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PubMed1992

Error monitoring in people who stutter: evidence against auditory feedback defect theories.

Several theories purport that people who stutter suffer a speech-auditory feedback defect. The disordered feedback creates the illusion that some kind of error has intruded into the speech flow. Stuttering then results from actions aimed to correct the suspected, but nonexistent, error. These auditory feedback defect theories thus predict deviant error detection performance in people who stutter during speech production. To test this prediction, subjects who stuttered and those who did not had to detect self-produced (phonemic) speech errors while speaking with normal auditory feedback and with the auditory feedback masked by white noise. The two groups did not differ significantly in error detection accuracy and speed, nor in false alarm scores. This opposes auditory feedback defect theories and suggests that the self-monitoring processes of people who stutter function normally. In a condition in which errors had to be detected in other-produced speech, i.e., while listening to a tape recording, subjects who stuttered did detect fewer errors. Whether this might signal some general phonological problem is discussed.

Adult↗

PubMed1993

Role of visual feedback treatment for defective /s/ sounds in patients with cleft palate.

The role of visual feedback in the treatment of defective /s/ sounds in patients with cleft palate is described. Six patients with cleft palate who were similar in age, velopharyngeal function, and type of misarticulation were selected for this study. Treatment was provided using either visual feedback or no visual feedback. Visual feedback for tongue placement was provided by the Rion Electropalatograph (EPG). Visual feedback for frication was provided by a multi-function speech training aid (MFSTA). Improvement in /s/ sound production was assessed objectively using a method described previously (Michi et al., 1986). The results indicated that visual feedback for tongue placement and frication was especially useful in the treatment of defective /s/ sounds in patients with cleft palate who exhibited abnormal posterior tongue posturing during the production of dental or alveolar sounds.

Articulation Disorders↗

PubMed2000

Attenuation of hypothalamic-pituitary-adrenal axis stress responses in late pregnancy: changes in feedforward and feedback mechanisms.

The hypothalamic-pituitary-adrenal axis is hyporesponsive to stress in late pregnancy, exemplified as reduced adrenocorticotropic hormone (ACTH) and corticosterone responses to restraint, but the mechanisms are unknown. We investigated forward drive and negative feedback upon the hypothalamic-pituitary-adrenal axis in pregnant rats. Corticotropin-releasing hormone (CRH) and vasopressin mRNA expression in the parvocellular paraventricular nucleus and mineralocorticoid and glucocorticoid receptor expression in the paraventricular nucleus and hippocampus were quantified with in situ hybridization. Because it can enhance the corticosterone negative feedback signal, 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) bioactivity in these brain regions and anterior pituitary was measured in vitro, and ACTH and corticosterone stress responses were measured after intracerebroventricular glycyrrhetinic acid, an 11beta-HSD inhibitor. Changes in corticosterone feedback on ACTH secretion were examined after pharmacological adrenalectomy by metyrapone and aminoglutethimide. Parvocellular paraventricular nucleus CRH mRNA content was reduced on day 21 and the CRH mRNA : vasopressin mRNA ratio was unaltered, indicating decreased production of both CRH and vasopressin. An increase in glucocorticoid receptor mRNA expression in the dentate gyrus (mineralocorticoid receptor mRNA expression was unaltered) and increased 11beta-HSD1 activity in the paraventricular nucleus and anterior pituitary suggest an increase in slow negative feedback mechanisms in pregnancy, but glycyrrhetinic acid did not modify the stress response. After metyrapone/aminoglutethimide treatment, corticosterone decreased ACTH secretion more slowly in pregnancy, indicating a decrease in rapid feedback sensitivity. Thus, reduced forward drive rather than increased effectiveness of glucocorticoid negative feedback may underlie stress hyporesponsiveness of the hypothalamic-pituitary-adrenal axis in pregnancy.

11-beta-Hydroxysteroid Dehydrogenase Type 1↗

PubMed2001

A new perspective on glucocorticoid feedback: relation to stress, carbohydrate feeding and feeling better.

