No description available.

No description available.

No description available.

No description available.

The purpose of this thesis is to study aspects of the function of the primary sensory endings of muscle spindles using morphometric and immunohistochemical techniques. For morphometry the right tenuissimus muscles of three adult cats, whose right hind limbs were fixed with the hip and knee flexed at various acute angles, have been compareed with the corresponding muscles from the fully extended left hind limbs of the same animals. The aim of this project is a better understanding of morphometric changes in the muscle spindle including intrafusal fibre diameter, sarcomere length, and (in particular) changes in the primary nerve endings in response to passive stretch. Immunohistochemical studies of the calcium-binding protein, calretinin, and immunogold labelling for glutamate were also carried out on the primary nerve endings as detailed below. All the work reported in this thesis was carried out in the School of Biological and Biomedical Sciences, at the University of Durham. This thesis is divided into five chapters. Chapter one is an introduction to the structure and innervation of the muscle spindle andtendon organ, discussing briefly the presence of calretinin and glutamate in muscle spindle nerve endings. This provides general introduction and background to the work. Chapter two describes the deformation of the nerve endings in the muscle spindle when the cat tenuissimus muscle is subjected to different degrees of flexion of the hip and knee on the experimental side, the control side being extended so that the angles between the hip and the knee were approximately equal in the each case. For rapid and optimum fixation, both sides were perfused with fixative solution. The results show morphometric changes in the experimental muscles compared with the controls in tem1s of diameter, sarcomere length, and sensory nerve terminal deformation. Muscle fibres in the experimental (flexed) side have a greater diameter, and shorter sarcomeres, with nerve endings more indented into the intrafusal fibres, compared with those on the extended, control side. Nuclei of the equatorial region in both the experimental and control muscles differed in arrangements of nuclei and their outline. Chapter three discusses the calcium-binding proteins, with the emphasis on calretinin and its distribution in the nerve endings of rat muscle spindles and tendon organs as shown by histochemical examination of rat soleus muscle. The calretinin distribution was evident in the primary endings of both bag 1 and bag2 fibres and also in the primary endings of the chain fibres, although no secondary endings or tendon organs were observed.Chapter four describes quantitative immunological study carried out on the muscle spindle of the cat tenuissimus muscle to assess the comparative level of glutamate -like immunoreactivity in the equatorial region of the primary nerve endings, and their associated intrafusal fibres, were all found to show less glutamate -LI compared with the secondary nerve endings and their associated intrafusal fibre, but not the intrafusal fibrenuclei. In chapter five the results are summarised, and possible further studies outlined.

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No description available.

One of the unique advantages of human gait is that it can be perceived from a distance. A varied range of research has been undertaken within the field of gait recognition. However, in almost all circumstances subjects have been constrained to walk fronto-parallel to the camera with a single walking speed. In this thesis we show that gait has sufficient properties that allows us to exploit the structure of articulated leg motion within single view sequences, in order to remove the unknown subject pose and reconstruct the underlying gait signature, with no prior knowledge of the camera calibration. Articulated leg motion is approximately planar, since almost all of the perceived motion is contained within a single limb swing plane. The variation of motion out of this plane is subtle and negligible in comparison to this major plane of motion. Subsequently, we can model human motion by employing a cardboard person assumption. A subject's body and leg segments may be represented by repeating spatio-temporal motion patterns within a set of bilaterally symmetric limb planes. The static features of gait are defined as quantities that remain invariant over the full range of walking motions. In total, we have identified nine static features of articulated leg motion, corresponding to the fronto-parallel view of gait, that remain invariant to the differences in the mode of subject motion. These features are hypothetically unique to each individual, thus can be used as suitable parameters for biometric identification. We develop a stratified approach to linear trajectory gait reconstruction that uses the rigid bone lengths of planar articulated leg motion in order to reconstruct the fronto-parallel view of gait. Furthermore, subject motion commonly occurs within a fixed ground plane and is imaged by a static camera. In general, people tend to walk in straight lines with constant velocity. Imaged gait can then be split piecewise into natural segments of linear motion. If two or more sufficiently different imaged trajectories are available then the calibration of the camera can be determined. Subsequently, the total pattern of gait motion can be globally parameterised for all subjects within an image sequence. We present the details of a sparse method that computes the maximum likelihood estimate of this set of parameters, then conclude with a reconstruction error analysis corresponding to an example image sequence of subject motion.

