No description available.

No description available.

There is growing knowledge that neuronal circuitry undergoes alteration throughout development. Experience plays a key role in the reorganization of neuronal circuitry through the various mechanisms of learning. For example, when an animal is deprived of sensory input such as light in one or both sides of the eye, it can result in blindness on that side. In a study of rats placed in either isolated or enriched environments, those placed in enriched environments performed better on learning tests (maze test) than those placed in isolated environment. There was increased neurogenesis, synaptogenesis, myelination and angiogenesis in rats placed in enriched environments. These were all as a result of learning, which induces neuroplasticity in the nervous system. The goals of this study were to determine how evoked movement is altered by changes in key parameters of light stimulation: intensity and period and to determine if one hour of light (optogenetic) stimulation could give rise to plastic changes in the nervous system as indicated by alterations in spontaneous motility. To ascertain how evoked motor activity influences neuronal activity through learning and experience, optogenetics was employed to evoke movement in an embryonic chick at embryonic day nine (E9) after electroporation of a channelrhodopsin variant, ChIEF, into the neural tube. I first attempted to determine the optimal intensity needed to cause neuroplasticity in an embryonic chick by varying current to a LED light to produce three different light intensities. A protocol of 5 pulses of light with a period of 2 seconds was used to illuminate the right leg of 5 embryonic chicks with each intensity. To determine the optimal period of stimulation, I varied the period to 3 s and 4 s with one animal. Stimulation for an hour with a training protocol of 1800 pulses/hour (with a period of 2 s) of blue light (470 nm) was then used to illuminate the right thigh of the embryonic chick. There were varied responses to light of all intensities used for stimulation, but high light intensity (maximum - 100%) seemed to have produced the best responses in terms of producing the largest joint angle changes and shortest latencies of movement in all joints of the leg of embryonic chick. Movements of the hip and ankle joints were the most robust. This was closely followed by those of the mid (83.33%) intensity. Therefore, it can be inferred that the greater the intensity of light, the better the response. The training protocol did not produce significant changes in embryonic activity. There were some decreases in joint angles and variable spontaneous movement duration in all animals used but there could be some changes going on at the neuronal or muscular level which were beyond the scope of this study to investigate. It is my hope that this study will provide some knowledge pertinent to the treatment or management of neurodevelopmental disorders that may result in paraplegia or Erb's palsy.

The human motor system exhibits remarkable adaptability, enabling us to maintain high levels of performance despite ever-changing requirements. There are many potential sources of error duringmovement to which the motor system may need to adapt: the properties of our bodies or tools may vary over time, either at a dynamic or a kinematic level; our senses may become miscalibrated over time and mislead us as to the state of our bodies or the true location of an intended goal; the relationship between sensory stimuli and movement goals may change. Despite these many varied ways in which our movements may be disturbed, existing models of human motor adaptation have tended to assume just a single adaptive component. In this thesis, I argue that the motor system maintains multiple components of adaptation, corresponding to the multiple potential sources of error to which we are exposed. I outline some of the shortcomings of existing adaptation models in scenarious where multiple kinds of disturbances may be present - in particular examining how different distal learning problems associated with different classes of disturbance can affect adaptation within alternative cerebellar-based learning architectures - and outline the computational challenges associated with extending these existing models. Focusing on the specific problem in which the potential disturbances are miscalibrations of vision and proprioception and changes in arm dynamics during reaching, a unified model of sensory and motor adaptation is derived based on the principle of Bayesian estimation of the disturbances given noisy observations. This model is able to account parsimoniously for previously reported patterns of sensory and motor adaptation during exposure to shifted visual feedback. However the model additionally makes the novel and surprising prediction that adaptation to a force field will also result in sensory adaptation. These predictions are confirmed experimentally. The success of the model strongly supports the idea that the motor system maintains multiple components of adaptation, which it updates according to the principles of Bayesian estimation.

