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PubMed1979

Frontal electromyographic feedback. Stress attenuation and generalization.

This study evaluated the effects of one session of frontal electromyographic (EMG) feedback on (1) frontal EMG, (2) frontal EMG response to stress, (3) cardiovascular variables, and (4) cardiovascular responses to stress. Eighteen male and female undergraduate volunteers received either frontal EMG feedback or a relaxation instructions control procedure and were then exposed to a fear stimulus (visualization of a feared situation) and a post-stress adaptation period while several cardiovascular measures were monitored. In comparison to the control group, frontal EMG feedback significantly reduced resting levels of frontal EMG and frontal EMG response to stress but had no significant effect on cardiovascular measures. The results of this study suggest that one session of frontal EMG feedback may attenuate response to stress but, within the paradigm utilized, may be confined to the specific muscle groups monitored. Additional areas of needed research were noted including individual differences in generalization, the effects of EMG feedback from multiple sites sequentially and concomitantly, and the generalized effects from symptom-specific sites.

Adolescent↗
PubMed1994

A spatiotemporal dipole model of the stimulus preceding negativity (SPN) prior to feedback stimuli.

Ten subjects performed a time production task, in which they were instructed to press a button four seconds after the presentation of an auditory stimulus. Two seconds after the button press they received either auditory or visual feedback on the temporal accuracy of their response. In such a paradigm negative slow brain potentials can be recorded preceding the response (Movement Preceding Negativity, MPN) as well as preceding the feedback stimulus (Stimulus Preceding Negativity, SPN). Spatiotemporal dipole modelling is used to gain insight in the possible generators of MPN and SPN. From the models it follows that the MPN can be described by one contralateral radial dipole and a bilateral pair of tangential dipoles. All three dipoles are located near central electrode positions, so the generators of the MPN probably reside within the motor cortex. The SPN is modelled by a bilateral frontotemporal pair of dipoles, hypothetically representing activation of the Insulae Reili. The insular cortex is involved in the processing of affective-motivational input, such as carried by the feedback in the present paradigm. However, processing of the information content of the feedback stimulus might by itself also activate the frontal cortex. Both the response and the feedback stimulus are followed by a positive peak, which can be described by the same deep posterior dipole. Both peaks probably represent a P3, which is related to context updating.

Adult↗
PubMed1997

Biofeedback retraining in patients with functional constipation and paradoxical puborectalis contraction: comparison of anal manometry and sphincter electromyography for feedback.

PURPOSE: This study was undertaken to assess the effect of biofeedback therapy in patients with constipation and paradoxical puborectalis contraction and to compare two different feedback modes. METHODS: Twenty-six patients were randomly allocated to either of two feedback modes: anal pressure using a manometry probe or anal sphincter electromyography (EMG) using surface electrodes. RESULTS: Six patients were unable to complete their training; ten patients were retrained using anal manometry and ten patients using EMG. The paradoxical puborectalis contraction disappeared after retraining with manometry feedback in eight of ten patients and with EMG feedback in ten of ten patients. A significant improvement in both bowel function and abdominal symptoms was found after training and a continued improvement at follow-up six months later. Six patients in the manometry group and nine in the EMG group experienced an overall improvement in symptoms. The two feedback methods did not differ in terms of efficacy. CONCLUSIONS: Our results suggest that biofeedback, using either manometry or EMG, is effective in improving symptoms and anorectal function caused by paradoxical puborectalis contraction.

Adult↗
PubMed1999

Effects of visual feedback on manual tracking and action tremor in Parkinson's disease.

Visual feedback is one of the key elements in on-line control of smooth manual tracking. To in- vestigate the effects basal ganglia dysfunction have on visual feedback control, we have tested six advanced Parkinson's disease (PD) patients in comparison with normal controls using visually guided wrist tracking tasks. Tracking performance was assessed under three visual conditions: (1) both guiding target and movement cursor were displayed continuously; (2) the target display was turned off for the second half of each trial; or (3) the cursor display, but not the target, was turned off for the second half of each trial. Thus, for the second half of each trial under conditions 2 and 3, no visual feedback of the relationship between the target and the cursor was available. Results showed that although PD patients had significantly larger tracking errors than controls, and errors significantly increased in both PD patients and controls after withdrawing either visual cue, increases in tracking errors in PD were not significantly different from those in controls. Nor were any significant changes found in the frequency (6-8 Hz) or magnitude of the PD patient's action tremor after withdrawing visual feedback. These results suggest that on-line movement control of wrist tracking movements in advanced PD is not especially reliant on visual feedback. In conjunction with our previous study of multiple sclerosis (MS) patients, the present results confirm that the basal ganglia is less involved in visual guidance of smooth manual tracking than the cerebellar circuits.

