Biological feedback of bodily processes: basic mechanisms and clinical applications

The Institute is internationally leading in research in biological feedback (biofeedback) and its clinical applications, particularly involving brain processes and muscular tension. Over the last 17 years techniques were developed for the biofeedback of slow cortical potentials of the human brain. Subjects observe their own slow cortical potentials from a particular brain area on a video screen for 8-12 seconds. They are asked to change the cortical polarization from the targeted brain area in an electricically negative or positive direction. Negative slow potentials indicate a state of cortical mobilization, positive brain potentials indicate a neuronal state of inhibition. Healthy subjects are able to acquire self-control after about 100 repetitive trials in one hour with and without feedback. The acquisition of specific control of the polarization of localised brain areas is also possible. Several experiments showed that after about five 1-hour sessions subjects are able to increase excitation in the left motor hand area and at the same time inhibit excitation in the right motor brain area. After the acquisition of self-regulation of a particular brain area, behavioral and cognitive performance is changed in a specific manner. For example, tactile perception is improved in the left hand after self-produced cortical negativity in the right frontal area. Subjects who have learned to regulate one brain hemisphere develop a tendency to use the contralateral side of the body for carrying out a motor behavior. After years of basic research biofeedback of slow cortical potentials was applied to several clinical disorders: Subjects with functional or traumatic lesions of the frontal lobe such as attention deficit disordered children and schizophrenics have difficulties acquiring cortical self-control even with extended feedback exercise They are unable to maintain self-control in the absence of feedback from the video-screen. The application of slow cortical potentials biofeedback in epilepsy yielded dramatic improvements. Figure 1 on page 14 depicts a typical biofeedback situation as it is used for the treatment of epilepsy in several controlled studies. Patients who suffer from drug resistant generalized epilepsies (mostly temporal lobe epilepsy) need a minimum of 20-30 sessions to acquire self-control of their electrical brain processes. After extended training one third of these previously treatment-resistant patients were seizure-free, one third substantially improved and one third unchanged. With support of the German Research Foundation (DFG) this methodology was implemented in the three largest epilepsy centers in Germany (Kehl-Kork, Bethel-Bielefeld and Ravensburg-Weissenau). Germany thus became the leading nation in the application of behavioral treatment for epilepsy. Since one third of epilepsy patients are refractory to medication or surgery, the biofeedback technique developed in our department makes a major contribution towards the management of a previously untreatable disease. For the behavioral treatment of chronic back pain, chronic facial (temporo-mandibular) pain and tension headache electromyographic feedback (EMG) of the specific muscles involved in the transmission of the pain process was developed. Patients receive feedback of the electromyographic response which is roughly proportional to the muscular tension from the specific muscle which is involved in pain. Back pain patients receive biofeedback of their spinal muscles, facial pain patients receive biofeedback from the masseter muscle and tension headache patients receive feedback from their neck muscles. After 10-12 training sessions 65% of the patients are pain-free or substantially improved. It is important to note however, that the treatment is effective only if it is embedded in a broad behavioral treatment concept: patients have to train muscle tension and muscle relaxation with biofeedback in those situations which are personally relevant and cause substantial stress. A purely technical application of the biofeedback technology alone without a clinical-psychological background is not successful.

The physiological meaning of slow cortical potentials and their relation to behavior and thought

A threshold regulation theory of cortical excitation and inhibition was formulated and a mathematical model for the simulation of slow cortical potentials and their relationship to behavior was developed. It is postulated that slow negativities of the cortex are the result of ultralong excitatory postsynaptic potentials arising from afferent input to layer I of the apical dendrites of the cerebral cortex mainly from intracortical fibers and from unspecific thalamocortical and hippocampal afferents. Thus simultaneous arrival of excitation at the apical dendrites depolarizes the cell assemblies above a critical threshold and mobilizes the cell assembly for future incoming neural stimulation. If the excitation threshold is lowered below a critical level inhibition is provided by a cortical-striatal-basal ganglia-thalamo-cortical loop. The time delay of the loop is about 40 msec causing cerebral positivities after large negativities. Therefore all cortical negativities with a duration of longer than 100 msec are interpreted as lowering the excitation threshold of the cortical cell assemblies, while cortical positivities are the consequence of a disfacilitation of the cortical networks. In a series of psychophysiological experiments with healthy and neurologically impaired subjects we confirmed the main elements of this theory. Behavior originating from a certain cortical assembly is strengthened and its probability increased if the respective cortical area is in a negative electrical state. Accordingly, the behavior of an organism, is the result of an unspecific excitatory process with the specificity of the behavior determined by the topographic distribution of the excitation on the cortical surface. On the basis of predictions of this theory behavioral and medical disorders for which a disregulation of cortical excitation may be responsible, were found to be treatable by a self-regulation procedure (biofeedback of slow cortical potentials) described on page 14f.

