Anodal transcranial direct current stimulation (tDCS) is an intervention which is thought to enhance motor learning in healthy and stroke-injured states, when applied adjunctively during skill learning. We set out to investigate whether anodal tDCS might enhance functional rehabilitation from incomplete tetraplegic SCI. To address current limitations in the measurement of task-dependent skill, a novel integrated skill training and measurement task, the Motor Skill Rehabilitation Task (MSRT) was designed and developed. Measures of performance from this task delivered the functional measure of spatial motor skill learning, Task Productivity Rate (TPR). TPR was analysed and validated as a univariate dependent outcome, which is of potential importance to the future development of clinical measures measuring goal-directed motor skills. The MSRT was included alongside conventional behavioural measures in a repeated-measures RCT pilot study, the first to investigate the effect of anodal tDCS on rehabilitation of motor skill from chronic spinal cord injury. Adjunctive application of anodal tDCS had a statistically significant benefit upon retention of skill in the incomplete spinal cord injured population, but only when the independent factor of sensory acuity was included in the analysis. Differences between the development of task-dependent skill and generic dexterity over time suggested that spatial skill development was subject to an interaction of short-term and lasting effects. A larger study in healthy persons further investigated these phenomena, also applying Transcranial Magnetic Stimulation (TMS)–evoked measurements to investigate intervention-dependent effects upon the excitability of projections between the primary motor cortex and muscles involved in the prehension task. The findings revealed that active tDCS did not enhance skill learning at 7 days beyond the training period, but did significantly alter the development of motor skill following a period of learning and subsequent skill consolidation which was associated with underlying perturbation of motor control strategy. Significant and divergent patterns of cortical plasticity were evoked in projections to muscles necessary for reaching and grasping. The main findings of this thesis do not support anodal tDCS as an effective adjunctive means of enhancing spatial motor skill in rehabilitation from incomplete tetraplegic SCI. If applied in patient populations, the clinical benefits of anodal tDCS may be contingent both on the nature of the sensorimotor deficit affecting upper limb function and the spatial demands of the behavioural task. The findings of this project serve to inform further research in relation to the effect of anodal tDCS on the brain and behavioural outcomes, the potential for efficacy in target patient groups and the sensitivity of outcome measures to spatial and temporal dimensions of practical motor skills.

Movement is essential to human life because it provides us with the freedom of mobility and the power to affect our surroundings. Moreover, movements are vital to communication: from hand and finger movements when writing, mouth and throat movements when speaking, to painting, dancing, and other forms of artistic self expression. As people grow and experience new environments, adaptively maintaining the accuracy of movements is a critical function of the motor system. In this dissertation, I explore the key mechanisms that underlie the adaptability of simple visually guided reaching movements. I specifically focus on two key facets of this adaptability: how motor learning rate can be predicted by motor variability and how motor learning affects the mechanisms which underlie movement planning. Inspired by reinforcement learning, I hypothesized that greater amounts of motor variability aligned with a task will produce more effective exploration, leading to faster learning rates. I discovered that this relationship predicts person-to-person and task-to-task differences in learning rate for both reward-based and error-based learning tasks. Moreover, I found that the motor system actively and enduringly reshapes motor output variability, aligning it with a task to improve learning. These results indicate that the structure of motor variability is an activelyregulated, critical feature of the motor system which plays a fundamental role in determining motor learning ability. Combining prominent theories in motor control, I created a model which describes the planning of visually guided reaching movements. This model computes a weighted average of two independent feature-based motor plans: one based on the goal location of a movement, and the other based on an intended movement vector. Employing this model to characterize the generalization of adaptation to movements and movement sequences, I find that both features, movement vector and goal location, contribute significantly to movement planning, and that each feature is remapped by motor adaptation. My results show that multiple features contribute to the planning of both point-to-point and sequential reaching movements. Moreover, a computational model which is based on the remapping of multiple features accurately predicts how visuomotor adaptation affects the planning of movement sequences. / Engineering and Applied Sciences