The aim of this programme of work was to examine how the manipulation of organismic and task constraints affected movement variability during a basketball shooting task. The specific constraints that were manipulated included task expertise, state anxiety and dioptric blur (organismic constraints), and, shooting distance and attentional focus instruction (task constraints). The aim of Study 1 was to investigate the effect of shooting distance and task expertise on movement variability. Task expertise was characterised by decreased coordination variability and heightened compensatory variability between wrist, elbow and shoulder joints. However, no significant difference was found in joint angle variability at release as a function of task expertise. There was no significant change in movement variability with shooting distance, a finding that was consistent across all expertise groups. In Study 2, the aims were to examine the effect of induced dioptric blur on shooting performance and movement variability during basketball free-throw shooting, and, to ascertain whether task expertise plays a mediating role in the capacity to stabilise performance against impaired visual information. Significant improvements in shooting performance were noted with the introduction of moderate visual blur (+1.00 and +2.00 D). This performance change was evident in both expert and novice performers. Only with the onset of substantial dioptric blur (+3.00 D), equivalent to the legal blindness limit, was there a significant decrease in coordination variability. Despite the change in coordination variability at +3.00 D, there was no significant difference in shooting performance when compared to the baseline condition. The aims of Study 3 were to examine the effect of elevated anxiety on shooting performance and movement variability and, again, to determine whether task expertise plays a mediating role in stabilising performance and movement kinematics against perturbation from emotional fluctuations. Commensurate with the results of Study 2, both expert and novice performers were able to stabilise performance and movement kinematics, this time with elevated anxiety. Stabilisation was achieved through the allocation of additional attentional resources to the task. Study 4, had two aims. The first was to examine the interactive effects of practice and focus of attention on both performance and learning of an accuracy-based, discrete multi-articular action. The second was to identify potential focus-dependent changes on joint kinematics, intra-limb coordination and coordination variability. Support was found for the role of an external focus of attention on shooting performance during both acquisition and retention. However, there was evidence to suggest that internal focus instruction could play a pivotal role in shaping emerging patterns of intra-limb coordination and channelling the learners‟ search towards a smaller range of kinematic solutions within the perceptual-motor workspace. Collectively, this programme of work consistently highlighted the fundamental role that constraints play in governing shooting performance, movement variability and, more broadly, perceptual-motor organisation. For instance, task expertise was characterised by decreased coordination variability and heightened compensatory control. However, in light of the data pertaining to joint angle variability at release, general assumptions about expertise-variability relations cannot be made and should be viewed with caution. In addition, there is strong evidence to suggest that adaptation to constraints is, perhaps, a universal human response, and consequently not mediated by task expertise. Further research is needed to fully elucidate this proposition.

Movement at the subtalar joint is believed to be a fundamental contributor to foot function during walking. The complex structure and movement, and inaccessibility of the joint have resulted in limited published data with which to substantiate or refute theories regarding its movement during walking. This study investigated the use of the CODA M PX30 three d imensional motion analysis system and a purpose designed marker placement model as a strategy for measuring the movement of the subtalar joint during the contact phase of walking. The in vitro reliability of the measurement strategy was tested and the combination of the CODA M PX30 and the marker placement model shown to be reliable. The effect of skin movement on surface marker location was investigated. Although markers were shown to move relative to the bones, angular orientations calculated from marker positions were shown to be representative of those calculated directly from the bones. The in vivo reliability of the measurement strategy was tested using multiple data sets from a single subject. Results showed the measurement strategy to be reliable and to produce results comparable to previous published data. Subsequent testing on m u ltiple subjects produced a similar outcome. The novel measurement strategy described in this study was shown to be a valid non-invasive, i n vivo method of assessing the movement of the subtalar joint during the contact phase of walking.