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PubMed2005

Tissue-specific positive feedback requirements for production of type I interferon following virus infection.

Type I interferon (IFN) is synthesized by most nucleated cells following viral infection. Robust IFN production in cell culture requires positive feedback expression of inducible signaling components, such as the transcription factor IRF7. However, the role of positive feedback and IRF7 in vivo may be more complex. We found that IFN produced locally in the respiratory tract of influenza virus-infected mice displayed characteristics of positive feedback, including Stat1-dependent induction of IRF7 and IFN gene expression. IRF7 expression was similarly stimulus-dependent in most tissues. However, lymphoid tissue constitutively expressed high levels of IRF7 in the absence of induction or positive feedback, and this expression was largely confined to plasmacytoid dendritic cells (DC). These cells rapidly produced large quantities of multiple IFN alpha species following viral infection without positive feedback, whereas other hematopoietic cells, including other DC subtypes, expressed little IRF7 and were poor IFN producers in the absence of positive feedback. These data reveal a dual mechanism for the regulation of IFN production by differential expression of IRF7, involving positive feedback at local sites of infection combined with robust systemic production by IRF7-expressing plasmacytoid DC.

Animals↗
PubMed2001

Learning a coordination skill: interactive effects of instruction and feedback.

Information prior to and during the acquisition of a continuous bimanual task was manipulated. Participants practiced a difficult coordination pattern, which produced circular shapes on the computer, when they moved their arms correctly. Four groups were examined, which differed in the type and amount of information provided. Either limb or circle feedback was provided in the presence or absence of instructions detailing how to move the limbs. Circle feedback facilitated learning relative to the limb feedback in which the explicit displacements of the limbs was displayed. Under circle feedback conditions, instructions hindered acquisition. Little instructional effects were observed under limb feedback conditions, despite the prediction that instructions would benefit learning when the feedback was more compatible. Findings are discussed in relation to the complexity of the feedback and processing demands.

Adult↗
PubMed2005

The influence of visual feedback on closed-set word test performance over time.

Closed-set word tests can be implemented with or without trial-by-trial visual feedback. Feedback is considered to increase subject motivation yet its influence on performance is unknown. The aim of this study was to compare performance on the Four Alternative Auditory Feature (FAAF) test with and without visual feedback over a 24-week period following fitting of a hearing aid. A total of 32 elderly subjects were recruited as new users and fitted monaurally with the same model of linear, programmable hearing aid that provided in excess of 20 dB insertion gain at 2-4 kHz. Half of the subjects were provided with visual feedback. In these subjects, mean performance increased by 5% across the study period. The improvement in performance over time was statistically significant on analysis of variance (p < 0.05). Mean performance did not increase in the remaining subjects who were not provided with feedback. If closed-set word tests are to be used with visual feedback to measure changes over time, the potentially confounding effects of practice must be controlled carefully. Alternatively, omitting feedback leads to simpler experimental designs.

Aged↗
PubMed2005

An fMRI study of verbal self-monitoring: neural correlates of auditory verbal feedback.

The ability to recognize one's own inner speech is essential for a sense of self. The verbal self-monitoring model proposes that this process entails a communication from neural regions involved in speech production to areas of speech perception. According to the model, if the expected verbal feedback matches the perceived feedback, then there would be no change in activation in the lateral temporal cortices. We investigated the neural correlates of verbal self-monitoring in a functional magnetic resonance (fMRI) study. Thirteen healthy male volunteers read aloud presented adjectives and heard their auditory feedback which was experimentally modified. Decisions about the source of the feedback were made with a button-press response. We used a 'clustered' fMRI acquisition sequence, consisting of periods of relative silence in which subjects could speak aloud and hear the feedback in the absence of scanner noise, and an event-related design which allowed separate analysis of trials associated with correct attributions and misattributions. Subjects made more misattribution responses when the feedback was a distorted version of their voice. This condition showed increased superior temporal activation relative to the conditions of hearing their own voice undistorted and hearing another person's voice. Furthermore, correct attributions during this condition were associated with greater temporal activation than misattributions. These findings support the self-monitoring model as mismatches between expected and actual auditory feedback were associated with greater temporal activation.

