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PubMed1986

The role of biofeedback in Kegel exercise training for stress urinary incontinence.

This study examined the effectiveness of teaching pelvic floor exercises with use of bladder-sphincter biofeedback compared to training with verbal feedback based on vaginal palpation in 24 women with stress urinary incontinence. Verbal feedback training consisted of instructing the patient to squeeze the vaginal muscles around the examiner's fingers and providing her with verbal performance feedback. Biofeedback patients received visual feedback of bladder pressure, abdominal (rectal) pressure, and external anal sphincter activity. The biofeedback group improved the strength and selective control of pelvic floor muscles; the verbal feedback group did not. Both groups significantly reduced the frequency of incontinence. The biofeedback group averaged 75.9% reduction in incontinence, significantly greater than the 51.0% reduction shown by the verbal feedback group. Twelve of 13 patients in the biofeedback group improved by 60% or better. Six patients in the verbal feedback group improved by 68% or better, and five were less than 30% improved.

Adult↗
PubMed2004

Bimanual directional interference: the effect of normal versus augmented visual information feedback on learning and transfer.

When performing movements with different spatial trajectories in both upper limbs simultaneously, patterns of interference emerge that can be overcome with practice. Even though studies on the role of augmented feedback in motor learning have been abundant, it still remains to be discovered how overcoming such specific patterns of spatial interference can be optimized by instructional intervention. In the present study, one group acquired a bimanual movement with normal vision, whereas a second group received augmented feedback of the obtained trajectories on a computer screen in real time. Findings revealed that, relative to normal vision, the augmented feedback hampered skill learning and transfer to different environmental conditions. These observations are discussed in view of the benefits and pitfalls of augmented feedback in relation to task context and instructional condition.

Adolescent↗
PubMed1996

Role of posterior parietal cortex in the recalibration of visually guided reaching.

Visually guided reaching requires complex neural transformations to link visual and proprioceptive inputs with appropriate motor outputs. Despite the complexity of these transformations, hand-eye coordination in humans is remarkably flexible, as demonstrated by the ease with which reaching can be adapted to distortions in visual feedback. If subjects attempt to reach to visual targets while wearing displacing prisms, they initially misreach in the direction of visual displacement. Given feedback about their reaching errors, however, they quickly adapt to the visual distortion. This is shown by the gradual resumption of accurate reaching while the prisms remain in place, and by the immediate onset of reaching errors in the opposite direction after the prisms have been removed. Despite an abundance of psychophysical data on adaptation to prisms, the functional localization of this form of sensorimotor adaptation is uncertain. Here we use positron emission tomography (PET) to localize changes in regional cerebral blood flow (rCBF) in subjects who performed a prism-adaptation task as well as a task that controlled for the sensory, motor and cognitive conditions of the adaptation experiment. Difference images that reflected the net effects of the adaptation process showed selective activation of posterior parietal cortex contralateral to the reaching limb.

Adaptation, Physiological↗
PubMed2001

Motor learning enhances perceptual judgment: a case for action-perception transfer.

Transfer from perception to action is well documented, for instance in the form of observational learning. Transfer from action to perception, on the other hand, has not been researched. Such action-perception transfer (APT) is compatible with several learning theories and has been predicted within the framework of common coding of perceptual and motor events (Prinz, 1992, 1997). Our first experiment aimed at an empirical evaluation of APT and involved motor practice of timed two-cycle arm movements on verbal command without visual feedback. In a transfer test, visual judgments of similar patterns had to be made. In addition, transfer from the visual to the motor task was studied. In Experiment 2 we separated kinesthetic aspects of motor practice from preparatory and efferent contributions to APT. The experiments provide evidence that transfer between perception and action is bi-directional. Transfer from perception to action and, more importantly, from action to perception was found. Furthermore, APT was equally pronounced for participants who had actively practiced movements during training and for passive participants who had received merely kinesthetic feedback about the movement. This kinesthetic-visual transfer is likely to be achieved via visuomotor-kinesthetic matching or via timekeeping mechanisms that are involved in both motor and visual performance.

Adult↗
PubMed2004

Effect of sensory substitution on suture manipulation forces for surgical teleoperation.

Bilateral telemanipulation, which applies haptic feedback to the operator, is not yet available in most commercial robot-assisted surgical systems. We have shown in previous work that the lack of haptic (force or tactile) feedback is detrimental in applications requiring fine suture manipulation. In this paper, we study the effect of substituting direct haptic feedback with visual and auditory cues. Using the da Vinci robot from Intuitive Surgical, we observed the difference between applied forces during a knot tying procedure for four different sensory feedback substitution scenarios: no feedback, auditory feedback, visual feedback, and a combination of auditory and visual feedback. Our results indicate that visual feedback, which provides continuous force information, would improve robot-assisted performance during complex surgical tasks such as knot tying with fine sutures. Discrete auditory feedback gives additional useful support to the surgeon.

