ABSTRACT
Stopping a clinical trial without reaching the final objective is not the ideal outcome any researcher wants; sometimes ceasing is inevitable. Due to marginal inclusion of patients we were forced to cease our randomized clinical trial on the effectiveness of proprioceptive training on the development of chronic whiplash complaints a year after the start. Although incidence figures demonstrate that recruitment of the planned number of whiplash patients would be easily feasible, we were unable to enroll the amount of subjects. Several motives can be proposed that would have prevented this obliged halting from happening. Other studies also report impracticability of the planned number of whiplash injury patients.
Subject(s)
Patient Selection , Randomized Controlled Trials as Topic/methods , Humans , Physical Therapy Modalities , Proprioception , Research Design , Whiplash Injuries/rehabilitationABSTRACT
Williams Syndrome (WS, [MIM 194050]) is a disorder caused by a hemizygous deletion of 25-30 genes on chromosome 7q11.23. Several of these genes including those encoding cytoplasmic linker protein-115 (CYLN2) and general transcription factors (GTF2I and GTF2IRD1) are expressed in the brain and may contribute to the distinct neurological and cognitive deficits in WS patients. Recent studies of patients with partial deletions indicate that hemizygosity of GTF2I probably contributes to mental retardation in WS. Here we investigate whether CYLN2 and GTF2IRD1 contribute to the motoric and cognitive deficits in WS. Behavioral assessment of a new patient in which STX1A and LIMK1, but not CYLN2 and GTF2IRD1, are deleted showed that his cognitive and motor coordination functions were significantly better than in typical WS patients. Comparative analyses of gene specific CYLN2 and GTF2IRD1 knockout mice showed that a reduced size of the corpus callosum as well as deficits in motor coordination and hippocampal memory formation may be attributed to a deletion of CYLN2, while increased ventricle volume can be attributed to both CYLN2 and GTF2IRD1. We conclude that the motor and cognitive deficits in Williams Syndrome are caused by a variety of genes and that heterozygous deletion of CYLN2 is one of the major causes responsible for such dysfunctions.
Subject(s)
Microtubule-Associated Proteins/genetics , Microtubule-Associated Proteins/physiology , Muscle Proteins/genetics , Muscle Proteins/physiology , Nerve Tissue Proteins/genetics , Nerve Tissue Proteins/physiology , Nuclear Proteins/genetics , Nuclear Proteins/physiology , Trans-Activators/genetics , Trans-Activators/physiology , Williams Syndrome/pathology , Williams Syndrome/psychology , Animals , Cognition/physiology , Conditioning, Operant/physiology , DNA/genetics , Eye Movements/physiology , Fear/psychology , In Situ Hybridization, Fluorescence , Intelligence Tests , Magnetic Resonance Imaging , Mice , Mice, Knockout , Motor Activity/physiology , Neuropsychological Tests , Postural Balance/physiology , Psychomotor Performance/physiology , Williams Syndrome/geneticsABSTRACT
Handedness and eye sighting dominance were assessed in a sample of 50 individuals (25 male, 25 female; aged 5-38 years) with Williams-Beuren syndrome (WBS). The prevalences of left-handedness and left-eyedness were compared to the normative prevalences in the general population. We found significantly higher prevalences of left-handedness and left-eyedness in the WBS sample. The higher prevalences were more salient in younger than in older individuals and in male than in female individuals. We suggest that the increased prevalence of left-handedness in WBS is a consequence of a slower maturation rate, which allows deviation from a predetermined laterality pattern.
Subject(s)
Dominance, Ocular/genetics , Functional Laterality/genetics , Williams Syndrome/genetics , Williams Syndrome/physiopathology , Adolescent , Adult , Aging/physiology , Child , Child, Preschool , Female , Humans , Male , Reference Values , Sex CharacteristicsABSTRACT
Patients with Williams-Beuren Syndrome (WBS, also known as Williams Syndrome) show many problems in motor activities requiring visuo-motor integration, such as walking stairs. We tested to what extent these problems might be related to a deficit in the perception of visual depth or to problems in using this information in guiding movements. Monocular and binocular visual depth perception was tested in 33 patients with WBS. Furthermore, hand movements to a target were recorded in conditions with and without visual feedback of the position of the hand. The WBS group was compared to a group of control subjects. The WBS patients were able to perceive monocular depth cues that require global processing, but about 49% failed to show stereopsis. On average, patients with WBS moved their hand too far when no visual feedback on hand position was given. This was not so when they could see their hand. Patients with WBS are able to derive depth from complex spatial relationships between objects. However, they seem to be impaired in using depth information for guiding their movements when deprived of visual feedback. We conclude that the problems that WBS patients have with tasks such as descending stairs are not due to an inability to judge distance.
Subject(s)
Depth Perception/physiology , Williams Syndrome/physiopathology , Adolescent , Adult , Child , Hand , Humans , Movement/physiology , Psychomotor Performance/physiology , Vision, Binocular/physiology , Vision, Monocular/physiologyABSTRACT
Numerous studies have described the poor visuo-spatial processing capacities of subjects with Williams-Beuren syndrome (WBS), a genetically based developmental disorder. Since visual perception and eye movements are closely related we hypothesized that the poor visuo-spatial processing capacities of subjects with WBS might be related to a poor saccadic control. Thereto, we recorded horizontal and vertical saccadic eye movements to targets using infrared video-oculography in 27 subjects with WBS and eight healthy controls. In the WBS group saccadic gains were highly variable, both between and within individual subjects, and they often needed more than one correction saccade to reach the target. Ten (out of a subgroup of 22) WBS subjects showed a large number of hypometric and/or hypermetric saccades, and, also a left-right asymmetry in saccadic gains was observed in WBS. We conclude that the observed impairments in saccadic control are likely to affect the proper processing of visuo-spatial information.
