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At least 415 records · Page 23Linked to original sources
PubMed2000

Effectiveness of supplemental grasp-force feedback in the presence of vision.

Previous studies have shown that supplemental grasp-force feedback can improve control for users of a hand prosthesis or neuroprosthesis under conditions where vision provides little force information. Visual cues of force are widely available in everyday use, however, and may obviate the utility of supplemental force information. The purpose of the present study was to use a video-based hand neuroprosthesis simulator to determine whether grasp-force feedback can improve control in the presence of realistic visual information. Seven able-bodied subjects used the simulator to complete a simple grasp-and-hold task while controlling and viewing pre-recorded, digitised video clips of a neuroprosthesis user's hand squeezing a compliant object. The task was performed with and without supplemental force feedback presented via electrocutaneous stimulation. Subjects had to achieve and maintain the (simulated) grasp force within a target window of variable size (+/- 10-40% of full scale). Force feedback improved the success rate significantly for all target window sizes (8-16%, on average), and improved the success rate at all window sizes for six of the seven subjects. Overall, the improvement was equivalent functionally to a 35% increase in the window size. Feedback also allowed subjects to identify the direction of grasp errors more accurately, on average by 10-15%. In some cases, feedback improved the failure identification rate even if success rates were unchanged. It is thus concluded that supplemental grasp-force feedback can improve grasp control even with access to rich visual information from the hand and object.

Adult↗
PubMed2005

Medication compliance during a smoking cessation clinical trial: a brief intervention using MEMS feedback.

This study examined the role of a Medication Event Monitoring System (MEMS) to assess pill-taking behavior and enhance compliance within a randomized trial of bupropion-SR for smoking cessation. Female participants (N = 97) received MEMS bottles containing bupropion-SR 150 mg or placebo, to be taken twice daily. A randomly selected "feedback" group of participants was told about the recording device in the bottle cap and received weekly graphic feedback showing their pill-taking behavior with specific instructions for improving compliance. A "no-feedback" group was not informed about the MEMS bottles, and did not receive further instruction or feedback beyond the standard dosing instructions. Compliance outcomes were the total doses taken and number of doses taken within the prescribed time interval. Results indicated significantly higher compliance over time for the feedback group. Participation in the feedback group predicted higher compliance beyond demographic, smoking, and health belief variables, suggesting significant benefit in providing brief feedback and instruction throughout the medication regimen.

Bupropion↗
PubMed1993

Feedback of ankle joint angle and soleus electromyography in the rehabilitation of hemiplegic gait.

A computer-assisted feedback system was developed to present to walking subjects instantaneous feedback of their muscle activity or joint angular excursions during gait. Targets for muscle activity or joint motion were displayed on the feedback screen along with timing cues that prompted muscle activity or joint flexion/extension at specific times during the gait cycle. The purpose was to compare the effectiveness of joint angle and electromyographic (EMG) feedback to a focused program of physical therapy for gait. Eight hemiplegic stroke patients were treated with ankle joint angle feedback, EMG biofeedback from the soleus muscle, and conventional physical therapy for gait in a three-period crossover design. PT was given either first or last in the sequence of treatments. Gait analysis prior to and following each type of treatment revealed that the feedback treatments resulted in significant increases in stride length and walking velocity and in positive changes in push-off impulse, gait symmetry, and standing weight-bearing symmetry, as evaluated in a general linear model and paired t-tests. Overall, physical therapy produced no significant changes. However, when physical therapy was the first treatment of the sequence, significant increases in stride length and velocity were observed. When physical therapy was last, there were significant negative changes in gait symmetry and standing weight-bearing symmetry, and negative trends in stride length, walking velocity, and push-off impulse. It is concluded that computer-assisted feedback is an effective tool for retraining gait in stroke patients.

Ankle Joint↗
PubMed1990

Right hemisphere sensitivity to feedback.

