Dissertations / Theses on the topic 'Motor behaviour'

There is a dearth of knowledge on the functional organization of the anatomically complex human masseter muscle. Limited physiological studies suggest a functional organization which may differ significantly from human limb muscles. The present studies aimed to examine the putative relationship between structure and function in the human masseter muscle as a basis for understanding function and dysfunction in human jaw muscles. In the first experiment single motor unit (SMU) activity was recorded from pairs of recording sites distributed throughout the masseter muscle. In each case SMU activity at a chosen location was used as a reference to search for synchronized SMU activity at another selected site. The locations of the needle tips were estimated in 3-dimensions (3-D) by means of an optical system, then transferred to 3-D reconstructions derived from Magnetic Resonance images. This approach permitted calculation of the linear distances between verified muscle recording sites. The mean separation of the sites from which synchronous SMU activity could be recorded was 8.8±3.4mm. The putative territories had a preferred orientation in the antero-posterior axis. Motor unit territories were larger than described previously, and appeared to be related to anatomical compartments. The second experiment involved recording activity from stereotactically mapped masseter SMUs. In each case, the lowest sustainable firing frequency (LSFF) was reached by slow increases and decreases in voluntary firing rate, followed by sustained firing at the lowest possible rate. Pulse-discrimination and digital sampling of consecutive inter-spike intervals (ISIs) were then used to measure LSFF for 2-6 separate occlusal and postural tasks to which each unit contributed. There were significant differences between mean ISIs for the tasks performed by most units, which suggests descending drive to masseter units is highly task-dependent. There were also regional differences in unit task specificities. In the third paradigm, reflex SMU activity was recorded from units in the masseter muscle and the inferior head of the lateral pterygoid muscle. Bipolar electrodes fixed to the gingiva near the maxillary canine delivered single pulses of 1ms duration at sub-noxious levels of intensity. At constrained firing frequencies (10, 15Hz), pulses were injected sequentially, with increasing delays, after preselected spikes. More profound inhibition occurred in units firing at 10 than 15Hz. There were significant differences in masseter inhibitory responses when the unit task varied. Reflex inhibition in masseter and lateral pterygoid SMUs is highly frequency-dependent, and also task-dependent in masseter units. The fourth study involved recording activity from SMUs in the masseter muscle. A midline load cell was fixed to the incisor teeth and aligned either perpendicular (P) or 30 degrees anterior (A) to the occlusal plane, without altering jaw position. A rigid spike-triggered averaging (STA) paradigm was used to extract the contribution of individual SMUs to the overall force at load cell orientations P and A. Spikes preceded or followed by an interval of less than 100ms were rejected prior to averaging. At background bite forces from 0.06-8N, the isometric forces apparently developed by individual units varied randomly with load cell orientations, (P range 36.2±19.6mN; A range 38.2±28.4mN). All units could be fired slowly with varying degrees of muscle coactivation, in some instances without contact on the load cell. The use of STA as a method for determining SMU tension in the masseter muscle appears to be task-dependent and in the presence of coactivation may be inappropriate. The findings collectively indicate the heterogeneous nature of SMU behaviour in the human masseter muscle which is consistent with internal muscle compartments based on anatomical features and functional behaviour. There thus appear to be both physiological and anatomical substrates for differential motor control of selected regions of the human masseter muscle.
Dentistry, Faculty of
Graduate

The primary motor cortex (M1) is a key brain area for the generation and control of motor behaviour. Output from M1 can be driven in part by long-range inputs from a collection of thalamic nuclei termed the motor thalamus (MTh), but how MTh input shapes activity in M1 and forelimb motor behaviour remains largely unresolved. To address this issue, we first defined the 3D anatomical coordinates of mouse forelimb motor thalamus (MThFL) by employing conventional retrograde and virus-based tracing methods targeted to the forelimb region of M1 (M1FL). These complimentary approaches defined MThFL as a ~0.8 mm wide cluster of neurons with anatomical coordinates 1.1 mm caudal, 0.9 mm lateral to bregma and 3.2 mm below the pial surface. Thus, MThFL incorporates defined areas of the ventrolateral, ventral anterior and anteromedial thalamic nuclei. To investigate the importance of M1FL and MThFL during skilled motor behaviour, we developed and optimised a quantitative behavioural paradigm in which head-restrained mice execute forelimb lever pushes in response to an auditory cue to receive a water reward. Forelimb movement trajectories were mapped using high-speed digital imaging and multi-point kinematic analysis. We inactivated both M1FL and MThFL of mice performing this motor behaviour using a pharmacological strategy, which in both cases resulted in a significant reduction in task performance. Inactivating M1FL significantly affected forelimb coordination and dexterity, resulting in erratic motion and posture. In contrast, mice with MThFL inactivated displayed a reduction in total motor output, although correct posture was maintained. We performed extracellular recordings in MThFL of expert-level mice, demonstrating that motor thalamic output during execution of task was dominated by a robust response to the onset of the auditory cue. Cue-evoked responses were also observed in motor thalamic neurons of naive mice. We have developed a novel solution to the stability problem encountered when performing whole-cell patch-clamp recordings from the motor cortex of head-restrained mice performing forelimb motor behaviour, and present preliminary recordings maintained through the execution of forelimb behaviour.

The late 20th century brought with it substantial evidence showing that many vertebrate species are capable of exhibiting brain and behavioural lateralisation (i.e. functional and/or structural specialisations of the left and right sides of the brain/behaviour), undermining the traditional view that this attribute is uniquely human. Motor lateralisation, a specific form of behavioural lateralisation, in which an organism displays a directional preference whilst making movements, has previously been identified in many vertebrates but has received little attention in invertebrate species, particularly insects. Considering this, I investigated motor lateralisation in the desert locust (Schistocerca gregaria) and the red wood ant (Formica rufa) using a combination of a gap-crossing paradigm and a ‘Y'-maze choice experiment. Using these paradigms, I show that the relatively small nervous systems of insects are capable of producing lateralised motor behaviour, providing evidence that being strongly lateralised can be advantageous and, more generally, adding support to the hypothesis that social organisms are more likely to align their lateralisation with others in their group. The gap-crossing paradigm demonstrates that both desert locusts and red wood ants display a forelimb preference, the first direct evidence that an arthropod possesses a preference in the use of otherwise symmetrical limbs. Studying locusts in this paradigm also produced the first evidence that strong lateralisation confers an advantage to the individual because more strongly biased locusts display fewer reaching errors. In addition, wood ants display inter-colony variation in their preference, the first demonstration of a previously undescribed form of lateralisaton, colony-level lateralisation. By testing wood ants over both the gap-crossing and ‘Y'-maze paradigms I show that within the same insect species, lateralisation can be expressed in different forms of motor behaviour.

Sequence learning is a fundamental brain function that allows for the acquisition of a wide range of skills. Unlearned movements become faster and more accurate with repetition, due to a process called prediction. Predictive behaviour observed in the eye and hand compensates for the inherent temporal delays in the sensorimotor system and allows for the generation of motor actions prior to visual guidance. We investigated predictive behaviour and the brain areas associated with this processing in (i) the oculomotor system (Eye Only (EO): saccade vs. pursuit) and (ii) during eye and hand coordination (EH). Participants were asked to track a continuous moving target in predictable or random sequence conditions. EO and EH experiments were divided into 1) EO behavioural and 2) EO fMRI findings, and 3) EH behavioural and 4) EH fMRI findings. Results provide new insights into how individuals predict when learning a sequence of target movements, which is not limited to short--‐term memory capacities and that forms a link between shorter and longer--‐term motor skill learning. Furthermore, brain imaging results revealed distinct levels of activation within and between brain areas for repeated and randomized sequences that reflect the distinct timing threshold and adaptation levels needed for the two oculomotor systems. EH results revealed similar predictive behaviour in the eye and the hand, but also demonstrated enhanced coupling between the two motor systems during sequence learning. EH brain imaging findings have provided novel insights into the brain areas involved in coordination, and those areas more associated with sequence learning. Results show evidence of common predictive networks used for the eye and hand during learning.

