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PubMedDate not supplied

The effect of physician feedback and an action checklist on diabetes care measures.

The objective was to evaluate whether physician feedback accompanied by an action checklist improved diabetes care process measures. Eighty-three physicians in an academic general medicine clinic were provided a single feedback report on the most recent date and result of diabetes care measures (glycosylated hemoglobin [A1c], urine microalbumin, serum creatinine, lipid levels, retinal examination) as well as recent diabetes medication refills with calculated dosing and adherence on 789 patients. An educational session regarding the feedback and adherence information was provided. The physicians were asked to complete a checklist accompanying the feedback on each of their patients, indicating requested actions with respect to follow-up, testing, and counseling. The physicians completed 82% of patient checklists, requesting actions consistent with patient needs on the basis of the feedback. Of the physicians, 93% felt the patient information and intervention format to be useful. The odds of urine microalbumin testing, serum creatinine, lipid profile, A1c, and retinal examination increased in the 6 months after the feedback. The increase was sustained at 1 year only for microalbumin and retinal exams. There was no significant change in refill adherence for the group overall after the feedback, although adherence did improve among patients of physicians attending the educational session. No significant change was noted in lipid or A1c levels during the study period. In conclusion, a simple physician feedback tool with action checklist can be both helpful and popular for improving rates of diabetes care guideline adherence. More complex interventions are likely required to improve diabetes outcomes.

Adult↗
PubMed2002

Doppler-shift compensation behavior in horseshoe bats revisited: auditory feedback controls both a decrease and an increase in call frequency.

Among mammals, echolocation in bats illustrates the vital role of proper audio-vocal feedback control particularly well. Bats adjust the temporal, spectral and intensity parameters of their echolocation calls depending on the characteristics of the returning echo signal. The mechanism of audio-vocal integration in both mammals and birds is, however, still largely unknown. Here, we present behavioral evidence suggesting a novel audio-vocal control mechanism in echolocating horseshoe bats (Rhinolophus ferrumequinum). These bats compensate for even subtle frequency shifts in the echo caused by flight-induced Doppler effects by adjusting the frequency of their echolocation calls. Under natural conditions, when approaching background targets, the bats usually encounter only positive Doppler shifts. Hence, we commonly believed that, during this Doppler-shift compensation behavior, horseshoe bats use auditory feedback to compensate only for these increases in echo frequency (=positive shifts) by actively lowering their call frequency below the resting frequency (the call frequency emitted when not flying and not experiencing Doppler shifts). Re-investigation of the Doppler-shift compensation behavior, however, shows that decreasing echo frequencies (=negative shifts) are involved as well: auditory feedback from frequencies below the resting frequency, when presented at similar suprathreshold intensity levels as higher echo frequencies, cause the bat's call frequency to increase above the resting frequency. However, compensation for negative shifts is less complete than for positive shifts (22% versus 95%), probably because of biomechanical restrictions in the larynx of bats. Therefore, Doppler-shift compensation behavior involves a quite different neural substrate and audio-vocal control mechanism from those previously assumed. The behavioral results are no longer consistent with solely inhibitory feedback originating from frequencies above the resting frequency. Instead, we propose that auditory feedback follows an antagonistic push/pull principle, with inhibitory feedback lowering and excitatory feedback increasing call frequencies. While the behavioral significance of an active compensation for echo frequencies below RF remains unclear, these behavioral results are crucial for determining the neural implementation of audio-vocal feedback control in horseshoe bats and possibly in mammals in general.

Animals↗
PubMed2006

Does personalized feedback improve the outcome of cognitive-behavioural guided self-care in bulimia nervosa? A preliminary randomized controlled trial.