Input to and regulation of activity in the hypothalamic-pituitary-adrenal (HPA) axis is diverse and complex. Glucocorticoid feedback is a major component that determines activity in this classic neuroendocrine axis and, while feedback occurs through the brain, the pathways that mediate glucocorticoid feedback remain unknown. In this review, I discuss findings that have led us to view glucocorticoid feedback in the HPA axis in a new light. Much of what has precipitated this view comes from a very surprising finding in our laboratory; sucrose ingestion normalizes feeding, energy balance and central corticotropin releasing factor expression in adrenalectomized (ADX) rats. Since this discovery, a diverse set of literature that supports this view of glucocorticoid feedback has been found. Taken together, recent findings of the well-known importance of glucocorticoids to feeding and energy balance, and the modulatory actions of carbohydrate ingestion on both basal and stress-induced activity in the HPA axis, strongly suggest that many metabolic (e.g. obesity) and psychological (e.g. depression) pathologies, which often present together and have been associated with stress and HPA dysregulation, might, in part, be understood in light of our new view of glucocorticoid feedback.

Affect↗

PubMed2003

The N-acetylglutamate synthase/N-acetylglutamate kinase metabolon of Saccharomyces cerevisiae allows co-ordinated feedback regulation of the first two steps in arginine biosynthesis.

In Saccharomyces cerevisiae, which uses the nonlinear pathway of arginine biosynthesis, the first two enzymes, N-acetylglutamate synthase (NAGS) and N-acetylglutamate kinase (NAGK), are controlled by feedback inhibition. We have previously shown that NAGS and NAGK associate in a complex, essential to synthase activity and protein level [Abadjieva, A., Pauwels, K., Hilven, P. & Crabeel, M. (2001) J. Biol. Chem.276, 42869-42880]. The NAGKs of ascomycetes possess, in addition to the catalytic domain that is shared by all other NAGKs and whose structure has been determined, a C-terminal domain of unknown function and structure. Exploring the role of these two domains in the synthase/kinase interaction, we demonstrate that the ascomycete-specific domain is required to maintain synthase activity and protein level. Previous results had suggested a participation of the third enzyme of the pathway, N-acetylglutamylphosphate reductase, in the metabolon. Here, genetic analyses conducted in yeast at physiological level, or in a heterologous background, clearly demonstrate that the reductase is dispensable for synthase activity and protein level. Most importantly, we show that the arginine feedback regulation of the NAGS and NAGK enzymes is mutually interdependent. First, the kinase becomes less sensitive to arginine feedback inhibition in the absence of the synthase. Second, and as in Neurospora crassa, in a yeast kinase mutant resistant to arginine feedback inhibition, the synthase becomes feedback resistant concomitantly. We conclude that the NAGS/NAGK metabolon promotes the co-ordination of the catalytic activities and feedback regulation of the first two, flux controlling, enzymes of the arginine pathway.

Acetyltransferases↗

PubMed1988

Sex-specific postnatal development of negative oestrogen feedback in rats.