The present studies sought to determine whether feedback-related emotional states influence perceptual and/or response processes within the right hemisphere. The task involved the presentation of a positive, neutral or negative feedback signal followed by a target in the left (LVF) or right (RVF) visual field which was spatially compatible or incompatible with its assigned response. The first two studies demonstrated that when a LVF target required a left-hand response, RTs were delayed following negative feedback and facilitated following positive feedback. These effects occurred when the target followed the feedback signal by either 100 or 500 msec, and were evident when the response selection was based on either the target's spatial location or its form. Experiment 3 showed that these feedback effects disappeared when verbal information conveyed the appropriate response. These findings indicate that feedback-related emotional processes modulate sensory-response translation processes within the right hemisphere.

Adult↗
PubMed2005

The feedback-related negativity reflects the binary evaluation of good versus bad outcomes.

Electrophysiological studies have utilized event-related brain potentials to study neural processes related to the evaluation of environmental feedback. In particular, the feedback-related negativity (FRN) has been shown to reflect the evaluation of monetary losses and negative performance feedback. Two experiments were conducted to examine whether or not the FRN is sensitive to the magnitude of negative feedback. In both experiments, participants performed simple gambling tasks in which they could receive a range of potential outcomes on each trial. Relative to feedback indicating monetary gain, feedback indicating non-rewards was associated with a FRN in both experiments; however, the magnitude of the FRN did not demonstrate sensitivity to the magnitude of non-reward in either experiment. These data suggest that the FRN reflects the early appraisal of feedback based on a binary classification of good versus bad outcomes. These data are discussed in terms of contemporary theories of the FRN, as well as appraisal processes implicated in emotional processing.

Affect↗
PubMed2006

Effects of visual feedback on manipulation performance and patient ratings.

OBJECTIVE: This study examined the explicit targeted outcome (a criterion standard) and visual feedback on the immediate change in and the short-term retention of performance by novice operators for a high-velocity, low-amplitude procedure under realistic conditions. METHODS: This study used a single-blind randomized experimental design. Forty healthy male (n = 26) and female (n = 14) chiropractic student volunteers with no formal training in spinal manipulative therapy participated. Biomechanical parameters of an L4 mammillary push spinal manipulation procedure performed by novice operators were quantified. Participants were randomly assigned to 2 groups and paired. One group received visual feedback from load-time histories of their performance compared with a criterion standard before a repeat performance. Participants then performed a 10-minute distractive exercise consisting of National Board of Chiropractic Examiners review questions. The second group received no feedback. An independent rating of performance was conducted for each participant by his/her partner. Results were analyzed separately for biomechanical parameters for partner ratings using the Student t test with levels of significance (P < .01) adjusted for repeated testing. RESULTS: Expressed in percent change for each individual, visual feedback was associated with change in the biomechanical performance of group 2, a minimum of 14% and a maximum of 32%. Statistical analysis rating of the performance favored the feedback group on 4 of the parameters (fast, P < .0008; force, P < .0056; precision, P < .0034; and composite, P < .0016). CONCLUSION: Quantitative feedback, based on a tangible conceptualization of the target performance, resulted in immediate and significant improvement in all measured parameters. Newly developed skills were retained at least over short intervals even after distractive tasks. Learning what to do with feedback on one's own performance may be more important than the classic teaching of how to do it.

Adult↗
PubMed2006

Spatiotemporal analysis of feedback processing during a card sorting task using spatially filtered MEG.

A card sorting paradigm was used to observe the neural correlates of feedback processing in adult participants. Visually presented feedback was used to indicate response accuracy and the requirement to shift response set in a 2-category card sorting task. Magnetoencephalography (MEG) responses to feedback cues were analysed using a beamformer-based spatial filtering algorithm (event-related Synthetic Aperture Magnetometry, erSAM). Analysis of source power revealed activity in rostral anterior cingulate cortex (ACC) only to negative feedback processing, which peaked at 260 ms after stimulus onset. The results are in agreement with both evidence from fMRI on spatial characteristics of negative feedback processing, and evidence from event-related potentials (ERPs) on the temporal profile of this ACC response. The superior temporal gyrus was activated only with positive feedback, reflecting integration of actions with successful outcomes. The present MEG erSAM findings are the first to provide both accurate spatial localization as well as temporal specificity for the neural correlates of feedback processing.