Adult↗
PubMed2005

The effect of sodium profiling and feedback technologies on plasma conductivity and ionic mass balance: a study in hypotension-prone dialysis patients.

BACKGROUND: Sodium profiling improves haemodynamic tolerance in haemodialysis (HD) patients but may also influence sodium homeostasis. Changes in blood volume and plasma conductivity (PC) during HD can be modelled by feedback technology, but their effects on sodium homeostasis are not widely studied. METHODS: This randomized crossover study compared PC and ionic mass balance (IMB) as surrogate markers of sodium balance between standard HD [dialysate conductivity (DC) 14.0 mS/cm], sodium profiling (DC 15.0-->14.0 mS/cm), blood volume (BV)-controlled and PC-controlled feedback (target: post-HD PC: 14.0 mS/cm) in 10 HD patients with frequent hypotension. RESULTS: 440 treatments were studied. Pre-dialytic PC was significantly higher during SP (14.4+/-0.2 mS/cm) compared to standard HD (14.2+/-0.3 mS/cm), and was not different between the other manoeuvres: PC-controlled (14.1+/-0.3 mS/cm), and BV-controlled feedback (14.2+/-0.2 mS/cm). Except for the first treatment, during which IMB was lower during the sodium profile, IMB did not differ significantly between the various manoeuvres and was strongly dependent upon ultrafiltration volume and the difference between pre-dialytic PC and DC. Symptomatic hypotensive episodes occurred least frequently during BV-controlled feedback (8%) compared to the other manoeuvres (standard HD, 16%; sodium profile, 14%; PC-controlled feedback, 17%), but differences were not significant. Inter-dialytic weight gain and pre-dialytic systolic blood pressure did not differ. CONCLUSIONS: Pre-dialytic PC increased during the sodium profile, and did not differ between BV- or PC-controlled feedback compared to standard HD. Thus, it appears that both BV- and PC-controlled feedback can be safely prescribed without substantial salt- and water-loading, at least in the short term. Analysis of IMB is useful to assess differences in sodium balance between single treatment sessions but appears of less value in a steady-state situation.

Aged↗
PubMed2005

Effects of value and reward magnitude on feedback negativity and P300.

Feedback negativity is a negative component of the event-related brain potential observed 250-300 ms after feedback stimuli. The present study investigated the effects of value (correct or incorrect) and reward magnitude (no, small or large) on feedback negativity and P300. Feedback negativity was larger after incorrect feedback than after correct feedback, irrespective of reward magnitude. In contrast, P300 amplitude increased with reward magnitude, irrespective of value. The amplitude of feedback negativity was correlated with a trait score of negative affect and not positive affect, whereas P300 amplitude was correlated with positive affect and not negative affect. These results suggest that value and reward magnitude are processed separately in the brain.

Adult↗
PubMed2002

Feedback and reflection: teaching methods for clinical settings.

Feedback and reflection are two basic teaching methods used in clinical settings. In this article, the authors explore the distinctions between, and the potential impact of, feedback and reflection in clinical teaching. Feedback is the heart of medical education; different teaching encounters call for different types of feedback. Although most clinicians are familiar with the principles of giving feedback, many clinicians probably do not recognize the many opportunities presented to them for using feedback as a teaching tool. Reflection in medicine-the consideration of the larger context, the meaning, and the implications of an experience and action-allows the assimilation and reordering of concepts, skills, knowledge, and values into pre-existing knowledge structures. When used well, reflection will promote the growth of the individual. While feedback is not used often enough, reflection is probably used even less.

Clinical Medicine↗
PubMed2004

Do volunteer community-based preceptors value students' feedback?

