People commonly ask the questions : "Why?", "How does a thing work?" and "How can I fix it?". I do not attempt to answer "Why?" because it is a metaphysical question. Much of this article answers the question of "How can I fix it?". I shall mainly describe "How does the brain work?" which I freely acknowledge is an immodest goal. The nervous system is built upon a living network of feedback, constantly adapting

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A chapter from
Textbook of Neurofeedback, EEG Biofeedback, qEEG and Brain Self Regulation

I. Introduction.
2. The brain functions as a communication system.
3. The brain functions as a gland, with neurotransmitters and neuropeptides.
4. The brain functions as a system of adaptation.
5. The brain controls emotions. Mood related to patho-physiology.
6. The brain controls activity and behavior. Hypo-activity and hyper-activity.
7. The nervous system is built on stimulus-response mechanisms.
8. Biofeedback as a treatment modality in neuropsychiatry.
9. Biofeedback as a treatment modality in restorative neurology.

1. INTRODUCTION
People commonly ask the questions : "Why?", "How does a thing work?" and "How can I fix it?". I do not attempt to answer "Why?" because it is a metaphysical question. Much of this article answers the question of "How can I fix it?".
I shall mainly describe "How does the brain work?" which I freely acknowledge is an immodest goal.
The nervous system is built upon a living network of feedback, constantly adapting to the environment, both the internal and the external. The prefix"bio" in biofeedback is semantically unnecessary since we are dealing with systems during life. However, because of the historical use of "biofeedback" as a treatment modality the term can be accepted.
Biofeedback is an important technique in the wide spectrum of behavioral medicine. Behavior is the motor output of the nervous system which depends upon the conscious and unconscious reception and acceptance of stimuli by an individual. It is the response to a continuous stream of stimuli in the waking and the sleeping state. Biofeedback professionals learn the art of encouraging self-awareness both of themselves and of their patients, in order for perception of stimuli to be changed if desired.
Therefore we need to become more self-aware of the physiology that generates our behavior. We need to harness our feedback forces, and to use the inherent physiological mechanisms of feedback to the best advantage of ourselves and of those whom we contact.
Behavioral responses can be modified by the way the individual perceives these incoming stimuli. Similar stimuli are experienced differently by different people, and they also vary according to the actual psycho-physiological state of the individual, including their age and experiences.
A.R. Luria in his classic book "Higher Cortical Function in Man" analysed "the reflex mechanisms by means of which the organism maintains its equilibrium with the environment" and "the problem of the cerebral mechanisms of mental activity". Replace the word "reflex" by "biofeedback" and we see how we are perpetually studying these mechanisms.
For an excellent review of the central autonomic network (CAN), with its functional organization and dysfunction, the reader is referred to the article by Eduardo Benarroch (1993), (see Fig 1).

2. THE BRAIN AS A COMMUNICATION SYSTEM
The brain functions as a system for communication over the entire body. The nervous system consists of a CENTRAL part (the brain and the spinal cord) and a PERIPHERAL part which comprises the nerves that arises from the brain and spinal cord. These nerves supply the special senses, the musculature and the sensation of the trunk and the four limbs.
This chapter deals with the central nervous system (CNS). It is a bilateral and in many ways symmetrical group of structures consisting of 6 parts: (1) the Spinal cord; (2) the Brain stem subdivided into 3 regions, the midbrain, the pons and the medulla; (3) the Cerebellum, important for modulating and co-ordinating motor movement together with (4) the Basal ganglia, (the caudate nucleus, putamen and globus pallidus); (5) the Diencephalon (the thalamus, hypothalamus, subthalamus, and epithalamus) and (6) the Cerebral Hemispheres capped by the cerebral cortex or rind with higher perceptual cognitive and motor functions, (Kandel). (see fig 2). The brain weighs 3 lbs. The spinal cord is like a tail arising from the base of the brain and its thickness averages that of a human finger.
Broadly speaking the tasks of the brain can be divided into three categories:
(1) the RECEPTION OF STIMULI (this is the sensory system);
(2) the association of stimuli and the analysis or PERCEPTION OF INCOMING STIMULI; and (
3) the MOTOR RESPONSE to those stimuli. These motor responses summate so as to constitute the behavior of the individual. At the cellular level, sensory signals are transformed into motor acts.