Subject(s)
Cerebellar Ataxia/etiology , Saccades , Williams Syndrome/complications , Adolescent , Adult , Child , Female , Fixation, Ocular/physiology , Humans , Male , Psychomotor Performance , Reaction Time/physiology , Saccades/physiology , Visual Perception/physiologyABSTRACT
In the present study, eve movements during the copying of a pattern were analyzed to compare visual strategies of adults and children. Subjects had to build an accurate copy of spatial block patterns. Tested variables were the incidence and the duration of ocular dwelling in the pattern area (where the pattern to be copied was located), the work area (where the copy was made), and the source area (where the blocks were that could be used for creating the copy). Furthermore, to unravel employed strategies, sequences of dwelled areas were investigated. Previous studies reported that adults employ repetitive visual scanning strategies to accomplish the task instead of strategies depending upon an internal representation. The present results show that the II children, within the ages of 7 to 12 years, made more eye movements and fixations of longer duration during copy tasks than the 11 adults. The visual strategies of the children were highly comparable to those of adults. Memory was restricted to one block, while color and location seemed to be remembered together.
Subject(s)
Pattern Recognition, Visual , Psychomotor Performance , Adult , Child , Color Perception , Eye Movements , Female , Humans , Male , Mental Recall , Middle Aged , OrientationABSTRACT
Blindfolded, sitting subjects were asked to feel whether two bars were parallel or not. In 50% of the presentations the bars were parallel to each other. In all presentations either one or two bars were oriented vertically, horizontally, 45 degrees or 135 degrees. In this situation the best accuracy was found when the bars were vertically and horizontally oriented in space. The experiments were repeated with the subjects tilted laterally by 45 degrees. Now the best accuracy was found when the bars were at an angle of 45 degrees or 135 degrees to the length-axis of the body. This means that the oblique effect in the somatic sensory system is of vestibular origin.
Subject(s)
Orientation/physiology , Sensation/physiology , Forearm/physiology , Humans , Pronation/physiology , Supination/physiology , Vision, Ocular/physiologyABSTRACT
Rabbits were trained to discriminate striated patterns of different orientation in a two-choice discrimination box. After the 90% correct level had been reached, motor behaviour was studied during visual discrimination. It was found that the animals made their decision after seeing one of the two stimuli. This finding is in disagreement with an earlier study from which it was concluded that the animal's choice is mainly controlled by the unrewarded stimulus (Van Hof and Van Hof-van Duin 1984).
Subject(s)
Discrimination, Psychological/physiology , Animals , Rabbits , Vision, Ocular/physiologyABSTRACT
Rabbits were trained to discriminate between vertical and horizontal striations. After the 90% correct level had been reached transfer to vertical and horizontal rows of dots was studied. It was found that performance depended on the distance between adjacent dots. With angular dot separations (measured from the centers) larger than 4.9 degrees, performance was below the 75% correct level. This result is discussed in relation to the size of the receptive fields of orientation-selective neurons in the binocular visual cortex.
Subject(s)
Attention , Discrimination Learning , Form Perception , Generalization, Stimulus , Orientation , Pattern Recognition, Visual , Animals , Arousal/physiology , Attention/physiology , Cues , Discrimination Learning/physiology , Form Perception/physiology , Generalization, Stimulus/physiology , Orientation/physiology , Pattern Recognition, Visual/physiology , Rabbits , Retina/physiology , Visual Cortex/physiologyABSTRACT
Two types of visual discrimination apparatus for rabbits can be distinguished: one in which the animal is free to move close to the targets and another in which the choice has to be made at a distance. Previously, it had been found that rabbits have a tendency to fixate the patterns with the temporal retina for visual discrimination in the first type of apparatus. The present experiments show that this is also the case in an apparatus where the rabbit discriminates at a distance.
Subject(s)
Discrimination Learning/physiology , Form Perception/physiology , Pattern Recognition, Visual/physiology , Retina/physiology , Visual Fields , Animals , Orientation/physiology , Rabbits , Visual Pathways/physiologyABSTRACT
In the rabbit, unilateral ablation of the occipital lobe leads to a severe impairment of striated pattern discrimination with the eye contralateral to the lesion. In the present report it is studied whether the acute reduction of the overall visual field, due to closure of the eye contralateral to the intact hemisphere shortly before each testing session, leads to results which underestimate the animal's capability to discriminate striated patterns via the ipsilateral fibres. The experiment described in the present report suggests that this is not the case and that there is a genuine visual discrimination deficit after unilateral ablation of the visual cortex.
Subject(s)
Discrimination Learning/physiology , Dominance, Cerebral/physiology , Form Perception/physiology , Occipital Lobe/physiology , Pattern Recognition, Visual/physiology , Sensory Deprivation/physiology , Animals , Orientation/physiology , Rabbits , Visual Pathways/physiologyABSTRACT
The contribution of the rewarded and unrewarded stimulus in two-choice pattern discrimination after a unilateral ablation of the occipital lobe was studied in 14 rabbits. With the eye contralateral to the intact hemisphere the correct decision is mainly based on avoidance of the unrewarded stimulus. The results with the eye contralateral to the lesion suggest that both the unrewarded and rewarded stimulus play a role in the decision.