Experiments were performed in immature and adult male and female rats to study the postnatal development of the negative oestrogen feedback in males and to investigate the mechanisms underlying this development. The following results were obtained: 1. Immature male and neonatally androgenized female rats were less responsive to the LH-inhibiting effect of oestradiol benzoate (OB) than untreated females. In contrast, long-term castrated adult males and females with the androgen-induced persistent oestrus syndrome were distinctively more sensitive than cyclic females to the negative feedback action of oestrogen. 2. The low oestrogen sensitivity in prepubertal males is probably caused by the testicular androgen secretion during the perinatal critical differentiation phase, because after neonatal castration, the LH response to OB injected at 21 days of age did not differ between both sexes. 3. As opposed to the peripubertal desensitization to the negative feedback action of testosterone, the sensitivity to the inhibitory effect of oestrogen on LH secretion did not decrease in males at the time of puberty. 4. Whereas former studies have shown that implantation of OB in the medial preoptic area results in significant reduction of the oestrogen sensitivity in female rats, medial preoptic implants containing oestradiol, testosterone or 5 alpha-dihydrotestosterone did not diminish the LH-suppressing effect of s.c. injected OB in males. The results suggest that 1. a marked sex difference exists in the postnatal development of the negative oestrogen feedback in rats. 2. Higher oestrogen sensitivity in adult male as compared to adult female rats may depend, at least partly, on prepubertal and cyclic desensitization of the negative oestrogen feedback in females and more or less constant sensitivity in males from infancy to adulthood. 3. In males the oestrogen sensitivity seems to be settled for long by the testicular androgen secretion during the perinatal critical differentiation phase. 4. The prepubertal increase of gonadotrophin secretion necessary for the induction of male puberty may mainly be caused by diminution of the gonadotrophin-inhibiting effect of androgens and by the decline of testicular release of inhibin. 5. The oestrogen-induced desensitization of the negative oestrogen feedback mediated by the medial preoptic area is probably a sex-specific mechanism that is only operative in female rats.

Aging↗

PubMed2006

Theoretical and experimental studies of parameter estimation based on chaos feedback synchronization.

In this paper, we perform theoretical and experimental studies of parameter estimation based on chaos feedback synchronization. The Chua chaotic system is applied as the original system, and its time series of a single variable is applied as a feedback variable to drive a simulative system. The simplex method is employed to minimize the synchronization error in the simulative system to iteratively approach the original system parameters. Furthermore, the effects of feedback function, feedback weight, and noise are investigated. The parameter estimation method based on feedback synchronization shows its robustness to noise perturbation. Finally, the circuit experiment of parameter estimation is implemented in order to examine its practical applicability. The original Chua circuit parameters can be well approached from its recorded time series of a single variable. The results show the parameter estimation method based on feedback synchronization may be capable of estimating real system parameters from a chaotic time series.

Algorithms↗

PubMed2005

Multimodal feedback for the acquisition of small targets.

This paper examines how multimodal feedback assists small-target acquisition in graphical user interfaces. All combinations of three feedback modes are analysed: non-speech audio; tactile; and pseudo-haptic "sticky" feedback. The tactile conditions used stimulation through vibration (rather than force-feedback), and the sticky conditions were implemented by dynamically reconfiguring mouse control-display gain as the cursor entered the target. Results show that for small, discretely located targets all feedback modes reduce targeting times, with stickiness providing substantial improvements. Furthermore, stickiness and tactile appear to combine well. However, the results of a more ecologically oriented menu-selection task show the need for caution, revealing that excessive feedback can damage interaction though "noise" that interferes with the acquisition of neighbouring targets.

Adult↗

PubMed2006

The ironies of vehicle feedback in car design.

Car drivers show an acute sensitivity towards vehicle feedback, with most normal drivers able to detect 'the difference in vehicle feel of a medium-size saloon car with and without a fairly heavy passenger in the rear seat' (Joy and Hartley 1953-54). The irony is that this level of sensitivity stands in contrast to the significant changes in vehicle 'feel' accompanying modern trends in automotive design, such as drive-by-wire and increased automation. The aim of this paper is to move the debate from the anecdotal to the scientific level. This is achieved by using the Brunel University driving simulator to replicate some of these trends and changes by presenting (or removing) different forms of non-visual vehicle feedback, and measuring resultant driver situational awareness (SA) using a probe-recall method. The findings confirm that vehicle feedback plays a key role in coupling the driver to the dynamics of their environment (Moray 2004), with the role of auditory feedback particularly prominent. As a contrast, drivers in the study also rated their self-perceived levels of SA and a concerning dissociation occurred between the two sets of results. Despite the large changes in vehicle feedback presented in the simulator, and the measured changes in SA, drivers appeared to have little self-awareness of these changes. Most worryingly, drivers demonstrated little awareness of diminished SA. The issues surrounding vehicle feedback are therefore similar to the classic problems and ironies studied in aviation and automation, and highlight the role that ergonomics can also play within the domain of contemporary vehicle design.