PURPOSE: A key component of educational practice is to provide feedback and evaluation to teachers and learners to improve the teaching and learning process. The purpose of this study was to determine whether volunteer community preceptors value evaluation and feedback by students as much as they value other resources or rewards. METHOD: In Fall 1999, a questionnaire concerning the resources and rewards of preceptorship was mailed to 236 community preceptors affiliated with the Mercer University School of Medicine, Macon, Georgia. Preceptors were asked to rate 20 factors on a five-point Likert scale (5 = very important to 1 = not very important). The mean values were compared using t-tests. RESULTS: One hundred sixty-eight preceptors (71%) completed questionnaires. Preceptors rated evaluation and feedback from students significantly higher (p < .001) than all other factors (mean = 4.02, standard deviation [SD] = .87). Continuing medical education for teaching was the next most highly valued factor (mean = 3.67, SD = 1.14). Preceptors rated financial compensation the lowest (mean = 2.01, SD = 1.19) of all factors. The high rank of feedback and evaluation from students persisted across gender, specialty, length of time as a preceptor, practice location, and years practicing medicine. CONCLUSION: This study demonstrates that feedback and evaluation from students is highly valued. The knowledge that community-based preceptors highly value feedback and evaluation from students should stimulate medical school programs to provide feedback and evaluation to preceptors that will enhance the educational outcomes for both faculty and learners.

Data Collection↗
PubMed1986

Delayed feedback of physician performance versus immediate reminders to perform preventive care. Effects on physician compliance.

In an academic general medicine clinic, we performed a randomized, controlled trial to compare (1) the effects of supplying monthly feedback reports of compliance with preventive care protocols by 135 internal medicine house staff with (2) the effects of specific reminders given to them at the time of patient visits. The protocols were randomly divided into two groups, A and B, and half the house staff were given feedback for Group A and half for Group B. Thus, each group served as a control for the other. Each feedback group was also randomly assigned to receive reminders for either Group A or B protocols. House staff receiving feedback more often complied with fecal occult blood testing, mammography, pneumococcal vaccination, use of metronidazole, and combined Group A and B protocols than did controls (P less than 0.01). There was also significantly more compliance with the same protocols by house staff receiving reminders, but the increase for fecal occult blood testing, pneumococcal vaccination, and combined Group A protocols was twice that seen in physicians given feedback alone. In addition, reminders alone increased compliance with oral calcium supplementation. Overall compliance with the preventive care protocols was low: 10-15% in physicians receiving neither feedback nor reminders, increasing to 15-30% in those receiving reminders. Physician compliance with suggested preventive care protocols can be increased by both delayed feedback and immediate reminders, but reminders have a greater effect.

Clinical Competence↗
PubMed1997

Identification of the location, extent, and pathway of sensory neurologic feedback after mechanical stimulation of a lateral spinal ligament in chickens.

STUDY DESIGN: This study traced the location, extent, and pathway of sensory feedback after the mechanical stretching of a lateral spinal ligament in young chickens. The pathway was traced by locating the sites of Fos protein production in neuronal cell bodies at various sites in the nervous system. OBJECTIVES: To trace the location, extent, and pathway of sensory feedback after the mechanical stretching of a lateral spinal ligament in young chickens. SUMMARY OF BACKGROUND DATA: The innervation of ligaments is thought to form part of a protective feedback mechanism to provide stability for joints. The precise pathway and extent of the feedback for spinal ligaments is currently unknown. Such information would provide a clear focus for future studies, especially for diseases such as scoliosis where it has been suggested that there is abnormality in perception of sensory feedback. METHODS: The intertransverse ligament on the right side at T3-T4 in 4-week-old chickens was exposed by blunt dissection. After Fos production resulting from the surgery had been stopped, the ligament was stretched mechanically and repeatedly for 60 minutes using a 300-g weight. Various areas of the nervous system then were sectioned and processed immunohistochemically to identify areas of Fos production in nerve cell bodies. The presence of Fos indicated neurons that had been stimulated by the stretching the ligament, including interneurons along the feedback pathway. RESULTS: Fos protein was identified in nerve cell bodies in the dorsal root ganglia and intermediate gray matter of the spinal cord at the level of stimulation as well as at several spinal cord levels above and below the site of stimulation. Identification was made on the ipsilateral and the contralateral sides, although the extent of Fos production was less on the contralateral side. Fos presence also was identified in sympathetic ganglia at these sites. Nerve cell bodies in the combined nucleus cuneatus and gracilis in the medulla oblongata, the vestibular nuclei, and the thalamus also contained Fos-positive particles. CONCLUSIONS: Stretching a single lateral ligament of the spine produces a barrage of sensory feedback from several spinal cord levels on both sides of the spinal cord. This sensory information also is transferred to higher levels in the brain, including the nucleus gracilis and cuneatus, the vestibular nuclei, and the thalamus. These sites of Fos production suggest the locations of pathways for this sensory information, which include the dorsal columns and the spinocerebellar tracts. The information obtained from this study provides a clear focus for future studies in this area, particularly for diseases such as scoliosis where it is thought that incorrect perception of sensory information from the ligaments might be a major contributing factor.

