Method of double feedback from EEG oscillators of the patient for correction of stress-induced functional disorders

Method of correction of human stress-induced functional disorders is proposed which is based on two feedback contours from narrow-band EEG oscillators of the patient. The first one is a usual biofeedback contour in which the feedback signals from the narrow-band EEG oscillator are consciously perceived by the patient and serve him as a guide for voluntary reduction/activation of these EEG components. The second one is an additional contour of resonance stimulation which helps a subject to overcome the difficulties of conscious control of feedback signals. In this contour the parameters of audio-visual stimulation are automatically tuned to the frequency of the dominant narrow-band EEG oscillator of the patient (from the same or other EEG frequency range) to reach its resonance activation. Scientific basis of the method is provided, the results of its experimental testing are presented.     

Utilization of feedback signals from patient's own endogenous rhythms for non-drug correction of human functional disturbances

The most advanced approach to non-drug correction of human functional disturbances via utilization of feedback signals from patient's own endogenous rhythms, i.e., EEG rhythms, respiratory and heart rate is presented and substantiated. The advantages of its application to biofeedback training procedures are reviewed. Alternative way to utilize the feedback signals through automatic modulation of stimulation parameters by patient's endogenous rhythms is analyzed. The author's own contributions to the field are presented and the most promising ways of further approach development are delineated.     

脑电生物反馈系统的研制和脑电α成分反馈的研究

本文介绍了我们研制的微机化脑电反馈系统.并报告了我们所进行的正常人脑电α成分生物反馈训练实验,证明了脑电生物反馈提升α成分比例的可行性.本文还论讨了国际上现行关于脑电α成分生物反馈研究中存在的问题,提出了有效的解决方法.     

Biofeedback training and human functional state control

Biofeedback (BFB) training paradigm has outstanding place among various approaches to non-phrarmacological human functional state correction. Being an universal way for voluntary self-regulation of physiological functions, it is characterized by efficacy, accessibility and absence of side effects. However, the lack of fundamental knowledge about the BFB mechanisms leads to existence of numerous difficulties and problems that seriously limit the BFB possibilities. Most difficulties seem to concern the problem of adequate choice of BFB type or parameter being voluntary controlled via feedback signals. Some ways to solve this problem are drown on the base of general systems theory. It is shown that BFB procedures could be especially effective in conditions of close interaction between the BFB mechanisms and the central regulatory mechanisms. Such interaction could be reacheb by utilization of certain characteristics of brain electrical activity reflected in the electroencephalogram (EEG). The most perspective seems to be the utilization of discrete narrow band EEG spectral components, individual resonance EEG oscillators or some correlates of human EEG amplitude modulation processes.     

Biofeedback in optimizing psychomotor reactivity: I. Comparison of biofeedback and common performance practice

To estimate the role of biofeedback technology in the optimization of psychomotor reactivity, 29 healthy young (aged 22.3 ± 1.5 years) musical performers were examined. On the first day of the study, they followed instructions for the voluntary control of finger motor comfort when performing musical passages for the right hand during standard performance practice without an adaptive feedback. On the second day, biofeedback was used, the muscle tone and EEG α-rhythm power being voluntarily controlled. Eventually, a biofeedback method was developed that simultaneously stimulated the activity of the EEG α rhythm and decreased the tone of the muscles not involved in the playing movement. This improved the performance in 75.8% of musicians (versus 13.8% using commonly practiced methods). The changes in the EEG parameters after effective biofeedback training were the same as in the case of successful traditional performance practice: an increase in the frequency, width, and power of the α activity and a decrease in the powers of the θ and β rhythms. The biofeedback method developed in this study can be recommended as an approach to the formation of the skills necessary for voluntarily controlling psychomotor reactivity and has prognostic implications for improving performance skills.     