The larynx is the mammalian organ of vocalization. Humans have a degree of control over this organ considerably beyond the abilities of other primates, most notably in our control over the larynx during speech. Although there is an abundance of research on the neural basis of speech, relatively little of this research has focused on the control of the larynx. First, I performed a meta-analysis to search for brain areas responsible for making explicit judgments about affective prosody to identify candidate premotor areas in prefrontal cortex that may also plan the affective component of affective prosody (Chapter 2). The inferior frontal gyrus pars orbitalis was the only prefrontal region preferentially engaged by affective vocalizations. Second, I used functional magnetic resonance imaging to determine whether there are discrete neural systems for producing innate-affective versus arbitrary non-affective vocalizations in the human brain, as has been predicted from non-human primate models (Chapter 3). The vocal-motor system demonstrated a lack of specialization since both types of vocalizations engaged the entire network. Third, I searched for brain areas that were preferentially engaged during vocal imitation (Chapter 4), which is a key process in vocal learning. Vocal imitation preferentially engaged a cortico-striate network similar to that predicted from avian models of vocal imitation. Finally, I performed a meta-analysis to explore the neural basis of persistent developmental stuttering (Chapter 5), a speech disorder that is associated with poor control of the laryngeal muscles. Among other brain areas, primary motor regions controlling the larynx were abnormally activated in the brains of people who stutter. Together these studies advance our knowledge of the human vocal-motor system, how it relates to that in other species, and how this system may be disrupted in persistent developmental stuttering. I discuss remaining gaps in our knowledge that will be the focus of my future research. / Dissertation / Doctor of Philosophy (PhD) / One hallmark of the human species is our ability to talk. This dissertation describes a body of research that uses modern brain imaging technology ¬to study the brain systems that underlie this ability in humans –referred to as the vocal-motor system. It then compares this system in humans to the closest equivalent in monkeys, since monkeys lack this ability but share relatively recent common ancestry with humans. It also makes comparisons with the brains of songbirds, since the ability of juvenile songbirds to learn songs may share similarities with the human ability to learn speech. Finally, it looks at the potential dysfunction of this system in the brains of people who stutter.

Elite swimmers can be distinguished from novice swimmers by freestyle stroke technique. Elite swimmers move through multiple coordination modes, increases in stroke lengths, stroke rates, and body roll allowing for a more symmetrical stroke and increased speed compared with novice swimmer during 100m freestyle. Coaches strive to improve swimmers’ performance by providing feedback about stroke technique, mostly from the pool deck where view of the full stroke cycle is obstructed by the water. Tools to assess swimming are often expensive and require extra training, which does not provide a pragmatic solution. A dryland rotational swimbench would provide a means to evaluate freestyle swimming. The aim of the present study is to evaluate the sensory motor system of elite and novice level swimmers by comparing kinematic, coordinative structures and spatial-temporal characteristics of freestyle stroke on a dryland swimbench with a rotational component. Thirty elite and novice collegiate and masters swimmers were instrumented with reflective markers bilaterally on the upper extremity and torso. A series of four ten second trials of freestyle sprint swimming were performed on the swimbench. Repeated measures were used for statistical analysis for comparison between and within groups. Bonferroni corrections were used as post-hoc analysis. Results indicated no significant difference between elite and novice swimmers’ sensory-motor system, kinematics or spatio-temporal systems on a rotational swimbench. Similarities could be accounted for by swimmers perceiving a novel task due to differences in sensory feedback, and mechanical limitations of the bench. It is noteworthy that catch-up/opposition coordination are more common than superposition which provides support for the swimbench providing a more similar representation to in water swimming.

The current thesis explores semantic and action effects on visual perception and specifically how higher-level knowledge can co-affect the process of visual perception, along with the well established effects of low level image characteristics, such as colour, image/object saliency and general gist of the scene. Recent evidence on object recognition supports perceptual grouping effects of familiar pairings of functionally interacting objects. This leads to an advantage for their perception as compared with objects positioned in a non-interacting configuration, in cases where there are attentional limitations in perception. Similar effects were previously reported in clinical cases of people diagnosed with neglect (Humphreys & Riddoch, 2001, 2007; Riddoch et al, 2003, 2006), but the fact that they are also present in normally functioning individuals (Green & Hummel, 2006) makes them a clear example of higher order effects on perception. Given the evidence about the abstract nature of the information stored in visual memory and the fact that orientation is part of the spatial information related to an object representation, our first series of experiments aimed at further exploring the nature of this perceptual grouping and whether objects separation would have an effect on it. By combining this paradigm with a paradigm used to explore linguistic factors of perceiving space (Carlson-Radvansky & Radvansky, 1996; Carlson-Radvansky, Covey & Lattanzi, 1999; Carlson-Radvansky & Tang, 2000), we additionally explored the effect of functional interactions at higher levels of post-perceptual processing. We manipulated the locations of various pairs of objects as well as the semantic and functional relationship between them to explore if spatial configurations affect the way people talk about the relationship of the objects in the same way as they affect the same objects‟ recognition. The results revealed a difference, with the same distance manipulation affecting linguistic descriptions of spatial relationships between pairs of objects but having no effect in their perceptual grouping. One of the aims of this thesis is the interpretation of such effects according to a recently growing body of evidence on the interaction between action and perception systems. These systems which were traditionally considered to be two separate disciplines seem to connect, with information from action systems feeding on perceptual systems. Through such an interaction, for example, information about the functionally related objects could lead to their perceptual grouping. A series of experiments have demonstrated effects of action affordances on object perception and their combined results seem to imply pre-attentive effects on object perception independent of the person‟s intention to act on an object (Riddoch, Humphreys, Edwards, Baker & Wilson, 2002; Tipper, Paul & Hayes, 2006; Symes, Ellis & Tucker, 2007).To further explore the role of functional relationships and action affordances in natural scene viewing, a second series of experiments was designed. These experiments also provided evidence to an old debate about the nature of visual memory and its organisation, adding further evidence for the role of semantic relationship and action affordances in the memory encoding of a scene. This series of experiments took advantage of the phenomenon of object prioritization during unexpected object onsets or feature changes while viewing real world scenes (Brockmole & Henderson, 2005a). Using a variation of classic change detection paradigms, eye-tracking data were recorded to measure at which point action affordance manipulations would have an effect and to reveal whether object functionality changes can still produce attention capture (quantified as fixation probability to the object of interest), similarly to previously tested semantic changes. Functionality manipulation was achieved by orientation changes of a critical object in the scene, but in a way which constitutes it non functional to the specific context. By comparing action affordance interference during object onsets against interference during object orientation changes we differentiated between pre-attentive and post-selection mechanisms. Our results indicate that although there is no evidence of pre-attentive modulation of object prioritization, action affordances do have an effect in post-selection mechanisms, with functionally inconsistent objects attracting attention faster and affecting the encoding of an object in the scene representation during memory guided prioritization but not during oculomotor capture. Our results also support the existence of two separate mechanisms for object prioritization. As a summary, this family of semantic relationships, action affordances and the interplay between action and perception systems has been tested during my PhD research from the very early stages of perception until post perceptual and linguistic accounts of the perceived image. Their role in attention capture and their mediating role to visual memory have also been explored using eye-tracking technology and realistic and rich in information real world scenes. Overall my thesis is oriented towards the aspects that tie all these effects together and further explores the role of action affordances in memory encoding.