Maged1 appartient à la famille des gènes Mage (pour Melanoma antigen gene). Bien que les gènes Mage aient tout d'abord été découverts dans des cellules tumorales, le gène Maged1 est également exprimé dans un grand nombre de tissus sains et particulièrement dans le système nerveux central, aussi bien au cours du développement que chez l'animal adulte. Les fonctions exercées par la protéine Maged1 dans le système nerveux restent actuellement fort méconnues bien que des études aient pu mettre en évidence son implication dans des processus tels que l'homéostasie du rythme circadien, certaines formes d'apprentissages, les comportements sociaux et sexuels ainsi que dans des pathologies telles que la dépression et l'obésité. Au laboratoire, nous avons pu montrer que la délétion de l'allèle Maged1 chez la souris cause une diminution d'activité locomotrice spontanée et un déficit de coordination motrice. Les animaux ne possédant plus l'allèle Maged1 montrent également une absence complète de réponse à l’administration de drogues comme la cocaïne et la morphine. Au cours de ce travail de thèse, nous avons recherché les mécanismes liant le gène Maged1 et ces comportements. La dopamine étant un neurotransmetteur connu pour réguler à la fois les comportements moteurs et les comportements liés à la dépendance aux drogues, nous avons tout d'abord fait l'hypothèse qu'un déficit en dopamine pouvait expliquer les phénotypes observés. En effet, des expériences de microdialyse in vivo ont montré que l'augmentation de concentration en dopamine dans le nucleus accumbens suite à une injection de cocaïne était significativement réduite chez les souris dépourvues de l'allèle Maged1. L'implication directe de Maged1 dans la physiologie des neurones dopaminergiques a été étudiée par la génération de souris transgéniques dont la délétion du gène Maged1 a été ciblée spécifiquement dans ces neurones. Cependant, cette lignée de souris ne récapitule pas les phénotypes observés chez les souris entièrement dépourvues de l'allèle Maged1. Ces résultats indiquent que l'expression de Maged1 dans les neurones dopaminergiques n'est pas nécessaire au contrôle moteur et à la réponse comportementale à l'administration de cocaïne. Nous avons ensuite étudié les régions innervées par les neurones dopaminergiques en réalisant des enregistrements électrophysiologiques sur tranches de cerveaux en survie. Nous avons ainsi pu mettre en évidence une altération de la transmission glutamatergique entre le cortex préfrontal et le nucleus accumbens chez les souris dépourvues du gène Maged1. La délétion spécifique de l'allèle Maged1 dans chacune de ces deux régions a ensuite été effectuée. Les souris dont la délétion de Maged1 a été ciblée dans les neurones du striatum n'ont pas montré d'altération comportementales. Cependant, lorsque la délétion de Maged1 est effectuée spécifiquement dans le cortex préfrontal, les souris montrent un déficit d'apprentissage moteur ainsi qu'une réduction de l'effet de sensibilisation à des injections répétées de cocaïne. Chez ces mêmes souris, la réduction de sensibilisation est accompagnée d'une réduction de la réponse dopaminergique à la cocaïne telle qu'observée au cours d' expériences de microdialyse in vivo. Au cours de ce travail, nous avons donc pu montrer que la présence de la protéine Maged1 dans le cortex préfrontal est nécessaire à l'apprentissage moteur et à l'expression de la sensibilisation comportementale à la cocaïne. Cette protéine exerce probablement sa fonction en régulant la neurotransmission au niveau du compartiment présynaptique.
Doctorat en Sciences biomédicales et pharmaceutiques (Médecine)
info:eu-repo/semantics/nonPublished

This thesis proposes and experimentally demonstrates an approach enabling a humanoid robot to adapt its behaviour to match a human’s behaviour in real-time human-humanoid interaction. The approach uses the information distance synchrony detection method, which is a novel method to measure the behaviour synchrony between two agents, as the core part of the behaviour adaptation mechanism to guide the humanoid robot to change its behaviour in the interaction. The feedback of the participants indicated that the application of this behaviour adaptation mechanism could facilitate human-humanoid interaction. The investigation of motor interference, which may be adopted as a possible metric to quantify the social competence of a robot, is also presented in this thesis. The results from two experiments indicated that both human participants’ beliefs about the engagement of the robot and the usage of rhythmic music might affect the elicitation of the motor interference effects. Based on these findings and recent research supporting the importance of other features in eliciting the interference effects, it can be hypothesized that the overall perception of a humanoid robot as a social entity instead of any individual feature of the robot is critical to elicit motor interference in a human observer’s behaviour. In this thesis, the term ‘overall perception’ refers to the human observer’s overall perception of the robot in terms of appearance, behaviour, the observer’s belief and environmental features that may affect the perception. Moreover, it was found in the motor coordination investigation that humans tended to synchronize themselves with a humanoid robot without being instructed to do so. This finding, together with the behaviour adaptation mechanism, may support the feasibility of bi-directional motor coordination in human-humanoid interaction.

The thesis examines the influence of visual misperceptions of the primary environmental constraints related to motor behaviour, and explores whether motor adaptation can be caused implicitly by introducing systematic, undetectable changes in key constraints in the performance environment. The first two experiments (Chapter 2) were conducted to determine if a simple manipulation of the height of the uprights can cause participants to perceive the dimensions of the rugby goalposts differently. The findings support the existence of a rugby goalpost illusion. Misperceptions of the dimensions of the goalposts may influence decisions about where to place the ball when converting a try. In Chapter 3, a series of experiments tested this hypothesis both in a laboratory setting and in real life games. Experiment 3 showed that narrow goalposts caused kickers to place the ball further from the try-line than wide goalposts. Furthermore, misperceptions of the uprights width induced by the rugby posts illusion caused kickers to place the ball differently when making kicks (Experiment 4). By introducing pitch-markings in Experiment 5, we tested whether the effect of the illusion is moderated by use of familiar cues in the environment. An observational study (Experiment 6) suggested that the influence of the rugby posts illusion, intimated in our experimental work, is not evident in real life. Both Chapters 4 and 5 were designed to examine whether very subtle changes in constraints in the environment can be used specifically to induce implicit motor learning. In Chapter 4, the smallest detectable difference between two levels of sensory stimulus was determined for simple line drawings representative of rugby goalpost uprights (Experiment 7) or crossbars (Experiment 8). The findings from Chapter 5 suggested that (implicit) motor adaptations might be caused by gradual incremental changes in environmental constraints.
published_or_final_version
Human Performance
Doctoral
Doctor of Philosophy

Colliding with objects in our environment is a common feature of daily activity. Skilled behaviour often involves the precise regulation of these collisions. Traditional approaches to skilled behaviour are criticised for confusing the constraints of their approach with behavioural constraints. The following investigation combines aspects of several approaches laid out in the Introductory Chapter 1 to examine the visual and motor processes involved in controlling collisions. In Chapter 2 performance is assessed in a one-handed catching task, when the physical characteristics of the ball are manipulated. The results indicate that viewing-time and the nature of grasping affect perfomance. In Chapters 3 and 4 a hitting task is used to investigate the visual processes involved in intercepting an object. Task performance is compared across monocular and binocular viewing conditions. In Chapter 3, results show that timing performance is unaffected by this manipulation and this provides support for the direct pick up of time-to-collision information. In Chapter 4, binocular information is found to be necessary for the spatial location of an object. In Chapters 5, 6 and 7, a tapping task is used to investigate the motor aspects involved in controlling a collision. In Chapter 5 force waveforms recored when tapping on a strain gauge vary in accordance with 'external' and 'internal' manipulations of load and stiffness. In Chapter 6, a mass-spring model is proposed to describe the collision. Changes in impact are related to changes in the parameters of the model. These effects are simulated on a computer. In Chapter 7, the mechanisms of effecting collision change are directly investigated from kinematic recordings. The results suggest that speed of impact is the controlled parameter. The findings are compatible with the mass-spring model. The final Chapter concludes that a multi-dimensional approach is required for a full understanding of skilled-motor behaviour. The possible applications of this approach to the assessment of clumsiness are discussed.