Feedback↗
PubMed1991

Proprioceptive control of goal-directed movements in man, studied by means of vibratory muscle tendon stimulation.

The purpose of this study was to investigate the role of propriomuscular feedback in the control of pluriarticular pointing movements, performed without visual feedback toward visual targets. The proprioceptive inputs were distorted during movements by applying vibration to the distal tendon of the biceps muscle. Various movement and vibration durations were imposed. The results show that vibration affects the spatial outcome of the movements. The effects of vibration were movement time-independent when the durations were shorter than 450 ms and became movement time-dependent with longer durations. Moreover, the effects of vibration became more marked when a short vibration was applied at the end rather than at the beginning of a slow movement. These studies suggest that at least two types of proprioceptive control loops may be involved in correcting this kind of movement, depending on the execution time. In slow movements, the final phase might be a privileged period for on-line, propriomuscular-based corrections. Lastly, it emerged that the regulation of a goal-directed movement on the basis of proprioceptive feedback processing can take place within at most 200 ms.

Journal Article↗
PubMed2005

Effects of rearranged vision on event-related lateralizations of the EEG during pointing.

We used event-related lateralizations of the EEG (ERLs) and reversed vision to study visuomotor processing with conflicting proprioceptive and visual information during pointing. Reversed vision decreased arm-related lateralization, probably reflecting the simultaneous activity of left and right arm specific neurons: neurons in the hemisphere contralateral to the observed action were probably activated by visual feedback, neurons in the hemisphere contralateral to the response side by the somatomotor feedback. Lateralization related to the target in parietal cortex increased, indicating that visual to motor transformation in parietal cortex required additional time and resources with reversed vision. A short period of adaptation to an additional lateral displacement of the visual field increased arm-contralateral activity in parietal cortex during the movement. This is in agreement with the, which showed that adaptation to a lateral displacement of the visual field is reflected in increased parietal involvement during pointing.

Adult↗
PubMed1989

The role of short-term visuo-spatial memory in control of rapid multi-joint prehensive movements.

How memorized visuo-spatial information influences motor control and whether this information is able to replace the feedback processing in cases of visual deprivation was studied using an unrestrained finger- and hand-movement paradigm. Nineteen right-handed subjects were asked to grasp and lift a small block with the index finger and thumb of the right hand, as quickly as possible. The efficiency of motor performance was analysed by measuring the grasping time derived from tangential velocity profiles of the fingertips. The data revealed significantly shorter grasping times under continuous visual guidance than during blind grasping. Grasping times increased under conditions with stepwise prolongation of visual deprivation time prior to the movement onset. The results support the general concept that within the first seconds of visual deprivation, stored visuo-spatial information can partly compensate for the lack of continuous visual feedback.

Adult↗
PubMed2004

The effect of visual and haptic feedback on computer-assisted needle insertion.

OBJECTIVE: We present a study evaluating the effects of visual and haptic feedback on human performance in a needle insertion task. MATERIALS AND METHODS: A one-degree-of-freedom needle insertion simulator with a three-layer tissue model (skin, fat and muscle) was used in perceptual experiments. The objective of the 14 subjects was to detect the puncture of each tissue layer using varying haptic and visual cues. Performance was measured by overshoot error-the distance traveled by the virtual needle after puncture. RESULTS: Without force feedback, real-time visual feedback reduced error by at least 87% in comparison to static image overlay. Force feedback, in comparison to no force feedback, reduced puncture overshoot by at least 52% when visual feedback was absent or limited to static image overlay. A combination of force and visual feedback improved performance, especially for tissues with low stiffness, by at least 43% with visual display of the needle position, and by at least 67% with visual display of layer deflection. CONCLUSION: Real-time image overlay significantly enhances controlled puncture during needle insertion. Force feedback may not be necessary except in circumstances where visual feedback is limited.

Adult↗
PubMed2001

Cerebellar lesions impair context-dependent adaptation of reaching movements in primates.