(1) The RECEPTION OF STIMULI by the brain occurs via the AFFERENT PATHWAYS FOR SENSATION. (The term"afferent" indicates travelling towards the brain, and "efferent" travelling away from the brain.) The pathways for light touch, (tickle), pain, pressure, heat, cold and vibration from the periphery to the cerebral cortex are well-known and they do not vary significantly. It is the conscious PERCEPTION by the individual of these stimuli (when they reach the appropriate area of the cerebral cortex) which varies constantly throughout life.
In order to prevent overloading of the individual by a continous stream of stimuli, the nervous system has developed a variety of methods of INHIBITION. Inhibition is an important neurological concept for biofeedback professionals since learning how to inhibit sensations, thoughts or behavior is basic in biofeedback training. Inhibition as applied to synaptic transmission refers to an active process by which excitatory transmission is prevented. Inhibition occurs in the CNS both before and after the synapse ("pre-synaptic" and "post-synaptic"). A major pre-synaptic neurotransmitter, which is inhibitory in many processes, is gamma-amino-butyric-acid (GABA). In the thalamus (its nucleus is the main way-station for sensation) there is both pre- and post-synaptic inhibition. At higher levels in the brain, both in the cerebellum and in the cerebral cortex, inhibition is mainly post-synaptic.
Inhibition can be directed from the cerebral cortex. Efferent pathways from the sensori-motor cortex excite thalamo-cortical relay cells. By exerting inhibition the cerebral cortex is able to block the synapses and thus to protect itself from being stimulated by cutaneous stimuli; it can neglect these stimuli. This happens for example when one is deep in thought, preoccupied with an experience or intensely involved in carrying out an action. Counter-irritation to relieve pain acts in this way. Discharges from the cerebral cortex down the pyramidal tracts and other pathways may exert an inhibitory blockage at the relays in the spino-cortical pathways. This can inhibit unwanted motor movements.

INHIBITORY FUNCTIONS OF THE CEREBELLUM.
The cerebellum is the great "smoother" of all motor activities. The Purkinje cells are large nerve cells in the cerebellar cortex. The unique feature of the cerebellar cortex is that its output is expressed entirely by the inhibitory Purkinje cells.
Nowhere else in the brain is inhibition so dominant. How can information be conveyed effectively in this negative manner? Because this inhibitory action is exerted on nuclear cells that have a strong background discharge.
Eccles gives the analogy of the sculpture of stone. A sculptor has a block and achieves form by "taking away" stone through chiselling. Similarly the Purkinje cells of the cerebellum achieve form in the nuclear cell discharge by taking away from the background discharges through the process of inhibition.

(2) The association of stimuli and the analysis or PERCEPTION OF INCOMING STIMULI is carried out in the cerebral hemispheres. Here memory, judgement, thought association, verbal and non-verbal communication, the emotional coloring of stimuli all combine to create the personal interpretation of on-going stimuli. This is the meeting-ground which regulates the psycho-physiology of the individual.

(3) THE MOTOR RESPONSE TO THE STIMULI. This is the output of the brain, the efferent system, via the pyramidal, extra-pyramidal and non-pyramidal pathways.
These responses require exquisite MOTOR COORDINATION.
The CEREBELLUM is concerned with the reliable and regulated control of movement. The cerebellum is the part of the brain which through the process of evolution has come to function as a special computer by handling all the complex inputs from receptors or from other parts of the brain. The articulation of speech is subserved by cerebellar mechanisms.
Let us visualize the neural events in the cerebro-cerebellar circuits during a skilled action, such as running a machine at work or playing the piano. There will be initially a motor command with a preprogramming of the movements by circuits in the association cortex, cerebellum, basal ganglia and thalamic nuclei. The learned skills are mobilized and the discharge leads on to the action impulses in the pyramidal tract, with the consequent report of the discharge to the part of the cerebellar cortex receiving and projecting both to the cerebrum and the spinal cord. Cerebral"willing" of a muscle movement sets in train neural events that lead to the discharge of pyramidal cells.
There is a sequence of neuronal events, a chain reaction, such that one part is called into operation (in the temporal or time sense) and this leads other parts to go into action which generates further activity . Since, however, all areas of the brain are constantly (and therefore concurrently) active, many elements are carrying out their own intrinsic activities (cross-talks between the cells) which are not apparent to an outside observer; these do not impinge on the consciousness of the individual concerned. It is clear, therefore, that a good deal of cerebral activity goes unheeded by the originator and all observers.
Biofeedback treatment is based on learning. How does the brain as the organ of communication bring about learning?
The process of learning consists of excluding from consciousness all stimuli except the one which the individual chooses to focus upon, and to which his attention is directed. The acquisition of new data thus involves a process of selective listening and consists mainly of rejection or ignoring of stimuli which are nonrelevant at that time.
Biofeedback consists of acquiring a technique for selective "listening" to a particular set of stimuli, which may come from the external environment or from inside the individual's own body (internal environment) . The purpose of the technique is for the student to have the ability to regulate psycho-physical function himself. In order to acquire and to teach this technique, we have to know, first, the GEOGRAPHY OF SPECIALIZED FUNCTIONING, meaning the localization within the brain of neurons with specialized function. These neurons in different parts of the brain vary greatly one from another. For example they vary in size as a petunia varies from an oak tree, (Stevens). Second, we have to understand the interconnections (neural connections) or microstructural changes in SYNAPSES, linkages or pathways of the brain, because this gives a basis of the HOW of behavior, both of the patient and of ourselves. Third, we have to understand the concept of EXCITATION and INHIBITION. The neurons are either excitatory or inhibitory and/or secretory. When two parts of the brain (two neuronal populations) interact, they may each exert an excitatory or an inhibitory effect.
A neuronal impulse may release a neurotransmitter which excites or inhibits. If one part fails to act, there is uncontrolled or deafferented functioning of neurones, because they are lacking their accustomed stimulation or input.