A strategy of correction of adolescent deviant behavior based on adaptive self-regulation

A preliminary study has been performed in order to substantiate the strategy of adaptive self-regulation with external feedback for correction of adolescent deviant behavior. The strategy combines voluntary and involuntary components of correction of the functional state by employing two methods: EEG-controlled switching of an appetent signal (music) (the EEG-controlled biofeedback (EEG-BFB) method) and “tuning” of the patient’s own EEG transformed into an acoustic signal (the EEG bioacoustic correction (EEG-BAC) method). These methods have been demonstrated to be highly effective in normalizing the brain bioelectric activity, psychological state, and behavior of adolescents. It has been demonstrated that it is reasonable to use the EEG-BAC method, which does not impose strict requirements on intelligence, memory, and attention levels, at early stages of treatment, followed by EEG-BFB treatment, which allows the patient to efficiently form a stable skill of transition to a comfortable state.     

Attention and regulation of EEG alpha-attenuation responses

Two experiments with 16 normal adults of both sexes tested the hypothesis that inattention to a biofeedback display is associated with increased variability of those physiological processes that had been regulated by the biofeedback. Each experiment was a repeated-measures-on-independent-subjects-design. Dependent variables were the time durations and the mean rms power of two mutually exclusive segments of the parietal-occipital EEG: alpha and not-alpha segments. Independent variables were combination of counting tasks and instructions to look at, listen to, and count visual and auditory flashes and clicks. The durations of alpha and not-alpha segments were controlled or regulated by means of an alpha-contingent visual feedback stimulus, Attention to the feedback stimulus was challenged by instructions to count other, noncontingent stimuli. Control of alpha and not-alpha segments was least for conditions of (1) “sham” feedback, and (2) feedback with instructions to count noncontingent auditory clicks, which were presented 3/sec while the feedback visual stimuli were occurring. A new EEG test of attention and distraction was suggested.     

Neuroleptic-like electroencephalographic changes in schizophrenics through biofeedback

Nine schizophrenic patients participated in a study which explored whether EEG feedback techniques could effect changes in the EEG similar to those associated with neuroleptic-induced improvement. During five sessions, each patient was presented feedback signals which continuously reflected the discrepancy between characteristics of the patient's EEG power spectral profile and spectral profile characteristics associated by past research with neuroleptic induced clinical improvement. Significant within-session changes were observed for two of three EEG power spectrum bands of interest. No significant session-to-session EEG changes were observed. The results suggest that the EEG of schizophrenics can be temporarily altered, using feedback techniques, in a way that mimics the EEG changes that have been shown to occur with neuroleptic induced clinical improvement.     

Adiposity signals and food reward: expanding the CNS roles of insulin and leptin

The hormones insulin and leptin have been proposed to act in the central nervous system (CNS) as adiposity signals as part of a theoretical negative feedback loop that senses the caloric stores of an animal and orchestrates adjustments in energy balance and food intake. Much research has provided support for both the existence of such a feedback loop and the specific roles that insulin and leptin may play. Most studies have focused on hypothalamic sites, which historically are implicated in the regulation of energy balance, and on the brain stem, which is a target for neural and humoral signals relating to ingestive acts. More recent lines of research, including studies from our lab, suggest that in addition to these CNS sites, brain reward circuitry may be a target for insulin and leptin action. These studies are reviewed together here with the goals of providing a historical overview of the findings that have substantiated the originally hypothesized negative feedback model and of opening up new lines of investigation that will build on these findings and allow further refinement of the model of adiposity signal/CNS feedback loop. The understanding of how motivational circuitry and its endocrine or neuroendocrine modulation contributes to normal energy balance regulation should expand possibilities for future therapeutic approaches to obesity and may lead to important insights into mental illnesses such as substance abuse or eating disorders.     

Neuroleptic-like electroencephalographic changes in schizophrenics through biofeedback

Nine schizophrenic patients participated in a study which explored whether EEG feedback techniques could effect changes in the EEG similar to those associated with neuroleptic-induced improvement. During five sessions, each patient was presented feedback signals which continuously refected the discrepancy between characteristics of the patient's EEG power spectral profile and spectral profile characteristics associated by past research with neuroleptic induced clinical improvement. Significant within-session changes were observed for two of three EEG power spectrum bands of interest. No significant session-to-session EEG changes were observed. The results suggest that the EEG of schizophrenics can be temporarily altered, using feedback techniques, in a way that mimics the EEG changes that have been shown to occur with neuroleptic induced clinical improvement.The authors are indebted to Turan M. Itil, John W. Fredrickson, Michael Madwed, and Irene B. Francis. Senior authorship is shared equally.     