The early years of a child's growth and development are crucial for health, wellbeing and success in later life. Adequate stimulation during the pre-school years is a critical factor that can be associated with higher levels of achievement and better adjustment in school (Arnold, Barlett., Gowani, & Merali, 2006). Some children, for example those growing in contexts of adversity, are in particular need of pre-school assistance. This research evaluates a one-year implementation of the Psychomotor Education Programme (PMEP) at the Dalton Trust Education Centre, KwaZulu-Natal, South Africa. PMEP is an educational programme that stimulates the child‟s psychomotor functions and supports the development of the whole child through play in the pre-school years. An evaluation of the programme was required to establish if the PMEP had achieved the envisaged objectives of improving preparedness of children for their entrance into the formal school system. This summative evaluation used focus group discussions to collect data on whether the outcomes had been achieved from the perspective of the trained and experienced family facilitators who had participated in the PMEP. The participants were asked about the strengths, weaknesses, opportunities and threats of the PMEP. The areas identified as being attributable to the PMEP include social-emotional competence, self-awareness, emotional regulation and autonomy. The participants reported that PMEP had enabled the children to achieve the learning outcomes described by the Revised National Curriculum Statement (South African Department of Education, 2005). However, further research is needed to overcome the difficulty of maintaining the achieved outcomes in a new environment, such as the formal school context, where methods of teaching and resources may differ substantially from those provided by the PMEP. / Thesis (M.Soc.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

Ten experiments examined the interactions between vision and audition in stimulusdriven spatial attention orienting and inhibition of return (IOR). IOR is the demonstration that subjects are slower to respond to stimuli that are presented at a previously stimulated location. In each experiment, subjects made go/no-go responses to peripheral targets but not to central targets. On every trial, a target was preceded by a sensory event, called a "cue," either in the same modality (intramodal conditions) or in a different modality (crossmodal conditions). The cue did not predict the location of the target stimulus in any experiment. In some experiments, the cue and target modalities were fixed and different. Under these conditions, response times to a visual target were shorter when it appeared at the same location as an auditory cue than when it appeared on the opposite side of fixation, particularly at short (100 ms) cue-target stimulus onset asynchronies (Experiments 1A and IB). Similarly, response times to an auditory target were shorter when it appeared at the same location as a visual cue than when it appeared at a location on the opposite side of fixation (Experiments 2A and 2B). These crossmodal effects indicate that stimulus-driven spatial attention orienting might arise from a single supramodal brain mechanism. IOR was not observed in either crossmodal experiment indicating that it might arise from modality specific mechanisms. However, for many subjects, IOR did occur between auditory cues and visual targets (Experiments 3A and 3B) and between visual cues and auditory targets (Experiment 4A and 4B) when the target could appear in the same modality as the cue on half of the trials. Finally, the crossmodal effects of stimulus-driven spatial attention orienting on auditory and visual event-related brain potentials (ERPs) were examined in the final two experiments. Auditory cues modulated the ERPs to visual targets and visual cues modulated the ERPs to auditory targets, demonstrating that the mechanisms for spatial attention orienting cannot be completely modality specific. However, these crossmodal ERP effects were very different from each other indicating that the mechanisms for spatial attention orienting cannot be completely shared.

No description available.

The motor nervous system is one of the main systems of the body and is our principle means ofbehavior. Some of the most debilitating and wide spread disorders are motor systempathologies. In particular the basal ganglia are complex networks of the brain that control someaspects of movement in all vertebrates. Although these networks have been extensively studied,lack of proper methods to study them on a system level has hindered the process ofunderstanding what they do and how they do it. In order to facilitate this process I have usedcomputational models as an approach that can faithfully take into account many aspects of ahigh dimensional multi faceted system.In order to minimize the complexity of the system, I first took agnathan fish and amphibians asmodeling animals. These animals have rather simple neuronal networks and have been wellstudied so that developing their biologically plausible models is more feasible. I developedmodels of sensory motor transformation centers that are capable of generating basic behaviorsof approach, avoidance and escape. The networks in these models used a similar layeredstructure having a sensory map in one layer and a motor map on other layers. The visualinformation was received as place coded information, but was converted into population codedand ultimately into rate coded signals usable for muscle contractions.In parallel to developing models of visuomotor centers, I developed a novel model of the basalganglia. The model suggests that a subsystem of the basal ganglia is in charge of resolvingconflicts between motor programs suggested by different motor centers in the nervous system.This subsystem that is composed of the subthalamic nucleus and pallidum is called thearbitration system. Another subsystem of the basal ganglia called the extension system which iscomposed of the striatum and pallidum can bias decisions made by an animal towards theactions leading to lower cost and higher outcome by learning to associate proper actions todifferent states. Such states are generally complex states and the novel hypothesis I developedsuggests that the extension system is capable of learning such complex states and linking themto appropriate actions. In this framework, striatal neurons play the role of conjunction (BooleanAND) neurons while pallidal neurons can be envisioned as disjunction (Boolean OR) neurons.In the next set of experiments I tried to take the idea of basal ganglia subsystems to a new levelby dividing the rodent arbitration system into two functional subunits. A rostral group of ratpallidal neurons form dense local inhibition among themselves and even send inhibitoryprojections to the caudal segment. The caudal segment does not project back to its rostralcounterpart, but both segments send inhibitory projections to the output nuclei of the rat basalganglia i.e. the entopeduncular nucleus and substantia nigra. The rostral subsystems is capableof precisely detecting one (or several) components of a rudimentary action and suppress othercomponents. The components that are reinforced are those which lead to rewarding stateswhereas those that are suppressed are those which do not. The hypothesis explains neuronalmechanisms involved in this process and suggests that this subsystem is a means of generatingsimple but precise movements (such as using a single digit) from innate crude actions that theanimal can perform even at birth (such as general movement of the whole limb). In this way, therostral subsystem may play important role in exploration based learning.In an attempt to more precisely describe the relation between the arbitration and extensionsystems, we investigated the effect of dynamic synapses between subthalamic, pallidal andstriatal neurons and output neurons of the basal ganglia. The results imply that output neuronsare sensitive to striatal bursts and pallidal irregular firing. They also suggest that few striatalneurons are enough to fully suppress output neurons. Finally the results show that the globuspallidus exerts its effect on output neurons by direct inhibition rather than indirect influence viathe subthalamic nucleus. / <p>QC 20131209</p>

