms that underlie EEG Feedback. This refers essentially to the mechanisms of neuro-regulation in the bio-electrical domain, a relatively new field of study in the neurosciences. The brain must be understood as an interacting network whose function is dependent on precise timing. The means by which the brain organizes and shapes its own timing must therefore be thoroughly understood. This involves first of all the "small-world" model of networks, which supports the high level of functional integration that we observe, as well as the hierarchical structure of regulation. It also involves the "time binding" model of sensory integration; the ensemble character of information in the brain; and the frequency-basis of organization of cortical activation and de-activation. Cortical and sub-cortical architecture must be re-evaluated in terms of its role in the maintenance of brain timing at the microscopic level, of ensembles at the intermediate level, and of networks at the global level.
Psychopathologies are then understood, in their physiological aspect, as failures of brain internal communication. Such failures may arise from inappropriate activation at certain sites, or from the inadequacies in communication within the networks, or from inappropriate coupling between different EEG frequencies. The latter has recently come to the fore through a general model of "thalamocortical dysrhythmias." This model complements, but does not contradict, neurochemical models of brain dysfunction. Neurochemical models are completely incapable on their own of yielding an understanding of the temporal dynamics of brain function, for which we must rely on bioelectrical models that can describe the time course of brain events. We must bring frequency-based analysis to bear.
Neurofeedback is then understood as an appeal to the mechanisms by which the brain maintains its own timing and frequency relationships. The brain must obey the laws that apply to any regulatory system. Moreover, it must assure its own stability entirely through self-regulatory means. By either operant conditioning or overt visual or electro-magnetic stimulation, the brain is arbitrarily moved out of its instantaneous state, thus invoking the brain’s own resources of control in the task of re-establishing regulation. Neurofeedback is therefore a gradual learning process in which the brain enhances its native skills of self-regulation. This holds true for all of those functions that are subject to regulation by timing, which includes all discrete events that involve synaptic information transport. The above is referred to as the "Regulatory Challenge" model of Neurofeedback.
We are able to deploy the technique of Neurofeedback successfully even before the underlying mechanisms of brain self-regulation are fully understood. This is because the brain can be viewed as a self-organizing nonlinear dynamical system. Through numerous internal feedback loops the brain is strongly constrained against large excursions in state space. When these do occur in the compromised brain, such deviations can be readily detected in the EEG and employed in negative feedback to the brain in order to further constrain its behavior. Over time, learning occurs and brain behavior improves. Neurofeedback can therefore be considered "behavior mod for the brain." Through thousands of cues per minute, based on increasingly sophisticated analysis of the EEG, the brain is shaped toward improved self-regulation. When remediation occurs systematically, we have our evidence for the validity of the initial assumption that the condition at issue was in fact mediated by frequency-based or timing-based disregulation.
It is in light of the above that claims of efficacy of Neurofeedback for a variety of conditions are to be understood. In some instances, such as Attention Deficit Disorder and PMS, we believe disregulation to be at the heart of the matter. The operative word in Attention Deficit Hyperactivity Disorder is Disorder. It follows that a self-regulation strategy should constitute a comprehensive remedy. Moreover, once re-regulation has been achieved, by whatever means, the defining aspects of the condition will no longer meet criteria to sustain a diagnosis.
In other conditions, however, disregulation merely accompanies a more structural deficit. This is the case for autism, for example, or traumatic brain injury, or Fetal Alcohol Syndrome. In these instances, the possible progress is constrained by organicity. The attempt at remediation seems, nevertheless, to be quite generally worthwhile. Finally, there are the degenerative conditions such as Parkinsonism and the dementias, where the EEG training may succeed in restoring and then maintaining function even in the face of continuing organic deterioration. In such cases, the training has to be kept up over time in order to maintain levels of function.
The benefit of Neurofeedback, whereas it has many explicit applications to psychopathologies and to neurological deficits, is deemed to be diagnostically non-specific. It addresses the broad functional disregulations that are part and parcel of all clinical syndromes in mental health, and accompany organic brain disorders as well. Neurofeedback can be seen as a generalization of what biofeedback has been traditionally concerned with. In the vernacular this has simply been called "relaxation," but in the scientific frame we are really concerned with self-regulation. By working with the EEG directly, the scope of our impact enlarges to all functions under the active management by the central nervous system.
This larger conception of EEG Neurofeedback addresses the entire activation-relaxation continuum of brain regulatory networks. It therefore impinges upon central and autonomic arousal, on attentional networks, on specific cognitive function, on working memory, and on other memory functions. It addresses the regulation of our moods and emotions; it covers motor control; and it modulates our sensitivity and reactivity to the sensory world. The training can moderate our fears as well as regulate our drives such as appetite, thrill-seeking, and drug-seeking. Most importantly, the training can confer essential stability on brain function, which heightens the threshold to such conditions as seizures, migraines, panic attacks, and bipolar excursions.
Neurofeedback may shortly be more generally recognized as being at the heart of Mind-Body Medicine, in that it utilizes volitional control in the training of sub-conscious brain processes that in turn regulate a variety of bodily functions. Whereas Neurofeedback has important medical implications, strictly speaking it is not intrinsically a medical procedure (although it becomes one when performed at the direction of an MD). It is simply a structured learning opportunity for the brain, one that can be supported by a variety of health or educational professionals. The technique is accessible to human beings of every age, provided there is sufficient sensory awareness at the brain level to respond to reinforcement.
As a non-medical procedure, Neurofeedback is likely to remain classified for some time as part of "Complementary or Alternative Medicine." This will remain true despite the fact that the concepts alluded to here will over time take a central place in our understanding of brain function. The understanding of the "Operating System of the Brain" will be one of the major preoccupations of the current century of neuroscience. How could that understanding not have therapeutic implications? In fact, those implications are already being realized in practice.
Even though our understanding may be limited, the reduction to practice is relatively straightforward. We simply have to know enough to cue the brain at any moment as to the direction in which improved performance lies, and that turns out not to be difficult at all in most instances. We simply monitor the brain's trajectory through state-space in the immediate past, and we reward the brain for moving to the more populated parts of state space, and discourage its migration toward the wings of the distribution. We reward the brain for moving to a state of higher complexity, or what is known as higher dimensionality. These regions of state space are intrinsically more stable. Remarkably, the brain learns from these cues and slowly changes its own habits. Life then reinforces the learned behavior so that the acquired skills of self-regulation are retained.
We invite the reader to return to this site occasionally for updates on this exciting research and clinical frontier, the frontier of functional remedies to disorders of disregulation, and the domain of bio-electrical self-regulation. Those who are already acquainted with this field are convinced that the budding professional community of Neurofeedback practitioners is defining the frontier of mental health and of optimum mental performance.
We have organized a brief bibliography with scientific articles about neurofeedback (PDF 92 pages).