Automation↗

PubMed2000

Prism exposure aftereffects and direct effects for different movement and feedback times.

The effects of movement time and time to visual feedback (feedback time) on prism exposure aftereffects and direct effects were studied. In Experiment 1, the participants' (N = 60) pointing limb became visible early in the movement (.2-s feedback time), and eye-head aftereffects increased with increasing movement time (.5 to 3.0 s), but larger hand-head aftereffects showed little change. Direct effects (terminal error during exposure) showed near-perfect compensation for the prismatic displacement (11.4 diopters) when movement time was short but decreasing compensation with longer movement times. In Experiment 2, participants' (N = 48) eye-head aftereffects increased and their larger hand-head aftereffects decreased with increasing movement time (2.0 and 3.0 s), especially when feedback time increased (.25 and 1.5 s). Direct effects showed increasing overcompensation for longer movement and feedback times. Those results suggest that aftereffects and direct effects measure distinct adaptive processes, namely, spatial realignment and strategic control, respectively. Differences in movement and feedback times evoke different eye-hand coordination strategies and consequent direct effects. Realignment aftereffects also depend upon the coordination strategy deployed, but not all strategies support realignment. Moreover, realignment is transparent to strategic control and, when added to strategic correction, may produce nonadaptive performance.

Adaptation, Physiological↗

PubMed1997

Augmented Feedback Presented in a Virtual Environment Accelerates Learning of a Difficult Motor Task.

One can use a number of techniques (e.g., from videotaping to computer enhancement of the environment) to augment the feedback that a subject usually receives during training on a motor task. Although some forms of augmented feedback have been shown to enhance performance on isolated isometric tasks during training, when the feedback has been removed subjects have sometimes not been able to perform as well in the "real-world" task as controls. Indeed, for realistic, nonisometric motor tasks, improved skill acquisition because of augmented feedback has not been demonstrated. In the present experiments, subjects (Experiment 1, N = 42; Experiment 2, N = 21) performed with a system that was designed for teaching a difficult multijoint movement in a table tennis environment. The system was a fairly realistic computer animation of the environment and included paddles for the teacher and subject, as well as a virtual ball. Each subject attempted to learn a difficult shot by matching the pattern of movements of the expert teacher. Augmented feedback focused the attention of the subject on a minimum set of movement details that were most relevant to the task; feedback was presented in a form that required the least perceptual processing. Effectiveness of training was determined by measuring their performance in the real task. Subjects who received the virtual environment training performed significantly better than subjects who received a comparable amount of real-task practice or coaching. Kinematic analysis indicated that practice with the expert's trajectory served as a basis for performance on the real-world task and that the movements executed after training were subject-specific modifications of the expert's trajectory. Practice with this trajectory alone was not sufficient for transfer to the real task, however: When a critical component of the virtual environment was removed, subjects showed no transfer to the real task.

augmented feedback↗

PubMed2005

Surgery residents and attending surgeons have different perceptions of feedback.

Feedback plays an important role in Postgraduate Medical Education and is indispensable in surgical training. Improvement in operating skills, for example, requires constant feedback between teacher and learner to promote reflection on performance. Prior to providing workshops on giving effective feedback, the goal of this study was to assess the perceptions of attending surgeons and residents on feedback practices in our program. We show a startling disparity in perceptions of feedback frequency and skills. The results were used in planning a Workshop on Giving Feedback for our faculty. The effectiveness of this Workshop will be assessed at a later date by administering the same questionnaire.

Attitude of Health Personnel↗

PubMed1991

Youth fitness testing: the effect of percentile-based evaluative feedback on intrinsic motivation.