The experiments in this thesis investigated the neuropharmacology of memory in the caudate nucleus, using the conditioned emotional response (CER) with visual and olfactory conditioned stimuli (CS). / In experiment 1, post-training, intrastriatal microinjections of both amphetamine and LY 171555, but not SKF 38393: (1) into the posteroventral area improved memory of a visual, but not an olfactory, CER; (2) into the ventrolateral area improved memory of an olfactory, but not a visual, CER. In experiment 2, sulpiride, but not SCH 23390, blocked the memory improving effect of amphetamine. These findings are consistant with the hypothesis that dopamine D2 receptor stimulation mediates the memory enhancement effect of amphetamine in the neostriatum. / In three experiments on a visual CER, pre-training intrastriatal micro-injections of scopolamine impaired acquisition; post-training micro-injections improved consolidation; and pre-testing micro-injections impaired retrieval. These findings are consistant with the hypothesis that striatal muscarinic receptor stimulation mediates some aspects of acquisition and retrieval of sensory-motor memory, and that blockade of these receptors following training has an effect on memory consolidation similar to that of D2-receptor stimulation. / In experiment 6, destruction of the dopaminergic nigrostriatal neurons abolished the memory improving effect of intrastriatal post-training micro-injections of scopolamine and AFDX-384, a specific muscarinic M2 antagonist. These results suggest that the post-training memory improvement produced by muscarinic blockade may be mediated by an M2 receptor, known to be located on dopaminergic nigro-striatal terminals.

Previous studies of physical guidance (PG - physically constraining error during practice of a motor task) have found it to be ineffective in enhancing motor learning. However, most studies have used a highly constraining form of physical guidance that may have encouraged undue dependency. In addition, previous research has not fully considered the interaction between visual feedback and PG, and many of the studies have failed to use standard delayed retention tests with knowledge of results unavailable (no-KR). The current experiment examine the effects of varying levels of constraint in PG, as well as the interaction of PG and visual guidance (VG), using no-KR retention tests. This study involved 99 subjects divided into nine acquisition trial condition groups, forming from a 3 x 3 factorial design with factors of PG x VG, each presented at levels designated as tight, bandwidth, or none. Subjects undertook a two-dimensional pattern drawing task with no KR, PG, or VG as a pre-test, before completing 100 practice trials under one of the nine conditions. The same test was given as a retention test (immediately after practice) and as a delayed retention test (two days later). A transfer test, using a different pattern, was also administered on the second day. Almost all groups performed better on the immediate transfer test than they had on the pre-test. However, after two days only three groups (PG bandwidth-VG tight, PG none-VG bandwidth, and PG none-VG none) retained this improvement and only two groups (PG bandwidth-VG bandwidth and PG none-VG none) performed significantly better on the transfer task than their pre-test. It is proposed that bandwidth guidance generally promotes learning and that bandwidth physical guidance may enhance proprioceptive cues. Independent of PG and VG effects, KR (an overall error score) also facilitated learning.