This PhD thesis contributes to a synthesis of the bibliographic material reviewed from original sources written in various languages (and thus sometimes unknown in the scientific community at international level, since they were not published in English) and to scientific research by findings and results from experimental work carried out at the Mira y López Laboratory of the University of Barcelona on topics related to individual differences in proprioception based on fine motor behaviour. The main aim of this work is to show the importance of proprioceptive sense, as a basis of individual differences, for human health and life quality. Most of the experimental work is related to sex and age-dependent differences in human fine behaviour, thus allowing analysis and understanding of those differences. When self-correction of behaviour is not possible (the person does not see the feedback of his/her movements), the expression reflects the intrinsic qualities of each person based both on biological or endogenous factors or ones specific to the nervous system and adaptive behaviour learnt during his/her own experience with environmental interactions. Experimental work was carried out with use of the latest proprioceptive diagnostics which was a result of many years of work within the Mira y Lopez myokinetic psychodiagnosis (MKP) tradition, Proprioceptive Diagnostics of Temperament and Character or DP-TC in Spanish abbreviation (Tous, Muiños, Tous, O. i Tous, R., 2012). DP-TC was a result of digitization and statistical validation of MKP lineograms’ and parallels` parts. Thus, due to this special software, graphomotor fine behaviour (precision and speed) can be registered and measured and converted to the metric system: from pixels to millimetres. For the study of individual differences, various movement types were used: frontal, transversal and sagittal, both hands and two sensory conditions: proprioceptive-visual (PV), where the integration function of both sensory conditions can be observed, and proprioceptive-only (P). The experimental studies were cross-sectional and analysed for sex- and age-dependent individual differences mainly, although a brief résumé of other studies was included, showing the relationship between proprioceptive information feedback and both emotion and cognition, at the end of this thesis. The major contributions of this work are the following: - synthetic bibliographical work on the topic of proprioception and individual differences and importance for human health and quality of life, which is conducted for the first time and can be used for wider understanding in order to carry out future research and application (more effective therapeutic and educational work), and can be used and adapted to form part of a program, especially for psychological, pedagogical and neurological faculties; - brief description of fine motor behaviour in different cultures: Arabic (in which the custom is to write in a different direction to Western people); and Belarus (for the latter some results are given, together with relationships to verbal and other physical parameters) is represented in the initial part of the thesis; - an age-dependent proprioceptive differences study based on fine motor behaviour in 196 participants from 12 to 95 years old, in which the polynomial function was of the best fit for size (line length tracings) in frontal and transversal movements; - it was shown that proprioception function was the first to deteriorate in precision with increasing age value if compared to the integrative function of both sensory inputs (proprioceptive and visual); - the crucial ages for age-dependent changes were shown for the first time; these results give the first experimental support for the age of the mid-life crisis (approx. 40 years); - sex-dependent differences and sex*age-dependent differences were analysed and discussed also; - a correlational analysis was performed between precision and fine motor speed in two sensory conditions of the test; - practical applications of study results together with the future potential research interests in the area of proprioception and individual differences are given in the final part of the work.
Aquesta tesi doctoral contribueix tant a la sinterització del material bibliogràfic, revisat de fonts originals, escrit en diferents idiomes (a vegades desconegudes en la comunitat científica a nivell internacional, ja que no van ser publicades en anglès) com a la investigació científica amb els resultats de les investigacions experimentals, dutes a terme al Laboratori Mira i López de la Universitat de Barcelona, en l'estudi empíric de les diferències individuals en la propiocepció, basades en el comportament motor fi. L'objectiu principal teòric d'aquest treball és mostrar la importància de la propiocepció, com a base de les diferències individuals, per a la salut humana i la qualitat de vida. La major part del treball experimental es basa en la constatació de les diferències individuals en la motricitat fina propioceptiva relacionades amb l'edat i el sexe que permet analitzar i entendre aquestes diferències en el comportament humà. Quan la autocorrecció de la conducta no és possible (la persona no veu els traços dels seus moviments en la part propioceptiva del test), l'expressió grafomotora reflecteix les qualitats intrínseques de cada persona, basades en factors biològics, o endògens, específiques del sistema nerviós i la conducta adaptativa, apreses en les seves pròpies experiències amb les interaccions ambientals. Els treballs experimentals s'han realitzat amb l'ús del Diagnòstic Propioceptiu de Temperament i el Caràcter o DP-TC, en abreviatura espanyola (Tous, Muiños, Tous, O. i Tous, R., 2012), que és el resultat més recent de molts anys de treball dins la línia de la tradició del Psicodiagnòstic Miokinético (PMK) de Mira i López. El DP-TC és el resultat de la digitalització i validació estadística dels subtests corresponents als lineogramas i les paral • leles del PMK. Mitjançant aquest programa especial, el comportament grafomotor fi (precisió i velocitat) pot ser registrat i mesurat, ja que permet transformar les mesures en mil•límetres, del sistema mètric, a píxels. Per a l'estudi de les diferències individuals es van utilitzar diferents tipus de moviment: frontal, transversal i sagital, amb les dues mans per separat i dues condicions sensorials: propioceptiva-visual (PV), on es pot observar la funció d'integració de les dues condicions sensorials i només propioceptiva (P) on es pot observar la informació propioceptiva en la conducta motora fina. Els estudis experimentals van ser sobre les diferències individuals en el sexe i l'edat, encara que es dóna també, al final d'aquesta tesi, un breu resum d'altres estudis -alguns transculturals- que mostren la relació de la informació propioceptiva amb l'emoció i la cognició. Les principals contribucions d'aquest treball són els següents: - Treball bibliogràfic comentat sobre el tema de la propiocepció i les diferències individuals i la importància per a la salut humana i la qualitat de vida que es realitza per primera vegada i es pot utilitzar per a una comprensió més àmplia a l'hora de realitzar futures investigacions i aplicacions (treballs terapèutics i educatius més eficaços). La informació recollida es pot utilitzar i adaptar per formar part del programa formatiu, especialment en les facultats de psicologia, pedagogia i neurologia. - S'ha realitzat una breu descripció de la conducta motora fina en diferents cultures: Àrab, (que té l'hàbit d'escriure en una altra direcció que a Occident) i Bielorussa (per a aquests últims, alguns resultats es donen amb relació als paràmetres físics i verbals) que es representa a la part inicial del tesis. - L'estudi de les diferències propioceptives dependents de l'edat, basades en la conducta motora fina, en 196 participants 12-95 anys d'edat, que va permetre constatar que la funció polinòmica era la millor opció per a la descripció de l'evolució de la reproducció de la longitud de línia de traços en els moviments frontals i transversals. - Es va constatar que la funció de propiocepció era la primera que empitjorava en la precisió amb l'augment de l'edat abans de l'empitjorament de la funció integradora realitzada per les dues entrades sensorials (propioceptiva i visual); - Es posen de manifest les edats crucials per als canvis propioceptius dependents de l'edat; els resultats per primera vegada donen el suport experimental de l’edat de la crisi de l’edat mitjana (aprox. 40 anys). - S'han analitzat i discutit les diferències de sexe i la interacció sexe per edat; - S’ha fet anàlisi correlacional entre precisió motora fina i la velocitat en dues condicions sensorials del test. - Es dona en la part final de la tesi la descripció de les aplicacions dels resultats de la tesi i els interessos potencials de la investigació futura en l'àrea de la propiocepció i les diferències individuals.
Esta tesis doctoral contribuye tanto a la sintonización del material bibliográfico, revisado de fuentes originales, escrito en diferentes idiomas (a veces desconocidos en la comunidad científica a nivel internacional, ya que no fueron publicadas en inglés) como a la investigación científica con los resultados de las investigaciones experimentales, llevadas a cabo en el Laboratorio Mira y López de la Universidad de Barcelona, en el estudio empírico de las diferencias individuales en la propiocepción, basadas en el comportamiento motor fino. El objetivo principal teórico de este trabajo es mostrar la importancia de la propiocepción, como base de las diferencias individuales, para la salud humana y la calidad de vida. La mayor parte del trabajo experimental se basa en la constatación de las diferencias individuales en la motricidad fina propioceptiva relacionadas con el sexo y la edad que permite analizar y entender esas diferencias en el comportamiento humano. Cuando la autocorrección de la conducta no es posible (la persona no ve los trazos de sus movimientos en la parte propioceptiva del test), la expresión grafomotora refleja las cualidades intrínsecas de cada persona, basadas en factores biológicos, o endógenos, específicos del sistema nervioso y la conducta adaptativa, aprendidas en sus propias experiencias con las interacciones ambientales. Los trabajos experimentales se han realizado con el uso del Diagnóstico Propioceptivo de Temperamento y el Carácter o DP-TC, en abreviatura española (Tous, Muiños, Tous, O. y Tous, R., 2012), que es el resultado más reciente de muchos años de trabajo dentro de la línea de la tradición del Psicodiagnóstico Miokinético (PMK) de Mira y López. El DP-TC es el resultado de la digitalización y validación estadística de los subtests correspondientes a los lineogramas y las paralelas del PMK. Mediante este software especial, el comportamiento grafomotor fino (precisión y velocidad) puede ser registrado y medido; ya que permite transformar las medidas en milímetros, del sistema métrico, a píxeles. Para el estudio de las diferencias individuales se utilizaron diferentes tipos de movimiento: frontal, transversal y sagital, con ambas manos por separado y dos condiciones sensoriales: propioceptiva-visual (PV), donde se puede observar la función de integración de ambas condiciones sensoriales y solamente propioceptiva (P) donde se puede observar la información propioceptiva en la conducta motora fina. Los estudios experimentales fueron sobre las diferencias individuales en el sexo y la edad, aunque se da también, al final de esta tesis, un breve resumen de otros estudios -algunos transculturales- que muestran la relación de la información propioceptiva con la emoción y la cognición. Las principales contribuciones de este trabajo son los siguientes: - Trabajo bibliográfico comentado sobre el tema de la propiocepción y las diferencias individuales y la importancia para la salud humana y la calidad de vida de estos estudios que se realiza por primera vez y se puede utilizar para una comprensión más amplia a la hora de realizar futuras investigaciones y aplicaciones (trabajos terapéuticos y educativos más eficaces) que se puede utilizar y adaptar para formar de un parte programa formativo, especialmente en las facultades de psicología, pedagogía y neurología. - Se ha realizado una breve descripción de la conducta motora fina en diferentes culturas: Árabe, (que tiene el hábito de escribir en otra dirección que en Occidente) y Bielorrusa (para estos últimos, algunos resultados se dan con relación a los parámetros físicos y verbales) que se representa en la parte inicial de la tesis. - El estudio de las diferencias propioceptivas dependientes de la edad, basadas en la conducta motora fina, en 196 participantes 12 a 95 años de edad, que permitió constatar que la función polinómica era la mejor opción para la descripción de la evolución de la reproducción del tamaño (longitud de línea de trazos) en los movimientos frontales y transversales. - Se constató que la función de propiocepción la primera que empeora en la precisión con el aumento de la edad antes del empeoramiento de la función integradora realizada por las dos entradas sensoriales (propioceptiva y visual); - Se ponen de manifiesto las edades cruciales para los cambios propioceptivos dependientes de la edad; por la primera vez experimentalmente se justifican las fases de desarrollo y de la crisis de edad media en la base de propiocepción. - Se han analizado y discutido las diferencias de sexo y la interacción sexo por edad. - Las aplicaciones prácticas de los resultados derivados de la tesis y los intereses potenciales de la investigación futura en el área de la propiocepción y las diferencias individuales están representados en la parte final del manuscrito.
Кандидатская диссертация на тему «Возрастные и половые различия в проприоцепции на основе исследования тонкой моторики» даёт детальный анализ библиографического материала, собранного из первоисточников, написанных на различных языках (иногда неизвестных в научном международном сообществе, так как не были опубликованы на английском языке); а также научных исследований, выводов и результатов экспериментальных работ, выполненныхв Лаборатории Мира Лопес Барселонского Университета Барселоны на темы, связанные с индивидуальными различиями в проприоцепции на основе проявлений тонкой моторики. Основной целью данной работы является показать важность изучения проприоцептивного чувства в исследовании индивидуальных различий, так и в связи с исследованием здоровья человека и качества жизни. Большинство экспериментальных работ, представленных в диссертации, связаны с половыми и возрастными индивидуальными различиями в проявлении тонкой моторики; таким образом, результаты этих работ позволяют проанализировать и понять эти индивидуальные различия. В проприоцептивной части теста самостоятельная коррекция моторного акта на основе зрительного контроля невозможна. В связи с этим характеристика этих движений отражает индивидуальные качества каждого человека, формирующихся как на основе биологических (эндогенных факторов или специфических свойств нервной системы), так и на базе адаптивно усвоенного поведения (его собственного опыта, полученного в результате взаимодействия с окружающей средой). Экспериментальная работа проводилась с использованием новейшей проприоцептивной диагностики, которая является результатом многих лет работы в традициях миокинетической психодиагностики (MKP) Мира и Лопеса, Проприоцептивная Диагностика Темперамента и Характера или DP-TC в испанской аббревиатуре (Tous, Muiños, Tous, О.,Tous, R., 2012). DP-TC возник как результат применения новейших технологий (компьютеров и тактильных экранов), а также статистической проверки MKP, линеограмм и параллелей. Таким образом, с помощью специального программного обеспечения, мелкое графомоторное поведение (точность и скорость) может быть зарегистрировано, измерено и преобразовано в метрическую систему: с пикселей в миллиметры. Для изучения индивидуальных различий были использованы различные типы движения: фронтальный, трансверсальный и сагиттальной, обе руки и два сенсорных условия: проприоцептивно-визуальное (PV), с интегральной опорой на проприоцептивную и сенсорную афферентацию, и с опорой только на проприоцептивную афферентацию (P). Экспериментальные исследования были трансверсального типа и анализировали главным образом половые и возрастные индивидуальные различия. Также в диссертации приводится обзор данных других исследований, показывающих взаимосвязь показателей проприоцепции с эмоциями и познавательной сферой (памятью). Основные результаты этой работы: - анализ литературы по теме «Проприоцепция и индивидуальные различия, и ее значение для здоровья человека и качества жизни», который характеризуется теоретической новизной и большой практической значимостью (для более эффективных терапевтической и воспитательной работы), данный анализ литературы может быть с успехом использован при разработке образовательных программ, особенно для психологических, педагогических и неврологических факультетов; - краткое описание проявлений тонкой моторики в разных культурах: арабской (где практикуется письмо справа налево, в отличие от письма в западной культуре) и Беларуси (для последних некоторые результаты приведены вместе с корреляционным анализом взаимосвязи проприоцептивного метода с вербальными методиками и другими физическими параметрами) представлено в начальной части диссертации; - исследование возрастных различий в проприоцептивной функции на основе проявлений тонкой моторики, в котором приняли участие 196 испытуемых в возрасте от 12 до 95 лет, результаты которого показали, что полиномиальная функция наилучшим образом подходила для длины линий (трассировки длины линии) во фронтальных и трансверсальных движениях; - было показано, что проприоцептивная функция начинала ухудшаться первой с увеличением возраста по сравнению с интегративной функцией (проприоцептивно-визуальной); - критические точки (точки перегиба) возраста для возрастных изменений были показаны впервые экспериментально, что также в некоторой степени соответствует обозначенному возрасту кризиса середины жизни (около 40 лет) и другим фазам развития; - обсуждены и проанализированы половые и поло-возрастные различия тонкой моторики; - предоставлен корреляционный анализ зависимости точности тонкой моторики и скорости выполнения задания в двух сенсорных условиях теста; - практические применения результатов и перспективы дальнейших исследований в области проприоцепции и индивидуальных различий рассмотрены в заключительной части диссертации.