Adult↗
PubMed2006

Quality of out-of-hospital cardiopulmonary resuscitation with real time automated feedback: a prospective interventional study.

AIMS: To compare quality of CPR during out-of-hospital cardiac arrest with and without automated feedback. MATERIALS AND METHODS: Consecutive adult, out-of-hospital cardiac arrests of all causes were studied. One hundred and seventy-six episodes (March 2002-October 2003) without feedback were compared to 108 episodes (October 2003-September 2004) where automatic feedback on CPR was given. Automated verbal and visual feedback was based on measured quality with a prototype defibrillator. Quality of CPR was the main outcome measure and survival was reported as specified in the protocol. RESULTS: Average compression depth increased from (mean +/- S.D.) 34 +/- 9 to 38 +/- 6 mm (mean difference (95% CI) 4 (2, 6), P < 0.001), and median percentage of compressions with adequate depth (38-51 mm) increased from 24% to 53% (P < 0.001, Mann-Whitney U-test) with feedback. Mean compression rate decreased from 121 +/- 18 to 109 +/- 12 min(-1) (difference -12 (-16, -9), P = 0.001). There were no changes in the mean number of ventilations per minute; 11 +/- 5 min(-1) versus 11 +/- 4 min(-1) (difference 0 (-1, 1), P = 0.8) or the fraction of time without chest compressions; 0.48 +/- 0.18 versus 0.45 +/- 0.17 (difference -0.03 (-0.08, 0.01), P = 0.08). With intention to treat analysis 7/241 control patients were discharged alive (2.9%) versus 5/117 with feedback (4.3%) (OR 1.5 (95% CI; 0.8, 3), P = 0.2). In a logistic regression analysis of all cases, witnessed arrest (OR 4.2 (95% CI; 1.6, 11), P = 0.004) and average compression depth (per mm increase) (OR 1.05 (95% CI; 1.01, 1.09), P = 0.02) were associated with rate of hospital admission. CONCLUSIONS: Automatic feedback improved CPR quality in this prospective non-randomised study of out-of-hospital cardiac arrest. Increased compression depth was associated with increased short-term survival. TRIAL REGISTRATION: ClinicalTrials.gov (NCT00138996), http://www.clinicaltrials.gov/.

Aged↗
PubMed2001

The effects of failure feedback and pain-related fear on pain report, pain tolerance, and pain avoidance in chronic low back pain patients.

The aim of this study was to investigate the influence of non-pain-related failure experiences and pain-related fear on pain report, pain tolerance and pain avoidance in chronic low back pain (CLBP) patients. Moreover, the mediating and moderating role of negative affectivity (trait-NA) in the relationship between failure experiences and pain was examined. Seventy-six patients were divided into high and low pain-related fear groups and within each group they were randomly assigned to the failure or success feedback condition. In the first part of the study patients completed a 'social empathy test' and experimenter 1 subsequently delivered false failure or success feedback. A second experimenter, who was blind for the condition, subsequently administered two lifting tasks in order to obtain measures of pain report, tolerance and avoidance. Failure feedback did have an effect on pain avoidance but unexpectedly, and not as hypothesized, pain avoidance was reduced instead of enhanced. With regard to pain report and pain tolerance similar patterns were found, but these were not statistically significant. The effect of failure feedback on pain avoidance was moderated by trait-NA. Only in the subgroup of patients who scored low on trait-NA did failure feedback decrease pain avoidance. State-NA did not mediate the effects of feedback. In line with previous findings, pain-related fear resulted in lower pain tolerance. Moreover, this study was the first to show that pain-related fear predicted higher pain report in CLBP patients. Pain-related fear did not predict pain avoidance when pre-lifting pain and gender were controlled for. Finally, pre-lifting pain turned out to be the strongest predictor with regard to all pain measures. The role of pain-related fear and unexpected findings with regard to feedback are discussed as well as some clinical implications.