NEURONAL FUNCTION.
Neurons have four main functions: (1) they respond to specific neurotransmitters by altering membrane permeability to common ions (sodium, chloride, potassium, calcium); (2) they conduct electrical impulses; (3) they secrete transmitters (see below in "Neurotransmitter"); (4) they communicate with other post-synaptic cells by the process of synaptic transmission.
Neurons are able to respond and act as "receptors"; this is because their intrinsic membranes (coverings) contain proteins which can receive messages and are therefore called receptors. The membranes of different neurons contain different receptors.. These receptors are protein-complexes bound in the intrinsic membrane of the neuron.

3. THE BRAIN AS A GLAND
When we add together the concepts of the brain as the organ for communication and the brain as a gland, secreting chemicals, we see that the sensory messages that arrive at the brain from the periphery are being continuously changed, altered, modified, censored, embellished, intensified or inhibited by NEUROTRANSMITTERS. A transmitter is a chemical substance that is released synaptically by one neuron and that affects another cell (neuron or effector organ) in a specific manner. However, a given transmitter does not always open the same ionic gates or bring about the same biochemical change in the postsynaptic neuron; the receptor determines whether the synapse will be excitatory or inhibitory.
These transmitters act at the neuro-muscular junctions, the interneuronal junctions and the sensory way-stations, and they are either repressed or further attended to and analysed according to the state of the "receiving" cortex. The incoming sensations are matched with previous experiences. The brain can discard anything "foreign" in the same way that foreign substances like grafts, bacteria or other non-self substances are rejected by the tissues which represent the "self". Some nerve cell receptors have been found to be isomers of immune cell receptors.

SYNAPTIC TRANSMISSION. There are four biochemical steps in synaptic transmission: (1) synthesis of the neurotransmitter substance; (2) release of transmitter into the synaptic cleft; (3) binding of transmitter to the postsynaptic receptor, and (4) removal or destruction of the transmitter substance, (Schwartz).
There are eight substances which are the original classical neurotransmitters: Acetylcholine, the 4 biogenic amines: Dopamine, Histamine, Nor-epinephrine (the locus caeruleus is rich in nor-epinephrine), and Serotonin (5-hydroxy-tryptamine) ; and 3 amino-acids: Gamma-amino-butyric acid (GABA), Glycine and Glutamate.
NEUROPEPTIDES. Some neurotransmitters are, chemically, neuropeptides.
Neuroactive peptides or neuropeptides have been found to be localized in neurons. More than 50 neuropeptides have now been isolated and arranged in a chemical sequence. They range is size from small peptides (two amino acids joined by a single peptide bond) to a large molecule such as corticotropin-releasing-factor (CRF) which is comprised of 41 amino acids.(Nemeroff). The amino acids arranged in chains include Glycine, Alanine, Leucine, Aspartine and Arginine.
These neuropeptides act as hormones in some tissues, (a hormone is a chemical messenger, a substance released at considerable distance from its intended site of action); and in other tissues these peptides act as neurotransmitters
( a neurotransmitter is released directly onto the site of the intended action).
Neuropeptides are important in the field of biofeedback because their action is closely related to the psycho-physical state of the individual.
Certain neuropeptides are involved in the perception of pain, pleasure, fear, depression and other emotions. Others are involved in the control of blood pressure, reproduction, and the mobilizing of energy. Some can be termed neuromodulators because they are substances that modulate the action of classical neurotransmitters, (the first 25 or so neurotransmitters to be isolated), but the field is increasing so rapidly that terms change their exact meaning.
The brain, functioning as a gland secreting chemicals, regulates our psycho-physical state through many systems, including the gastro-intestinal, the cardio-vascular and the immune systems. Many brain areas are particularly involved, including the hypothalamus. the pituitary, and the amygdala. We shall discuss these biochemical factors as they relate to mood and behavior.
First we review the brain areas identified as specially important.

