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Call number: LD2668 .T4 1985 D37 / Master of Science

The purpose of the investigation was to determine the effect of the tonic neck posture upon fatigue induced by exhaustive exercise of the knee extensor muscles of college women. The subjects were college females enrolled in physical education activity classes at North Texas State University. The F ratio was used to determine significance of the difference in fatigue measures in the three head positions. The results of the present investigation revealed no statistically significant difference between the three head positions with respect to their influence on endurance of the leg extensors. Conclusions were that the tonic neck reflex does not facilitate or inhibit leg extensor endurance.

Aortic baroreflex (ABR) control of blood pressure was examined in 7 untrained (UT) and 8 endurance exercise trained (EET) young men. ABR control of blood pressure was determined during a steady state phenylephrine infusion to increase mean arterial pressure 10-15 mmHg, combined with positive neck pressure to counteract the increased carotid sinus transmural pressure, and low levels of lower body negative pressure to counteract the increased central venous pressure. Functioning alone, the ABR was functionally adequate to control blood pressure. However, ABR control of HR was significantly diminished in the EET subjects due solely to the decrease in the ABR sensitivity. The persistent strain from an increased stroke volume resulting from endurance exercise training could be the responsible mechanism.

The diploma thesis is focused on psychomotor development in children with cerebral palsy in context of persisting primitive reflexes. Opening chapters summarize theoretical knowledge about cerebral palsy, its etiology, clinical picture, forms and comprehensive diagnostics, including special education. The next part of the thesis focuses on psychomotor development of a child with cerebral palsy, in particular the gross and fine motor activity development and speech development. The main section of the thesis discusses the neurophysiological principles of primitive reflexes and their relevance for early development of a child. The primitive reflexes, one by one, as well as the influence of their persistence on the psychomotor development of the child with cerebral palsy and options of their integration by selected therapeutic concepts are presented. Attention is also paid to the importance of multidisciplinary cooperation of medical rehabilitation and special pedagogical care in the field of primitive reflexology. The practical part is based on qualitative methodology ad its operates with data gained from three case studies. The aim of the diploma thesis is to examine by means of case studies whether or not the integration of primitive reflexes demonstrably improves the psychomotor skills, behavior,...

Bibliography: p.90-91. / Contract no. DA36-039-AMC-03200(E).

The subject of the thesis is a study of the projections from low threshold oral and face afferents to the cerebral cortex and of descending motor control mechanisms originating in the cerebral cortex or the hypothalamus and influencing the jaw reflexes.Cats anaesthetized with chi oral ose were used for the experiments. Ipsi- and contralateral nerves from the oral cavity and the face were stimulated electrically. Cortical potentials were averaged and recorded. The location of the projections was related to the cytoarchi-tectonic areas of the cerebral cortex. It was found that the afferents projected to separate maximum points in areas 3a, 3b, 5a and 6aß. The projections to areas 3a and 3b were somatotopically organized, but the layout of the projections on the cortex was not facelike.The effect of monopolar anodal stimulation of the cerebral cortex on the monosynaptic jaw closing and the di synaptic jaw opening reflexes was investigated. A sequence of facilitation and inhibition of both reflexes was elicited by cortical stimulation. The effects were of short latency (2.5 ms) and could start with either facilitation or inhibition. The timecourse of the sequence was sinuslike with a period of 10 ms. The largest effect originated in the "sensory" areas 3a and 3b and not in the "motor" areas 4y and 6ag. It is suggested, that a tri gemino-cortico-tri geminai loop via area 3a may function in reflex modulation of jaw movements.The hypothalamic effects on the jaw reflexes were evoked by electrical stimulation in those parts of the hypothalamus, which are w known to generate defence, attack or feeding responses. A tenfold facilitation of the jaw closing reflex and a facilitation followed by almost complete inhibition of the jaw opening reflex were observed in the anaesthetized animal with intact cerebral cortex. The effects remained but were diminished in amplitude after cortical ablation. The descending path was located in the ventral midbrain tegmentum.It is suggested that the observed hypothalamo-tri geminai mechanism may exercise a tonic influence on the trigeminal motoneurones, thereby controlling the set points of the biting force and the rest position. The implications of this hypothesis on the etiology of bruxism and the myofascial pain-dysfunction are discussed. / <p>Härtill 3 rapporter.</p> / digitalisering@umu

