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At least 253 records · Page 14Linked to original sources
PubMed1975

Assessment of an audio-visual feedback device used in motor training,.

A miniature biofeedback device, the Basmajian-Emory Muscle Trainer, has been developed at the Emory University School of Medicine. A training and testing protocol was designed for using this device in the training of precise voluntary control of individual skeletal muscles. Thirteen normal subjects were trained to abduct the big toe of the right foot, eleven of whom displayed increases in maximum motion. Use of a biofeedback device to improve a subject's ROM capabilities requires consideration of four factors: (1) initial emphasis must be on making the subject aware of his muscle activity, (2) the muscle activity must be increased, (3) the positive re-enforcement of feedback must be continual, and (4) the newly acquired muscle activity must be used to perform a greattting.

Adult↗
PubMed1990

Reaching in the dark: enhanced responses in posterior parietal cortex.

In order to assess the relative importance of visual input to area 7 reach-related neuronal activity, a monkey was trained to reach to visual targets displayed on a video-monitor, both with and without visual feedback. Visual feedback was removed by having the monkey reach in darkness to a previously illuminated target. Of 19 reach-related cells recorded in area 7 both in the light and the dark, ten showed an enhancement of discharge in the dark. These included area 7b cells sensitive to screen contact and area 7a cells active during reach. Dark enhancement of active somatic responsiveness may partially compensate for the loss of visual guidance.

Animals↗
PubMed1985

Sensory feedback in the learning of a novel motor task.

The role of different forms of feedback is examined in learning a novel motor task. Five groups of ten subjects had to learn the voluntary control of the abduction of the big toe, each under a different feedback condition (proprioceptive feedback, visual feedback, EMG feedback, tactile feedback, force feedback). The task was selected for two reasons. First, in most motor learning studies subjects have to perform simple movements which present hardly any learning problem. Second, studying the learning of a new movement an provide useful information for neuromuscular reeducation, where patients often also have to learn movements for which no control strategy exists. The results show that artificial sensory feedback (EMG feedback, force feedback) is more powerful than "natural" (proprioceptive, visual, and tactile) feedback. The implications of these results for neuromuscular reeducation are discussed.

Journal Article↗
PubMed2002

Temporal capacity of short-term visuomotor memory in continuous force production.

The focus of this article is on the temporal capacity of short-term visuomotor memory as reflected by changes in the time and frequency patterns of force output. In experiment 1, subjects produced continuous force output (isometric index finger flexion) to a target force level (from 5 to 75% of maximum voluntary contraction, MVC) displayed on a video monitor for 20 s. In the full visual feedback condition, visual feedback was displayed throughout each trial, while, for the visual feedback-withdrawal condition, visual feedback was occluded for the final 12 s of each trial. With visual feedback present, subjects matched their force output to the target force level for 20 s. When visual feedback was removed, participants continued to match the target force level for approximately 0.5-1.5 s; thereafter force output decayed exponentially. In line with this decay, short time-frequency analysis revealed a decrease in force intensity in the 0- to 5-Hz band. Force level did not influence the time before decay; however, greater forces led to larger decay. Experiment 2 assessed whether the force decay in experiment 1 was a property of visual or motor short-term memory by having participants set their own target force levels with no visual information provided throughout. In agreement with the findings of experiment 1, force output decayed, emphasizing the importance of a motor memory source. It is concluded that the 0.5- to 1.5-s time period represents a limit on the temporal capacity that precise visuomotor information is held in short-term memory.

Adult↗
PubMed1983

Attention and regulation of EEG alpha-attenuation responses.

Two experiments with 16 normal adults of both sexes tested the hypothesis that inattention to a biofeedback display is associated with increased variability of those physiological processes that had been regulated by the biofeedback. Each experiment was a repeated-measures-on-independent-subjects-design. Dependent variables were the time durations and the mean rms power of two mutually exclusive segments of the parietal-occipital EEG: alpha and not-alpha segments. Independent variables were combination of counting tasks and instructions to look at, listen to, and count visual and auditory flashes and clicks. The durations of alpha and not-alpha segments were controlled or regulated by means of an alpha-contingent visual feedback stimulus, Attention to the feedback stimulus was challenged by instructions to count other, noncontingent stimuli. Control of alpha and not-alpha segments was least for conditions of (1) "sham" feedback, and (2) feedback with instructions to count noncontingent auditory clicks, which were presented 3/sec while the feedback visual stimuli were occurring. A new EEG test of attention and distraction was suggested.

Adult↗
PubMed1982

Feedback effects on target search and velocity extrapolation by mentally retarded and nonretarded adolescents.

Equal-CA EMR and nonretarded adolescents stylus-tracked an intermittently disappearing rotary pursuit target with no feedback, auditory feedback, and visual feedback. With no feedback both groups demonstrated an approximately equal increase in distance errors during an 18-second period following disappearance of the target. With auditory and visual feedback, the nonretarded group remained closer to the target than with no feedback and closer than the retarded group under all three feedback conditions. Retarded subjects made more distance errors on a static search task requiring the use of auditory or visual feedback to locate a stationary target. Matching subsets of subjects from both groups on the basis of performance during the static search task eliminated differences in tracking performance during feedback. The ability to use feedback during static search predicted the ability to use feedback during rotary pursuit tracking.