The HYPOTHALAMUS.
The hypothalamus is a minute collection of nuclei situated just below the thalamus. These nuclei are distinguished microscopically, and they include the median eminence, the peri-and para-ventricular nuclei, the preoptic nuclei, the arcuate nucleus and many others.

HYPOTHALAMIC-RELEASING HORMONES include Thyrotropin-releasing hormone (TRH), Luteinizing hormone (LH), and somatostatin (growth hormone release-inhibiting factor, SRIF).

The PITUITARY. The pituitary is the pea-like body sitting in the pituitary fossa at the base of the skull. PITUITARY PEPTIDES include Adrenocorticotropin (ACTH), Beta-Endorphin, Vasopressin and Oxytocin. The hypothalamic-pituitary-adrenal axis is central to many aspects of the stress response.

The AMYGDALA. (plural for amygdalum). The amygdalum is a nucleus the shape of an almond situated deep in each temporal lobe. The two nuclei constitute the amygdala and are part of the limbic system, the so-called affective brain, associated with emotionally-based behavior. The amygdala within the limbic system connects to the cerebral cortex, to the thalamus and hypothalamus, and to the brainstem and spinal cord. The amygala is important for the mediation of normal responses to fear-evoking or anxiety-producing stimuli. Epileptic seizures where the abnormal neuronal discharge involves the amygdalum can be manifested by severe sensations of fear and memories of events full of fear. Autonomic changes can accompany this fear with increases in heart rate and blood pressure, dialation of the pupils and pallor. "A majority of the peptides that have been localised with neurons of the brain are found within either neuronal cells bodies or terminals of the amygdala" (Gray). These include cortocotropin-releasing factor (CRF), neurotensin, Enkephalin, Somatostatin and Substance P.

Next we review the systems where neuropeptides are particularly involved.

THE GASTR0-INTESTINAL SYSTEM.
GUT-BRAIN PEPTIDES give us the concept of the MINIBRAIN in the intestinaltract. They include vasoactive intestinal polypeptide (VIP), Cholecystokinin (CCK), Substance P, Neurotensin, Methionine enkephalin, Leucine enkephalin, Insulin and Glucagon.

GASTRO-INTESTINAL (GI) FUNCTION. The stomach and intestines have been known for a long time to have a large nerve supply, mainly of non-medullated sympathetic fibers and medullated preganglionic fibers of the parasympathetic. Nerve fibers between two layers of smooth circular muscle form the plexus of Auerbach. From there they pass to the submucosa of the gut to form the plexus of Meissner.
Details of the enteric nervous system are now described with brain peptides effecting GI transit (motility), and this gives the concept ot the MINIBRAIN in the gut. Many neuropeptides are involved: the Opioids, Bombesin, CRF, Thyrotropin-releasing hormone (TRH), Somatostatin, Calcitonin, Neurotensin and Substance P. Opium and opiates such as morphine have been known since antiquity to inhibit gastro-intestinal transit. Endogenous (naturally produced) opioid peptides like beta-Endorphin act on gut motility, mainly inhibiting it. CRF is a critical mediator of stress responses acting on the hypothalamus as described above. It has been shown experimentally to inhibit transit in the small intestine and to stimulate it in the colon. Biofeedback techniques can be helpful in reducing stress, plus modulating neuropeptide activity, and thereby regulating the motility of the gut, and altering patterns of motility.