Marketers are faced with informed and highly complex consumers. The consumer market is becoming more competitive and more difficult to predict as consumers make purchase decisions in their everyday life. An ongoing need exists for information and an examination of purchasing behaviour for marketers to succeed in their pursuit of business endeavours. This study examines the influence of selected variables on motor vehicle-related purchasing behaviour. Five independent variables, namely branding, price, promotion, safety features and colour were investigated and the dependent variable (purchasing behaviour) was examined. In doing so, various stages which consumers undergo when making purchasing decisions were discussed. These stages were outlined as need recognition, information search, and evaluation of alternatives, purchase and post-purchase behaviour. The primary research objective of this study was to determine the influence of selected variables on motor vehicle-related purchasing behaviour. In order to achieve the objectives of the study, an empirical investigation was undertaken. The quantitative (positivistic) paradigm was used in this study, as the aim was to test the hypotheses and conceptualmodel of the study using statistical analysis. In gathering primary data, 192 self-administered questionnaires were issued to respondents for completion by means of convenience and quota non-probability sampling. Upon completion of all the questionnaires, data was analysed in order to arrive at the conclusions regarding the research questions. The empirical findings and analysis followed a systematic and statistical process, where exploratory factor analysis using target rotation was used to test the validity of the measuring instrument. Cronbach alpha correlation coefficients were used to confirm the reliability of the measuring instrument, while multiple regression analysis was carried out to test the hypothesised relationships between the independent variables and the dependent variable of the study. ANOVA was applied to determine differences in the demographic characteristics of respondents. The main findings on the validity and reliability of the measuring instrument proved to be statistically satisfactory. The main findings which emerged from the multiple regression analysis suggested that price and colour had statistically significant influence on motor vehicle-related purchasing behaviour. Findings revealed that branding, promotion and safety conditions had no significant effects on motor vehicle related purchasing behaviour. Accordingly, the hypotheses for price and colour were accepted and those for branding, promotion and safety conditions were rejected. Therefore according to respondents, price and colour of a motor vehicle are the most important considerations when undertaking purchasing decisions regarding motor vehicles. Additionally, the empirical investigation revealed that significant differences exist between age groups of respondents, meaning that different age groups of respondents had different perceptions and opinions with regard to their purchasing patterns relating to price. Furthermore, significant differences were also found between male and female respondents in terms of price and colour, meaning that the two genders had different perceptions and opinions with regard to their purchasing patterns in these areas. The empirical findings of this study are relevant for motor vehicle retailers and original equipment manufacturers, as the findings provide important information regarding the influence of selected variables on motor vehicle-related purchasing behaviour. Secondly the findings of this study contribute to the body of knowledge regarding purchasing behaviour.

