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PubMed1997

Prism Adaptation During Target Pointing From Visible and Nonvisible Starting Locations.

The performance of subjects whose starting limb location was visible when pointing to a sagittal target during exposure to prismatic displacement showed immediate target acquisition, but aftereffects of exposure were absent. When starting limb location was not visible, accurate exposure performance was slow to develop, but aftereffects were substantial. Visible starting location evoked a zeroing-in control strategy on the basis of relative-location coding, which rapidly reduced performance error but disabled detection of spatial misalignment between sensorimotor systems. When starting location was not visible, absolute-location coding of the displaced target initiated movement that had to be corrected subsequently by visual feedback. In this case, comparison of the initial erroneous movement code with the limb location that achieved the target enabled misalignment detection and consequent realignment.

coordination↗

PubMed1999

Goal-Directed Aiming: Correcting a Force-Specification Error With the Right and Left Hands.

In 2 experiments, the authors examined manual aiming asymmetries as well as the ability of participants to adjust their aiming trajectories following an unexpected change to the inertial resistance to movement. In Experiment 1, participants (N = 11) were able to rapidly adjust their movement trajectories to conform to the new movement requirements. They were faster and more consistent when aiming with their right hand than with their left hand, regardless of whether or not the movement was perturbed. In Experiment 2, participants' (N = 11) vision of the hand was manipulated so that the role of visual feedback in the corrective process could be examined. Vision had an impact not only on performance but also on the characteristics of the movement trajectories. Manual asymmetries in aiming were associated with a right hand superiority during the final corrective stages of the movement.

Journal Article↗

PubMedDate not supplied

Speech habilitation of hard of hearing adolescents using electropalatography and ultrasound as evaluated by trained listeners.

Four adolescents with moderate to severe sensorineural hearing losses and moderately unintelligible speech participated in a 14-week speech therapy study using two dynamic visual feedback technologies, electropalatography and ultrasound imaging. Electropalatography provides information about tongue-hard palate contact points. Ultrasound displays images of tongue shape and movement in two dimensions from the tip to the root. Treatment targets for all participants included a sibilant place contrast (/s/ versus /[symbol: see text]/), liquids /l/ and /[symbol: see text]/, and the tense-lax vowel contrast with the high vowels. Trained listener evaluations of pre- and post-treatment transcripts are reported in this paper. Significant improvements in speech production were noted across students and targets. Treatment targets improved significantly more than non-treatment test targets overall. Students showed greatest gains on consonants that were absent or marginal in their speech pre-treatment. No particular advantage of one technology over the other was evident in this sample.

Adolescent↗

PubMedDate not supplied

Efficacy of speech intervention using electropalatography with a cochlear implant user.

Electropalatography (EPG) has become relatively well established as a safe and convenient technique for use in the assessment, diagnosis and treatment of children and adults with articulation disorders. EPG's wide applicability is reflected in the range of different cases that has been researched in recent years. Some research has been carried out using EPG therapy for deaf individuals who use hearing aids, however there are no similar studies for cochlear implant users. The purpose of this single case study is to explore the technique of EPG as a therapeutic intervention to treat voiceless velar stop consonant sound production in a deaf child cochlear implant user. EPG therapy was offered as a last resort when traditional therapy failed to achieve specific changes. During therapy, a list of familiar words was practised, using the visual feedback provided by EPG. The client's articulation was assessed using objective (EPG printouts) and subjective (listener ratings) measures at four assessment points. Changes were found to be statistically significant. Generalization of the newly-acquired skills to untaught words containing voiceless velars was also observed. The results are discussed in the broader context of implications of this type of therapy with deaf clients.

Articulation Disorders↗

PubMed2002

Arm movement control: differences between children with and without attention deficit hyperactivity disorder.

The purpose of this study was to examine performance differences in arm movement control (programmingvs. "on-line" control) between children with and without attention deficit hyperactivity disorder (ADHD). Twenty children (10 with ADHD and 10 without ADHD) from the ages of 8 to 13 years participated in the study. On the surface of a digitizer, each participant completed three types of aiming arm movements (10 trials for each) and 10 baseline trials (without accuracy requirement). Multivariate analyses of variance with repeated measures were used to analyze the variables of reaction time, movement time, normalized jerk, intersegment-interval (ISI), and movement timing. Children with ADHD appeared to use "on-line " monitoring during the arm movement and did not perform the entire movement sequence as afunctional unit. They executed the arm movements more slowly, had greater variability in movement timing, and demonstrated longer ISIs than their counterparts. Children with ADHD had multiple peaks in the velocity profiles. Children withoutADHD, however, appeared to program their entire arm movements and execute the sequence as a unit. Their velocity profiles were symmetrical with a single peak, and the movement segments were temporally coordinated. Thesefindings suggested that cognitive functions are important resources for controlling rapid aiming arm movements. Children with ADHD might rely more on visual feedback during the movements, which resulted in slower and more variant movement outcomes than children who did not have ADHD.