OBJECTIVES: Feedback has long been a part of psychosocial and health behaviour interventions and with the advent of computerised assessment and treatment tools, is gaining greater importance. The aim of the present study was to evaluate the addition of personalized feedback to a guided cognitive-behavioural (CBT) self-help programme for patients with bulimia nervosa. DESIGN: Randomised-controlled trial. METHOD: 61 patients with DSM-IV bulimia nervosa or eating disorder not otherwise specified (EDNOS) were randomly allocated to receive 14 sessions of cognitive behavioural guided self-care with or without added personalised feedback on current physical and psychological status, risk and problems, and variables facilitating or hindering change. Feedback to patients was delivered in a number of ways: (a) personalised letters after assessment and at the end of treatment, (b) a specially designed feedback form administered half-way through treatment, (c) computerised feedback about bulimic and other symptoms, such as anxiety, depression and interpersonal functioning repeated at intervals throughout treatment and follow-up. RESULTS: Outcome was assessed using patient-rated measures of bulimic symptoms at the end of treatment and at 6-month follow-up. The data were analysed using maximum likelihood methods of assess group differences at the follow-up. Added feedback did not have an effect on take-up or drop-out from treatment. However, it improved outcome by reducing self-induced vomiting and dietary restriction more effectively. CONCLUSIONS: The findings lend support to the notion that the addition of repeated personalised feedback improves outcome from guided CBT self-help treatment and deserves further study.

Adult↗
PubMed2007

An HIV feedback resistor: auto-regulatory circuit deactivator and noise buffer.

Animal viruses (e.g., lentiviruses and herpesviruses) use transcriptional positive feedback (i.e., transactivation) to regulate their gene expression. But positive-feedback circuits are inherently unstable when turned off, which presents a particular dilemma for latent viruses that lack transcriptional repressor motifs. Here we show that a dissipative feedback resistor, composed of enzymatic interconversion of the transactivator, converts transactivation circuits into excitable systems that generate transient pulses of expression, which decay to zero. We use HIV-1 as a model system and analyze single-cell expression kinetics to explore whether the HIV-1 transactivator of transcription (Tat) uses a resistor to shut off transactivation. The Tat feedback circuit was found to lack bi-stability and Tat self-cooperativity but exhibited a pulse of activity upon transactivation, all in agreement with the feedback resistor model. Guided by a mathematical model, biochemical and genetic perturbation of the suspected Tat feedback resistor altered the circuit's stability and reduced susceptibility to molecular noise, in agreement with model predictions. We propose that the feedback resistor is a necessary, but possibly not sufficient, condition for turning off noisy transactivation circuits lacking a repressor motif (e.g., HIV-1 Tat). Feedback resistors may be a paradigm for examining other auto-regulatory circuits and may inform upon how viral latency is established, maintained, and broken.

Feedback, Physiological↗
PubMed2004

Modeling feedback loops of the Mammalian circadian oscillator.

The suprachiasmatic nucleus governs daily variations of physiology and behavior in mammals. Within single neurons, interlocked transcriptional/translational feedback loops generate circadian rhythms on the molecular level. We present a mathematical model that reflects the essential features of the mammalian circadian oscillator to characterize the differential roles of negative and positive feedback loops. The oscillations that are obtained have a 24-h period and are robust toward parameter variations even when the positive feedback is replaced by a constantly expressed activator. This demonstrates the crucial role of the negative feedback for rhythm generation. Moreover, it explains the rhythmic phenotype of Rev-erbalpha-/- mutant mice, where a positive feedback is missing. The interplay of negative and positive feedback reveals a complex dynamics. In particular, the model explains the unexpected rescue of circadian oscillations in Per2Brdm1/Cry2-/- double-mutant mice (Per2Brdm1 single-mutant mice are arrhythmic). Here, a decrease of positive feedback strength associated with mutating the Per2 gene is compensated by the Cry2-/- mutation that simultaneously decreases the negative feedback strength. Finally, this model leads us to a testable prediction of a molecular and behavioral phenotype: circadian oscillations should be rescued when arrhythmic Per2Brdm1 mutant mice are crossed with Rev- erbalpha -/- mutant mice.

Adaptation, Physiological↗
PubMed2004

Effects of changes in climate on landscape and regional processes, and feedbacks to the climate system.

