Motor coordination and motor learning processes are vital for animal survival. Both functions require the participation of cerebellar Purkinje neurons, which are the integrating center as they receive both excitatory and inhibitory inputs from various neurons and send out the sole inhibitory output of cerebellar cortex. Secretin, a classical peptide hormone, has been shown previously as a retrograde factor to up-regulate GABAergic inhibitory transmission on basket-Purkinje cell synapses in rats. In behavioral perspectives, there have been studies reporting changes of motor function, anxiety level, spatial memory and social interactions after application or deprivation of secretin. Based on current knowledge, secretin is hypothesized to modulate mouse motor coordination and motor learning behaviors through its effects on Purkinje neurons. To test this hypothesis, a Purkinje cell-specific secretin gene knockout moue model (Pur-Sct-/-) has been developed using Cre-Loxp recombination technique. Using immunohistochemical staining and in situ hybridization, secretin expression has been shown to be specifically eliminated in Purkinje neurons. Pur-Sct-/- mice had intact general motor ability and anxiety level in an open field. Neuromuscular strength of Pur-Sct-/-mice was impaired compared to wild type littermates in wire hanging test. Motor coordination ability was compromised as shown by vertical climbing and rotarod tasks. Further tests using repeated training on rotarod suggested impaired motor learning ability. All these behavioral changes have also been observed in secretin-null (Sct-/-) and secretin receptor-null (Sctr-/-) mice, suggesting that normal motor control and motor learning depend on integrity of secretin-secretin receptor axis in cerebellum. Postnatal neural developmental study revealed later occurrence of two motor reflexes –righting and negative geotaxis –in Pur-Sct-/-juveniles. Motor deficits in rotarod tasks persisted across mice aging from month 2 to month 9 while wire hanging impairments occurred early in Pur-Sct-/-. Secretin thus may also play a role in early postnatal cerebellar development and neural protection in mature cerebellum. To investigate the underlying mechanism, Purkinje neurons were voltage-clamped for current recording. Secretin potentiated both spontaneous and miniature inhibitory postsynaptic currents (sIPSC and mIPSC) in wild type Purkinje cells. InPur-Sct-/- and Sctr-/- mice, basal levels of sIPSC and mIPSC were significantly decreased, suggesting a role of endogenous secretin in maintaining cerebellar inhibitory transmission. The exogenous application of secretin restored IPSC in Pur-Sct-/- but not in Sctr-/- mice to comparable wild type levels, indicating the specific binding of Purkinje-derived secretin and secretin receptor underlyingthis inhibitory potentiation. In summary, secretin released in Purkinje neurons has significant role in maintaining normal motor coordination and motor learning functions. Secretin also participates in the facilitation of inhibitory transmission on interneuron-Purkinje synapses. This inhibitory potentiation is likely to coordinate motor behaviors, although further in vivo studies are required for substantiation. This study has demonstrated the function of secretin in modulating mouse motor coordination and motor learning behaviors, and in Purkinje neuron inhibitory transmission, suggesting its potential usage in drug development against cerebellar-related motor disorders. / published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

ABSTRACT: The C3 Logix system (i-comet technologies, 2013) is a portable evaluation tool on the iPad Air tablet computer that is currently being used as for screening concussion severity in an athlete population. The application employs a neurocognitive exam that is comprised of a battery of tests to evaluate both cognition and motor skills: reaction time, memory, processing time, postural stability, vision, and the vestibulo-ocular reflex. With the exclusion of the concussion screening questionnaire, the C3 Logix program may be an effective, portable tool to study developmental changes in executive function. The Developmental Motor and Cognition Laboratory at The University of Texas at Austin has begun a project to 1) create a functional test battery from the C3 Logix system that is portable, simple and reliable in measuring motor development in children. The extant literature contains reports on individual measures of executive function as they change with age. However, the C3 Logix system provides a battery of data on the same individual that may allow for coupling of the executive function data with an assessment of motor skills into a full data collection of multiple measures. The assessment protocol developed in this report will also include functional performance measures to complement the executive function data of the C3 Logix system. The inclusion of functional assessments will yield a tool that is capable of screening for physical readiness to engage in activities that demand greater movement competence. For example, activities of competitive sport require both decision making (executive function) and physical ability for safe and satisfactory execution. The objective of this report is to support this project in three ways: 1) Create an annotated bibliography for background understanding of the tests in the C3 Logix System. 2) Consult with the literature to devise procedures for administration of three function performance tests that challenge the individual’s performance capability beyond basic fundamental motor competency, and 3) complement the description of the selected functional performance tests with video demonstrations. / text

