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At least 487 records · Page 27Linked to original sources
PubMed1982

Proprioception in schizophrenia.

B. Ritzler (J. Abnorm. Psychol., 86: 501-504, 1977) failed to replicate previous weight-lifting studies showing a proprioceptive deficit in schizophrenics. However, Ritzler did not use the same standard weights that the previous studies employed. Could this difference in procedure have caused his failure to replicate? Two experiments were completed to provide additional information about this question and related issues. In Experiment I, chronic hospitalized schizophrenics and normals were tested with light and heavy weights. Rosenbaum's original modified method of limits and the method of constant stimuli were utilized. Both methods provided comparable results, which, like Ritzler's data, failed to show a differential impairment in the discrimination of the light weights for paranoid schizophrenics. In Experiment II, outpatient paranoid schizophrenics, outpatient nonparanoid schizophrenics, outpatient psychiatric patients, and aged normals were evaluated utilizing the same psychophysical procedure and standard weights employed in the original studies. No differential impairment was found for the light weights for any group. These results provide strong support for Ritzler's position that a proprioceptive deficit is not unique to schizophrenia.

Adult↗
PubMed1984

Clinical trial with commercial aspheric aphakic lenses.

A clinical trial with 11 subjects was conducted to compare the Armorlite Multiple Drop, the Signet Hyperaspheric, the Sola Hi-Drop, and the American Optical Fulvue types of aspheric aphakic lenses. Reasonable off-axis visual acuities were obtained with the Signet, Sola, and Fulvue types, but poor visual acuities were found with the Armorlite type. Similar visual field limits were found with the armorlite, Signet, and Sola types. Considerably larger limits were found with the Fulvue type than with the other types. However, subjects failed to appreciate these larger limits; this was attributed to the extremely poor image quality near the edge of the visual field with this lens type. Some subjects disliked the poor off-axis image quality with the Armorlite lens type, and it had poor acceptance relative to the other types. Concerning subjective perception of weight, cosmetic appearance, and visual field size, and subjective evaluation of performance of everyday activities, there were no significant differences between lens types. It was concluded that reducing lens off-axis power errors, corresponding to the rotating eye, should remain the most important principle of aphakic spectacle lens design.

Aged↗
PubMedDate not supplied

Proprioceptive function in children with adolescent idiopathic scoliosis.

Recent studies in Japan and in Sweden have suggested that a disturbance of postural equilibrium exists in idiopathic scoliosis. Proprioceptive function is one of the factors involved, and therefore a study of proprioception in patients with adolescent idiopathic scoliosis (AIS) was carried out. No difference was noted in joint position sense and in fine motor control between 24 scoliotics and matched controls taken from a group of 70 normal children of the same age group. Blindfold weight discrimination, a test of muscle spindle and tendon stretch receptor function, also showed no abnormality in scoliotic children. The Charpentier test, thought to be a test of control of muscle spindle function, showed a tendency to an infantile response in patients with adolescent idiopathic scoliosis, while the control subjects showed a normal size-weight response.l This suggests that the muscle spindle system may be at fault in AIS and supports the suggestion that postural equilibrium reactions may be abnormal in this disease.

Adolescent↗
PubMed1998

Relation between functional characteristics of the trunk and the occurrence of low back pain. Associated risk factors.

STUDY DESIGN: A 2-year prospective study relating a set of subject characteristics (professional and extraprofessional constraints, personal and anthropometric characteristics, and static and dynamic performance of the trunk) and incidence of low back pain in a population of male Belgian steel workers. OBJECTIVES: To investigate the relation between occurrence of new cases of low back pain and prior personal, anthropometric, or functional characteristics. SUMMARY OF BACKGROUND DATA: Some functional characteristics--in particular, dynamic parameters of the trunk such as the velocity--have been shown to be significantly reduced for low back pain in workers in cross-sectional studies. The question remained as to whether modifications of these parameters preceded the development of low back pain. METHODS: The protocol included a questionnaire, a clinical examination, anthropometric measurements, and a set of functional tests on an isoinertial dynamometer. It was carried out twice, after a 1-year interval, on a sample of 215 workers without any history of low back pain. The reports of low back pain were again investigated 1 year later. RESULTS: The development of low back pain is related to frontal plane imbalance of the trunk, lower body weight, and perception of heavy lifting efforts at the workplace. Individuals performing dynamic tests at higher velocities appear also to be at a greater risk of low back pain. CONCLUSIONS: Although workers with a history of low back pain performed dynamic tests at significantly lower velocities, the probability for development of low back pain in the following year is greater for workers performing such tests at greater velocities.