Aged↗
PubMed2005

Feedforward-feedback control of dissolved oxygen concentration in a predenitrification system.

As the largest single energy-consuming component in most biological wastewater treatment systems, aeration control is of great interest from the point of view of saving energy and improving wastewater treatment plant efficiency. In this paper, three different strategies, including conventional constant dissolved oxygen (DO) set-point control, cascade DO set-point control, and feedforward-feedback DO set-point control were evaluated using the denitrification layout of the IWA simulation benchmark. Simulation studies showed that the feedforward-feedback DO set-point control strategy was better than the other control strategies at meeting the effluent standards and reducing operational costs. The control strategy works primarily by feedforward control based on an ammonium sensor located at the head of the aerobic process. It has an important advantage over effluent measurements in that there is no (or only a very short) time delay for information; feedforward control was combined with slow feedback control to compensate for model approximations. The feedforward-feedback DO control was implemented in a lab-scale wastewater treatment plant for a period of 60 days. Compared to operation with constant DO concentration, the required airflow could be reduced by up to 8-15% by employing the feedforward-feedback DO-control strategy, and the effluent ammonia concentration could be reduced by up to 15-25%. This control strategy can be expected to be accepted by the operating personnel in wastewater treatment plants.

Aerobiosis↗
PubMed2006

Transfer of heart rate feedback training to reduce heart rate response to laboratory tasks.

To examine whether transfer of heart rate (HR) feedback training to tasks not used during training could be improved by using multiple tasks during training, a modified multiple baseline across tasks, single subject design study was conducted using six high HR-reactive young adults. Participants received HR feedback training during the presentation of a videogame, and transfer of training was assessed to a mental arithmetic challenge and handgrip task. Transfer of training was next assessed following training with the mental arithmetic challenge and handgrip task. HR responses to each training task with no HR feedback were assessed during a pre-treatment session, an immediate post-training period following training on each task, a short delay (1-2 days) post-training session, and a long delay (1-2 weeks) post-training session. HR response to a novel speech task was assessed at pre-treatment and during short delay and long delay post-training sessions. Results revealed that participants reduced HR during training and generally maintained this reduction in HR during the immediate post-training assessment when HR feedback was not present. Participants were not able to reduce HR responses to tasks during short delay and long delay post-training sessions, and they were unable to transfer HR reduction skills to the speech task. Transfer of HR feedback training to new tasks was limited in nature and efforts to train across multiple stressors did not appear to improve transfer of training.

Adolescent↗
PubMed2006

The influence of stress and energy level on learning muscle relaxation during gross-motor task performance using electromyographic feedback.

The aim was to investigate the influence of mood on learning muscle relaxation. Self-reported mood (assessed by the Stress-Energy Checklist) at baseline was related to learning muscle relaxation induced by electromyographic feedback training during performance of a gross-motor task. Feedback training was provided either intermittently (Intermittent Feedback Task, IF, n=12) or continuously (Continuous Feedback Task, CF, n=9). Results reveal a negative correlation between the learning effect at short-term and energy dimension for the IF Task. It can be concluded that mood experienced prior to a learning task is relevant for the learning effect and this effect may be dependent on the schedule of feedback used.

Adult↗
PubMed1979

The effect of feedback on keying performance.

The introduction of new telephone signalling systems and new technologies for telephone keypads has stimulated interest in the effect of providing electronic feedback on keying performance. An experiment using a conventional keypad is reported which shows that electronic auditory feedback had no significant effect on keying speed, accuracy or subject's opinion. A further series of experiments investigating the best type of feedback to improve performance with 'touch' keypads is then described. It was found that an electronic tone presented through the telephone earpiece was the best feedback. Finally, performance with two types of touch keyphones incorporating the optimum form of feedback was compared with performance using a conventional keyphone. It was found that accuracy was significantly greater with the conventional keyphone, although performance with the touch keypads could be improved by electronically removing some of the very short spurious signalling times produced by them.