Biological and physical processes in the Arctic system operate at various temporal and spatial scales to impact large-scale feedbacks and interactions with the earth system. There are four main potential feedback mechanisms between the impacts of climate change on the Arctic and the global climate system: albedo, greenhouse gas emissions or uptake by ecosystems, greenhouse gas emissions from methane hydrates, and increased freshwater fluxes that could affect the thermohaline circulation. All these feedbacks are controlled to some extent by changes in ecosystem distribution and character and particularly by large-scale movement of vegetation zones. Indications from a few, full annual measurements of CO2 fluxes are that currently the source areas exceed sink areas in geographical distribution. The little available information on CH4 sources indicates that emissions at the landscape level are of great importance for the total greenhouse balance of the circumpolar North. Energy and water balances of Arctic landscapes are also important feedback mechanisms in a changing climate. Increasing density and spatial expansion of vegetation will cause a lowering of the albedo and more energy to be absorbed on the ground. This effect is likely to exceed the negative feedback of increased C sequestration in greater primary productivity resulting from the displacements of areas of polar desert by tundra, and areas of tundra by forest. The degradation of permafrost has complex consequences for trace gas dynamics. In areas of discontinuous permafrost, warming, will lead to a complete loss of the permafrost. Depending on local hydrological conditions this may in turn lead to a wetting or drying of the environment with subsequent implications for greenhouse gas fluxes. Overall, the complex interactions between processes contributing to feedbacks, variability over time and space in these processes, and insufficient data have generated considerable uncertainties in estimating the net effects of climate change on terrestrial feedbacks to the climate system. This uncertainty applies to magnitude, and even direction of some of the feedbacks.

Arctic Regions↗
PubMed1985

Androgen feedback-dependent and -independent control of photoinduced LH secretion in male tree sparrows (Spizella arborea).

Photoperiodic control of gonadotrophin secretion in male tree sparrows was studied by examining changes in plasma LH in castrated birds retained on short daylengths and in castrated birds transferred to long daylengths. Plasma LH concentrations were markedly higher in photostimulated birds than in non-photostimulated birds throughout the 25-day experiment, and implantation of the antiandrogen cyproterone (free alcohol), which should have blocked the action of castration-resistant androgens, did not increase plasma LH in either group. Such results, obtained from birds in which testosterone feedback was inoperative, indicate that the gonadostimulatory effect of long daylengths in intact males must be mediated, at least in part, by an androgen feedback-independent mechanism. To determine whether changes in testosterone feedback facilitate gonadotrophin secretion during photostimulation, two feedback performance characteristics (i.e. set point (minimum concentration of testosterone that suppresses plasma LH) and sensitivity (change in plasma LH per unit change in testosterone)) were quantified by evaluating plasma LH responses of non-photostimulated castrated birds and of photostimulated castrated birds to replacement testosterone (0-4.16 mumol). The data indicate that, in addition to stimulating LH secretion by an androgen feedback-independent mechanism, long daylengths reduce feedback inhibition of LH secretion by increasing the putative set point and decreasing the sensitivity of the testosterone feedback mechanism. The feedback-independent effect is the predominant effect of photostimulation on LH secretion in male tree sparrows.

Animals↗
PubMed1995

Training residential supervisors to provide feedback for maintaining staff teaching skills with people who have severe disabilities.

We evaluated procedures for training supervisors in a residential setting to provide feedback for maintaining direct-service staff members ' teaching skills with people who have severe disabilities. Using classroom-based instruction and on-the-job observation and feedback, 10 supervisors were initially trained to implement teaching programs themselves. The training improved supervisors' teaching skills but was insufficient to improve the quality of feedback they provided to direct-service staff regarding the staff members' teaching skills. Subsequently, classroom-based instruction and on-the-job observation and feedback that targeted supervisors' feedback skills were provided. Following training in provision of feedback, all supervisors met criterion for providing feedback to their staff. Results also indicated that maintenance of teaching skills was greater for direct-service staff whose supervisors had received training in providing feedback relative to staff whose supervisors had not received such training. The need for analysis of other variables that affect maintenance of staff performance, as well as variables that affect other important areas of supervisor performance, is discussed.