The CARDIO-VASCULAR SYSTEM.
CARDIO-VASCULAR REGULATION. Adreno-cortico-trophic hormone (ACTH) has important effects on blood pressure and sodium metabolism. Chronic treatment with ACTH can cause hypertension and sodium retention. ACTH is primarily synthesized in the anterior pituitary and its major role is the regulation of the adrenal cortex, but its role within the CNS is unclear. (see below in mood-regulation). Vasopressin can cause excitation of the sympathetic system. Endogenous opioid peptides appear to confer protection against the arrhythmias that arise during stress, (Verrier). Indeed, many investigators have shown that these opioids play a role in modulating the cardiovascular response to circulatory stressors, (Frantz and Liang).

The IMMUNE SYSTEM.
IMMUNE FUNCTION. There is strong evidence for a functional effect of opioids on the immune system. Opioid peptides have an effect onreceptor sites of many subgroups of leucocytes (white blood cells) including natural killers (NK) cells, monocytes, macrophages, mast cells, lymphocytes and thymocytes which are all involved in reactions to infections, and in auto-immune disease processes, such as multiple sclerosis.
Natural killer (NK) cells are thought to play an important role as tumor cell scavengers and also in transplant rejection. NK cell activity has been shown in humans to be enhanced by exercise (Brahmi et al.).

The COGNITIVE - EMOTIONAL SYSTEM
Neuropeptides have effects which overlap several systems and therefore repetition is inevitable when we review some of the chemical control mechanisms of mood, behavior and reactions to stressors.
The age-old drug from the poppy, opium, gives a "pleasurable" or antidepressant effect. Substances produced in the body which give"pleasure" are therefore called opioids. ENDOGENOUS OPIOID PEPTIDES have been implicated as being either causative or curative agents in a variety of mental disorders. Stress, opioid peptides (endorphins) and cardiac arrhythymias are often inter-related, and this aspect of the cardio-vascular system is well-known as suitable for biofeedback treatment.
Stress stimulates the secretion of corticopin-releasing- factor (CRF) from the hypothalamus. CRF is carried down the pituitary stalk and stimulates secretion of ACTH and beta-endorphin into the periphery. CRF produces activation of the sympathetic nervous system resulting in secretion of epinephrine (adrenaline) and nor-epinephrine from the adrenal medulla.
Leu-and met-enkephalin are co-secreted along with epinephrine and nor-epinephrine from the adrenal medulla into the bloodstream. Also, inhibitory feedback pathways go from the pituitary to the adrenal and cortisol in the blood stream can inhibit the hypothalamus as well as ACTH and endophins in the pituitary.

ENDOCRINE REGULATION for the prevention of stress and/or depression involves the hypothalamic-pituitary-adrenal axis.

Corticotrophin-releasing factor (CRF) is the hypothalamic releasing hormone that controls the hypothalamic-pituitary-adrenal axis (HPA axis). Stress increases ACTH and glucocortisol concentrations. Apparently the activation of the HPA axis by stress is due to the release of several neuro-modulators including CRF, Arginine, Vasopressin, Oxytocin, Angiotensin II, Vasoactive intestinal peptide (VIP). Epinephrine, and Norepinephrine.
Corticotrophin-releasing factor (CRF), however, is THE major regulator of ACTH.
Patients suffering from major depression, when not medicated, are as a group hypercorticolemic (too much cortisol in the blood), and they may therefore be chronically over (hyper) secreting CRF. The possible mechanisms involving CRF and the pathogenesis of depression are numerous and await detection. Biofeedfack as a treatment can help the symptom by modifying the behavior.