This thesis explores the elastic behaviour of the mechanical double action press and draw die system commonly used to draw sheet metal components in the automotive industry. High process variability in production and excessive time spent in die try-out are significant problems in automotive stamping. It has previously been suggested that the elastic behaviour of the system may contribute to these problems. However, the mechanical principles that cause the press system to affect the forming process have not been documented in detail. Due to a poor understanding of these problems in industry, the elasticity of the press and tools is currently not considered during the die design. The aim of this work was to explore the physical principles of press system elasticity and determine the extent to which it contributes to problems in try-out and production. On the basis of this analysis methods were developed for controlling or accounting for problems during the design process. The application of frictional restraining force to the edges of the blank during forming depends on the distribution and magnitude of the clamping force between the binders surfaces of the draw die. This is an important control parameter for the deep drawing process. It has been demonstrated in this work that the elasticity of the press and draw die can affect clamping force in two ways. The response of the press system, to the forces produced in the press during forming, causes the magnitude of clamping force to change during the stroke. This was demonstrated using measured data from a production press. A simple linear elastic model of the press system was developed to illustrate a definite link between the measured force variation and the elasticity of the press and tools. The simple model was extended into a finite element model of the complete press system, which was used to control a forming simulation. It was demonstrated that stiffness variation within the system could influence the final strains in a drawn part. At the conclusion of this investigation a method is proposed for assessing the sensitivity of a part to clamping force variation in the press during die design. A means of reducing variation in the press through the addition of a simple linear spring element is also discussed. The second part of the work assessed the influence of tool structure on the distribution of frictional restraining forces to the blank. A forming simulation showed that tool stiffness affects the distribution of clamping pressure between the binders. This was also shown to affect the final strains in a drawn part. However, the most significant influence on restraining force was the tendency of the blank to increase in thickness between the binders during forming. Using a finite element approximation of the try-out process it was shown that the structure of the tool would also contribute to the problems currently experienced in try-out where uneven contact pressure distributions are addressed by manually adjusting the tool surfaces. Finally a generalised approach to designing draw die structures was developed. Simple analysis methods were combined with finite element based topology optimisation techniques to develop a set of basic design guidelines. The aim of the guidelines was to produce a structure with uniform stiffness response to a pressure applied at the binder surface. The work concludes with a recommendation for introducing the methods developed in this thesis into the standard production process.

The remapping of cortical networks after stroke is hypothesized to be one of the mechanisms subserving functional recovery. Our understanding of cortical remapping remains limited due to the inability to resolve which cells are active while performing motor tasks with high temporal and spatial specificity. The experiments presented in the first chapter of this thesis evaluate the ability of the inducible Arc-CreERT2:Rosa-YFPf/f model to label cells in the motor cortex activated by a motor-related behaviour. Through the modification of previously published 4-hydroxytamoxifen treatment paradigms, this model can differentiate between animals that performed the rotarod task at two time points and home cage controls. In addition, 65% of cells active at the first behavioural time point are reactivated. Taken together, these data suggest that the Arc-CreERT2:Rosa-YFPf/f model is able to reliably label networks used to perform the same behavioural task at two time points. The second chapter of this thesis details a pilot study in which the Arc-CreERT2:Rosa-ChR2:YFPf/f model was used to test the effect of daily optogenetic stimulation of the contralateral cortex on functional recovery. The results of this chapter suggest that stimulating the contralesional motor cortex may impair functional recovery. Overall, the results of this thesis lay the foundation to use this model to investigate motor networks in both naïve and pathological conditions, such as stroke.

This investigation aimed to pinpoint the elements of motor timing control that are responsible for the increased variability commonly found in children with developmental dyslexia on paced or unpaced motor timing tasks (Chapter 3). Such temporal processing abilities are thought to be important for developing the appropriate phonological representations required for the development of literacy skills. Similar temporal processing difficulties arise in other developmental disorders such as Attention Deficit Hyperactivity Disorder (ADHD). Motor timing behaviour in developmental populations was examined in the context of models of typical human timing behaviour, in particular the Wing-Kristofferson model, allowing estimation of the contribution of different timing control systems, namely timekeeper and implementation systems (Chapter 2 and Methods Chapters 4 and 5). Research examining timing in populations with dyslexia and ADHD has been inconsistent in the application of stimulus parameters and so the first investigation compared motor timing behaviour across different stimulus conditions (Chapter 6). The results question the suitability of visual timing tasks which produced greater performance variability than auditory or bimodal tasks. Following an examination of the validity of the Wing-Kristofferson model (Chapter 7) the model was applied to time series data from an auditory timing task completed by children with reading difficulties and matched control groups (Chapter 8). Expected group differences in timing performance were not found, however, associations between performance and measures of literacy and attention were present. Results also indicated that measures of attention and literacy dissociated in their relationships with components of timing, with literacy ability being correlated with timekeeper variance and attentional control with implementation variance. It is proposed that these timing deficits associated with reading difficulties are attributable to central timekeeping processes and so the contribution of error correction to timing performance was also investigated (Chapter 9). Children with lower scores on measures of literacy and attention were found to have a slower or failed correction response to phase errors in timing behaviour. Results from the series of studies suggest that the motor timing difficulty in poor reading children may stem from failures in the judgement of synchrony due to greater tolerance of uncertainty in the temporal processing system.

The series of experiments reported in this thesis concern the ability to make perceptual-motor judgements of distance (Ex. 1 to Ex. 7) and size (Ex. 8). Experiments 1 and 2 indicated that visual judgements of maximum step length were effected by; distance from the site of action, the angle at which the obstacle was presented and whether monocular or binocular vision was used. This suggested that perceived maximum ability was not based on a body scaled invariant as suggested by Gibson (1979). Experiments 3 and 4 were designed to investigate the effect of altering the length of distance to-be-remembered, and compared performance across both visual and kinaesthetic conditions. The results suggested that the reproduction of distance is normally based on memory for the location of the end point, rather than the extent of the distance. No support was found for the claim that differences between the accuracy of recall of location and extent was due to the differential rehearsability of visual and kinaesthetic codes. Instead, it was proposed that changes in the procedure may have influenced performance by reducing the usefulness of a 'landmark' based form of coding in the extent trials. Experiments 5 and 6 were designed to investigate predictions arising from one of the dominant models of cross-modal performance (Connolly and Jones, 1970). Connolly and Jones's model postulated that differences between intra- and cross-modal performance could be explained in terms of the characteristics of modality specific short-term storage codes, and that translation between codes occurs prior to short-term storage. In general the results obtained were supportive of the pattern of accuracy reported by Connolly and Jones. However, the effect of delaying until the end of the retention interval knowledge of the reproduction mode was inconsistent with the model, that is, withholding information about the required reproduction mode appeared to increase the accuracy of judgements. One explanation for this effect is that pre-translated information was held in a form which was associated with high levels of both accuracy and attention. This speculative explanation was seen to have parallels with the Working Memory model (Baddeley and Hitch, 1974). Experiments 7 and 8 used an interference task paradigm to investigate whether a separate visuo-spatial store could be demonstrated to exist in relation to perceptual-motor information. The results failed to find conclusive support for such a store. The cumulative findings of Experiments 1 to 8 are discussed in relation general models of perceptual-motor performance.