Motor unit synchronization is phenomenon driven by a common input that results in the near-simultaneous firing of two or more motor units, which is referred to as short-term synchronization. The relationship between motor unit synchronization and force steadiness is still unclear, even after numerous experiments and simulations. Our main hypothesis was that the decreased force tetanus brought on by motor unit synchronization would be correlated to reduced steadiness at very low hand muscle forces. To determine if this correlation existed, young, healthy adults performed a submaximal, isometric pinch at four forces to determine if motor unit synchronization increased with a progressive decrease in force steadiness driven by reduced force levels. However, before performing synchronization analyses, we had to establish the best technique for measuring motor unit coherence, which quantifies the strength and frequency of a periodic common input. We used a pool of simulated spike trains with various firing rates, coefficients of variation (CV), common input frequencies and trial durations to explore the effects of data segmentation and spike train properties on coherence. We found that tapered segments overlapped by at least 50% maximized coherence measurements, regardless of taper type and that increasing common input frequency CV from 0.15-0.50 made coherence measurements unusable, even at high synchronization levels. During an isometric pinch at 2, 4, 8, and 12% of maximum digit force, we recorded thumb and index finger forces and EMG from the first dorsal interosseous (FDI) and adductor pollicis (AdP) muscles. As expected, the force CV dropped as each digit force increased. Pooled coherence revealed a dominant peak for the 2-10 Hz, but power for both digits' forces was limited to the 0-2 Hz bandwidth. There was a weak correlation for thumb force CV and coherence for within-AdP pairs, but no significant correlations were found for within-FDI pair coherence and finger force CV. Therefore, motor unit synchronization was not a strong driver of force steadiness for this protocol. To ensure that inherent firing rate nonstationarity of spike train data did not affect coherence measurements, we produced a new set of spike train pairs with firing rates and variances that approximated those for physiological motor units, which varied from 0-25%. Stationarity level was not significantly correlated to peak coherence (max R² = 0.082). Therefore, coherence measurements of spike train data with characteristics similar to those of the simulated trains were not significantly affected by nonstationarity. The establishment of the best method for computing coherence, the lack of a strong correlation between force steadiness and motor unit synchronization for submaximal isometric forces, and the knowledge that spike train nonstationarity has no significant effect on coherence measurements are all important discoveries needed for progress in the areas of basic neuromuscular function, motor unit synchronization, and pathological force unsteadiness.

Abstract Orientation: The informal sector serves as an untapped reservoir of skilled individuals practising the motor mechanic trade, who are ready for possible reclamation into the formal sector. Research purpose: The objective of this study was to develop a recognition of prior learning (RPL) strategy to link informal practising motor mechanic artisan training to the formal sector to enhance these artisans’ employability status. Motivation for the study: The current formal sector training initiatives for motor mechanics do not provide for or acknowledge the non-formal learning of the informal sector practising motor mechanics. South African desperately needs a national artisan development programme that includes all the components of artisan growth. Although the national artisan development programme will primarily focus on the development of artisans in the formal sector, the large numbers of persons who are involved in artisan work in the informal sector need to be progressively incorporated into the formal sector process. Research design, approach and method: A qualitative design was used and a purposive snowball sample applied. An exploratory qualitative study was conducted to answer the research question. Semi-structured interviews were applied to solicit data from 16 experts representing the motor mechanic training environment. The data were analysed utilising the ATLAS.ti 7.0 program. Contribution/value-add: This study attempted to conduct ground-breaking research in theory building to improve the employability status of people involved in motor mechanic artisan work in the informal sector. The findings of this study could lead to the development of new theory for SETAs to engage in the training and funding of informal practising motor mechanics. The study conceptualises a focused RPL strategy for motor mechanics that could be systematically applied to integrate the informal and formal sector training for the trade.

Thesis (MTech. degree in Mechanical Engineering.)--Tshwane University of Technology, 2008.

The purpose of this report is to review critically research focused on oral motor based treatment for pediatric swallowing disorders with the aim of assisting speech-language pathologists in making informed clinical intervention decisions. Oral motor based treatment has become a popular intervention approach among some speech-language pathologists, but the evidence supporting the approach is limited. This report will discuss research studies and review articles with high levels of evidence of treatment efficacy and propose when to use oral motor based treatment approaches in clinical intervention for pediatric swallowing disorders. / text

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