Adaptation, Psychological↗
PubMed2000

Maximising handwashing rates in the critical care unit through yearly performance feedback.

Handwashing following patient contact reduces the incidence of nosocomial infections. Despite this, handwashing rates by health care workers (HCWs) are often poor. Feedback on handwashing has been shown to significantly improve its rates. This study determined the optimum time to repeat performance feedback on handwashing rates of hospital staff in order to maximise its incidence. The baseline incidence of handwashing by staff following patient contact was determined by covert observation. This was followed by a period of feedback on handwashing performance by means of histograms displayed in the unit. Handwashing incidence was reassessed 6 and 12 months after the feedback ended. Performance feedback induced significant increases in handwashing incidence amongst nurses (p = 0.0433), resident medical officers (p = 0.0134), specialists (p = 0.0021) and radiographers (p = 0.0001). Non-significant increases were noted in handwashing rates amongst wardsmen/women and physiotherapists. Overall, handwashing incidence declined significantly (p = 0.0001) 12 months post feedback. This study demonstrated that feedback should be repeated within 12 months in order to maximise handwashing rates with the minimum intervention.

Critical Care↗
PubMed1979

Feedback regulation of nephron filtration rate during pharmacologic interference with the renin-angiotensin and adrenergic systems in rats.

Tubuloglomerular feedback has been defined as a mechanism in which changes in distal tubular sodium chloride delivery induce changes in glomerular arteriolar resistance. Experiments were performed in rats to test the hypothesis that the alterations in vasomotor activity are controlled by local hormonal mechanisms. Early proximal flow rate (EPFR), used as an index of filtration rate, was assessed at loop perfusion rates of 10 and 40 nl/min and during zero loop flow before and during intravenous administration of agents which interfere with the reninangiotensin or adrenergic systems. During infusion of the angiotensin (A) antagonists [Sar1,Ile8-]-AII or [Me2,Gly1,Ile8]-AII at doses ranging from 4.8 to 30.6 micrograms/kg . min, feedback response, expressed as percent change of EPFR during loop flow elevation from 3 to 40 nl/min, fell from a mean of 47.6 +/- 3.3% to 33.2 +/- 2.9% (P less than 0.05). Likewise, after administration of the converting enzyme inhibitor SQ 20881 in a dose ranging between 5.5 and 34.0 mg/kg, feedback response decreased from 48.5 +/- 2.1% to 25.9 +/- 1.9% (P less than 0.001) and returned to 43.1 +/- 5.1% after the inhibitory effect of SQ 20881 on the pressure response to angiotensin I had disappeared. Luminal application of [Sar1,Thr2]-AII (5mM) or of SQ 20881 (5 or 10 mM) had no effect on the feedback response. A significant reduction in the feedback response was noted also during intravenous infusion of propranolol (46.4 +/- 3.2% vs. 29.0 +/- 2.8%, P less than 0.001), whereas 6-OH-dopamine, reserpine, or phenoxybenzamine had no detectable effect. Our results are in agreement with the concept that the renin-angiotensin system may mediate feedback-induced resistance changes. In addition, circulating catecholamines may, in some unknown manner, act as modulators of the feedback response.

Adrenergic alpha-Antagonists↗
PubMed2001

Robustness of the bistable behavior of a biological signaling feedback loop.