Adult↗

PubMed2006

Programming strategies for rapid aiming movements under simple and choice reaction time conditions.

Increases in reaction time (RT) as a function of response complexity have been shown to differ between simple and choice RT tasks. Of interest in the present study was whether the influence of response complexity on RT depends on the extent to which movements are programmed in advance of movement initiation versus during execution (i.e., online). The task consisted of manual aiming movements to one or two targets (one- vs. two-element responses) under simple and choice RT conditions. The probe RT technique was employed to assess attention demands during RT and movement execution. Simple RT was greater for the two- than for the single-target responses but choice RT was not influenced by the number of elements. In both RT tasks, reaction times to the probe increased as a function of number of elements when the probe occurred during movement execution. The presence of the probe also caused an increase in aiming errors in the simple but not choice RT task. These findings indicated that online programming was occurring in both RT tasks. In the simple RT task, increased executive control mediated the integration between response elements through the utilization of visual feedback to facilitate the implementation of the second element.

Adolescent↗

PubMedDate not supplied

Aging and rapid aiming arm movement control.

The authors explored the motor control of target-oriented arm movements across 3 age groups: 20 20- to 30-year-olds, 2 groups (n = 38) of older adults (54 to 64, and 65 to 80). Each individual completed 2 arm movement tasks that had the same movement difficulty but different movement directions. A mixed design was used to examine the differences among age groups and movement directions in reaction time (RT), variability in RT, movement time (MT), timing variability, and inter-segment-interval (ISI). Comparing to the young participants, the senior adults initiated movement tasks slower (RT) and with more RT variability, and executed the arm movements slower and less consistently. The two older groups had greater timing variability in their movements, showed more delays (longer ISI) when reversing arm movement direction, and had lower correlations among segments of the movements than the younger group. The quality of the elderly's control of rapid aiming arm movements showed a regression, which suggests a lack of movement planning, resulting in greater use of visual feedback during movement execution.

Adult↗

PubMed2003

Force matching at the elbow joint is disturbed by muscle soreness.

These experiments are concerned with the ability of human subjects to match isometric torque in their elbow flexor muscles when biceps of one arm is made sore. Pain was induced by injection of hypertonic saline. Subjects were asked to generate a level of torque, 30% of maximum, with one arm, the reference arm. To achieve the required torque, subjects were given visual feedback. Subjects were then asked to match this torque with their other arm, the indicator arm. In control measurements, subjects were consistent in their matching ability and often were quite accurate. However, when biceps of one arm was made sore, subjects consistently and significantly underestimated the level of torque being generated by the sore arm. Painful heat applied to the skin over biceps produced a similar pattern of errors. Heating skin remote from elbow flexors had no significant effect. One interpretation of these findings is that the nociceptive input from the sore region of skin or muscle leads to reduced excitability of the motor cortex. That, in turn, disturbs the relationship between the centrally generated effort and motor output, leading to matching errors.

Adult↗

PubMed1997

Matching object size by controlling finger span and hand shape.

The ability of human subjects to accurately control finger span (distance between thumb and one finger) was studied. The experiments were performed without visual feedback of the hand and were designed to study the dependence of accuracy on object size, shape, distance, orientation and finger configuration. The effects of finger combination and sensory modality used to perceive object size (vision and haptics) were also studied. Subjects were quite proficient at this task; the small errors tended to be predominantly negative, i.e., finger span < object size. The thumb-little finger combination was less accurate than the other finger combinations, irrespective of the sensory modality used. Subjects made larger under-estimating errors when matching the size of cylinders than when matching cubes and parallelepipeds. No effect of viewing distance, object orientation and finger configuration was found. Accuracy in matching object size was not dependent on the sensory modality used. The question of how the individual degrees of freedom of the fingers and thumb contributed to the control of finger span was also addressed. Principal components analysis showed that two components could characterize the hand postures used, irrespective of object size. The amplitude of the first principal component was constant, and the amplitude of the second scaled linearly with object size. This finding suggests that all of the degrees of freedom of the hand are controlled as a unit. This result is discussed in relation to the 'virtual finger' hypothesis for grasping.

Adult↗

PubMed2000

Computer usage with cold hands; an experiment with pointing devices.