Biofeedback and the behavioral treatment of disorders of disregulation.

This paper reviews biofeedback research from the perspective of cybernetic/feedback theory and applies the theory to the behavioral treatment of psychosomatic disorders. The concept of disregulation is used to elucidate how environmental factors can modulate the central nervous system and effect homeostatic, self-regulatory control of peripheral organs. When feedback from peripheral organs is disrupted, it is hypothesized that disregulation occurs, leading to physiological instability and functional disease. Within this framework, biofeedback provides a new feedback loop that can help individuals regain physiological self-control. Basic research using biofeedback to enhance self-regulation of cardiovascular responses is reviewed. The use of biofeedback in the behavioral treatment of disorders such as tension and migraine headache, hypertension, and epilepsy are selectively reviewed and critically evaluated. The need to consider feedback mechanisms in behavioral and biomedical approaches to treatment is highlighted. Predictions regarding the potential inadvertent perpetuation of disregulation and disease through inappropriate biomedical intervention is also considered.     

Feedback regulation of growth hormone synthesis and secretion in fish and the emerging concept of intrapituitary feedback loop

Growth hormone (GH) is known to play a key role in the regulation of body growth and metabolism. Similar to mammals, GH secretion in fish is under the control of hypothalamic factors. Besides, signals generated within the pituitary and/or from peripheral tissues/organs can also exert a feedback control on GH release by effects acting on both the hypothalamus and/or anterior pituitary. Among these feedback signals, the functional role of IGF is well conserved from fish to mammals. In contrast, the effects of steroids and thyroid hormones are more variable and appear to be species-specific. Recently, a novel intrapituitary feedback loop regulating GH release and GH gene expression has been identified in fish. This feedback loop has three functional components: (i) LH induction of GH release from somatotrophs, (ii) amplification of GH secretion by GH autoregulation in somatotrophs, and (iii) GH feedback inhibition of LH release from neighboring gonadotrophs. In this article, the mechanisms for feedback control of GH synthesis and secretion are reviewed and functional implications of this local feedback loop are discussed. This intrapituitary feedback loop may represent a new facet of pituitary research with potential applications in aquaculture and clinical studies.     

Cyclic Negative Feedback Systems: What is the Chance of Oscillation?

Many biological oscillators have a cyclic structure consisting of negative feedback loops. In this paper, we analyze the impact that the addition of a positive or a negative self-feedback loop has on the oscillatory behavior of the three negative feedback oscillators proposed by Tsai et al. (Science 231:126–129, 2008) where, in contrast with numerous oscillator models, the interactions between elements occur via the modulation of the degradation rates. Through analytical and computational studies we show that an additional self-feedback affects the oscillatory behavior. In the high-cooperativity limit, i.e., for large Hill coefficients, we derive exact analytical conditions for oscillations and show that the relative location between the dissociation constants of the Hill functions and the ratio of kinetic parameters determines the possibility of oscillatory activities. We compute analytically the probability of oscillations for the three models and show that the smallest domain of periodic behavior is obtained for the negative-plus-negative feedback system whereas the additional positive self-feedback loop does not modify significantly the chance to oscillate. We numerically investigate to what extent the properties obtained in the sharp situation applied in the smooth case. Results suggest that a switch-like coupling behavior, a time-scale separation, and a repressilator-type architecture with an even number of elements facilitate the emergence of sustained oscillations in biological systems. An additional positive self-feedback loop produces robustness and adaptability whereas an additional negative self-feedback loop reduces the chance to oscillate.     