4. THE BRAIN AS A SYSTEM OF ADAPTATION
There is a plethora of data generated in the last decade on the various physiological alterations that occur after exposure to stressful stimuli. This shows how the brain functions for adaptation. It is important for biofeedback professionals to have some understanding of these alterations, because the technique of biofeedback teaches the subject to modify his/her responses to stressors in order to maintain psycho-physiological balance when battered by these stimuli.
The hypothalamic-pituitary-adrenal (HPA) axis has been the focus of many investigations on the manifestations of the stress response ever since Hans Selye described in 1936 the hypertrophy of the adrenal gland and the atrophy of lymph glands in response to chronic stress. With the discovery of corticotropin-releasing factor (CRF) by Vale and co-workers in 1981, the hypothalamic component of this axis became available for investigation.
The HPA axis is a multistep integrated process involving several CNS sites (cerebral cortex, amygdala, locus caeruleus, hippocampus, etc). In the hypothalamus these signals are transduced to humoral-type messages, release and release- inhibiting hormones. These travel a short distance to the anterior pituitary where they are funneled into the general circulation and travel to their appropriate target organs. The responses that these signals engender have major influences on blood pressure, reproductive function and energy mobilization. In addition the various neuroendocrine axes are also influenced by a variety of feedback control loops. These feedback controls can be of both a fast and a slow nature and involve both central and peripheral sites (Ritchie and Nemeroff). In major depression, corticotropin-releasing factor ( CRF) is most likely hypersecreted (see above).
It is also possible that the precipitous fall in CRF, in ACTH and in cortisol levels in maternal plasma at the time of delivery leaves the HPA axis uncompensated, and postpartum depression may develop because of sudden changes.
The locus caeruleus is important in the process of adaptation to the environment because it is rich in nor-epinephrine, (nor-adrenaline). The locus caeruleus (literally the "blue spot") is so-called because of melanin-pigment granules found in human infants and increasing with age. It has a very rich blood supply enabling this nor-epinephrive to be rapidly transported over the body. It is a microscopic nucleus in the floor of the 4th ventricle in the upper pons, near structures that regulate respiration with changes in the relative carbon dioxide and oxygen content of the blood.
It is important to understand something of the neuropeptide involvement in STRESS. Since stress is the result of an individual's response to stressors, we can see that the brain is the organ of adaptation, acting through its neuro-humoral network. Neuropeptides are part of this network. They mediate the regulation of the neuroendocrine and the autonomic responses to stress.
The neuropeptides identified in this network include : (1)Corticotropin-releasing-factor (CRF); (2) thyrotropin-releasing factor (TRF); (3) Bombesin and related peptides: and (4) Somatostatin-related peptides. All 4 groups of these peptides effect both the sympathetic and the parasympathetic systems. For example, CRF increases the plasma concentration of glucose and glucagon, increases cardiac output, heart rate and blood pressure, decreases kidney and mesenteric blood flow, gastric motility and acid secretion, and inhibits ovulation, (Brown). TRF and Somatostatin-related peptides have cardiorespiratory, metabolic, gastrointestinal and pancreatic effects demonstrated in animal experiments (Brown). "Bombesin acts within the CNS to decrease regulatory heat production and oxygen consumption during cold exposure" (Brown). Thus Bombesin slows an animal's metabolism.
The brain reacts in many ways to drinking behavior, drinking bouts and signals that initiate or terminate drinking. For example, Angiotensin II is a neuropeptide with three physiological mechanisms appropriate to a response to water loss. (a) vasoconstriction (b) increased release of aldosterone and (c) increased release of antidiuretic hormone.

5. MOOD RELATED TO PATHO-PHYSIOLOGY
Dr. Eliot Stellar, a physiological psychologist, author of the well-known books "Physiological Psychology" in 1950 and "The Neurobiology of Motivation and Reward" in 1985, illuminated the interdependence of psychology and physiology. This interdependence may seem self-evident but must be understood in detail.
Mood and emotional reactions are sensitively related to our physiological well-being or our pathological ill-state. Everyone is aware that sleep and food intake effect mood. Thus a sleep deprived person is "grumpy", irritable and lacks judgement. People are less aware that sleep deprivation can cause seizures; that over-activity (hyperfunction) of the thyroid gland can lead to thyrotoxic emotional lability; and that under-activity (hypo-function) of the thyroid gland (myxedema) can lead to "myxedema madness". With an insulin tumor, a patient may develop bursts of irrational behavior. A phaeochromocytoma is a tumor of certain cells of the adrenal medulla. The tumors secrete an excess of adrenaline and noradrenaline but because the output may be continuous or paroxysmal, the clinical features vary greatly. Apart from hypertension, anxiety and fear can be severe in attacks, (Lishman, 1987). Depression is frequent after influenza and other viral infections. Episodes of abnormal behavior may occur in patients with epilepsy, unrelated in time to a seizure.
Other evidence of mood related to pathology includes depression in Parkinson's disease, the on-off drug effects in the treatment of Parkinson's disease; chemical imbalance in manic-depression; pre-menstrual syndrome; depression in cerebral arteriosclerosis; drug-related mood changes; hallucinatory drugs; oxygen lack causes loss of judgement; sensory deprivation illusions; vitamin deficiences cause lack of energy; and toxic disorders like lead poisoning are associated with low IQ.
Changes in personality are frequently observed due to cerebral tumors (mainly frontal), to head injury, to cerebrovascular disorders, to senile dementia, and to presenile dementia (Alzheimer's disease). All these disorders show that disfunction in any organ, including the brain, changes mood, emotions and behavior.
For many people, mood is associated with the "mind". However they can understand that the brain is as much part of the body as all the other organs, such as heart, lungs, thyroid. They can see that disfunction of any of these organs can cause psychological disfunction. Because the brain regulates the other organs through feedback mechanisms, it is pivotal in psychology. The "mind"is a concept and from the physiological point of view its workings are those of the brain.
Biofeedback treatment is directed to the brain mechanisms that control all our physiological functions. When this biofeedback treatment is inappropriate for patients because of their significant cognitive deterioration, biofeedback may be offered to their relatives suffering from reactive anxiety and distress.

