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During the first two postnatal weeks postural reflexes were either absent or abortive. First adult-like patterns of reactions were seen at the end of the 3rd week but they could be regularly elicited only by the 6th-9th week.
A relationship is considered between abnormal postural reflex activity and its effect on vocal processes in infants and very young children having cerebral palsy. Neurodevelopmental treatment concepts are interpreted as they may apply to evaluation and intiial management of hypertonic children who exhibit voice usage deviations. Interdisciplinary team function in the areas of physical therapy, occupational therapy, and speech pathology is suggested.
Young normal subjects adapt the size of posturally stabilizing reflexes in the lower extremity to predictable and unpredictable perturbations through shifts in cognitive set. It is unknown whether limitations in this ability to shift cognitive set may contribute to impaired scaling of postural reflexes in patients with Parkinson's disease. In this study, we have addressed this issue in 12 posturally unstable Parkinson patients and 13 age- and sex-matched controls. Postural stability was disturbed by sudden toe-up rotations of a supporting platform upon which subjects were standing. Subjects' cognitive set was altered by varying the perturbation amplitude either predictably (serial 4 degrees versus serial 10 degrees) or unpredictably (random mixture of 4 degrees and 10 degrees). Posturally stabilizing long latency (LL) reflexes were recorded from the shortened tibialis anterior muscle of both legs. We found that Parkinson patients, unlike some control subjects, were unable to scale the size of their LL reflex in response to variations in perturbation amplitude during predictable conditions. In addition, we observed that Parkinson patients could not modify the amplitude of the LL reflex through alterations in cognitive set during random conditions. We conclude that Parkinson patients have a fundamental difficulty in modifying the size of posturally stabilizing LL reflexes, as reflected by both problems with amplitude scaling and difficulties with changes in cognitive set. It is possible that this inability to modify LL reflexes may be a factor contributing to postural instability in Parkinson's disease.
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Injection of local anaesthetic into the knee joint space in a series of 5 cats produced obvious postural abnormalities in 3 animals. However, on employing a more sensitive test, all animals exhibited abnormalities of postural reflexes on abolishing knee joint afferent discharge. Control experiments indicated that this could not be attributed to the local anaesthetic diffusing locally out of the joint capsule and affecting muscle and cutaneous afferents around the knee joint.
Changes in the forelimb extensor reflexes during fixed shifts and cyclic tilting of the head were investigated in decerebrated vestibuloectomized cats. In the used frequency range (0.05-1.0 Hz) the phase lead (10-15 degrees) of these changes was observed. The increase of tested reflexes was more pronounced during cyclic tilts than during fixed shifts. It is suggested that neck postural reflexes, primarily postulated as exclusively tonic, should be regarded as those having a phasic component.
The development of postural reflexes and static functions were analysed in children with different forms of central nervous system damage developing in the first three years of life. A correlation was found between the persistence of tonic reflexes and disturbances of development of static functions and this finding may be used in differential diagnosis of early central nervous system lesions and in selection of appropriate treatment.
Spinal hemisection in the adult cat results in motor impairments followed by substantial recovery of function (16, 20, 39, 53). The present study was undertaken to assess the contribution of undamaged ipsilateral segmental and contralateral descending systems to recovery of motor function. Quantitative behavioral methods were used to examine monopedal reflex and bipedal locomotor functions after thoracic hemisection. Different facets of motor behavior recover at different times. The recovery of monopedal postural reflexes precedes the recovery of more complex motor behavior. Since the reflexes tested are initiated by segmental afferent input and show recovery and normal motor patterns during locomotion, as defined by kinematic analysis show recovery, it is likely that dorsal root input compensates for the loss of descending input to one side of the spinal cord. Quantitative immunocytochemical methods for visualizing the central projections of dorsal root fibers (monoclonal antibody RAT-102; 49) and the descending serotoninergic pathway were used to examine the response of these pathways to hemisection. Hemisection results in a permanent decrease in the density of serotoninergic projections and a permanent increase in dorsal root projections in the spinal cord. The increased density of RAT-102 may represent an increase in the projection of dorsal root fibers and provide the increased input necessary to mediate enhanced reflex control. A transient increase in GAP-43 in the dorsal horn ipsilateral to the hemisection suggests that the increased density of RAT-102 immunoreactivity is associated with growth. Taken together, our results suggest that sprouting of primary afferents within the spinal cord is one mechanism underlying the recovery of function after hemisection.