Adolescent↗
PubMed2000

The role of feedback in manual tracking of visual targets.

The role of visual feedback in manual tracking was investigated in 24 subjects who tracked 5-, 10-, and 40-mm/diameter targets, moving on a screen at 18 to 25 mm/sec., along various paths, by moving an unseen handle over a digitizing tablet. A cursor indicating instantaneous handle position was visible at all times on half the trials and hidden within a circle coaxial with the target but double its diameter in the other half. The handle had to be within the instantaneous target's digitizer-defined boundaries for the latter to keep moving. All tracking movements were segmented into small movement steps. A tendency to outrun the target was seen, indicating predictive control. Absence of visual feedback had negligible effect on movement velocity. Movement direction appeared to involve open-loop programming but improved significantly when subjects could see the cursor. Occasional corrective movements occurred only when visual feedback was given. Otherwise, a large positional error accumulates despite reasonable ability to control tracking direction.

Adult↗
PubMed1999

Externally guided control of static grip forces by visual feedback-age and task effects in 3-6-year old children and in adults.

This study has been devised to examine the visual feedback control of static grip force levels by pinch and by hand grip during pre-school age and in adults. 69 3-6-year old children and 17 adults were asked to establish and hold grip force levels defined by a visual target and feedback on the dominant and non-dominant hand by hand grip and by pinch grip. From 3 to 6 years of age, the time needed to establish requested grip force levels decreased by a third and the precision increased two-fold for hand grip but four-fold for pinch grip; in contrast to younger children, 5-6-year olds showed a marked superiority of 60% for the pinch grip compared to hand grip, decreasing to about 40% in adults. In the case of pinch grip, all individuals had worse results on higher force levels (children: 50%, adults: 32%). The young children generally tended to use too much force. Older children and adults were better by 75% under the condition of visual feedback vs. internal proprioceptive control (after withdrawing visual feedback). In contrast to previous findings in anticipatory grip force regulation, externally guided force regulation begins to develop during late nursery age. Specific developmental effects were found for grip style and for the ability to use visual feedback and to change from external to internal (proprioceptive) control, and to a lesser extent for force magnitude but not for hand laterality and gender. The findings are interpreted by different developmental velocities of motor areas which are responsible for force regulation mechanisms and for grip style.

Adult↗
PubMed2006

Watching your foot move--an fMRI study of visuomotor interactions during foot movement.

The objective of this study was to investigate brain areas involved in distinguishing sensory events caused by self-generated movements from similar sensory events caused by externally generated movements using functional magnetic resonance imaging. Subjects performed 4 types of movements: 1) self-generated voluntary movement with visual feedback, 2) externally generated movement with visual feedback, 3) self-generated voluntary movement without visual feedback, and 4) externally generated movement without visual feedback, this design. This factorial design makes it possible to study which brain areas are activated during self-generated ankle movements guided by visual feedback as compared with externally generated movements under similar visual and proprioceptive conditions. We found a distinct network, comprising the posterior parietal cortex and lateral cerebellar hemispheres, which showed increased activation during visually guided self-generated ankle movements. Furthermore, we found differential activation in the cerebellum depending on the different main effects, that is, whether movements were self- or externally generated regardless of visual feedback, presence or absence of visual feedback, and activation related to proprioceptive input.

Adolescent↗
PubMed2003

Neural basis for the processes that underlie visually guided and internally guided force control in humans.

Despite an intricate understanding of the neural mechanisms underlying visual and motor systems, it is not completely understood in which brain regions humans transfer visual information into motor commands. Furthermore, in the absence of visual information, the retrieval process for motor memory information remains unclear. We report an investigation where visuomotor and motor memory processes were separated from only visual and only motor activation. Subjects produced precision grip force during a functional MRI (fMRI) study that included four conditions: rest, grip force with visual feedback, grip force without visual feedback, and visual feedback only. Statistical and subtractive logic analyses segregated the functional process maps. There were three important observations. First, along with the well-established parietal and premotor cortical network, the anterior prefrontal cortex, putamen, ventral thalamus, lateral cerebellum, intermediate cerebellum, and the dentate nucleus were directly involved in the visuomotor transformation process. This activation occurred despite controlling for the visual input and motor output. Second, a detailed topographic orientation of visuomotor to motor/sensory activity was mapped for the premotor cortex, parietal cortex, and the cerebellum. Third, the retrieval of motor memory information was isolated in the dorsolateral prefrontal cortex, ventral prefrontal cortex, and anterior cingulate. The motor memory process did not extend to the supplementary motor area (SMA) and the basal ganglia. These findings provide evidence in humans for a model where a distributed network extends over cortical and subcortical regions to control the visuomotor transformation process used during visually guided tasks. In contrast, a localized network in the prefrontal cortex retrieves force output from memory during internally guided actions.

Adult↗