Adult↗
PubMed1975

Role of feedback in voluntary control of heart rate.

The relative effectiveness of biofeedback techniques on the voluntary control of heart rate was examined by randomly assigning 32 Ss to one of four feedback conditions in a bi-directional heart-rate control task: (1) no feedback, (2) binary feedback--S was signaled when an interbeat interval had changed in the correct direction, (3) "real-time," proportional feedback--S was provided information about the relative duration of successive interbeat intervals, and (4) numerical, proportional feedback--each interbeat interval was represented as a numeral indicating its relationship to pre-trial mean by direction and magnitude. Significant over-all heart-rate changes were evidenced for both increase and decrease directions, but no differences were found between the feedback conditions. While these data suggest that feedback may be a relatively insignificant factor in voluntary heart-rate control, it was recommended that further investigation examine the role of feedback within the context of other training, mediating and motivational variables.

Adult↗
PubMed2001

Strength of German accent under altered auditory feedback.

Borden's (1979, 1980) hypothesis that speakers with vulnerable speech systems rely more heavily on feedback monitoring than do speakers with less vulnerable systems was investigated. The second language (L2) of a speaker is vulnerable, in comparison with the native language, so alteration to feedback should have a detrimental effect on it, according to this hypothesis. Here, we specifically examined whether altered auditory feedback has an effect on accent strength when speakers speak L2. There were three stages in the experiment. First, 6 German speakers who were fluent in English (their L2) were recorded under six conditions--normal listening, amplified voice level, voice shifted in frequency, delayed auditory feedback, and slowed and accelerated speech rate conditions. Second, judges were trained to rate accent strength. Training was assessed by whether it was successful in separating German speakers speaking English from native English speakers, also speaking English. In the final stage, the judges ranked recordings of each speaker from the first stage as to increasing strength of German accent. The results show that accents were more pronounced under frequency-shifted and delayed auditory feedback conditions than under normal or amplified feedback conditions. Control tests were done to ensure that listeners were judging accent, rather than fluency changes caused by altered auditory feedback. The findings are discussed in terms of Borden's hypothesis and other accounts about why altered auditory feedback disrupts speech control.

Adult↗
PubMedDate not supplied

Modeling corticofugal feedback and the sensitivity of lateral geniculate neurons to orientation discontinuity.

We model feedback from primary visual cortex to the dorsal lateral geniculate nucleus (dLGN). This feedback makes dLGN neurons sensitive to orientation discontinuity (Sillito et al., 1993; Cudeiro & Sillito, 1996). In the model, each dLGN neuron receives retinotopic input driven by layer 6 cortical neurons in a full set of orientation columns. Excitation is monosynaptic, while inhibition is through perigeniculate neurons and dLGN interneurons. The stimulus consists of drifting gratings,k one within and the other outside a circular region centered over the receptive field of the model dLGN relay neuron we study. They appear as a single grating when they are aligned with equal contrast. The model reproduces experimental results showing an increasing inhibitory effect of feedback on the firing rate of dLGN neurons as the two gratings move towards the aligned position. Moreover, enhancement of dLGN cell center-surround antagonism by feedback is revealed by measuring the responses to drifting gratings inside a circular window, as a function of window radius. This effect is related to the observed length tuning of dLGN cells. Sensitivity to orientation discontinuity could be mediated in the model by feedback from either simple or complex cells. The model puts constraints on the feedback synaptic footprint and shows that its elongated shape does not play a crucial role in sensitivity to orientation discontinuity. The inhibitory component of feedback must predominate overall, but the feedback signal from a cortical neuron to a dLGN neuron with the same or nearby receptive-field center can be dominated by excitation. Predictions of the model include (1) robust stimuli for layer 6 cortical neurons give pronounced nonlinearities in the responses of dLGN neurons; (2) the sensitivity to orientation discontinuity at low contrast is twice that at high contrast.

