Emancipating the forelimbs from locomotion for use in other activities, such as food manipulation, is a major evolutionary milestone. A variety of selective forces and evolutionary correlates may influence the evolution of various degrees of skill with which the forelimbs are used. Using the order Carnivora as a test group, I assesed the relative influence of six factors: relative brain size, neocortical volume, manus proportions, body size, phylogenetic relatedness, type of locomotion and diet. I developed a rating system to describe the dexterity of individual species and compared the scores to the six factors using modern comparative methods. Only phylogeny and diet were significanly correlated with forelimb dexterity. More specifically, forelimb dexterity tends to be higher in caniform than in feliform carnivorans and decreases with increasing specialisation on vertebrate prey. I conclude that food handling and feeding niche breath have a significant effect upon the evolution of skilled forelimb movements. / xii, 151 leaves : ill. ; 28 cm.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1962. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 110-115).

No description available.

No description available.

Because horses are animals of flight, bone fractures in the horses' limbs are quite common. When foals fracture a bone in their leg, the healthy leg is often compromised. During convalescence, the animal tends to overstress the healthy leg in an attempt to relieve the stress on the injured leg. This results in angular limb deformities, lax tendons, laminitis, and similar problems. These problems could possibly be avoided through a load-bearing device that would relieve the additional weight from the foal's limbs. In order to allow for in-vitro testing of such a load-bearing device, this thesis describes the design, analysis, and procedure of construction of a robotic replica of a foal's limb. In particular, the robotic replica has been designed to replicate all of the anticipated motion of a foal's limb, including walking, shifting weight from one leg to the other, and kicking, for example, using gait-analysis data from an actual horse's gait. From such data, the robotic replica has been designed in IDEAS and analyzed using multibody dynamics simulations code and the finite-element-analysis software ANSYS. To evaluate the function of the robotic replica, a control system was developed to reproduce observed gait characteristics. Comparison of the computer-simulated gait with the observed gait showed that a linear feedback control algorithm resulted in a response adequate for the proposed function. The proposed robotic replica has the potential for aiding in the development of several other bioassistive devices. With minor modifications, the robotic replica could be used to test a device design to transfer load from the cannon bone to the ground for an animal inflicted with laminitis (founder). These possibilities should be investigated in the future. / Master of Science

Postural control incorporates multiple neural and mechanical systems at various levels of the motor control system, yet the question of how all these systems interact remains unanswered. This dissertation describes development of a biologically based, three-dimensional mathematical model of the forelimb of the domestic cat that integrates skeletal anatomy, muscular architecture, and neural control. Previous work has shown that muscle architecture profoundly affects its function. However, even though the forelimbs of quadrupeds contribute to posture and locomotion differently from hindlimbs, most models of quadruped motion are based upon hindlimb mechanics. The proposed work consists of three main steps: (1) architectural and anatomical characterization, which involves acquisition of muscle attachment data, measurement of whole muscle and muscle fiber properties, and estimation of limb kinematic parameters; (2) model development and implementation, wherein the data will be integrated into a mathematical model using special-purpose software; and (3) model validation, including verification of model estimates against experimentally obtained measurements of muscle moment arms, and prediction of limb kinetics, namely end-point forces arising from perturbations to the limb. It was found that the forelimb does indeed possess structure, particularly at the shoulder and antebrachium, that allows for more diverse movements. The neural wiring in these regions is more complex than in the hindlimb, and there exists substantial muscular structure in place for non-sagittal motion and object suppression and retrieval. Other results showed that the kinematics of the limb alone produce a restorative response to postural disturbance but that the magnitude is reduced, indicating that neural input acts as a modulatory influence on top of the intrinsic mechanism of limb architecture. Furthermore the model demonstrated many of the essential features found in the experiments. This study represents the implementation of the first forelimb model of the cat incorporating mechanical properties and serves as a key component of a full quadruped model to explore posture and locomotion.