Biological signaling networks comprised of cellular components including signaling proteins and small molecule messengers control the many cell function in responses to various extracellular and intracellular signals including hormone and neurotransmitter inputs, and genetic events. Many signaling pathways have motifs familiar to electronics and control theory design. Feedback loops are among the most common of these. Using experimentally derived parameters, we modeled a positive feedback loop in signaling pathways used by growth factors to trigger cell proliferation. This feedback loop is bistable under physiological conditions, although the system can move to a monostable state as well. We find that bistability persists under a wide range of regulatory conditions, even when core enzymes in the feedback loop deviate from physiological values. We did not observe any other phenomena in the core feedback loop, but the addition of a delayed inhibitory feedback was able to generate oscillations under rather extreme parameter conditions. Such oscillations may not be of physiological relevance. We propose that the kinetic properties of this feedback loop have evolved to support bistability and flexibility in going between bistable and monostable modes, while simultaneously being very refractory to oscillatory states. (c) 2001 American Institute of Physics.

Journal Article↗
PubMed2004

The effect of feedback training on lumbosacral compression during simulated occupational lifting.

This study measured the effect of a feedback training program on lumbar compression during simulated occupational lifting. Two distinct types of feedback were compared: real-time electromyographic feedback, vs. an acceleration index delivered verbally post-lift. Kinematic data were collected from 28 subjects during symmetrical sagittal plane lifts. Following a baseline session, two feedback training sessions were provided, with a 1-week interval between each session. A control group followed the same protocols, but without receiving feedback training. A post-training session, using protocols identical to the baseline session, was used to assess pre-to-post changes in the dependent variable: peak lumbosacral compression computed using a dynamic linked-segment model. All three groups showed reductions in peak compression from pre-to-post: on average the control group improved by 11.2%, the EMG group by 16.7%, and the acceleration group by 25.3%. The results revealed an interaction between the improvement and the group (p=0.023), and a difference between the improvement in the control group and that in the verbal acceleration feedback group (p<0.01). These reductions in lumbosacral compression persisted after a 7-day interval without feedback training, suggesting that this approach could provide sustained risk-reduction during manual materials handling.

Acceleration↗
PubMed2006

Time-frequency intracranial source localization of feedback-related EEG activity in hypothesis testing.

The neural correlates of the response to performance feedback have been the object of numerous neuroimaging studies. However, the precise timing and functional meaning of the resulting activations are poorly understood. We studied the electroencephalographic response time locked to positive and negative performance feedback in a hypothesis testing paradigm. The signal was convoluted with a family of complex wavelets. Intracranial sources of activity at various narrow-band frequencies were estimated in the 100- to 400-ms time window following feedback onset. Positive and negative feedback were associated to 1) early parahippocampo-cingular sources of alpha oscillations, more posteriorly located and long lasting for negative feedback and to 2) late partially overlapping neural circuits comprising regions in prefrontal, cingular, and temporal cortices but operating at feedback-specific latencies and frequencies. The results were interpreted in the light of neurophysiological models of feedback and were used to discuss methodological issues in the study of high-level cognitive functions, including reasoning and decision making.

Adult↗
PubMed2002

Feasibility of AsthmaCritic, a decision-support system for asthma and COPD which generates patient-specific feedback on routinely recorded data in general practice.

BACKGROUND: Introducing decision-support systems as a tool to stimulate the dissemination of clinical guidelines in daily practice has been disappointing. Researchers have argued that integration of such systems with clinical practice is a prerequisite for acceptance. The big question concerns the feasibility of a true integration--if only routinely recorded data are used for such a system, can patient-specific feedback be produced? OBJECTIVE: The aim of this study was to assess the feasibility of generating patient-specific feedback based on routinely recorded data in general practice by AsthmaCritic, a decision-support system for asthma and chronic obstructive pulmonary disease (COPD). METHODS: We built the decision-support system AsthmaCritic and assessed its ability to detect asthma and COPD patient records and generate patient-specific feedback by retrospective analysis of routinely recorded data in 103 713 electronic patient records from primary care practices. We grouped feedback into categories of comments by age group (<12 years and > or =12 years). The main outcome measures were the number and percentage of "triggered" (selected) asthma and COPD patient records, and the number and percentage of records on which AsthmaCritic produced at least one feedback comment during the 1-year study period, by category of comments. RESULTS: AsthmaCritic detected 8784 (8.5%) asthma and COPD patient records. During the study period, AsthmaCritic generated 255 664 feedback comments (mean 3.4 per patient visit). The most frequently generated category of comments in the case of patients aged > or =12 years was "non-compliant prescription" (23.7%), whereas the most frequent category in the case of patients <12 years was "non-compliant route" (31.1%). CONCLUSIONS: This study shows that, using routinely recorded data only, AsthmaCritic is able to detect asthma and COPD patient records for further analysis and to produce patient-specific feedback.