To produce accurate movements when conditions change suddenly, the brain must be capable of learning multiple versions of a given motor task and must be able to access the appropriate program using sensory information linked to the context of the movement. The neural basis for context-dependent motor learning is uncertain, but the cerebellum is thought to play a fundamental role. In this study, we examined the effect of lesions of the dorsal vermal and paravermal cerebellar cortex on the adaptation of reaching movements produced by modified visual feedback and accessed with a visual cue. Two rhesus monkeys were trained to point to targets displayed on a video monitor while viewing monocularly with either eye. During the experimental sessions, visual information received by one eye (the "modified" eye) was displaced horizontally, while the information received by the other ("normal") eye remained unaltered. In the first set of experiments (noncontextual paradigm), the animals pointed to targets while viewing with the modified eye. This paradigm resulted in a gradual improvement in pointing accuracy when viewing with that eye, but also produced a shift in pointing responses of equivalent size when viewing with the normal eye. In the second set of experiments (contextual paradigm), the animals alternated six blocks of reaches while viewing monocularly with the modified eye with six blocks viewing with the normal eye. This paradigm improved the pointing accuracy when viewing with the modified eye, but produced only a small shift in pointing responses when viewing with the normal eye. After the dorsal vermal and paravermal cerebellar cortex were resected, no change occurred in the pattern of adaptation produced by the noncontextual paradigm. The contextual paradigm, however, no longer selectively adapted pointing responses for each eye, but rather produced a pointing shift of equivalent size when viewing with either eye. The results indicate that pointing responses can be differentially adapted for each viewing eye, which is a form of context-dependent motor learning. This capability was lost after focal lesions of the dorsal vermal and paravermal cerebellar cortex, suggesting that these regions of cerebellar cortex are required to learn or store multiple representations of a movement, or to retrieve the appropriate motor program in a given sensory context.

Adaptation, Physiological↗
PubMed2004

Computerized biofeedback knee goniometer: acceptance and effect on exercise behavior in post-total knee arthroplasty rehabilitation.

OBJECTIVE: To assess device accuracy, patient acceptance, and effect of a computerized biofeedback knee goniometer (CBG), on patients' compliance with active range of motion (AROM) exercises after total knee arthroplasty (TKA). DESIGN: Two-stage study: measurement validation on asymptomatic controls and an unblinded, multiple crossover trial. SETTING: Inpatient rehabilitation. PARTICIPANTS: Asymptomatic controls (n=14) and post-TKA inpatients (n=11). INTERVENTIONS: For measurement validation, CBG-angle measurements were compared with manual, clinician-obtained angles. To assess motivational effect, the CBG was worn after TKA; on alternating days, it either monitored AROM silently (no feedback) or provided audiovisual feedback about reaching preset range of motion (ROM) goals and prompted the patients to exercise when idle. MAIN OUTCOME MEASURES: To assess accuracy, the device's readings were compared with manual measurements. Patient satisfaction was determined by a self-report questionnaire; exercise compliance was assessed by calculating activity rate and stratified interactivity intervals. RESULTS: CBG readings reproduced clinician measurements reliably between 0 degrees and 100 degrees (eta(2)=98.5%). Auditory feedback was more helpful than visual feedback for motivating exercise. During feedback-on days, the mean total activity rate +/- standard deviation was 15.1+/-10.9 activity counts per hour, and the interactivity interval was 6.7+/-5.7 minutes. The activity rate was higher on feedback-off days-22.5+/-11.1 counts/hour (P=.11)-and the mean interactivity interval was 3.6+/-2.7 minutes (P=.07). CONCLUSIONS: The CBG provided reliable, unbiased estimates of clinician measurements of joint angle within the range of 0 degrees to 100 degrees. The CBG was accepted well by most patients. Surprisingly, slightly more ROM activity was noted during feedback-off days than feedback-on days.

Analysis of Variance↗
PubMed2002

Spine needle biopsy simulator using visual and force feedback.

OBJECTIVE: Biopsy with an inserted needle is an important procedure for lesion detection in the spine, but is difficult to perform due to the presence of many critical organs near the spine. This article presents a spine needle biopsy simulator, based on visual and force feedback, which can be used to plan the optimal path of a needle and to practice the procedure without risk. MATERIALS AND METHODS: The simulator is composed of a 3D human model, a visual-feedback component, a force-feedback component, and an evaluation module. The human model is based on 3D CT data. The visual-feedback component provides an oblique section, multiplanar reformatting images, and a volume-rendered image. Of these, the oblique section display is very useful for planning a 3D path for the needle. During simulation, the force-feedback component generates and provides realistic forces acting on the biopsy needle in real time by synchronizing them to visual feedback. After each simulation, the evaluation module provides a performance analysis for the trainee. RESULTS: For an XCT abdomen volume data set of 256 x 256 x 256, the update rate of image rendering due to needle movement is over 25 Hz, with a force-feedback rate of 1 kHz. This performance proved to be good enough for the trainee to learn the relationship between visual and force feedback. CONCLUSIONS: The simulator is useful for the planning of and training in complicated 3D spine needle biopsy procedures. It may be used as an educational tool for beginners, a practice tool to increase expertise, or a test bed for new procedures.