Stroke typically occurs in one hemisphere and often results in long-term disability in the contralateral body side (paretic side). Greater reliance on the non-paretic body side is used to compensate for this disability. Meanwhile, the brain undergoes degenerative and plastic changes in both hemispheres. Many previous studies have investigated post-stroke brain plasticity, and explored how it is shaped by behavioral experiences, to better understand the mechanisms of functional recovery. However, these studies have primarily focused on neurons and synapses. Given the abundant evidence that astrocytes actively control activity and plasticity of synapses, it seems reasonable to investigate how astrocytes are involved in behavior- and injury-driven brain plasticity. The central hypothesis of these studies is that synaptic plasticity underlying motor skill learning and post-stroke motor rehabilitation is coordinated with structural and functional plasticity of perisynaptic astrocytes. This was tested in a rat model of motor learning and "re-learning" after unilateral stroke-like damage to sensorimotor cortex. In the contralesional homotopic cortex, astrocytic volume varied with lesion size, as did the number of synapses. In the remaining motor cortex of the injured hemisphere, rehabilitative training with the paretic limb increased the proportion of astrocytic membrane apposed with synapses along with density of synapses. Furthermore, the percentage of synapses with astrocytic contacts was significantly correlated with functional outcome. Training with the non-paretic limb also induced greater synaptic density than controls in peri-infarct cortex, but functional outcome was negatively correlated with this and was not correlated with astrocytic contacts with synapses. These findings suggest that plasticity of, and association between, synapses and astrocytes vary with the type of experiences. Moreover, pharmacological upregulation of astrocytic glutamate uptake, which is one of the key ways that astrocytes modulate synaptic activity, interfered with functional recovery, supporting a critical role for astrocytic glutamate uptake in functional outcome following a stroke. Taken together, these studies contribute to better understanding of how lesions and experiences affect plasticity of astrocytes and synapses. These findings suggest that post-injury experiences alter astrocytic association with synapses, and that the coordinated plasticity of astrocytes and synapses is likely to be a critical mediator to functional outcome. / text

La position des membres le long du corps est reproductible chez une même espèce mais est très variable entre différentes espèces. Comment les membres acquièrent leur position et quel mécanisme est à l'origine de ces variations est à ce jour non élucidé. De part leur rôle dans la mise en place des axes embryonnaires, les gènes Hox sont depuis longtemps suspectés de jouer un rôle dans ce processus. Cependant les différentes preuves disponibles à ce jour restent indirectes et corrélatives. Chez l'embryon de poulet, je montre que la position des membres est établit précocement au cours du développement, lors de la gastrulation. Je démontre que la formation de la lame latérale (i.e. le tissue d'origine des membres) est un processus graduel et que l'activation séquentielle des gènes Hox spécifie ce tissue en domaines du membre et du flanc. Dans un second temps, une combinaison d'actions activatrice et répressive des gènes Hox sur le programme d'initiation du membre, actions liées à leur organisation colinéaire, est critique pour l'organisation de la lame latérale en domaines du membre et du flanc. Enfin, en étudiant des embryons de différentes espèces d'oiseaux présentant des variations dans la longueur de leur cou et donc dans la position de leur ailes (le poulet, l'autruche et le diamant mandarin), je montre que des changements relatifs dans la séquence d'activation colinéaire des gènes Hox au cours de la gastrulation sous-tendent les variations naturelles de la position de l'aile. L'ensemble de ces résultats montre que les gènes Hox jouent un rôle direct et précoce dans le positionnement des membres et propose un model général de mise en place d'un organisme par ces gènes. / Limb position along the main body axis is highly consistent within one species but very variable among tetrapods. Despite major advances in our understanding of limb patterning in three dimensions, how limbs reproducibly form along the anteroposterior axis remains largely unknown. Hox genes have long been suspected to play a role in this process, however supporting evidences are mostly correlative and a direct role has yet to be demonstrated. Here, using bird embryos, I show that limb position is established very early during development, during the process of gastrulation. I find that the formation of the Lateral Plate Mesoderm (i.e. the embryonic compartment from which limbs will form) is a progressive process and that co-linear activation of Hox genes sequentially patterns it along the antero-posterior axis. Subsequent combinatorial activation and repression activities of Hox genes on limb initiation are particularly critical to pattern the LPM into limb- and non-limb-forming domains. Finally, by analyzing chicken, zebra finch and ostrich embryos which exhibit variation in their forelimb position, I show that relative changes in the timing of co-linear Hox gene activation during gastrulation underlie variation in limb position. Altogether these result shed light on the cellular and molecular mechanism that regulate limb position by showing a direct and early role for Hox genes in this process during gastrulation and provide a mechanism for variation in body plan organization observed in tetrapods.