This study was a test of Deci and Ryan's (1985) cognitive evaluation theory in a fitness testing situation. More specifically, it was a test of Proposition 2 of that theory, which posits that external events that increase or decrease perceived competence will increase or decrease intrinsic motivation. Seventh and eighth grade schoolchildren (N = 105) volunteered for an experiment that was ostensibly to collect data on a new youth fitness test (the Illinois Agility Run). After two untimed practice runs, a specially adapted version of the Intrinsic Motivation Inventory (IMI) was administered as a pretest of intrinsic motivation. Two weeks later when subjects ran again, they were apparently electronically timed. In reality, the subjects were given bogus feedback. Subjects in a positive feedback condition were told their scores were above the 80th percentile, while those in a negative feedback condition were told their scores were below the 20th percentile. Those in a control condition received no feedback. The IMI was again administered to the subjects after their runs. Multivariate and subsequent univariate tests were significant for all four subscale dependent variables (perceived interest-enjoyment, competence, effort, and pressure-tension). Positive feedback enhanced all aspects of intrinsic motivation, whereas negative feedback decreased them. In a further test of cognitive evaluation theory, path analysis results supported the prediction that perceived competence would mediate changes in the other IMI subscales. Taken together, these results clearly support cognitive evaluation theory and also may have important implications regarding motivation for those who administer youth fitness tests.

Adolescent↗

PubMed1996

Delayed visual feedback while learning to track a moving target.

Two studies investigated the effects of delayed visual feedback on manual tracking. In Experiment 1, individuals practiced with visual feedback provided either immediately (0 delay) or with a 333-ms delay. During acquisition, the 0 delay group performed with less error than the 333-ms delay group. A retention test with 0 delay feedback was performed with the least error by the 0 delay group. A transfer test using a different 0 delay tracking pattern, was performed with the least error by the 333-ms delay group. In Experiment 2, individuals practiced at six different delays. Error increased as training feedback delay increased. For retention there were no differences between the delay groups during the 0 delay retention. At a 417-ms retention, test error decreased as training feedback delay increased. Results indicate that error during acquisition does not necessarily impair learning and that feedback delays can be beneficial for learning.

Analysis of Variance↗

PubMedDate not supplied

Treatment of anomia using errorless versus errorful learning: are frontal executive skills and feedback important?

BACKGROUND: Studies from the amnesia literature suggest that errorless learning can produce superior results to errorful learning. However, it was found in a previous investigation by the present authors that errorless and errorful therapy produced equivalent results for patients with aphasic word-finding difficulties. A study in the academic literature of phoneme discrimination learning found that errorful learning produced equivalent results to errorless learning when feedback was given. In the authors' previous study, feedback was available to the participants in the errorful therapy. It is possible, therefore, that this feedback may have improved the results from errorless learning -- thereby reducing an underlying difference between the two techniques. Generally, feedback is thought to aid learning, however, there is little information in the speech therapy literature about this factor. AIMS: The present investigation was conducted as a follow-up to authors' original study to compare errorless and errorful therapy for the amelioration of aphasic word-finding difficulties. The second aim was to replicate key findings from the original study: namely, that recognition memory, executive/problem-solving skills and monitoring ability predict immediate and long-term naming improvements but not the participants' remaining language ability. METHODS & PROCEDURES: Seven of the original 11 participants took part in a multiple baseline, crossover, case series design. OUTCOMES & RESULTS: The previous results were replicated: errorless and errorful therapy produced equivalent results immediately post-therapy and at follow-up. There was no effect of omitting feedback - the participants learnt equally well without therapist's feedback about whether or not their response was correct. In addition, executive/problem-solving skills and monitoring ability again predicted immediate naming improvements not language ability. CONCLUSIONS: The findings support the view that cognitive abilities and in particular executive function are important contributors to rehabilitation.

Adult↗

PubMed1993

Studies on the neuronal systems involved in the oestrogen-negative feedback effect on gonadotrophin releasing hormone neurons in the ewe.