Animals↗
PubMed2006

The impact of auditory and haptic feedback on computer task performance in patients with age-related macular degeneration and control subjects with no known ocular disease.

PURPOSE: To determine the impact of auditory and haptic (tactile) feedback on computer task performance of patients with age-related macular degeneration (AMD) compared to controls. METHODS: Thirty patients with AMD and 29 similarly aged controls with no known ocular disease completed timed computer icon "drag and drop" tasks under all four possible conditions of presence or absence of auditory and haptic feedback in a two-factor repeated measures design. Patient recruitment was stratified by best eye acuity: 20/20-20/50; 20/60-20/100; <20/100. Controls had best eye acuity>or=20/30. Task completion time was quantified using final target highlight time (FTHT) and total trial time, measured in milliseconds. RESULTS: Mean+/-standard deviation (SD) FTHT with neither feedback type in the three patient and control groups was, respectively: 1,110+/-356, 1,682+/-1,069, 1,763+/-831, 924+/-533. Auditory feedback improved performance [%FTHT decrease, p-value] in all groups, respectively: 18%, P=0.018; 38%, P=0.054; 57%, P=0.001; 19%, P=0.001. Haptic feedback improved performance in the worst acuity AMD group and controls: 46%, P=0.009; 17%, P=0.038. In the worst acuity AMD group, auditory and/or haptic feedback was associated with a 4-6 second mean (for each task) reduction in total trial time. CONCLUSION: Auditory and haptic feedback can substantially increase performance speed of computer "drag and drop" tasks for patients with AMD, particularly in those patients with the most compromised vision.

Aged↗
PubMed2005

Discrepancy between feedback negativity and subjective evaluation in gambling.

Feedback negativity is a negative event-related potential elicited by feedback indicating incorrect performance or monetary loss. It is unclear whether this negativity is elicited by neutral feedback (e.g. a draw in gambling) or is affected by the subjective rating of punishment. To investigate these issues, we performed a modified and computerized game of 'rock-paper-scissors' as a gambling task and measured feedback negativity in response to feedback indicating the outcome, which was accompanied by a monetary reward. The data demonstrated that feedback negativity was elicited not only by a monetary loss but also by an even outcome and was independent of the magnitude of monetary loss. Our results suggest feedback negativity is not always specific to both monetary loss and subjective rating of punishment.

Adult↗
PubMed2006

Asymmetric bagging and random subspace for support vector machines-based relevance feedback in image retrieval.

Relevance feedback schemes based on support vector machines (SVM) have been widely used in content-based image retrieval (CBIR). However, the performance of SVM-based relevance feedback is often poor when the number of labeled positive feedback samples is small. This is mainly due to three reasons: 1) an SVM classifier is unstable on a small-sized training set, 2) SVM's optimal hyperplane may be biased when the positive feedback samples are much less than the negative feedback samples, and 3) overfitting happens because the number of feature dimensions is much higher than the size of the training set. In this paper, we develop a mechanism to overcome these problems. To address the first two problems, we propose an asymmetric bagging-based SVM (AB-SVM). For the third problem, we combine the random subspace method and SVM for relevance feedback, which is named random subspace SVM (RS-SVM). Finally, by integrating AB-SVM and RS-SVM, an asymmetric bagging and random subspace SVM (ABRS-SVM) is built to solve these three problems and further improve the relevance feedback performance.

