Thesis (M.S.)--University of Missouri-Columbia, 2003. / Figure 1 referred to on leaf 2 is shown on leaf 20. Typescript. Includes bibliographical references (leaves 35-36). Also available on the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2003. / Figure 1 referred to on leaf 2 is shown on leaf 20. Typescript. Includes bibliographical references (leaves 35-36). Also available on the Internet.

Thesis (Ph.D.)--University of Delaware, 2009. / Principal faculty advisor: William B. Farquhar, Dept. of Health, Nutrition, & Exercise Sciences. Includes bibliographical references.

No description available.

Reflex control during walking has been shown to be specific to the behavioural context of a postural threat. Reflex modulation has been shown to be influenced by perturbations to the trunk, as well as by changes to arm activity that further affected the level of postural threat. The magnitudes of EMG responses in limbs and trunk to mechanical trip perturbations were differentially modulated depending on whether or not an earth- referenced railing was held. To further understand the neural control of limb and trunk muscles during walking contexts where changes to postural stability are solely linked to arm activity, we created 3 treadmill walking tasks each with the arms engaged differently to induce three levels of postural stability. Neurologically-intact participants walked on a treadmill using normal arm swing (NORMAL), holding a wheeled walker (WALKER), or holding the handrails (HANDRAIL). Subjects ranked the tasks according to degree of perceived challenge to stability; WALKER was ranked most challenging, followed by NORMAL and then HANDRAIL. Cutaneous reflexes were evoked via constant current stimulation (5 x 1.0 ms pulses at 300 Hz) of Superficial Peroneal (SP) nerve at the foot and Superficial Radial (SR) nerve at the wrist in separate trials during each walking task. EMG was recorded ipsilateral to nerve stimulation from arm and leg muscles and bilaterally from trunk muscles. Off-line analysis was conducted on eight phases of the step cycle after phase-averaging, contingent upon the timing of stimulation in the step cycle. The number of differences in bEMG and reflexes between tasks was graded with the proximity to the source of instability at the arms, progressively increasing from the legs to the arms. The gradient in bEMG differences suggests that the mechanical constraints of each task required different levels of muscle activation that was greatest for the arms, less for the trunk and least for the legs. The similar gradient seen for reflexes suggests functionally relevant changes in neural control of arm and trunk muscles in order to maintain postural stability during in each task. However, overall there were significantly fewer differences in reflexes between tasks compared to bEMG. We suggest that the mechanical constraints of the tasks yielded more significant changes in the muscle activation while requiring far fewer task-specific changes in reflex control suggesting a conservation of some elements of the neural control mechanisms across tasks. / Graduate

The kinematics of wiping movements to the back were examined in spinal adult Rana Catesbeiana. The aim was to identify the elements of the back wipe and their functional role. The data show that there are three essential phases of the wiping movement: a placing phase; a flexion of the hip and knee; and a whisk/extension phase. The first phase is the only one which is dependent upon stimulus location. The spinal frog adjusts the hindlimb to account for stimulus location in the rostro-caudal direction. There is no adjustment for stimulus position along the medial-lateral axis of the body. It is proposed that the second phase serves as a preparatory movement for the extension portion of the wipe. When the wipe is partitioned into these phases, the motion was found to be planar for the first and third phases. At the end of the first phase there was a transition between the two planes.

Master of Science / A mechanical stimulus producing stretch in human or animal muscle may evoke a reflex response in the muscle that tends to oppose the length change. In decerebrate preparations, limb flexion generates a tonic stretch reflex that manifests as a sustained increase in resistance (Liddell and Sherrington, 1924; Widmalm, 1976b). This tonic response is not readily apparent in the conscious human subject, however, the phasic response may be observed as a burst of action potentials produced by the synchronous firing of several motor units, and as such represents the classic tendon reflex. The analogous compound action potential in the jaw musculature may be demonstrated following a sudden downward mechanical impulse to the mandible in the human or animal subject (Goodwill, 1968; Matthews, 1976) and has been termed the jaw-closing reflex or the jaw jerk reflex, the latter so named in view of its similarity to the knee-jerk and other tendon reflexes induced by sudden stretch (Goodwill, 1968; Munro and Griffin, 1971; Tardieu, Tabary and Tardieu, 1973). The use of the term “jaw jerk” to describe this reflex may be inappropriate as it has been used to describe a sudden opening movement (Riblet and Mitchell, 1971). It would appear preferable therefore to avoid the term “jaw jerk” in in favour of less ambiguous terminology such as “jaw-closing” reflex or monosynaptic myotatic reflex potential (MSP; Widlam, 1976a and b). The jaw-closing reflex is considered a fundamental phenomenon of the facial and oropharyngeal areas (Dubner, Sessle and Stoery, 1978) as it utilises afferent and efferent components involved in the generation, learning and modulation of programmed jaw movement sequences. Thus the reflex would appear to form the basis of more complex functions such as mastication and swallowing (Sessle, 1981), although the response itself probably appears only infrequently in normal function. A downwards tap delivered to the chin in a relaxed human subject causes muscle stretch and this produces an afferent projection along group Ia and group II pathways (Figure:1) which in turn exert monsynaptic and polysynaptic influences on motoneurones in the trigeminal motor nucleus. Inter-segmental and suprasegmental projections onto alpha and fusimotoneurones located in this motor nucleus (Greenwood and Sessle, 1976; Sessle, 1977a and b) modulate ongoing motoneurone excitability thus influencing the mainifestation of evoked monosynaptic reflexes.

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 119-124).

Thesis (SC. D.)--University of Minnesota, 1917. / Cover title. "Reprinted from Minnesota medicine, July, 1919." Bibliography: p. 40-42.

Thesis (Ph. D.)--University of Pennsylvania, 1902.