6. THE BRAIN CONTROLS ACTIVITY.
Charles SHERRINGTON, the founder of modern motor physiology, wrote that : "To move is all mankind can do and for such, the sole executant is muscle, whether in whispering a syllable or in felling a forest".
Here the CNS operates through the peripheral nervous system. "Spinal interneurons constitute an important set of networks for processing both peripheral inputs and commands descending from higher brain centers" (Sherrington)
Both too little (hypo) and too much (hyper) activity can be pathological. HYPOACTIVITY is one of the hallmarks of clinical depression. The patho-physiology of depression is described in detail in the book:"Neuropeptides and Psychiatric disorders" edited by Charles B. Nemeroff.
Inability to "get going" can be pathologically based as in Parkinson's disease where patients have great difficulty in initiating a movement, for example walking; here the dopamine metabolism is disturbed. Many patients with Parkinsonism suffer from depression because their musculature does not respond to their desires; actual slowing of thinking processes may also be involved. On the other hand inability to "get going" may be psychologically based through lack of motivation or sensory deprivation on a socio-economic background.
HYPERACTIVITY with its corollary of defective attention in childhood is in many cases a contemporary phenomenon caused by excessive television-watching, an environment of "sound-bites" and methods of education.
Hyperactivity associated with various forms of neurological retardation is associated with lack of neuronal inhibition and poor control of responses.
The LIMBIC CHILDREN is a concept (Fischer-Williams ) that arose from the clinical observation of certain patients with "retardation"on an organic neurological basis. These subjects, children and young adults, have frequent mood changes with outbursts of uncontrolled activity, disturbed behavior and abnormal "drives". The limbic system regulates emotions and the activities of the frontal cerebral cortex through many anatomo-physiological pathways. When there is a lack of feedback control from the limbic system to the frontal cortex (where judgement is formed and social activity is analysed), these subjects show inappropriate hyperactivity. A more correct term would be "a-limbic children" because the condition indicates that the limbic structures never developed their functions or were lost through early disease. Information on the neuropeptides operating in the limbic system (particularly of the amygdala which are part of the limbic system) is now detailed.
THE BRAIN NEEDS FEEDING WITH BLOOD. Clearly, brain function depends on a healthy supply of blood. This subject, however, will not be discussed in this chapter. except to say that the heart can be likened to a pump, the blood vessels to a garden hose, and the brain to a garden.

7. STIMULUS - RESPONSE MECHANISMS
In biofeedback, there is a primary concern with two mechanisms: first, when the subject or patient becomes continuously aware of the stimulus of certain physiological activities, such as muscle tone or heart rate, and second when the subject has incentives or rewards for changing or controlling the feedback and therefore learns to control voluntarily the physiological response associated with the feedback. The continuous information fed back to the subject brings to consciouness something which has not previously been registered at a conscious level. Consequently information travels a different neuronal pathway.
It is therefore important to understand the principle of divergence and convergence of information, and some of the complex neuronal systems that can modify or modulate behavior. For example a great deal of information arrives (converges) at the retinal nerve cells. This information is compacted (reduced) and then passed down the visual pathways. At the occipital cortex it is received by cells with very specialized functions, so that the information is sorted out (teased out) and diverges to individual groups of cells. However the brain has learned to converge vision and the "normal" individual sees one picture. Psycho-physiological techniques can teach an individual to separate or to converge sensations.
The "expectancy " wave of Grey Walter. Another phenomenon may be relevant in this context. When two stimuli are associated and the subject is instructed to terminate the second one by pressing a button, a low voltage "intention" or "expectancy " wave develops and can be recorded in normal subjects with DC recording on the scalp. It is termed the negative contingent wave (Walter), and this electrical cortical event is important because it comes just before action. Grey Walter once suggested that a disturbance of this "intention" wave was related to the indecision sometimes seen in "neurotic" patients. It might be related to the "jitters" described in some golf players just before the action of putting.
Other phenomena may exist similar to those seen in patients with "split brains", where the two hemispheres have been disconnected after section of the corpus callosum and the anterior commissure in the treatment of intractable epilepsy. Division (separation) of information has been demonstrated in regard to perception, cognition, volition, learning and memory (Sperry). These phenomena allow one to speculate that during biofeedback training, new linkage pathways may be established between perception of the monitor measurements fed back and the unconcious physical changes in whatever modality is being monitored at the time. The patient's body makes physical changes in by-passing the ordinary sequence of volitional motor activity, just as motor skills are acquired by constant repetition.