Birbaumer, N., Lutzenberger, W., Elbert, T., Trevorrow, T. (1994). Treshold variations in cortical cell assemblies and behavior. In H.-J. Heinze, T.F. Münte & G.R. Mangun (Eds.): Cognitive Electrophysiology. Boston, Birkhäuser, pp. 248-264.

Brody, S., Rau, H., Köhler, F., Schupp, H., Lutzenberger, W. & Birbaumer, N. (1994). Slow cortical potential biofeedback and the startle reflex. Biofeedback and Self-Regulation, 19, 1, 1-11.

Drug resistant epilepsy is successfully treated with biofeedback of slow cortical potentials In two controlled studies epileptic patients with secondary generalized seizures were treated with biofeedback of slow cortical potentials. Most of these patients suffered from temporal lobe epilepsy which is known to be resistant to drug management. In 28 sessions subjects learned to regulate their cortical potentials with the help of a biofeedback device: they observed their cortical potentials from the central cortical area on a video screen and were asked to change them in an electrically positive direction (cortical disfacilitation or inhibition). They were also taught how to recognize the first subjective signs of an upcoming seizure before the cortical EEG showed pathological epileptic activity. At the end of training subjects had to perform the self-regulation task in a disctracting, realistic environment and to perceive their own cerebral negativity before it reached the threshold for the seizure. After the training one third of the patients were seizure-free, one third showed substantial improvement and one third was unchanged. Only subjects who had learned the feedback task improved. Subjects with signs of frontal involvement and neurological deficits and subjects older than 40 years remained unchanged. These data constitute an impressive confirmation that a medical disease can be substantially improved by a behavioral strategy. This behavioral strategy must, however, be tailored to the pathophysiological condition.

Rockstroh, B., Elbert, T., Birbaumer, N., Wolf, P., Düchting-Röth, A., Reker, M., Daum, I., Lutzenberger, W. & Dichgans, J. (1993). Cortical self-regulation in patients with epilepsies. Epilepsy Research, 14, 63-72.

Birbaumer, N., Rockstroh, B., Elbert, T., Wolf, P., Düchting-Röth, A., Reker, M., Daum, I., Lutzenberger, W. & Dichgans, J. (1994). Biofeedback of Slow Cortical Potentials in Epilepsy. In: J. Carlson, R. Seifert & N. Birbaumer (Eds): Clinical Applied Psychophysiology. New York: Plenum Press, pp. 29-42.

A behavioral treatment of scoliosis and kyphosis

A behavioral treatment of scoliosis and kyphosis was tested with 27 adolescent patients (19 scoliosis, 8 kyphosis patients) to determine in which cases the conspicuous and restraining brace treatment could be replaced. In 22 compliant patients posture biofeedback (PB) was highly effective compared to 5 non-compliant patients. Adolescent scoliosis patients (menarche at the beginning of treatment) seemed to profit more from PB. With kyphosis patients the PB-treatment resulted in rapid straightening of the spine and removal of structural deformities of Scheuermann's disease. PB may serve as an unobtrusive yet effective treatment alternative for both juvenile scoliosis and kyphosis.

Birbaumer, N., Flor, H., Cevey, B., Dworkin, B. & Miller, N.E. (1994) Behavioral treatment of scoliosis and kyphosis. Journal of Psychosomatic Research, 38, 623-628.

Home-Page
Hubert Preißl
Maintainer: hubert.preissl@uni-tuebingen.de(hubert.preissl@uni-tuebingen.de)