During these decades, Permanent Magnet Synchronous Motor (PMSM) has become a vital part of military, industry and civil applications due to the advantages of high power density, high efficiency, high reliability and simple structure, small volume and light weight. Sometimes, multiple PMSMs are used to carry out cooperative functions. For example, the bogie of a locomotive, the flight control surface of an airplane. These PMSMs usually operates at the same speed. To reduce the volume and weight, an idea of sharing the static power conversion devices, which is called Mono-Inverter Multi-PMSM system (MIMPMSM), is raised. Although many researchers have given different controller solutions for the MIMPMSM system, most of them are not clear in the aspects of system stability and efficiency issues. This has become the biggest obstacle to the practical use of MIMPMSM. Oriented with these problems, starting with a MIMPMSM system with 2 motors, in the first step, we have tested some control strategies by an experiment to verify the feasibility and performance of them. In final, based on the experiment data, we have figured that the overconstraint problem exists in some control strategies. Then, an analysis and controller design based on steady-state model of a Mono-Inverter Dual-PMSM (MIDPMSM) system is carried out.By studying the solution existence problem of the steady-state model, we give out the design guideline to the controller structure. Combining the open-loop stability and steady-state solution, the region of controllability and stability is obtained. Lagrange Multiplier is used develop theexpression of efficiency-optimal steady-staterelated to torque and speed. The experiment has shown that the efficiency of the new controller has improved significantly. Meanwhile, we have explored the influence of parameter variation in system stability and efficiency-optimization. The variation will influence the stability region. But its influence can be eliminated by using Master- Slave strategy. On the other hand, in the aspect of efficiency optimization, the simulation results have shown that parameter mismatch, especially the permeant flux, can cause high efficiency loss. In the last step, this controller is also adapted to a MIMPMSM system with more than two motors. The simulation results demonstrate the effectiveness.

In this thesis, I present my work on the modeling and control of a motor system using the Lego EV3 robot. The overall goal is to apply introductory systems and controls engineering techniques for estimation and design to a real-world system. First I detail the setup of materials used in this research: the hardware used was the Lego EV3 robot; the software used was the Student 2014 version of Simulink; a wireless network was used to communicate between them using a Netgear WNA1100 wifi dongle. Next I explain the approaches used to model the robot’s motor system: from a description of the basic system components, to data collection through experimentation with a proportionally controlled feedback loop, to parameter estimation (through time-domain specification relationships, Matlab’s curve-fitting toolbox, and a formal least-squares parameter estimation), to the discovery of the effects of frictional disturbance and saturation, and finally to the selection and verification of the final model through comparisons of simulated step responses of the estimated models to the actual time response of the motor system. Next I explore three different types of controllers for use within the motor system: a proportional controller, a lead compensator, and a PID controller. I catalogue the design and performance results – both in simulation and on the real system – of each controller. One controller is then selected to be used within two Controls Systems Engineering final course projects, both involving the robot traveling along a predetermined route. The controller’s performance is analyzed to determine whether it improves upon the accumulation of error in the robot’s position when the projects are executed without control.

No description available.