The purpose of this thesis was to investigate the potential mechanisms and sites of neural adaptations that mediate cross-limb transfer of strength and motor learning that can occur subsequent to unilateral training. Better understanding of the mechanisms should allow therapeutic benefits of this effect to be assessed. There are two main classes of mechanisms that could contribute to cross-limb transfer. The first is described by the ??bilateral access?? hypothesis, which suggests that neural adaptations induced by training reside in bilaterally projecting motor areas that are accessible to the untrained (ipsilateral) hemisphere during task execution to facilitate performance. According to the alternative ??cross-activation?? hypothesis, activation of the untrained hemisphere during unilateral training leads to adaptations in the untrained hemisphere that cause improved performance with the opposite untrained limb. A series of studies were conducted in this research. We directly tested the cross-activation hypothesis via a reliable twitch interpolation technique involving transcranial magnetic stimulation (TMS). Four-weeks of strength training for the right wrist increased neural drive (from the untrained motor cortex) to the untrained left wrist. The data demonstrate that strength training of one limb can influence the efficacy of corticospinal pathways that project to the opposite untrained limb, consistent with the cross-activation hypothesis. To investigate the contribution of each hemisphere in cross-limb transfer, we applied repetitive TMS (rTMS) to the trained or the untrained motor cortex to disrupt brain processing after unilateral ballistic training. Learning to produce ballistic movements requires optimization of motor drive to the relevant muscles in a way that resembles high-force contractions performed during strength training. Ballistic skill transferred rapidly to the untrained hand and the improved performance was accompanied by bilateral increases in corticospinal excitability. Performance improvement in each hand was specifically suppressed by rTMS of the opposite hemisphere. Thus the motor cortex ipsilateral to the trained hand is critically altered during unilateral training; and neural adaptations within this untrained hemisphere are crucial in cross-limb transfer of ballistic skill. Overall, the data are in agreement with the cross-activation hypothesis for high-force and ballistic tasks, although they do not exclude the potential involvement of bilateral access mechanisms.

This thesis describes three boys diagnosed with dyspraxia and their whanau (families and extended families) as they enter and become part of a community gymnastics group in a city in New Zealand. The study builds on literature that has defined dyspraxia in terms of dysfunction, but generally failed to resolve the disorder. Through the social perspective of health and well-being, participation of children and adults with disabilities has been explored in terms of the person and the environments in which they participate; however, the influence activity itself has on participation has not been thoroughly described. There has been a growing interest in the participation of children with disabilities in recreation and leisure activities and this study provides an in depth cultural perspective of such participation in New Zealand context. This study aims to answer the question "What do children with dyspraxia and their whanau do in a gymnastics group, and what does it mean to them to participate?". The overarching question is "What is the culture of a community gymnastics group in which children with dyspraxia participate?". Ethnographic methodology is employed to ensure that the participants' perspectives, including the beliefs, values and meaning that their participation holds is portrayed, while the associated activities and behaviours are also captured. As the boys with dyspraxia and their whanau entered the gym, they built on their previous experiences to make sense of what they needed to do and what meaning the environment held. I had not planned on the boys being integrated with an established group, but on the first night they spontaneously joined in with a noncompetitive, mixed age, boys group. The parents perceived the Club as professional, while the boys were initially intimidated. Fortunately, the equipment, which made the gym look like a playground, enticed the boys to participate. To shift the boys from their initial perception of the gym being a playground, the coaches used two styles of An Ethnography of Children with Dyspraxia Participating in Gymnastics coaching to support and encourage their participation, while suppressing behaviour that did not fit with the norms of the Club. The boys needed to develop gymnastics skills and fit into the group to become gymnasts. The boys succeeded in fitting into the group by both developing skills and adapting their behaviour, while the type of boys without dyspraxia, the style of coaching afforded, the range of equipment and the activity of gymnastics itself meant that some of their initial difficulties were accommodated and they were seen as group members. The participants developed values and beliefs about what the boys participation in the group meant. Having fun and developing confidence and fitness were highlighted, while the social aspects (making friends and the whanau experiences) were also seen as important. The parents and coaches felt that the boys' experiences in gymnastics had an impact on them that would transfer to the world beyond the gym. This study contributes a qualitative perspective on the participation of children with disabilities in a sports occupation, with a focus on the cultural context of their participation.