Journal Article↗
PubMed1992

The importance of visual feedback on the accuracy of jaw and finger positioning in man.

The anatomical position of the mandible means that direct visual feedback is not possible. To clarify the role of visual information, several jaw- and finger-positioning tasks were designed, both in a 'free-movement' and an 'isolated' (arm or head fixed) state, with or without a visual feedback display of the target position. The subjects had to position the mandible or the index finger of the preferred hand on to a movable metal bar and to maintain a defined position coinciding with the target level provided on an oscilloscope screen. The position signal was tape recorded and computer analysed off-line. Digital filtering differentiated between the drift and the oscillations around the target (root mean square). The results demonstrated a lack of precision in the free-movement, finger-positioning task after withdrawal of visual feedback. For jaw opening and closing muscles, position control was less impaired when a visual feedback display was abolished. It was suggested that the efficiency of jaw positioning is not primarily determined by visual feedback.

Adult↗
PubMed1978

EEG feedback training of epileptic patients: clinical and electroencephalographic analysis.

To evaluate the clinical efficacy and mechanisms underlying EEG feedback training of epileptic patients, 5 adult patients with poorly controlled seizures were studied for 4--10 months during which quantitative analysis of seizures, the EEG, and serum anticonvulsant levels was conducted. Sustained seizure reduction did not occur during the first 4--5 weeks in which feedback signals were presented randomly in relation to the EEG. When feedback was then made contingent upon central 9--14 c/sec activity, seizures declined by 60% in 3 patients. Power spectral analysis showed upward shifts in EEG frequency, decreases in abnormal slow activity, and enhancement of alpha rhythm activity as a function of contingent training, but no specific EEG change was associated with seizure reduction in all patients. No evidence was obtained for the hypothesized involvement of a 'sensorimotor rhythm' or motor inhibition in the training effects. The lack of effect in two patients could not be attributed to insufficient training, lack of motivation, or to differences in seizure classification. A second phase of research showed that continued laboratory training was both sufficient and necessary for maintaining clinical and EEG effects. Results indicate that: (1) significant seizure reductions can occur with EEG feedback training which are not related to placebo effects, non-specific factors or to changes in medication; (2) EEG changes associated with such training can best be described as 'normalization'; (3) continued clinical investigation of EEG feedback training as a non-pharmacological adjunct to conventional therapy appears justified.

Adolescent↗
PubMed1984

Steroid-monoamine feedback interactions in discrete brain regions using as a model the monosodium glutamate (MSG)-lesioned rat.

The present studies examine the effects of neonatal treatment with monosodium glutamate (MSG) on dopamine (DA), 5-hydroxytryptamine (5-HT) and norepinephrine (NE) metabolism in discrete brain regions and correlate them with steroid receptor kinetics in the anterior pituitary (PIT), preoptic hypothalamus (POA) and caudal hypothalamus (HYP), and with steroid negative and positive feedback effects on luteinizing hormone (LH) secretion. Substantial decreases in the neuronal activity of all three amines in the arcuate nucleus, decreased DA and 5-HT metabolism in the suprachiasmatic nucleus and, surprisingly, increased metabolism of 5-HT and NE in the median eminence was observed in adult ovariectomized (OVX), MSG-treated versus OVX, vehicle-treated litter mate controls. Measurement of estradiol receptors in the nuclear and cytosolic fractions of the POA, HYP and PIT from MSG- and vehicle-treated rats killed during diestrus or 2 weeks after OVX revealed no differences. Similarly, no differences in cytosolic progestin receptors between control and MSG unprimed or estradiol-primed, OVX rats or on progestin receptor translocation induced by progesterone in Eb-primed rats were observed. Negative and positive feedback effects of estradiol or the positive feedback of progesterone on LH secretion were not significantly impaired in MSG rats, and indeed, MSG animals actually were hyper-responsive to the administration of the steroids or of luteinizing hormone-releasing hormone. These results indicate that the MSG-induced damage to DA, 5-HT and NE elements observed within several preoptic and hypothalamic nuclei does not impair estrogen and progestin receptor kinetics, nor does it prevent adequate negative or positive steroid feedback responses, if appropriate steroid regimens are employed, and that the impaired gonadal function reported in these animals does not result primarily from inadequate steroid feedback mechanisms.