Oestrogen can act on the brain to exert negative and positive feedback effects on the secretion of gonadotrophin releasing hormone (GnRH), but this cannot be effected through the GnRH cells themselves because they have no oestrogen receptors. We have used intraventricular injection of agonists and antagonists of various transmitters to determine which systems are involved in the control of GnRH by steroid hormones. We have also developed a model for the injection of drugs directly into the medial pre-optic area of the sheep brain to study the action on the GnRH cell bodies. Opioid systems seem to be involved in the mediation of the feedback effects of progesterone, but not oestrogen. Noradrenaline appears to be involved in the negative feedback regulation of GnRH secretion during the anoestrous period. Thus, under the strong negative influence of oestrogen at this time GnRH/luteinizing hormone (LH) secretion is reduced but can be restored by the preoptic micro-injection of noradrenaline. Gamma-amino-butyric acid (GABA) agonists and antagonists inhibit LH secretion when injected into the medial pre-optic region of the hypothalamus of ovariectomized ewes with or without oestrogen treatment. We have no evidence that GABA is involved in the negative feedback regulation of GnRH, since neither agonists nor antagonists will reverse the effects of steroid feedback. There appears to be a shift in the GABA receptor subtype function with season; in the breeding season only GABAA ligands are effective, whereas during the non-breeding season both GABAA and GABAB type ligands will affect LH secretion. This suggests that the seasonal shift in responsiveness to the negative feedback effects of oestrogen involves a shift in the function of GABA receptor subtypes.

Animals↗

PubMed1985

Using feedback and evaluation effectively in clinical supervision. Model for interaction characteristics and strategies.

Feedback and evaluation are both integral parts of daily communications that supervisors and instructors use to help employees and students learn and grow. The purpose of this article is to provide guidelines for the effective use of feedback and evaluation in the supervision and performance assessment of students and staff therapists and assistants. I define feedback and evaluation and give examples of their uses. Reactions of students and staff to feedback and evaluation are identified. Carkhuff's phases of helping are described and integrated in a model with interaction characteristics and strategies that supervisors and instructors use when giving feedback and evaluation. I describe and suggest applications of the model for using feedback and evaluation to facilitate the development of independent and competent physical therapists and assistants.

Communication↗

PubMed1987

Closed-loop feedback control of methohexital anesthesia by quantitative EEG analysis in humans.

A combined pharmacokinetic and pharmacodynamic model of methohexital was used to establish and evaluate feedback control of methohexital anesthesia in 13 volunteers. The median frequency of the EEG power spectrum served as the pharmacodynamic variable constituting feedback. Median frequency values from 2-3 Hz were chosen as the desired EEG level (set-point). In 11 volunteers, the feedback system succeeded in maintaining a satisfactory depth of anesthesia (i.e., unresponsiveness to verbal commands and tactile stimuli). During feedback control, 75% of all measured median frequency values were in the preset range of 2-3 Hz. This distribution of median frequency was obtained by applying random stimulation (six different acoustic and tactile stimuli) to the volunteers approximately every 1.5 min. The decrease of median frequency from baseline to anesthetic values was primarily induced by increasing the fractional power in the frequency band of 0.5-2 Hz from 12.6 +/- 4.5% (mean +/- SD) to 46.0 +/- 2.5%. The median time to recovery (as defined by opening eyes on command) after cessation of the feedback control period was 20.6 min (10.7-44.5 min) when median EEG frequency was 5.2 Hz (4.7-8.4 Hz). The average requirement of methohexital (mean +/- SD) during the 2 h was 1.02 +/- 0.16 g. It is concluded that pharmacokinetic-pharmacodynamic models of intravenous anesthetics established previously may be used to form a suitable background for model-based feedback control of anesthesia by quantitative EEG analysis. This approach gives a possible solution to the problem of adapting pharmacokinetic and pharmacodynamic data to individuals when using population mean data as starting values for drug therapy.

Adult↗