A 56-year-old woman was admitted because of chronic postural reflex disorder. A cerebral MRI revealed symmetrical high intensity area mainly in the globus pallidus on T1-weighted image. The symptom became manifested as gait disturbance from the age of 2 and gradually progressed. Her condition has, however, remained stable since the age of 26. The only sign of parkinsonism was akinesia. There was clear retropulsion but cerebellar ataxia was minimal, and dystonia was negligible. She had no dementia. Her parents were cousins and similar symptoms and high intensity area were found in one of her sisters. Routine liver function tests were normal, with only ICG elevated. Serum copper and ceruloplasmin were normal. A hereditary factor was suspected. There are no similar cases reported in the literature, thus we thought it worth reporting.
OBJECTIVE: We studied whether medium latency (ML) and long latency (LL) postural reflexes, which are abnormal in a number of neurological conditions including basal ganglia disorders, provide an early marker of CNS involvement in HIV-positive patients. METHODS: Leg reflexes were elicited in 9 neurologically normal HIV-positive patients and 10 healthy controls who were standing upright, using toe-up forceplate rotations of varying amplitude (4 degrees and 10 degrees) and predictability (serial and random). RESULTS: For predictable amplitude perturbations, posturally destabilizing ML and stabilizing LL responses in HIV-seropositives did not differ from controls. However, for unpredictable amplitude perturbations, HIV-positive patients inappropriately manifested a mid-size default LL response, in contrast to healthy subjects who showed a maximum size default response. CONCLUSIONS: These results suggest that impaired modulation of LL reflex processing occurs in early stages of HIV infection, prior to the onset of clinical postural instability, and this dysregulation may be influenced by cognitive factors.
One group of dogs was trained to perform a placing movement of the right or left foreleg in response to tactile stimuli administered to the ipsilateral hindlimbs. The animals learned this task with difficulty. In another group of dogs the method of crossed reflexes was applied. As a correct response to the right tactile stimulus, the movement of the left foreleg was required, and vice versa. This task was solved rapidly. It is suggested that this was due to the facilitory effect of the Sherringtonian postural reflexes.
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The subject of investigation was the influence of ocular fixation on acquisition of habituation in experimental rotatory test in pigeons. The habituation training was performed in the three difference conditions: with full ocular fixation, fixation partly reduced and fixation excluded. Author confirmed that habituation with fixation excluded gave the best results of habituation of postural reflexes and head nystagmus in pigeons in rotatory training.
The purpose of this study was to investigate the possible pathways in the somatosensory system that relate to the postural reflexes in the leg muscles during a sudden, toes-up platform rotation. The inputs to the cutaneous mechanoreceptors in the sole of the foot as well as to the joint receptors in the ankle joint were modulated by standing on different supporting surfaces and by immobilizing the ankle joints; and three leg muscle responses (characterized by short latency, medium latency, and long latency) to the platform movement were recorded in 15 healthy young subjects. It was found that: (1) the short latency was not affected by the changes in either plantar pressure or ankle joint movement; (2) the medium latency was regulated by the plantar pressures under the foot, as sensed by the cutaneous mechanoreceptors in the sole of the foot, and by the ankle joint movement, as perceived by the joint receptors in the ankle joint; (3) the long latency was also related to the ankle joint movement, but this relation seems to be modulated by the plantar pressures under the foot; and (4) both medium and long latencies were well correlated with the time derivative of the pressure difference between the forefoot and the rear foot regions (r=0.7), as well as with the static pressure in the antagonist foot region (r>0.6).
The time course for the development of binocular vision is similar to the time course for the development of mature, symmetrical, monocular optokinetic nystagmus in response to movements of the visual field in the nasalward or temporalward direction. If binocular vision does not develop normally, then the monocular optokinetic response remains immature, or asymmetric. This paper examines the connection between the development of symmetrical OKN and binocular vision, and relates how disturbances in visual development affect the ability of postural reflex eye movements to adapt to changes in the visual environment.
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