Maintenance and generalization of 40-Hz EEG biofeedback effects

Maintenance of conditioning of 40-Hz EEG activity was investigated in six adults 1 to 3 years after they had experienced biofeedback training to increase 40-Hz EEG. Subjects were first retrained to alternately increase and suppress 40-Hz EEG. All six subjects achieved a preset performance criterion in 16–20 minutes. Five of these subjects also subsequently demonstrated significant control of 40-Hz EEG without feedback. The sixth subject did not demonstrate control after 76 minutes and four sessions of attempted retraining with feedback. Transfer of 40-Hz EEG control to a problem-solving task was tested in all subjects in a final session. Cognitive test items were presented and subjects were instructed to alternately increase and suppress 40-Hz EEG while solving the problems. Rates of 40-Hz EEG in suppression periods during problem solving were significantly greater than during suppression periods without problems. No significant differences in problem-solving performance were found comparing 40-Hz increase and suppression periods. This study supports previous research suggesting an association between 40-Hz EEG and mental activity, and suggests methods for further study of transfer of EEG biofeedback effects.     

Slow cortical potential biofeedback and the startle reflex

The negativity of slow cortical potentials (SCP) of the surface EEG is a measure of brain excitability, correlating with motor and cognitive preparation. Selfcontrol of SCP positivity has been shown to reduce seizure activity. Following SCP biofeedback from a central EEG electrode position, subjects gained bidirectional control over their SCP. The current study used a modified feedback methodology, and found a positive relationship between negativity and magnitude of EMG startle response (a measure of cortical and subcortical arousal, particularly aversive response disposition). Greater success in SCP differentiation was associated with self-report of less relaxation during negativity training.This research was supported by the Deutsche Forschungsgemeinschaft under grant No. SFB 307.     

Biofeedback in optimizing psychomotor reactivity: II. The dynamics of segmental α-activity characteristics

To estimate the EEG predictors of successful training in the voluntary control of psychomotor reactivity, 29 healthy young (aged 22.3 ± 1.5 years) musical performers were examined. The estimation was carried out in terms of segmental α-activity analysis using a biofeedback session as an example, simultaneously stimulating the EEG α rhythm and decreasing the muscle tone. On the first day of the study, the musicians followed instructions for the voluntary control of comfortable finger motor activity when performing musical passages for the right hand during a standard performance practice (without any use of an adaptive feedback). On the second day, the muscle tone and the power of the EEG α rhythm were voluntarily controlled in the context of a biofeedback technology. The analysis of the unsteady EEG segmentation showed that the dynamics of changes in the coherence and segmental characteristics of the α activity were the same for both effective biofeedback training and the standard successful performance practice: an increase in the α-rhythm coherence, an increase in the lifetime of α spindles, and a decrease in their amplitude variability. The results obtained are discussed in terms of the formation and dissociation of neuron ensembles in central mechanisms of optimal psychomotor functioning.     

Canonical bicoherence analysis of dynamic EEG data

Bicoherence has been used in quantifying quadratic phase coupling (QPC) in electroencephalography (EEG) signals. However, for high-dimensional EEG signals, the calculations of traditional auto– and cross–bicoherences of signals from multiple electrodes are computationally very expensive. This has been compounded by the recognition of the non-stationary character of EEG signals. This paper introduces a new approach, the time-varying canonical bicoherence (CBC) by short-time weighted Fourier transforms, for analyzing QPC nonlinearities of dynamic EEG signals. This new method shows both computational efficiency and simple interpretation of estimated canonical bicoherences. The canonical bicoherence analysis of EEG records, during a human visual stimulus-driven cognitive process, put into evidence of quadratic phase couplings of Beta waves and Delta waves in the frontal regions.     

Selecting EEG components using time series analysis in brain death diagnosis

In diagnosis of brain death for human organ transplant, EEG (electroencephalogram) must be flat to conclude the patient’s brain death but it has been reported that the flat EEG test is sometimes difficult due to artifacts such as the contamination from the power supply and ECG (electrocardiogram, the signal from the heartbeat). ICA (independent component analysis) is an effective signal processing method that can separate such artifacts from the EEG signals. Applying ICA to EEG channels, we obtain several separated components among which some correspond to the brain activities while others contain artifacts. This paper aims at automatic selection of the separated components based on time series analysis. In the flat EEG test in brain death diagnosis, such automatic component selection is helpful.