Algorithms↗
PubMed2006

Prospective assessment of the impact of feedback on colonoscopy performance.

BACKGROUND: Colonoscopy is an operator-dependent procedure. The medical literature describes disparity in colonoscopy performance with respect to polyp detection, caecal intubation rates and procedural times. AIM: To assess prospectively the impact of feedback among a large cohort of colonoscopists on three performance parameters: caecal intubation rate, insertion time and withdrawal time. METHOD: In a prospective clinical study, procedural data from all out-patient colonoscopies performed by attending gastroenterologists at our institution were recorded routinely in a computerized database. Enhanced serial feedback was provided on a quarterly basis for three procedure parameters: intubation to caecum, insertion time and withdrawal time. Feedback (absolute value, % rank and group distribution) was sent by email every 3 months beginning with January 2005 feedback for all of 2004, and subsequently quarterly in April 2005 (for January-March 2005), July 2005 (for April-June 2005) and October 2005 (for July-September 2005). RESULTS: Feedback was provided to 58 endoscopists with a median experience level of 8 years. There was a relative decline of 19% in incomplete procedures, with median caecal non-intubation rates decreasing from 4.7% to 3.8% following the introduction of feedback while median insertion times declined from 10.6 to 9.5 mins, P = 0.02. Median withdrawal times did not change significantly, 9.1-8.9 mins, P = 0.6. CONCLUSIONS: Feedback by email appears to improve colonoscopy performance, enhancing completion rates and shortening insertion times without compromising withdrawal times.

Clinical Competence↗
PubMed2006

In-training assessment: qualitative study of effects on supervision and feedback in an undergraduate clinical rotation.

BACKGROUND: Supervision and feedback are essential factors that contribute to the learning environment in the context of workplace learning and their frequency and quality can be improved. Assessment is a powerful tool with which to influence students' learning and supervisors' teaching and thus the learning environment. OBJECTIVE: To investigate an in-training assessment (ITA) programme in action and to explore its effects on supervision and feedback. DESIGN: A qualitative study using individual, semistructured interviews. SUBJECTS AND SETTING: Eight students and 17 assessors (9 members of staff and 8 residents) in the internal medicine undergraduate clerkship at Vrije Universiteit Medical Centre, Amsterdam, the Netherlands. RESULTS: The ITA programme in action differed from the intended programme. Assessors provided hardly any follow-up on supervision and feedback given during assessments. Although students wanted more supervision and feedback, they rarely asked for it. Students and assessors failed to integrate the whole range of competencies included in the ITA programme into their respective learning and supervision and feedback. When giving feedback, assessors rarely gave borderline or fail judgements. DISCUSSION AND CONCLUSION: If an ITA programme in action is to be congruent with the intended programme, the implementation of the programme must be monitored. It is also necessary to provide full information about the programme and to ensure this information is given repeatedly. Introducing an ITA programme that includes the assessment of several competencies does not automatically lead to more attention being paid to these competencies in terms of supervision and feedback. Measures that facilitate change in the learning environment seem to be a prerequisite for enabling the assessment programme to steer the learning environment.

Clinical Competence↗
PubMed1998

The influence of corticofugal feedback on the temporal structure of visual responses of cat thalamic relay cells.