Algorithms↗
PubMed1980

Cerebellar dyssynergia in humans--a quantitative analysis.

Patients with cerebellar lesions and limb ataxia performed two types of continuous tracking tasks involving flexion and extension of the index finger. In both tasks, patients were provided cutaneous and proprioceptive cues, but visual feedback was given in the first task (visual tracking) and not in the second (arbitrarily termed proprioceptive tracking). Raw records and Fourier-analyzed power spectra were compared with results in normal controls. Harmonic distortion was determined for each task. In all patients, as well as normal subjects, tracking performance was markedly improved and harmonic distortion substantially reduced during proprioceptive tracking. This surprising finding may result from a much shorter feedback loop for proprioceptive stimuli compared to visual stimuli. The tracking records, power spectra analysis, and determination of harmonic distortion provide both qualitative and quantitative data in patients with dyssynergia.

Cerebellar Ataxia↗
PubMed2006

Effects of vision and friction on haptic perception.

OBJECTIVE: Two experiments were conducted to examine the effects of vision and masking friction on contact perception and compliance differentiation thresholds in a simulated tissue-probing task. BACKGROUND: In minimally invasive surgery, the surgeon receives limited haptic feedback because of the current design of the instrumentation and relies on visual feedback to judge the amount of force applied to the tissues. It is suggested that friction forces inherent in the instruments contribute to errors in surgeons' haptic perception. This paper investigated the psychophysics of contact detection and cross-modal sensory processing in the context of minimally invasive surgery. METHOD: A within-subjects repeated measures design was used, with friction, vision, tissue softness, and order of presentation as independent factors, and applied force, detection time, error, and confidence as dependent measures. Eight participants took part in each experiment, with data recorded by a custom force-sensing system. RESULTS: In both detection and differentiation tasks, higher thresholds, longer detection times, and more errors were observed when vision was not available. The effect was more pronounced when haptic feedback was masked by friction forces in the surgical device (p < .05). CONCLUSION: Visual and haptic feedback were equally important for tissue compliance differentiation. APPLICATION: A frictionless endoscopic instrument can be designed to restore critical haptic information to surgeons without having to create haptic feedback artificially.

Adult↗
PubMedDate not supplied

The accuracy of perception of a pinch grip force in older adults.

The fact that humans can execute accurate movements and generate precise muscle forces is very important for hand function. Target-tracking tasks or target-matching tasks are often executed under combined visual and somatosensory feedback. When visual feedback is removed, subjects have to depend on their perception of force. The objective of the present study was to estimate the effects of aging on the perception of a pinch force produced by the thumb and index finger. In a first set of trials, young (n = 12, age = 25.3 +/- 2.4 years) and elderly (n = 12, age = 71.5 +/- 3.3 years) healthy individuals were asked to reproduce pinch forces which were equivalent to 5%, 20%, and 40% of their maximal pinch force (MPF). Prior to the execution of these trials, the subjects were familiarized with the force levels by matching targets displayed on a screen. They were then asked to reproduce each of these forces without any visual or verbal feedback. The results showed a larger error in the reproduced force for the elderly subjects when compared with the young adults. However, this larger error was mainly due to an initial overshoot in the force to be reproduced, followed by a gradual decrease towards the appropriate force. This transient overshoot was rarely seen in the performance of the younger subjects. In a second set of trials, the same subjects were asked to produce a pinch force of 5%, 20%, and 40% of MPF with 1 hand using visual feedback. They were also instructed to simultaneously apply a comparable pinch force with the other hand (without any feedback). For both young and older adults, the pinch forces produced by the 2 hands were the same. In addition, in both blocks of trials, hand dominance had no effects on the performance for all subjects. These results suggest that normal aging affects the production of force based on sensorimotor memory rather more than it affects comparative outputs from central descending commands.

Adult↗
PubMed2001

Proprioceptive feedback is reduced during adaptation to a visuomotor transformation: preliminary findings.

Adapting movements in relation to visual feedback is a ubiquitous characteristic of sensorimotor control and involves the integration of multiple sources of sensory information. We recorded sensory feedback from muscle spindle afferents during visuomotor adaptation while subjects performed an aiming task to investigate whether the activity of the muscle spindles was modulated by the fusimotor system under these learning conditions. None of the muscle spindles showed an increase in activity, rather in 83% of the trials the firing rates were decreased. These preliminary results suggest that the CNS reduces the sensory signals arising from muscle spindles perhaps as a means of resolving the conflict between visual and proprioceptive feedback during the task.

Action Potentials↗