Adult↗
PubMed2006

Long-term evaluation of eccentric viewing spectacles in patients with bilateral central scotomas.

PURPOSE: Yoked prism spectacles (eccentric viewing spectacles [EVS]) facilitate eccentric viewing in patients with bilateral central scotomas. This study was conducted to evaluate the long-term success and patient satisfaction of this type of low-vision aid. METHODS. In this retrospective cross-sectional study, we reviewed the low-vision rehabilitation records of all patients who received EVS since 1993. With an 18-item survey, 191 patients were questioned about the wearing characteristics, advantages, and disadvantages of the EVS. Descriptive and nonparametric statistics were applied to compare regular users with those persons who no longer use the EVS. RESULTS: The response rate was 83.2% and the average follow-up time was 4.5 years. Forty percent of all patients still used the EVS. The main disadvantages of these spectacles, mentioned mainly by the nonusers, included the heavy weight (41%), perception of curved lines (46%), dizziness during walking (46%), and poor cosmetic appearance (25%). Many successful long-term users considered the EVS suitable for home activities (86%) and walking in the street (70%) and reported that this device reduced eccentric viewing (77%), created better vision in the center of their visual field (67%), and helped with recognition of objects and faces (64%). CONCLUSIONS: The prescription of EVS aids eccentric viewing in patients with dense central scotomas. Although associated with a number of disadvantages and side effects, 40% of the patients continued to use EVS. The results of this study indicate that patients who experience difficulties with eccentric fixation are most likely to benefit from these low-vision aids. A thorough explanation of the advantages and disadvantages of the EVS is important to prevent unnecessary disappointments.

Adult↗
PubMed2003

Patient perception of the burden of weight gain and blood pressure increase among RA patients using celecoxib, rofecoxib, and non-specific NSAIDs.

Nonsteroidal anti-inflammatory medications (NSAIDs) may be accompanied by clinically important renal side effects. We compared the rate of reported side effects from celecoxib, rofecoxib, and nonspecific (NS) NSAIDs and their burden in RA patients. Patients on rofecoxib were more likely to report a problem with weight gain (P < 0.05) and an increase in blood pressure (P < 0.001). In addition, rofecoxib users were 28% more likely to be in a more severe category for being bothered by unintentional weight gain (OR = 1.28, P < 0.05) and 53% more likely to state that they were in a more severe category for blood pressure increase (OR = 1.53, P < 0.000), compared with patients receiving celecoxib. Weight gain and blood pressure were also increased by coexisting cardiovascular disease. Clinicians should be aware that patient-reported weight gain and increases in blood pressure can occur with all NSAIDs, and may be particularly increased with rofecoxib. Existing cardiovascular disease is also an independent predictor of weight gain and increased blood pressure.

Journal Article↗
PubMed1975

Field dependent eating and perception as a function of weight and sex.

It was hypothesized that the greater influence of external cues on obese than on normal individuals' eating behavior is a manifestation of a generalized sensitivity to external cues. Responsivity of nut consumption to the external cue of shells on the nuts and responsivity of judgment of verticality to the external cue of a tilted visual field were assessed for male and female, obese and normal-weight subjects. As predicted, both obese subjects' nut consumption and their judgments of verticality were more influenced by external cues than were those of normals. Females' judgments of verticality were more influenced by external cues than males' were, but the sex differences in eating behavior were not statistically significant. A significant correlation between the field dependence of subjects' eating behavior and their judgments of verticality suggests that a single cause may generate sensitivity to external cues in these two diverse situations.

Adolescent↗
PubMed1991

Kinaesthetic abilities of clumsy children.

Kinaesthesis was examined in 80 clumsy and 80 control children aged between six and nine years. Seven tasks were administered which required passive and active movements in both kinaesthetic and kinaesthetic-visual modes. Clumsy children performed inferiorly on three tasks which involved passive or active demands. A range of tasks appears to be necessary to identify kinaesthetic dysfunction.

Child↗
PubMed1977

Changes in motor commands, as shown by changes in perceived heaviness, during partial curarization and peripheral anaesthesia in man.