Animals↗
PubMed2006

Real-time augmented feedback benefits robotic laparoscopic training.

Robotic laparoscopic surgery has revolutionized minimally invasive surgery for treatment of abdominal pathologies. However, current training techniques rely on subjective evaluation. There is a lack of research on the type of tasks that should be used for training. Robotic surgical systems also do not currently have the ability to provide feedback to the surgeon regarding success of performing tasks. We trained medical students on three laparoscopic tasks and provided real-time feedback of performance during training. We found that real-time feedback can benefit training if the feedback provides information that is not available through other means (grip force). Subjects that received grip force feedback applied less force when the feedback was removed. Other forms of feedback (speed and relative phase) did not aid or impede training. Secondly, a relatively short training period (10 trials for each task) significantly improved most objective measures of performance. We also showed that robotic surgical performance can be quantitatively measured and evaluated. Providing grip force feedback can make the surgeon more aware of the forces being applied to delicate tissue during surgery.

Adult↗
PubMed1976

[Quantitative analysis of characteristics of the negative feedback regulation of ACTH secretion under stress (author's transl)].

Quantitative characteristics and a plausible mechanism of rapid rate-sensitive feedback inhibition of the CRF-ACTH-corticoid system were studied using Nembutal-anesthetized rats. The plasma corticosterone levels were varied by continuous infusion of corticosterone through a lateral caudal vein. The response to an intravenous injection of histamine (as a stressor) was distinctly inhibited in two phases of the dynamics of plasma corticosterone; one in its rapidly increasing phase (rapid rate-sensitive feedback inhibition) and the other, two hours or more after a high plasma steroid level has been attained (late level-sensitive feedback inhibition). On the other hand, there was no such inhibition between these two phases. A quantitative approach made by repeated blood sampling from single rats revealed that the critical rate of elevation of plasma corticosterone at which the rate-sensitive feedback inhibition). On the other hand, there was no such inhibition between these two phases. A quantitative approach made by repeated blood sampling from single rats revealed that the critical rate of elevation of plasma corticosterone at which the rate-sensitive inhibition begins to obviously occur was 4-6 mug%/min. Even with increasing strength of stress, the absolute size of inhibition at a fixed rate of elevation in plasma corticosterone remained almost the same. The increase in the median eminence-CRF activity, known to occur after stress, was effectively suppressed during the operation of rapid feedback inhibition. In addition, in brain noradrenaline-depleted rats, the rapid component in the feedback inhibition was thoroughly abolished, leaving the late component intact, while the opposite way in sorotonin-reduced rats. This finding suggests an involvement of brain biogenic amines in the negative feedback regulation of ACTH secretion in a rather specific way. Finally, on the basis of these results, a plausible model for the rapid rate-sensitive feedback regulation of ACTH secretion under stress was considered.

Adrenocorticotropic Hormone↗
PubMed1979

Reducing auditory feedback and the acquisition of motor response timing.

Three groups of subjects (n=10) attempted to move a lever 50 cm along a track in 1.50 sec under one of three auditory feedback conditions: Fully augmented increasing auditory feedback (FAF) in which a constant level of velocity-related auditory feedback was provided for all 25 learning trials, reducing auditory feedback (FAF) in which the level of feedback was progressively reduced over the learning trials, and no auditory feedback (NAF). All subjects performed 10 trials with no auditory feedback after a 10-min rest interval. The hypothesis that acquisition of the criterion task would be facilitated under RAF compared to FAF derived partial support. It was concluded that there is sufficient evidence to justify further investigation of reducing auditory feedback as a technique of motor skill acquisition.

Auditory Perception↗
PubMed1981

The macula densa sensing mechanism for tubuloglomerular feedback.