The ability to perform precise and relatively independent movements of the fingers is an important feature of the primate's motor repetoire. A substantial amount of evidence suggests a special role for the hand area of the motor cortex in the execution of these movements, and in particular, thoses cells which make direct cortico-motoneuronal connections with motoneurones innervating the hand muscles. The axons of these corticomotoneuronal (CM) cells form part of the pyramidal tract. The subject of this study is the influence of these CM cells upon the activity of hand muscles in the conscious monkey performing a precision grip task between thumb and index fingers. Three aspects of the cortico-motoneuronal connection have been investigated; 1. The effect of discharges in individual CM cells on the gross e.m.g. activity of intrinsic hand and forearm muscles, and the distribution of these effects over various muscles. 2. The effect of individual CM cell discharge on the single motor unit activity in the intrinsic thumb muscles. 3. The significance of differences in firing frequency of individual CM cells upon their modulation of gross e.m.g. The spike-triggered averaging technique was employed to study the overall effect of identified pyramidal tract neurones (PTN) on gross e.m.g. activity. Rectified gross e.m.g. was averaged with respect to the discharges of single PTNs. The influence of the triggering cortical cell was revealed in the averages as a transient increase in muscle activity at the appropriate time after the cell had fired. This effect is called post-spike facilitation (PSF). The occurance of PSF in the spike-triggered average was taken as evidence that the triggering cells made a direct, presumably monosynaptic, connection with the motoneurones of the muscle in question. Quantitative and qualitative aspects of PSF are discussed. The activity of 5 to 10 intrinsic hand and forearm muscles were averaged with respect to individual PTNs. In this way the PSF distribution over different muscles, produced by one cortical cell, could be determined. It was established that CM cells produce PSF in a relatively restricted number of muscles (2-3 out of 10 tested). The impact of CM cells on the discharge activity of single motor units was studied by cross-correlating both spike trains. To overcome the considerable sampling problem, the occurrence of PSF in the spike-triggered gross e.m.g. average was used as a criterion for further cross-correlation analysis. The cross-correlogram peaks half-width and onset latency were suggestive for monosynaptic excitation of the motoneurones. Different approaches are discussed to estimate the strength of these connections and to relate these strengths to the number of synpatic boutons that the CM cell makes upon its target motoneurones. In terms of the number of extra discharges fired by the single motor unit in response to CM cell firing, the effects can be described as weak (5-20 extra motor unit spikes per 1000 CM cell discharges). It was possible to study the connectivity of single CM cells with different motor units of the same muscle by simultaneously recording several (2-5) motor units. It was found that if a CM cell showed a correlogram peak with one of the concurrently sampled motor units, most other motor units sampled from the same muscle would give correlogram peaks with the same CM cell. This finding is suggestive for a rather diffuse collateralization of the CM cell axons within the motoneurone pool of the target muscle. Finally the influence of different firing frequencies of CM cells on the form and strength of PSF effects was investigated. A striking result was that discharges preceded by long interspike intervals (> 50ms)could still exert quite powerful excitatory effects. The results of this series of experiments further elucidate the nature of the corticomotoneuronal connection and give an impression of the facilitatory capacity of single CM cells on motoneurons innervating the hand muscles.

State misinterpretation has been identified as a causal factor in several accidents where humans were operating complex systems in dynamic domains. The concept of state misinterpretation, although undefined, is characterised by its unobservability, and its relative infrequency. These features make gathering data about state misinterpretation difficult. It was therefore decided to use archive incident report data; the NASA Aviation Safety Reporting System database was used. A definition of state misinterpretation was formulated and translated into database queries to retrieve relevant incident reports for a homogeneous set of expert pilots over a fixed time period. These reports were encoded using the Cognitive Reliability and Error Analysis Method suitably adapted to analysis of aviation incidents. Each report was categorised by the type of state misinterpretation, and a taxonomy of these types was developed. Those types which occurred more than 20 times were analysed at three levels of abstraction. First, a concordance of individual actions showed that communication failures, missed observations and distractions were the most common causal factors. Second, the sequences of possible causal actions showed that some sequences are common across different types of error and state misinterpretation. Third, the causal trees for each state misinterpretation type were quantitatively compared. The lack of measured similarity between the trees suggests that the types in the taxonomy are distinct. Most of the analysed incidents were preventable by better management of flight crew actions. Two particular sequences of actions dominated the results. The first is where the flight crew missed an observation when they were distracted by a competing task. The second is where a communication failure between the flight crew and air traffic control occurred. Some suggestions are offered about how flight crews can better manage their actions to prevent the occurrence of some types of state misinterpretation, thereby reducing incident numbers.

It is important to monitor the wheel-rail friction coefficient in railway vehicles to improve their traction and braking performance as well as to reduce the number of incidents caused by low friction. Model based fault detection and identification (FDI) methods, especially state observers have been commonly used in previous research to monitor the wheel-rail friction. However, the previous methods cannot provide an accurate value of the friction coefficient and few of them have been validated using experiments. A Kalman filter based estimator is proposed in this research project. The developed estimator uses signals from the traction motor and provides a new and more efficient approach to monitoring the condition of the wheel-rail contact condition. A 1/5 scaled test rig has been built to evaluate the developed method. This rig comprises 2 axle-hung induction motors driving both the wheelsets of the bogie through 2 pairs of spur gears. 2 DC generators are used to provide traction load to the rollers through timing pulleys. The motors are independently controlled by 2 inverters. Motor parameters such as voltage, current and speed are measured by the inverters. The speed of the wheel and roller and the output of the DC generator are measured by incremental encoders and Hall-effect current clamps. A LabVIEW code has been designed to process all the collected data and send control commands to the inverters. The communication between the PC and the inverters are realized using the Profibus (Process Field Bus) and the OPC (Object Linking and Embedding (OLE) for Process Control) protocol. 3 different estimators were first developed using computer simulations. Kalman filter and its two nonlinear developments: extended Kalman filter (EKF) and unscented Kalman filter (UKF) have been used in these 3 methods. The results show that the UKF based estimator can provide the best performance in this case. The requirement for measuring the roller speed and the traction load are also studied using the UKF. The results show that it is essential to measure the roller speed but the absence of the traction load measurement does not have significant impact on the estimation accuracy. A re-adhesion control algorithm, which reduces excessive creepage between the wheel and rail, is developed based on the UKF estimator. Accurate monitoring of the friction coefficient helps the traction motor work at its optimum point. As the largest creep force is generated, the braking and accelerating time and distance can be reduced to their minimum values. This controller can also avoid excessive creepage and hence potentially reduce the wear of the wheel and rail. The UKF based estimator development has been evaluated by experiments conducted on the roller rig. Three different friction conditions were tested: base condition without contamination, water contamination and oil contamination. The traction load was varied to cover a large range of creepage. The importance of measuring the roller speed and the traction load was also studied. The UKF based estimator was shown to provide reliable estimation in most of the tested conditions. The experiments also confirm that it is not necessary to measure the traction load and give good agreement with the simulation results. With both the simulation and experiment work, the UKF based estimator has shown its capability of monitoring the wheel-rail friction coefficient.

Accurate perception and control of self-motion is vital for human survival. Most animals rely on vision for navigating through complex environments. In this thesis, I investigated how vision influence perception and guide self-motion from two aspects: (1) what visual information humans pick up from the environment to form their perception and guide their self-motion; (2) how the degeneration of the basal ganglia and cerebellum, the two largest subcortical nuclei connecting the visual and motor areas of the brain, affect the controller’s performance. Study 1 examined the condition under which optic-flow information beyond velocity field helps heading perception. I systematically varied the amount of information in velocity field through manipulations of field of view (FOV). The amount of optic-flow information beyond velocity field was manipulated by two types of displays. I found heading bias increased with the reduction of FOV only when optic-flow information beyond velocity field was not available. Study 2 investigated whether the information investigated in Study 1 is sufficient and necessary for active control of heading. I used the similar display simulations as study 1 with the exception that the vehicle orientation was perturbed pseudo-randomly. Participants used a joystick, under both velocity and acceleration control dynamics, to continuously rotate the vehicle orientation back to its heading direction. The results showed that participants’ accurate performance under condition that only provided velocity field information was further improved when optic-flow information beyond velocity field was available. Study 3 examined the relative contributions of three visual cues (i.e., heading from optic flow, bearing, and splay angle) for lane-keeping control. Observers controlled the car’s lateral movement to stay in the center of the lane while facing two random perturbations affecting the use of bearing or splay angle information. I found that performance improved with enriched flow information. In the presence of splay angles, participants ignored bearing angle information. Study 4 investigated the roles of the basal ganglia and cerebellum in motor control task using brain-damaged patients. Participant’s task was to use the joystick to keep a blob in the center of the display while the horizontal position of the blob was perturbed pseudo-randomly. This task is not a self-motion task but mimics real-world lane-keeping control. Both the Parkinson’s disease patients and cerebellar patients showed impaired motor control performance in comparison with the healthy controls. In conclusion, the visual information used for motor control in general depends on the task. For traveling along a curved path, the velocity field contains sufficient information for heading perception and heading control. Optic-flow information beyond velocity field improves heading perception when the velocity field does not contain sufficient information. It also helps heading control when available. For lane-keeping control, adding optic flow information improves participants’ performance. Splay angle information plays a more important role than does bearing angle information. The visual information used for motor control changes when certain brain areas are damaged. Parkinson’s disease patients and cerebellar patients show the inability to process visual input effectively for online motor control.
published_or_final_version
Psychology
Doctoral
Doctor of Philosophy

Simple single-mode formulae are derived to present a general and straightforward understanding of the non-linear static and dynamic behaviour of postbuckled plates. The Rayleigh-Ritz method is used for multi-degrees-of-freedom analysis of postbuckled plates. A finite-element method using 16-nodes rectangular element is applied to postbuckling analysis of a composite plate with a central square hole. The magnitudes of multimodal linear response to random excitation are predicted using a simple formula based on results obtained by the Rayleigh-Ritz method and the trends of non-linear random responses are estimated using the single-mode formulae. Experimental techniques used include the Shadow Moire method to measure static displacement patterns, a point excitation test to find resonance frequencies and mode shapes, and acoustic testing to obtain random structural responses to sound pressure levels up to 163 dB. Experimental results were obtained for Aluminium alloy plates with two types of boundary conditions. These were compared with results from CFRP plates with similar types of boundary conditions. Finally, the acoustic response of a CFRP plate with a central square hole was examined. It was found that at high levels of acoustic exacitation, snap-through motion of amplitude larger than the oscillatory motion component can occur in the postbuckled plates and the overall r.m.s. strain value is comparable to the static strain value. In summary, the buckling of the plate changes the dominant deformations in the in-plane direction from those of in-plane effects to those of bending effects, whereas the large acoustic excitation changes the dominant dynamic deformations in the transverse direction from those of bending effects to those of in-plane effects.