Computers are used in the outdoors and in connection with cold store work. Cold hand and fingers limit data input, as studied here. Six input devices; trackballs, pens, and a mouse were tested by 19 participants in a Fitts' target acquisition task with 2 target sizes under 2 experimental conditions; warm and cold right hand. Measures were acquisition times, number of errors, participant's preferences, and observed handling of the devices. Effects of device, target size, and cold were significant. Learning and attempts to improve handgrip were confirmed. Large enough targets, a thick pen, and a mouse make computer work practicable in the cold. Direct visual feedback, as with pen on template with target images, shortened acquisition times by half a second.

Adult↗

PubMedDate not supplied

Changes in linguapalatal contact patterns during therapy for velar fronting in a 10-year-old with Down's syndrome.

BACKGROUND: Articulation errors in the speech of people with Down's syndrome are frequent and often resistant to speech therapy. This preliminary study investigates the use of electropalatography (EPG) to diagnose and treat abnormal articulation patterns associated with velar fronting in a 10-year-old girl. AIMS: The study measured changes in the accuracy and stability of linguapalatal (tongue-palate) contact patterns during a 14-week course of visual feedback therapy using EPG. Therapy aimed to resolve a pattern of velar fronting whereby targets /k, g, eta/ had alveolar placement [t, d, n]. METHODS & PROCEDURES: The participant was a girl (P) with Down's syndrome aged 10;11 years. P had a moderate-severe speech disorder, which included velar fronting. Her speech was recorded with EPG on three occasions during a 14-week course of therapy: first, before therapy; second, midway through therapy; and third, after therapy. Three analyses were conducted on the EPG data. The first used an EPG classification scheme that identified accuracy of placement for /t/ and /k/ targets. The second was a centre of gravity measure that detected whether P produced a significant difference between /t/ and /k/ targets. The third was a variability index that quantified the stability of contact patterns. OUTCOMES & RESULTS: The results of the EPG classification showed that before therapy, /t/ and /k/ targets had identical alveolar placement, reflecting the process of velar fronting. The results after therapy showed that 87% of /k/ targets had accurate velar placement. The centre of gravity measure showed no difference in contact patterns for /t/ and /k/ before therapy, but a statistically significant difference at the second and third recordings. The variability index showed stable contact patterns before therapy for /t/ and /k/ targets, but both became highly unstable midway through therapy, with a return to stability at the third recording. We embed a discussion of P's increased articulation instability during therapy in a recent theoretical framework--dynamic systems--that attempts to account for the emergence of new behavioural forms. CONCLUSIONS: These preliminary results suggest that EPG has potential as an effective diagnostic and therapy procedure for articulation errors in people with Down's syndrome. A major issue still to be addressed, however, is the extent to which others will benefit from this approach to intervention.

Articulation Disorders↗

PubMed2002

The use of electroglottography in the treatment of deaf adolescents with puberphonia.

Electroglottography (EGG) was used as a visual feedback tool in the treatment of four male profoundly deaf adolescents of 15 years of age with puberphonia. A laryngograph, oscilloscope, computer, and laryngostroboscope were used for this research. The EGG was used during phonopedic exercises, which consisted of the patient producing voiced coughing in modal register and extended these into prolonged vowels. The investigation showed that EGG facilitated the production of vocal fold vibration in the modal register. It was concluded that EGG was highly effective in changing the production of vocal register and could be recommended in the treatment of puberphonia in the deaf.

Adolescent↗

PubMed2004

Effects of two-month vocal exercising with and without spectral biofeedback on student actors' speaking voice.

Twelve student actors (6 males, 6 females) were given voice training for two months. Randomly selected, half of the students (3 males, 3 females) was trained in the traditional way, while the other half was given biofeedback with real-time spectrum analysis. The aim was a ringing voice quality with strong overtones at 3-5 kHz. Text samples read at different loudness levels were recorded before and after training. Fundamental frequency (F0), sound pressure level (SPL) and long-term-average spectrum (LTAS) analyses were made. Voice quality was evaluated by two voice trainers. Sound energy at 3-5 kHz increased by 3-4 dB (1.5-14.5 dB) across groups after training. This change, which was slightly larger for the biofeedback (BF) group, did not correlate with SPL. F0 increased slightly in the BF group and decreased in the control group. The relative dB level of fundamental decreased significantly more in the BF group probably suggesting a tighter adduction. Voice quality improved in both groups. Visual feedback seems to add some efficacy in voice training. However, there is a danger of hyperfunctional voice production if other sensory feedback is neglected.

Adult↗

PubMed1995

Optimizing the use of vision in manual aiming: the role of practice.