A series of studies on the signal responsible for initiating the tubuloglomerular feedback (TGF)-mediated changes in SNGFR have utilized a retrograde perfusion technique that permits close control of macula densa segment tubular fluid composition. The feedback response has been demonstrated to be an approximately linear function of luminal NaCl concentration between 15 and 60 mM, with increasing NaCl concentration resulting in lower nephron filtration rate. Feedback responses could be initiated by NaCl and NaBr solutions but not by NaI, NaNO3, NaF, NaHCO3, NaSCN, or Na acetate. All chloride salts tested, in which chloride was accompanied by a univalent cation, elicited a response. The feedback mechanism thus shows a special requirement for chloride or bromide and not for sodium. With the chloride salts the response varied in magnitude depending on the accompanying cation with the following order of decreasing response, Rb+, Na+, Cs+, NH4+, K+, choline+, and Li+, CaCl2 and MgCl2 did not elicit a feedback response. The feedback response was not influenced by large changes in luminal osmolarity by addition of urea, suggesting either that the feedback sensing site is water impermeable or that water movement does not influence the signal. When electrolyte-free solutions are perfused through the loop of Henle in an orthograde direction, sufficient electrolyte may enter the luminal fluid to transiently influence the feedback mechanism.

Animals↗
PubMed1978

Contingent vs. noncontingent EMG feedback and hand temperature in relation to anxiety and locus of control.

This study was designed to measure the effects of contingent and noncontingent EMG feedback on hand temperature, anxiety, and locus of control. Two groups of six subjects each were selected on the basis of high test-anxiety scores. The groups participated in a reverse design study in which Group 1 received five sessions of contingent EMG ffedback followed by five sessions of noncontingent feedback. Group 2 received noncontingent feedback followed by contingent feedback. Results indicate a significant order of treatment effect. Subjects who received contingent feedback first produced lower EMG readings, lower test-anxiety scores, and higher hand temperatures during noncontingent feedback sessions. Receiving noncontingent feedback first may actually have interfered with utilizing contingent feedback.

Anxiety↗
PubMed1976

Detection of EEG abnormalities with feedback stimulation.

A feedback method for testing the reactivity of the occipital-parietal EEG in selected brain-lesioned patients revealed abnormalities of (a) insufficient reactivity, (b) bilateral differences in reactivity, and (3) asynchrony. These abnormalities were more evident during feedback stimulation than in the baseline conditions. The utility of feedback method for detecting EEG abnormalities rests on the increased stability or decreased "noisy" variation in the EEG during feedback. The EEG becomes more predictable even to the "on-line" human observer. This makes it easier to detect aberrations or deviations from normal effects. Some effects can only be seen with feedback such as the bilateral differences which occur when the left side controls the feedback compared to when the right side controls it. The results show that feedback EEG is a useful tool in clinical research and indicate that a clinical diagnostic test could be developed with more research. However, the feedback EEG method is not yet a proven diagnostic technique.

Alpha Rhythm↗
PubMed1984

Effects of noncontingent feedback on EMG training, EMG responses, and subjective experience.

Various types of noncontingent feedback have been used as control procedures in EMG training; however, their effects on such training have received little attention. Experiment 1 in the present study examined the effects of noncontingent feedback on EMG training, and Experiment 2 assessed the effects of feedback characteristics on EMG responses. In Experiment 1, three noncontingent feedback groups (yoked control, randomly fluctuating tones, and decreasing tones) and one contingent group underwent 20 minutes of training for frontal EMG decreases. Procedures in Experiment 2 were identical to those in Experiment 1 except that subjects were instructed merely to listen to the feedback tones. Results of Experiment 1 indicated that contingent and noncontingent fluctuating feedback groups achieved significantly lower EMG levels than noncontingent decreasing and yoked control groups. In Experiment 2, however, no differences in EMG activity were found among groups. In both experiments, groups did not differ in terms of subjective variables such as frustration, suspiciousness about the tone, or length of time attending to the tone. Results of these two experiments suggest that differences in EMG responses to various types of noncontingent feedback result from interactions between characteristics of the feedback stimulus and instructions to decrease the stimulus.

Adolescent↗