Perinatal stroke, which occurs before or shortly after birth, may result in both beneficial and maladaptive plasticity in surviving tissue. However, current preclinical and clinical work have an unclear understanding on the relationship between functional outcome and neurophysiology. This thesis aims to dually characterize and correlate behaviour with cortical motor representations in a mouse model of perinatal stroke. On postnatal day 7, a unilateral photothrombotic stroke was produced in the primary motor cortex of Thy1-ChR2 mice. Sensorimotor function was evaluated in adulthood with a battery of behavioural tests. Subsequently, a transcranial window was implanted, and motor maps were created through optogenetic point stimulation. To evaluate the impact of skilled motor training on cortical reorganization, mapping was conducted before and after training on the single pellet reaching task. P7 stroke caused functional impairments across a battery of motor tasks, while both motor map size and movement latency were bilaterally impacted. Spontaneous limb use was positively correlated with map size of both hemispheres, but single pellet performance was only positively correlated with map size in the injured hemisphere. Following skilled motor training, both map size reductions and delayed latency was partially restored. Additionally, significant correlations between map size expansion and movement latency reduction following skilled motor training not only demonstrate that training-induced plasticity was beneficial, but also primarily mediated by the uninjured hemisphere. As the first study to conduct within-animal optogenetic motor mapping following perinatal stroke, we show that 1) perinatal stroke bilaterally impacts both cortical and descending aspects of the motor system, 2) the remaining movement sites in both the uninjured and injured hemispheres have a positive impact on functional outcome, and 3) skilled forelimb training can partially restore cortical and descending motor neurophysiology.

The use of variable frequency drives in centrifugal pump applications has raised the question of how to select a drive. Clogging obstacles in waste water applications create unknown transient loads for the pump system. A sudden load increase occurrence can clog the pump if the drive cannot supply enough current to reach the motor’s torque demand. In order to select a suitable drive, an empirical approach has been implemented, investigating three different drives. Results have shown that selecting a drive with the highest possible overload capabilities, even if for a short time is most suitable. Operation in vector speed control gives the most reliable operation if an automatic parameter tuning is performed by the drive.
Användningen av frekvensomriktare i centrifugalpumpar har väckt fr ågan om hur en omriktare skall väljas. Igensättande objekt i avloppsvatten kan ge upphov till transienta laster i pumpsystemen. En oförutsedd lastökning kan sätta igen pumpen om frekvensomriktaren inte kan förse motorn tillräckligt med ström för att möta momentbehovet. För att välja en lämplig omriktare har ett empiriskt tillvägag ångssätt valts i en undersökning av tre olika omriktare. Resultat har visat att det är lämpligast att välja en omriktare med högst överbelastningskapacitet, även om under en kort tid. Vektor hastighetskontroll är metoden som ger stabil körning om omriktaren f ått automatiskt ställa in motorparametrarna.

A fast and powerful gaze stabilization reflex supports self-motion es- timation and flight control in flies. Changes in body posture are conveyed by a variety of sensory modalities and compensated for by fast and accurate head movements. This thesis aims to further our understanding of the behavioural basis of compensatory head move- ments, and presents a first foray into the in vivo imaging of the motor systems that actuate these control reflexes. Major sensors that contribute to gaze stabilisation are the visual ocelli and compound eyes on the head, and the mechanosensory halteres on the thorax. The integration of visual feedback and mechanosensory feedforward control gives rise to a two-degree-of-freedom controller, a design which is extensively used in engineering applications. I per- formed a linear systems analysis of compensatory head roll in response to forced thorax oscillations in the fly. The feedforward pathway ex- hibited a high bandwidth and constant gain and reduced the response delay of the reflex. Large stability margins in the feedback pathway supplied by the compound eyes guaranteed stable behaviour in the face of response variability. The occlusion of the ocelli did not change the gain of the feedback pathway, but significantly reduced the la- tency. I investigated the use of iodine-enhanced computed x-ray microto- mography (microCT) to perform fast three-dimensional imaging of the neck and flight motor systems. Virtual dissections of major func- tional units illustrate the possibilities and limitations of microCT. To observe the configuration of motor systems in behaving flies I per- formed gated microtomography using hard x-rays at the TOMCAT beamline of the Swiss Light Source, a third generation synchrotron. While 3D tomograms of the neck motor system proved elusive, this thesis presents the first in vivo tomograms of the flight motor and wing hinge during tethered flight.

This thesis investigated efficient methods for learning locomotion behaviours for robots, and the challenges of combining several complex controllers. Experiments were performed with a dynamic biped in simulation required to walk across gaps, over steps and stairs, and jump over hurdles and blocks, and also in a real-world scenario with a large tracked platform negotiating small doorways. The developed solutions utilised perception to perform complex maneuvers while minimising retraining for new behaviours. Ideas from this thesis lead toward scalable behaviour libraries to enable robots to make their way into an increasing number of roles in our society.

Mestrado em Actuarial Science
IFRS 17 é a nova norma internacional para seguros que irá ter início em 2022, provocando dificuldades sem precedentes no mundo segurador. Desde novos requisitos quantitativos, até motores computacionalmente avultados. É o novo desafio para as empresas seguradoras e consultores em todo o mundo. Um dos novos componentes da norma é a Contractual Service Margin. Esta componente corresponde ao lucro não adquirido do grupo de contractos. Consoante os serviços prestados, este montante será lançado na insurance revenue e irá afectar directamente o lucro em cada período de reporte. Este é o tema principal do relatório e irá ser testado à força como reage face a eventos inesperados, diferentes daqueles que foram previsto no reconhecimento inicial. Companhias de seguros irão necessitar de desenvolver, ou recorrer a, novos motores de cálculo para a onda de informação que será requerida pela norma. Neste relatório, um motor totalmente automático foi criado de raiz e, apesar de estar calibrado para um tipo de contracto em específico, tem o potencial de reconhecer todos os tipos de contractos. Todos os resultados servem para fins ilustrativos, mas demonstram a importância da Contractual Service Margin nesta nova norma.
IFRS 17 is the new international insurance norm that will start in 2022, bringing an unprecedented difficulty to the insurance world. From new quantitative requirements, to enormous computational engines. It is the new challenge for insurance companies and consultants throughout the world. One of the new components of the norm is the Contractual Service Margin. This component reflects the unearned profit of a group of contracts. As insurance services are provided, this amount is released to the insurance revenue and it will affect the profit directly at each reporting period. We will test how it reacts when faced with unexpected events, different from the ones predicted at initial recognition. Insurance companies will need to develop, or resort to, new calculation engines for the wave on information that is required for this norm. In this report, a fully automatic engine was built from scratch and, although it is calibrated for one specific type of contract, it has the potential to recognise all types of contracts. All results are merely illustrative, but demonstrate the importance of the Contractual Service Margin in this new norm.
info:eu-repo/semantics/publishedVersion

A fundamental issue in the study of verbal behaviour is whether the underpinning representation of speech, while derived from different modalities, is itself amodal. The current thesis contributes to this debate, utilising two behavioural phenomena to show that verbal performance is not simply limited to representations independent of the modality through which they were derived. Firstly, similarities in verbal short-term memory performance across presentation modalities have been explained in terms of a phonological level of representation. Namely, both auditory and visual modes of presentation demonstrate similar patterns of performance within the recency portion of the serial position curve. However, it is shown that while recall at the terminal list item for an auditory list is immune to the disruptive effect of task-irrelevant background sound and articulatory suppression, lipread recency is note immune. In addition, although the effect of an auditory suffix on an auditory list is due to the perceptual grouping of the suffix with the list, the corresponding effect with lipread speech is shown to be due to misidentification of the lexical content of the lipread suffix. Furthermore, even though a lipread suffix does not disrupt auditory recency, an auditory suffix does disrupt recency for lipread lists due to attentional capture. These findings are subsequently explained in terms of modality-specific perceptual and motor-speech output mechanisms, rather than to the storage and manipulation at some phonological level of representation. Secondly, the mechanisms underlying the integration of seen and heard speech is investigated via the McGurk effect in order to understand the stage at which auditory and visual modes of speech come to be integrated. It is shown that concurrently articulating verbal material out loud or silently mouthing speech during syllable identification reduces he McGurk effect, whereas passive listening to task‐irrelevant speech or sequential manual tapping does not. On the basis that both concurrent articulation and silent mouthing mpede Subvocal speech production processes, that both manipulations also disrupt the McGurk effect suggests that subvocal motor mechanisms necessary for speech production are involved in audiovisual integration. Taken together, if progress is to be made in understanding the underlying representations of verbal behaviour, an approach should be adopted that not only requires an amodal, phonological representational form, but also considers the extent to which modality-specific systems primarily serving perceptual and motor processes contribute to performance.