The purpose of this study was to determine how subjects learn to adjust the characteristics of their manual aiming movements in order to make optimal use of the visual information and reduce movement error. Subjects practised aiming (120 trials) with visual information available for either 400 msec or 600 msec. Following acquisition, they were transferred to conditions in which visual information was available for either more or less time. Over acquisition, subjects appeared to reduce target-aiming error by moving to the target area more quickly in order to make greater use of vision when in the vicinity of the target. With practice, there was also a reduction in the number of modifications in the movement. After transfer, both performance and kinematic data indicated that the time for which visual information was available was a more important predictor of aiming error than the similarity between training and transfer conditions. These findings are not consistent with a strong "specificity of learning" position. They also suggest that, if some sort of general representation or motor programme develops with practice, that representation includes rules or procedures for the utilization of visual feedback to allow for the on-line adjustment of the goal-directed movement.

Adult↗

PubMed2002

Sensorimotor cortical activity in patients with complete spinal cord injury: a functional magnetic resonance imaging study.

Residual activation of the cortex was investigated in nine patients with complete spinal cord injury between T6 and L1 by functional magnetic resonance imaging (fMRI). Brain activations were recorded under four conditions: (1) a patient attempting to move his toes with flexion-extension, (2) a patient imagining the same movement, (3) passive proprio-somesthesic stimulation of the big toes without visual control, and (4) passive proprio-somesthesic stimulation of the big toes with visual control by the patient. Passive proprio-somesthesic stimulation of the toes generated activation posterior to the central sulcus in the three patients who also showed a somesthesic evoked potential response to somesthesic stimulation. When performed under visual control, activations were observed in two more patients. In all patients, activations were found in the cortical areas involved in motor control (i.e., primary sensorimotor cortex, premotor regions and supplementary motor area [SMA]) during attempts to move or mental imagery of these tasks. It is concluded that even several years after injury with some local cortical reorganization, activation of lower limb cortical networks can be generated either by the attempt to move, the mental evocation of the action, or the visual feedback of a passive proprio-somesthesic stimulation.

Adult↗

PubMed2001

Computerized system to improve voluntary control of balance in neurological patients.

The treatment of acquired impairments of balance is one of the most elusive problems that rehabilitative medicine faces. Computerized systems to measure how patients control their balance in static conditions were introduced long ago into clinical practice and proved to be useful; we have designed and developed a computerized system called "BioGP," which combines features of a classic stabilometric platform with those of a retraining device based on visual feedback The aim of this study was to identify homogeneous groups of patients and to provide objective proof of effectiveness for the rehabilitation of patients with balance disorders. The findings confirm that the new equipment provides clinically valid and sensitive information concerning subjects' ability to control voluntary shifts of center of pressure (COP) while standing. The information is relevant to applications using basically the same approach (1) and are encouraging for possible use of the system as a rehabilitation instrument.

Adult↗

PubMed2006

Usability of the remote console for virtual reality telerehabilitation: formative evaluation.

The Remote Console (ReCon) is a telerehabilitation application that allows therapists to remotely communicate with patients while monitoring and controlling their virtual rehabilitation exercises. It provides therapists visual feedback of patients' movements, their exercise simulations replicated in real time and with tools to conduct training without a face-to-face session. The Recon underwent a formative evaluation (a type of usability engineering methodology) used to refine its design. Five physical therapists from different practice settings acted as representative users. During the evaluation, these users made errors related to manipulation and finding and understanding controls. Technical issues with the server and audio communication were identified. These findings were used to fine-tune the ReCon system.

Computer Simulation↗

PubMed2002

A method for reducing adaptor misalignment when testing gloves using ISO 10819.

OBJECTIVES: International standard ISO 10819 was established in order to quantify the vibration attenuation characteristics of anti-vibration gloves. One problem that exists with the standard is possible misalignment of the palm adaptor that is placed underneath the test glove. If the adaptor becomes misaligned, the measured glove transmissibility will be lower than the actual value. A tri-axial accelerometer was installed in the adaptor and was used as the basis for providing visual feedback of the adaptor alignment to the test subjects. The objective of this study was to test the hypothesis that adaptor misalignment could be reduced by providing feedback to the test subjects. METHODS: Eight male volunteers (mean age 24.8 yr) were used in the study. Each subject performed two sets of tests: the standard ISO 10819 glove test and the modified version. Three different anti-vibration gloves were tested. Glove transmissibility and adaptor misalignment were calculated for each glove. A three-way analysis of variance was used to analyze the results. RESULTS: A comparison of the two testing methods showed that the modified glove testing method did reduce misalignment significantly, which, in turn, resulted in an increase in the measured glove transmissibility. CONCLUSIONS: The proposed method greatly improved the standard deviation of transmissibility and made the test results more consistent.

Adult↗