Previous research investigating the stability of the ankle joint complex may be categorised into two methodological groups, employing either an actuator to perturb the limb, or a form of standing balance disturbance such as a tilting platform, both of which test the joint in single degree of freedom (DOF). The aim of this thesis was to investigate how we control foot position and stabilise the joint when there is potential for movement in three DOF. A secondary aim of the thesis was to model the intrinsic mechanical properties of the ankle joint complex in three dimensions when coupled movement of the tibio-talar and talo-calcaneal joints are possible. This thesis details (i) the development of a perturbation rig that allows foot movement in single- or three-DOF with associated real-time visual target-matching software, and (ii) the use of the rig to investigate the stabilisation of the ankle joint complex in single- and three-DOF. The experimental procedure used a common task performed in three experimental conditions. Subjects were required to maintain a neutral foot position while developing varying levels of plantar-flexion torque. A perturbation was applied to the foot if subjects were within specified tolerance for both foot position and torque, represented by the visual display. Performance of the task in the first condition required the subject to only match torque as the foot position was fixed, with the perturbation being applied in dorsi-flexion (ie, single-DOF). The second experimental condition allowed the foot to move in the sagittal plane, hence subjects were required to control both torque and foot position in single-DOF, with perturbation applied in dorsi-flexion. The third condition enabled movement in dorsi/plantar-flexion, inversion/eversion and adduction/abduction (three-DOF) in both task and perturbation. Subjects were required to maintain the neutral foot position and the necessary torque level. There were three areas of interest common to each experimental protocol. The muscle strategy used to complete the task was investigated using a combination of surface and fine-wire electromyography on lower leg and thigh muscles. The 500ms period prior to perturbation was investigated to determine if synergies were evident between muscles such as medial and lateral gastrocnemius, soleus and peroneus longus. Two classes of activation strategies for the three-DOF condition emerged from the subject population: differential activation of the triceps surae group, and co-contraction. The former strategy may take advantage of the distinct morphology of the lateral gastrocnemius and peroneus longus muscles to best perform the position-matching component of the 3D task. The results suggest that the ankle joint is mostly stabilised in 3D by the intrinsic mechanical actions of the muscles producing plantar flexion moments. The muscles stabilised the foot in inversion, but not in eversion where there was very little motion. However, the different activation strategies employed may have varied efficacy in contributing to joint stability. This form of active stabilisation means that the previous literature focus on reflexes to stabilise the joint may need to be reassessed. Likewise, it may be appropriate to use the perturbation rig to quantify active ankle joint stability in order to assess the probability of ankle injury, rather than the current clinical measures employed. The reflexive response due to the perturbation was examined in the 200ms following perturbation. Variation in the modulation of monosynaptic reflexes was observed between subjects in various muscles in the higher DOF tasks. This is likely due to the differing activation strategies used to perform the task, and the variability in the kinematic response to perturbation. An attempt was made to calculate the intrinsic mechanical properties of the joint in 3-D using the kinematic and kinetic data during the first 15 ms period of perturbation. The system was modelled as a spring-damper using a constrained non-linear least squares, with stiffness and viscous terms for each axis, and inertial tensor elements as variables in the routine. The effect of increased muscle activation on the displacement of the foot about each of the anatomical axes was to significantly lower the movement of the sub-talar joint.

Thesis (M.S.)--University of Michigan, 2000. / Includes bibliographical references.

Thesis (M.S.)--University of Michigan, [2000] / Includes bibliographical references.