Animals↗
PubMed1989

Feedback EEG in the detection of subclinical hepatic encephalopathy: a preliminary report.

The detection, monitoring, and quantification of subclinical hepatic encephalopathy present difficult problems for the clinician caring for patients with liver disease. Traditionally, pencil and paper tests such as signature-writing have been used at the bed-side to measure early encephalopathy. More recently, the Trail-making test has been employed to detect and quantify encephalopathic changes. While the electroencephalogram has provided information about the extent of clinically-obvious encephalopathy, it has only recently proved useful in the detection of subclinical disease. In these cases, evoked potentials and spectral analysis methods have discriminated between 35 and 62% of patients with subclinical hepatic encephalopathy. The present study used the method of feedback electroencephalography to detect and quantify differences in cortical arousal in 5 cirrhotic patients and 5 normal age-matched controls. Subject were also compared with respect to baseline measures of cortical arousal. Finally, arousal during feedback EEG stimulation was correlated with Trail-making test performance. The data revealed that cirrhotic patients can be discriminated from normal controls by baseline (80% detection) and feedback stimulation conditions (100% detection). In addition, feedback EEG reactivity (cortical arousal) was inversely correlated with Trail-making test performance (-0.86, P less than 0.01). The results indicate that simple features of the conventional EEG can reliably discriminate cirrhotic patients from normals. Clinical application of the feedback method in other metabolic encephalopathies, as well as in hypoaroused states secondary to, for example, narcolepsy, is discussed.

Brain↗
PubMed1978

Efficacy of pattern feedback for the dissociation of heart rate and respiration rate.

The present study assessed the efficacy of pattern feedback for producing integrative and dissociative patterns of heart rate (HR) and respiration rate (RR). 60 uninformed subjects were assigned to six groups in which beat-by-beat feedback was contingent upon production of a specific pattern of increased ( ), decreased ( ), or unchanged (=) HR and RR during 11 feedback trials. Concomitant changes in respiratory volume and general activity (GA) were also recorded. Groups given feedback for HR and RR changes in the same directions (HR RR and HR RR ) ANd for changes in opposite directions (HR RR and HR RR ) were generally unable to produce the respective patterns, indicating that pattern feedback does not enable subjects to produce a wide range of HR-RR patterns. However, evidence of dissociation of HR and RR was obtained in the HR RR= and HR RR= groups in which HR changed significantly in the appropriate directions without significant changes in RR. These results are not consistent with the view that RR changes are necessary for HR control, although significant concomitant changes in respiratory volume and GA indicated that HR control was non-specific relative to these variables.

Adult↗
PubMed1979

Three experiments on the effects of information frequency and feedback timing on instructed heart rate speeding.

Three experiments are reported comparing different biofeedback displays in a heart rate speeding task. The first experiment examined the effects of heart rate feedback presented at three frequencies in a fixed-time format. Information was given at 0.5-sec, 2-sec and 8-sec intervals. Results indicated that both the 0.5-sec and 8-sec groups' speeding performances were superior to that of the 2-sec group. The second experiment compared a 1-sec fixed-time group with groups receiving displays in which feedback was presented synchronously with systole. Feedback was synchronized either with every heart beat or every tenth beat. The one-beat group was superior to both the 1-sec and 10-beat groups. Experiment III again presented displays which terminated with every beat or every tenth beat. However, in the previous experiment heart interval information was presented only briefly at the systole ending the sample period. In Experiment III, criterion terminations remained on the feedback screen throughout the subsequent interval. Thus, subjects did not have the additional task of attending to very briefly presented information. Nevertheless, speeding performances of the one-beat group were again superior to that attained by the 10-beat group. In all experiments a relationship between increased respiratory and skin conductance levels and heart rate speeding performances was found, suggesting that heart rate speeding was part of a generalized pattern of arousal. It was concluded that instructed heart rate speeding is highly sensitive to changes both in the frequency of feedback presentation, and to the type of display (fixed-time or heart-time) presented.