1. Visually driven single-unit activity was recorded in the dorsal lateral geniculate nucleus (dLGN) of the anaesthetized cat while inactivating or stimulating the corticofugal feedback from area 17/18 by means of cortical cooling or application of GABA (inactivation), or application of glutamate or quisqualate (Glu, Quis; stimulation) to layer VI. 2. Manipulations of the corticofugal feedback primarily affected the multimodal interspike interval pattern previously reported to be present in the tonic component of visual responses elicited by spot-like stimuli. 3. Sixty-three per cent of all neurons could be influenced, and temporally localized interspike interval distributions were measured which commonly consisted of one fundamental interval peak (leftmost peak) and integer multiples thereof (higher order peaks). During blockade of the corticofugal feedback, interspike intervals were redistributed into the higher order peaks in about 70 % of the cases, accompanied by a reduced mean firing rate. During stimulation the reverse effect occurred in 69 % of cases. 4. Increased synchronization of the EEG (increased power in the delta-wave range, 1-4 Hz) had an effect similar to cortex inactivation. The specificity of corticofugal effects was verified by consideration of these EEG effects and by dLGN double recordings with one dLGN cell topographically matched with the cortical inactivation/activation site and the second cell outside this area. Clear effects due to manipulation of the corticofugal feedback were found only for the matched dLGN site. 5. In addition we observed that the peaks of the interval distributions were narrower during active corticofugal feedback, such that the temporal dispersion of the signal transmission to the cortex was reduced. 6. The mechanisms underlying this effect were further analysed in a biophysically realistic model demonstrating that the timing of the spikes in the dLGN is improved as soon as the cortical feedback is active. The high degree of convergence/divergence between neurons along the closed feedback loop thereby leads to a temporal averaging effect which reduces the interval dispersion and also introduces synchronization between dLGN cells. 7. Such a mechanism may thus counteract the deterioration of spike timing accuracy which would otherwise occur as a consequence of synaptic noise and other uncorrelated sources of activity at a given neuron.

Action Potentials↗
PubMed2000

The feedback sanction.

The emergency department (ED) is a complex environment. Its equilibrium, or homeostasis, is critically dependent on the continuous action of feedback processes. For any system to function efficiently, it needs to know the outcomes of specific actions in a consistent, reliable, and expeditious way. Historical attitudes and the unique operating characteristics of the ED have combined to impose sanctions on the proper provision of feedback. The following features have been identified as obstructive to optimal feedback operation: incomplete awareness of the significance of the problem, excessive time and work pressures, case infrequency, deficiencies in specialty follow-up, communication failures, deficient reporting systems for near-misses, error, and adverse events, biases in case review processes, shift changeover times, and shiftwork. The result is that clinicians, nurses, and trainees are working in conditions that are suboptimal for the provision of safe care, as well as for learning and job fulfillment. Good feedback is a necessary condition for well-calibrated performance by individuals, and is integral to effective team function. More needs to be known about outcomes for feedback to work efficiently. The critical role of feedback in other aspects of ED function, such as education and human factors engineering, should be emphasized. The current interest in medical error and evolving attitudes toward a new culture of patient safety provide a unique opportunity to examine feedback and the critical role it plays in ED function.

Emergency Medicine↗
PubMed2006

Effect of tutorial input in addition to augmented feedback on manual dexterity training and its retention.

Virtual reality (VR) simulators can be used as tools in manual dexterity training. The visual feedback guides the subject towards proper performance but creates, at the same time, some dependency on this feedback. To overcome this drawback, the effect of adjunct tutorial input on motor learning behaviour was examined. Novice dental students were randomly assigned to one of two training groups or to a non-training control group, given the task of preparing a geometrical class 1 cavity in phantom teeth. The feedback (FB) group trained under augmented visual feedback conditions, provided by the VR system (DentSim). The feedback-plus (FB+) group received, in addition, standardised expert input to enrich the augmented feedback information. The control group, consisting of same year students, did not participate in any training programme. All preparations were evaluated by the VR scoring system. Performance analyses revealed an overall trend towards significant improvement with practice for the training groups. Performance of the FB+ group was most accurate across training. After 1 day and 3 weeks of no practice, both training groups outperformed the control group. After 4 months, however, only the FB+ condition was significantly more accurate than the control group. The same tendency was noted for the transfer tests. Consequently, cavity preparation experience on a VR system under the condition of frequently provided feedback supplemented with expert input was most beneficial to long time learning.

Computer Simulation↗