1. The centrally generated ;effort' or direct voluntary command to motoneurones required to lift a weight was studied using a simple weight-matching task when the muscles lifting a reference weight were weakened. This centrally generated input to motoneurones was increased when the lifting muscles were partially paralysed with curare or decamethonium as judged by the increased perceived heaviness of a reference weight lifted by the weakened muscles.2. If subjects were asked simply to make matching isometric contractions when the lifting muscles were weakened the isometric tension produced by a weakened muscle was over-estimated.3. When subjects matched weights by flexing the distal joint of the thumb the perceived heaviness of a reference weight during a control partial curarization was compared with its perceived heaviness during a similar partial curarization when the thumb was also anaesthetized. At any level of maximal strength during curarization the perceived heaviness (which reflects the motor command to lifting motoneurones) was increased when the thumb was anaesthetized.4. This increased voluntary command to lifting motoneurones may be required because automatic reflex assistance provided by apparent servo action from the long flexor of the thumb is suppressed by anaesthesia of the thumb (Marsden, Merton & Morton, 1971, 1973, 1976a; Dyhre-Poulsen & Djørup, 1976).

Anesthesia, Local↗
PubMed1980

Alterations in perceived heaviness during digital anaesthesia.

1. It was shown by Gandevia & McCloskey (1977) that anaesthesia of the thumb causes weights lifted by thumb flexion to feel heavier, and weights lifted by thumb extension to feel lighter. This was confirmed by Marsden, Rothwell & Traub (1979). Gandevia & McCloskey explained the effects in terms of altered motor command (and so, altered 'sense of muscular force, or heaviness') required when sources of peripheral reflex facilitation or inhibition were removed by anaesthesia. Marsden et al. proposed, instead, that co-contraction of antagonists altered in anaesthesia. They said that increases in heaviness occurred for flexion because anaesthesia was associated with increased activity in the thumb extensor and, similarly, that decreases in heaviness occurred for extension because anaesthesia reduced activity in the thumb flexor. 2. The apparent heaviness of weights lifted by flexion of the thumb is not systematically altered by paralysis of the extensor of the thumb (radial nerve block at the elbow). Heaviness is increased by local anaesthetization of the thumb (digital nerve block). If paralysis of the thumb extensor is induced after digital nerve block, no further alteration in apparent heaviness occurs. 3. If extensor co-contraction is encouraged for stabilization of the wrist, as by having subjects perform an isometric contraction with the index-finger while lifting weights by thumb flexion, the apparent heaviness of the weights is increased. If co-contraction of the extensors is prevented by radial nerve block the manoeuvre of simultaneous contraction of the index finger then fails to alter the heaviness of weights lifted by thumb flexion. 4. The middle finger can be postured in such a way that active extension but not active flexion of its distal joint is impossible. When co-contraction of the extensor cannot act at the distal joint, anaesthetization of the middle finger causes an increase in apparent heaviness of weights lifted by flexion of this joint. 5. The effects of digital anaesthesia on the apparent heaviness of objects lifted by digital flexion are not caused by co-contraction of the extensors of the digits, as proposed by Marsden et al. Where extensor co-contraction occurs unrelated to the digital flexion task, as in stabilization of the wrist during simultaneous flexion of more than one digit, it may affect the apparent heaviness of objects borne by individual digits.

Adult↗
PubMed1988

Changes in perceived heaviness and motor commands produced by cutaneous reflexes in man.

1. This study examined the relationship between the perceived heaviness of a weight and reflexes acting on the motoneurones required for the contraction. The perceived heaviness of low (100 g) and high (500 g) reference weights lifted by the first dorsal interosseous muscle was estimated using a matching task. Weights were also lifted during stimulation of the digital nerves of the index finger at two times and four times sensory threshold (T). Averages of force and EMG were also made when isometric forces of 100 and 500 g were maintained. 2. Stimuli at 4T produced a significant increase in perceived heaviness in each subject for both reference weights. Averages of EMG made under isometric conditions showed a short-latency inhibition with a reflex reduction in force following single stimuli. This inhibition was also observed during weight lifting when trains of stimuli were given. 3. Stimuli at 2T produced less-marked changes in EMG, averaged force, and perceived heaviness for individual subjects. However, for the group of subjects, perceived heaviness declined significantly with 2T stimuli for the 500 g but not the 100 g weight. This decrease in perceived heaviness was associated with evidence of short-latency facilitation within the motoneurone pool. 4. Inhibition of the motoneurone pool was associated with an increase and facilitation with a decrease in perceived heaviness. These observations favour a role for a signal of centrally generated motor command in the sensation of heaviness and provide insight as to how this signal must change when reflex inputs change and when high-threshold motoneurones are recruited.