Our daily lives are filled with routine behaviours that we develop with repeated practice over time. These routine behaviours, often executed automatically without requiring much attention become an integral part of our lives. However, a seemingly effective automatic behaviour can become inappropriate or inefficient with changes in the environment and we naturally turn to a more adaptable, perceptually guided behaviour to achieve the same goal. What are the networks that mediate these automatic and perceptually guided behaviours? This thesis focuses on understanding the role of frontal-striatal circuits in the cognitive motor control of sequential behaviour, as well as the contribution of dopamine (DA) in these areas. The aim of the studies presented in this work was to address these questions from a number of perspectives. Firstly, in an awake-behaving non-human primate study the goal was to develop a behavioural task that differentiates the automatic and attention demanding sequential actions. Secondly, ensembles of neurons in the frontal cortex and the dorsal striatum were recorded simultaneously with a multichannel single unit recording system to characterise neural responses to our different task conditions and thereby investigating the role of prefrontal cortex and the dorsal striatum in these behaviours. Thirdly, we locally injected DA receptor antagonists into the dorsal striatum, during the behavioural task to examine the effects of DA on behaviour. Finally, in a study using patients with Parkinson’s disease we examined their performance in a sequence learning task from positive and negative feedback processing while they were off and on their DA medication. This approach helped to strengthen the link between findings in the non-human primate and the human subjects with specific involvement of DA or disruption of the frontal-striatal circuits in sequence learning.

The workload of drivers has been increasing in modern times due to the growing use of In-Vehicle systems. The higher task demand resulting from these extra visual and auditory stimuli presents an increasingly challenging problem for drivers, and has become a growing safety concern, as the higher workloads can adversely affect driving performance and must be balanced against the benefits from in-vehicle systems. Existing models suggest that when the induced workload is relatively low, drivers can deal with this increased demand by using different coping strategies; however, when the workload increases above a certain level, drivers’ performance decreases. These models are relatively simplistic and do not describe the extent to which drivers’ coping strategies can impact on the relationship between workload and performance, which are difficult to observe by traditional measures. The literature suggests that visual behaviour or eye movements, with its physiological nature, combines attributes of both attention state and human behaviour, and can be used to provide sensitive, diagnostic, and instantaneous measurements to investigate the impact of increased workload on performance, and explore associated coping strategies. An on-road experiment was therefore conducted to observe drivers’ behaviour when their workload was increased by in-vehicle secondary tasks, and the impact this had on their performance, using eye movement as well as traditional vehicle control and manoeuvring measurements. The field experiment was run under two driving scenarios of Car-Following and Free-Driving, on two road sections in Hampshire over a period of three months, using the Transportation Research Group’s Instrumented Vehicle (IV) and a FaceLabTM eye monitoring system. An Operation Simulation System was developed for drivers to perform a series of in-vehicle auditory and visual tasks through touch screen and audio systems, which reflected two different types of workload (i.e. mental and visual), with three levels of difficulty. Surveys were also conducted during and after each test run to assess drivers’ workload perception and gain an understanding of their experiences of performing the tasks, and a database established to organise all the information collected to enable subsequent analyses to be conducted readily. The results show that drivers’ behaviour was significantly impacted by additional tasks, and their secondary task performance decreased steadily with task complexity. The effects were consistent across the two Scenarios, although driving performance generally deteriorated more for the visual tasks than auditory ones, which reflects the higher conflict of visual and manual resource caused by these tasks, and all drivers took action to compensate either by increasing their headways in Car-Following, or reducing their speed in Free-Driving. The effects were reflected in their visual behaviour, which showed higher blink rates and shrunk visual searching range for the auditory tasks, i.e. a higher mental workload over baseline driving, and higher saccade and more visual transactions between different objects for the visual ones. Differences were also found in the driving and visual behaviour of individual driver characteristics groups, including gender and different experience groups. While traditional performance measurements showed many differences in behaviour due to the extra in-vehicle tasks, the different coping strategies adopted by drivers were typically observed only through the analysis of their visual behaviour. The use of these additional measurements provides an improvement to existing models for describing the relationship between workload and performance in dual-tasking.

Motor neuron disease is an incurable neurodegenerative condition. A proportion of motor neuron disease is inherited in autosomal dominant manner, of which approximately 10% is due to mutations in the enzyme superoxide dismutase 1 (SOD1). The mechanism by which mutant SOD1 selectively kills motor neurons is not understood. Motor neuron disease due to mutant SOD1 has been modelled by the SOD1 transgenic mouse which possesses a SOD^{G93A} transgene array. This mouse develops progressive motor neuron loss, resulting in premature death. The Legs at odd angles (Loa) mouse, which has a missense mutation in the gene encoding cytoplasmic dunein, develops progressive – wild-type, Loa/+, SOD1 ^{G93A} and Loa/SOD1^{G93A}. Surprisingly, Loa/SOD1^{G93A} mice survive significantly longer than their SOD1^{G93A} littermates, thus the presence of a mutation in dynein reduces the toxic effect of mutant SOD1. To gain further understanding of how mutant SOD1 kills motor neurons, the behaviour of mutant SOD1 between neurons of these genotypes was compared. Differences in behaviour of mutant SOD1 between these genotypes may correlate with the observed differences in survival and thereby suggest toxic mechanisms. Methods of tagging SOD1 for live cell imaging were assessed and strategies of transfecting cultured motor neurons with tagged SOD1 evaluated. Lentiviral vectors were used to transduce cultured motor neurons with tagged SOD1. Methods of assessing anterograde axonal transport were evaluated. The localisation and movement characteristics of wild-type and mutant SOD1 were evaluated in wild-type motor neurons. No statistically significant differences were found. The localisation and movement characteristics of mutant SOD1 was evaluated in motor neurons of genotypes wild-type, Loa/+, SOD1^{G93A} and Loa/ SOD1^{G93A}. No statistically significant differences were found. Thus the behaviour of the toxic moiety, mutant SOD1, was not demonstrated to be different between neurons with different survival characteristics.

Walking is healthy, environmentally beneficial and sustainable to human society. Travellers increasingly are being encouraged to walk more. However, pedestrians’ interaction with motorised vehicles is a major constraint to their movement. Many innovative treatments have been developed to balance the two modes. Proper methods are required to evaluate and compare performances of different treatments to support decision making. Micro-simulation is a useful supplementary tool for such evaluation and comparison studies for its cost-effectiveness and non-intrusiveness. However, there is a significant gap between capabilities of existing simulation models and practical needs. New understandings of the Pedestrian-Vehicle Interaction (PVI) behaviour and corresponding micro-simulation models are required to conduct micro-simulation studies of the interaction process between the two modes to derive new knowledge of the mixed traffic. This dissertation presents the development and application of a micro-simulation model, PVISIM (Pedestrian-Vehicle Interaction SIMulation), to study PVI behaviour in a range of circumstances in an urban street environment. Key contributions relate to the collection of a substantial data base, development and validation of the model, an appreciation of the value of the approach and new understandings of PVI behaviour. A series of studies to measure behaviour based on the data collected in Beijing, China have been detailed. Intra vehicle and pedestrian behaviour models were developed and validated separately, incorporating the best available understandings from existing published studies and in accordance with the specific local data. The two modes were integrated by interpreting new findings from the study of microscopic interaction behaviour of the two modes. The complete model was validated against field data independent of those used in model development, covering a number of typical scenarios, including both unsignalised and signalised situations. The validated model was applied to study a typical unsignalised scenario by analysing system performances under different combinations of vehicular traffic and pedestrian crossing demand, in terms of efficiency, safety and environmental impact. Also, operations of different treatments including no-control, Zebra crossing, fixed-time signal crossing and Puffin crossing at two typical types of locations were compared. Interpretations and recommendations were given for each application. The results can be used to supplement existing guidelines for pedestrian related problems, and also contribute to the knowledge base to incorporate pedestrians into current micro-simulation tools in a more realistic way.