Adolescent↗
PubMed1978

EMG feedback as a muscle reeducation technique: a controlled study.

In an effort to evaluate the efficacy and function of EMG feedback in muscle reeducation, improvement of the abductor function of the abductor hallucis muscle was studied under three training conditions involving 1) EMG feedback, 2) sensory stimulation or 3) equal time for unassisted practice; and a fourth, control condition involving testing without training. Active range of motion was measured before and after training to assess ability to use the muscle as an abductor. EMG activity was quantified for a 1-minute test contraction to evaluate ability to maintain and maximize a voluntary contraction of the target muscle. The results indicated that EMG feedback was highly effective when subjects had little initial use of the target muscle. EMG feedback improved the ability of these subjects to maintain and maximize voluntary muscle contractions, as demonstrated on the EMG measure. EMG feedback did not add to the learning situation when only a relatively brief, phasic contraction was required, as on the range-of-motion measure; similar gains were made with equivalent practive without EMG feedback. When subjects already had considerable use of the target muscle prior to training, EMG feedback may have actually interfered with training; in this case unassisted practice was more effective.

Biofeedback, Psychology↗
PubMed1991

Electromyographic feedback for learning to activate thoracic inspiratory muscles.

The utility of EMG feedback for modifying the muscular pattern of breathing was investigated in twenty-four subjects divided into two groups (feedback, no feedback. Each took part in three 20-min training sessions, 24 h apart. All the subjects were instructed to increase the thoracic contribution of inspired gas. The feedback subjects were shown an EMG signal of the inspiratory muscles of the upper thorax and a signal indicating their current breathing phase (inspiration or expiration). The no feedback subjects only saw the breathing phase signal. The subjects' ability to control muscular activity was assessed as the relative increase in EMG from expiration to the subsequent inspiration. Analysis of variance with group and session as factors showed that feedback subjects performed significantly better, although the improvement in performance over the sessions by the two groups was not significantly different. These results lend some support to the clinical use of EMG feedback in breathing therapy aimed at changing the thoracoabdominal distribution of ventilation. However, further research for improving learning is necessary.

Adult↗
PubMedDate not supplied

Improving blood pressure estimation through internal and environmental feedback.

Different bodily sensations and situational factors covary with changes in systolic blood pressure (SBP). The present experiment explored whether an awareness of SBP-related cues could help individuals to estimate their own SBP levels more accurately. Sixty-four adults (53 women and 11 men) participated in two experimental sessions 3 months apart. Immediately following each of 13 task and intervening baseline periods of each of the two sessions, subjects estimated their SBP and rated the degree to which they were experiencing each of 10 physical symptoms and moods (i.e., internal cues). In addition, independent judges rated the extent to which various situational factors were present during each task and baseline. Within-subject correlations between internal and situational cues with SBP served as the basis for subjects' receiving one of four randomly assigned types of feedback: no feedback, internal cue feedback, situational cue feedback, or biosituational feedback based on both internal and situational cues. In the second experimental session 3 months later, subjects in the biosituational feedback condition were significantly better at estimating SBP than were individuals in any of the other conditions. Implications of biosituational feedback as an alternative to traditional biofeedback are discussed.

Adult↗