Action Potentials↗
PubMed1990

Accuracy of weight estimation for weights lifted by proximal and distal muscles of the human upper limb.

1. It is well established that tactile acuity is greater over digits than over the proximal parts of the upper limb and that the corticospinal projection is especially dense for distal muscles. To determine whether the acuity for judgements of forces exerted by distal muscles differed from that for proximal muscles, a weight-matching task was used with first dorsal interosseous, flexor pollicus longus and elbow flexors. 2. Reference weights equivalent to approximately 3% (light) and 15% (heavy) of the maximal voluntary contraction were lifted by one muscle group on the left. They were matched with a variable weight, lifted by the same group, on the right. 3. In naive subjects, the coefficient of variation for repeated estimates of perceived heaviness was significantly lower for proximal than distal muscles. Measured in this way, 'accuracy' (i.e. reproducibility of the estimates) was not greater for the intrinsic muscles of the hand. This result could not be explained by the way in which the weights were supported by the index finger. When the data were expressed as the relative difference between the reference and the matched weight, each muscle group behaved similarly. 4. For a particular muscle, accuracy was greater when the heavy rather than the light weights were lifted. 5. Given that estimates of forces and heaviness are biased by signals of central motor command (McCloskey, 1981; Gandevia, 1987; Cafarelli, 1988; Jones, 1988). these signals could be graded no more finely for distal than proximal muscles. Furthermore, relative accuracy was greater for forces at the high rather than the low end of the comfortable 'matching' range of force for a particular muscle.

Adult↗
PubMed1991

Independent digit control: failure to partition perceived heaviness of weights lifted by digits of the human hand.

1. A weight-matching task was used to investigate the ability to estimate heaviness when weight lifting was isolated to the extrinsic flexor muscles (or portions thereof) that act on the digits of the hand. 2. Subjects matched a reference weight (200 g) lifted by a digit on the right with a variable weight lifted by the left thumb; a concurrent weight was simultaneously lifted by a digit on the right (reference) side. The reference and concurrent weights were lifted either by the same muscle (digital portions of flexor digitorum profundus), or anatomically separate but functionally related muscles (flexor digitorum profundus and flexor pollicis longus). Anaesthesia of the radial nerve and/or posturing of the hand was used to eliminate any small forces generated by co-contraction of the extensor muscles of the digits. 3. When the concurrent weight was equal to or greater than the reference weight, the perceived heaviness of the reference weight increased significantly from control trials (in which no concurrent weight was lifted). Although perceived heaviness of the reference weight increased progressively as the concurrent weight increased, reproducibility (expressed as the coefficient of variation) did not deteriorate when a weight was lifted concurrently. These findings were qualitatively similar when the reference and concurrent weights were lifted by two digital portions of flexor digitorum profundus or when the weights were lifted by flexion of the thumb and index finger. Also, anaesthesia of the digits which lifted the reference and concurrent weights did not alter the changes in perceived heaviness. 4. Perceived heaviness of the reference weight lifted by flexor digitorum profundus did not change when subjects lifted the concurrent weight with a remote muscle group (ankle dorsiflexors). 5. This study shows that signals of heaviness are systematically overestimated whenever more than one portion of the extrinsic muscles which flex the different digits are simultaneously active. Given that estimates of heaviness are biased by the central motor command, one explanation is that when the total motor drive increases, the central nervous system is unable to partition precisely the destination of motor commands to functionally related 'muscles'.

Electromyography↗
PubMed2002

Effects of a limited class of nonlinearities on estimates of relative weights.

Perturbation analyses have been applied in recent years to determine the relative contribution of individual stimulus components in detection and discrimination tasks. Responses to stimulus samples are compared to stimulus parameters to determine the details of the decision rule. Often, a linear model is assumed and it is of interest to determine the relative contribution of different stimulus elements to the decision. Here, biases in estimated relative weights are considered for the case where the decision variable is given by D = (sigma(alphaiXn(i))k)m and the stimulus components, the Xi, are normally distributed, of equal variance, and mutually independent. The alphai are the "true" combination weights, and n, k, and m are positive reals. The method used to estimate relative weights is the correlation coefficient between the Xi and the observer's responses. Estimates of relative alphai do not depend on m but may depend on the mean values of the Xi and the values of n and k (a dependence on the variance, sigmai2, holds even for linear transformations).

Computer Simulation↗