Orientador: Cecilia Amelia de Carvalho Zavaglia / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-14T13:19:50Z (GMT). No. of bitstreams: 1 Polis_JoaoEduardo_M.pdf: 6036142 bytes, checksum: dadf234cb5c40223223dbe5c453fce7a (MD5) Previous issue date: 2009 / Resumo: Devido ao grande número de pessoas que necessitam do uso de prótese para substituir um membro com seu funcionamento normal afetado, seja por deficiência congênita ou nos casos em que haja necessidade de remoção, ocasionada por doenças ou lesões com trauma, como acidentes do trabalho e de trânsito, foi desenvolvido neste trabalho o projeto e construção da parte estrutural de uma prótese de mão humana, com dimensões e movimentos mecânicos em similaridade (física) com o membro original. Em analogia com uma máquina, a mão é uma ferramenta terminal com atuadores exercendo várias funções como preensão de objetos, movimentação, sensibilidade à textura e temperatura. Entre os membros superiores, é o mais utilizado, exposto e complexo, que quando demanda sua substituição por uma prótese encontra obstáculos em várias áreas, desde aspectos tecnológicos, morfológicos, psicológicos e ainda financeiros. O mercado mundial de próteses dispõe de modelos com tecnologia avançada, que oferecem grande gama de recursos, mas por se tratar de um produto que ainda não é produzido em larga escala, que possui componentes de alta tecnologia e alto custo, não atinge o grande número de pessoas que necessitam da sua utilização. A pesquisa desenvolvida neste trabalho adotou uma metodologia de projeto que buscou a facilidade de construção e a utilização de componentes e matérias-primas disponíveis no mercado e de custo relativamente baixo, podendo assim desenvolver a base estrutural de um produto em desenvolvimento, que incorporará em suas etapas futuras as áreas de motorização, sensorização e revestimento cosmético, visando a obtenção de uma prótese de mão humana que realize movimentos atendendo a impulsos mioelétricos gerados pelo paciente, e que seu custo final de construção, variedade de movimentos e praticidade na colocação viabilizem sua utilização por um maior número de pessoas. / Abstract: The number of handicapped people in need of a particular kind of prosthesis is a compelling reason for carrying out this study, for developing a design and fabrication of a human forelimb prosthesis with dimensions and mechanical movements in similarity (physical) with a human hand. Some of theses handicaps may be a result of accidents, congenital diseases, injuries, or even amputations. Analogous to a machine, a hand is a sensitive terminal tool that is able to grip, move, feel and measure temperatures of objects. It is a very useful and complex member of the human body, and when is necessary to replace it with a prosthesis, there are technological, morphological, psychological and also financial barriers. The world market of prosthesis offers high technology models and a very wide range of resources. However, these products are made of expensive hi-tech components. Moreover, most people cannot afford to buy these expensive products because there is still no large-scale production. Thus, this research project aims at building a prosthetic forelimb with dimensions and mechanical movements similar to those of the human hand, using relatively low cost components and raw materials for manufacturing the final product. This new prosthesis has sensitized "nerve" endings, cosmetic coating, and it is also motorized. It responds to myoelectric impulses generated by the patient. In addition, it is cheap, practical, and it has a variety of movements witch allow it to be used by a large number of people. / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

No description available.