8.Biofeedback as a treatment modality in Neuropsychiatry
Neuropsychiatry is based on the "delicate balance between our knowledge and understanding of the brain and our knowledge and understanding of people", (Lishman). As a neuropsychiatrist, Dr. Lishman wrote: "I tend to see patients with brain disease- - - and the decision we must often try to make is on whether the problems we see in the clinic are "organic" or "functional"--- more precisely whether they derive from a primary brain malfunction or from difficulties the patients are encountering in their lives," (Lishman). He wisely comments that "we must sidestep the risk of becoming too far seduced by one or other pole of this dual requirement". "Brain biochemistry - - with increasing relevance to emotional and behavioral disorder" (Lishman), pharmacotherapy, psycho-pharmacology, imaging of many areas in the brain including the limbic system during cognitive activities, all open up exciting vistas for health therapists to explore.
For example, Lishman quoted Weinberger: "We can visualize the increased blood flow to frontal regions when a normal subject engages in a category sorting task and show that equivalent dynamic shifts are defective in the schizophrenic brain". (Weinberger et al.)
We can ask other questions: is there a neurologic cause for obsessive-compulsive disorder? (Insel). How much is pre-menstrual tension a neurochemical dysfunction, and how much is it a psychological reaction to feedback mechanisms in normal cyclical events? Similar questions arise with sleep disorders when observed with the electroencephalogram (EEG) in the study of wake-sleep behavioral mechanisms.

9. Biofeedback as a treatment modality in RESTORATIVE NEUROLOGY.
Biofeedback treatment is useful as an adjunct in the therapy of neurological disorders. Criteria for sucessful treatment include basic knowledge of brain function, and honest motivation of both patient and therapist with reasonable self-knowledge. Expectations both of the patients and the therapist must be realistic.
The sad consequences of not keeping this in mind are described in the book: The Bitter Pill: Doctors, Patients and Failed Expectations, by Martin R. Lipp. They can often be avoided by close co-ordination with other treatment modalities and on-going co-operation with specialists in other fields.

Biofeedback is a technique to help reconnect the feedback systems. We can"listen to our thalamus" (part of the limbic system, sometimes designated as the emotional brain), we can use our dreams, our sensations, whatever messages come from our "unconscious". Add to this, we can "use our brain", meaning we can use our cerebral cortex to analyse our 10 emotions. This control of thought and action (cognitive and behavioral activities) can lead to synthesis and the acceptance of paradox.
Biofeedback can play an interventory role at many levels within the nervous system. It can facilitate re-inhibition, activation, re-balancing , stabilization or re-assignment of function. Once a patient is properly evaluated neurologically, biofeedback can be an adjunct or primary treatment of neurological disorders. The criteria for the use of biofeedback is discussed in A Textbook of Biological Feedback (Fischer-Williams, Nigl and Sovine) and in many chapters of this book. For cost-effective results, the expectations of both the patient and the therapist must be realistic. For long-lasting results, biofeedback effectiveness is often enhanced when co-ordinated with other modalities (Fischer-Williams, 1993).
For a better future, we trust that there will be expansion of methods of preventive medicine. This, however, depends on the health of therapists and the imaginative education of the public.

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Authors Bio:
Dr. Fischer-Williams received her M.D. in Edinburgh, Scotland, and practiced Neurology in Oxford England, and at the London Hospital, London, England. She was Assistant Professor of Neurology at Wayne State Univ., Detroit, MI; Research Associate and on the teaching faculty at the Mayo Clinic, Rochester, MI; Consultant Neurologist at Marshfield Clinic; and practed neurology in Milwaukee Wisconsin and Director of the Department of Clinical Neurophysiology and Biofeedback at Trinity Memorial Hospital, Cudahy, Wisconsin. She is a Pst-President of both the Central Association of Electroencephalographers and the Biofeedback SOciety of Wisconsin.