Arousal↗
PubMed1979

Effects of frontalis EMG feedback and reinforcement on frontalis EMG level.

This experiment employed a between-subjects design (N = 40) to investigate the effects of feedback and reinforcement on the lowering of frontalis electromyographic (EMG) activity. The feedback and reinforcement manipulations were combined in a 2 x 2 factorial design and each subject underwent one baseline and two training sessions on three consecutive days. The analogue feedback signal was a 55 dB tone whose pitch varied as a function of EMG activity, while the reinforcement consisted of points which were exchangeable for money. The training sessions were each divided into 10 2-min baseline periods and 10 2-min trial periods. The results indicated that although analogue feedback did not result in lowered EMG levels, trial period EMG level was significantly lower than baseline level under conditions of reinforcement. These results pose problems for Budzynski and Stoyva's (1972) views concerning the therapeutic usefulness of frontalis EMG feedback training.

Adolescent↗
PubMed1986

GSR feedback and Schultz relaxation in tension headaches: a comparative study.

A comparative study of the use of GSR feedback (n = 16) and Schultz relaxation (n = 15) with patients presenting tension headaches showed that there was no significant improvement in the group treated by relaxation at the end of the treatment whereas the group treated by GSR feedback showed significant improvements with respect to frequency and intensity of headaches and to anxiety as measured by subjects' self-evaluation (P less than 0.05). Intergroup comparison demonstrated a greater improvement in headache intensity for the GSR feedback group than for the relaxation group (P less than 0.05) at the post-treatment stage. Likewise, the percentage of patients showing at least 50% improvement as to headache frequency was significantly higher (P less than 0.05) in the GSR feedback than in the relaxation group. High pre-treatment EMG and high pre-treatment weekly pain level indicate a good prognosis of improvement with respect to post-treatment headache frequency and intensity respectively in the case of the GSR feedback group. We found no prognostic factor for post-treatment clinical improvement in the relaxation group.

Adult↗
PubMed2004

Effects of time-order, interstimulus interval, and feedback in duration discrimination of noise bursts in the 50- and 1000-ms ranges.

Participants compared durations of paired white-noise bursts, with interstimulus interval (ISI) 100, 300, 900, or 2700 ms, presented in the order standard (St)-comparison (Co) or Co-St. St was 50 or 1000 ms, and 75% difference thresholds for "longer" and "shorter" judgments were estimated. In Experiment 1 feedback was given; in Experiment 2, with ISIs 900 and 2700 ms, there was no feedback. For St=1000 ms, the just noticeable difference (JND) in noise duration was generally smaller with the order St-Co than with Co-St; for St=50 ms, the JND relation was the opposite. JNDs increased with shorter ISIs. Time-order errors were positive for St=50 ms and negative for St=1000 ms, and approached zero for longer ISIs. Using Hellström's sensation-weighting (SW) model, the ratio of the stimulus weights for the first and second burst was estimated; this ratio was generally >1 for St=50 ms and <1 for St=1000 ms. JNDs were smaller with feedback than without; the greatest reduction was found for St=1000 ms and an ISI of 2700 ms with the order Co-St, possibly because feedback increased participants' attention to the first stimulus. These results demonstrate the sensitivity of discrimination measures for long as well as brief durations to the factors of ISI, presentation order, and feedback. They also suggest different modes of stimulus processing for short and long durations.

Adult↗
PubMed2006

The efficacy of videotape feedback for enhancing the effects of exposure-based treatment for social anxiety disorder: a controlled investigation.

Correcting patients' faulty beliefs concerning social evaluative threats is the hallmark of cognitive-behavioral treatment of social anxiety disorder. The current study examined the efficacy of two videotape feedback procedures as adjuncts to exposure-based treatment. Participants suffering from social phobia (N=77) were randomly assigned to one of four conditions: (a) credible placebo treatment (PLA); (b) exposure + no feedback (EXP); (c) exposure + videotape feedback of performance (PER); or (d) exposure + videotape feedback of audience responses (AUD). Contrary to prediction, the videotape feedback procedures did not enhance the effects of exposure-based treatment. Clinical and theoretical implications are discussed.

Adult↗