This thesis presents a study on the role of internal impedance control in embodied perception. This study gives a novel perspective on how action and perception are coupled in a shared embodiment like a tendon in muscles used for both action and perception. The mode of perception discussed in this thesis is the sense of touch or “haptic perception” of both human and biologically inspired artificial systems. Firstly, this thesis explores the internal impedance control behavior of humans in haptic exploration during manual palpation of a soft phantom (presented by a soft silicone phantom) to detect and estimate the depth of an abnormality (presented by a hard nodule). The muscle actuation levels of humans were measured across human subjects to learn the pattern of such regulations. It was found that humans perform voluntary modulation of muscle co-contraction level during haptic exploration of a soft tissue. In addition, it was found that these regulations of muscle co-contraction can be learned and mapped using a Markov decision matrix. This raised the question, which became the main focus of this thesis, as to why humans perform such regulations of muscle co-contraction levels during haptic exploration. The influence of proprioceptive information and the muscular activity on the interpretation of the environment during haptic exploration is not understood yet. Therefore, the objective of this thesis is to understand the role of internal impedance and behavioral variables control during embodied sensing and haptic exploration. Secondly, it was found using a robotic manipulator with variable joint stiffness that the information-gain of the perception of its internal state can be maximized by controlling the joint’s stiffness (internal impedance). This leads to an enhanced accuracy in the estimation of its internal state. It was also found that the sensing of external environment, in this case, through haptic perception during robotic palpation could also benefit from this principle. The information gain about the environment can be maximized through the modulation of the internal stiffness. Thirdly, a Bayesian inference mechanism was used in addition to the information metrics in the robotic palpation task to infer real-time estimates of the depth of abnormality in soft silicone phantom based on past experience. The stiffness control pattern found in human’s manual palpation was implemented in the robotic probe to investigate whether controlling the probe’s internal impedance to follow the transition patterns of human’s co-contraction levels can enhance the nodule depth estimation accuracy. In comparison to the static stiffness; it was shown that this strategy of stiffness control in the robotic probe significantly improved the estimation accuracy of hard nodule’s depth. Lastly, this thesis also investigated both individual and collective roles of robotic probe’s internal stiffness, indentation level, and probe sweeping speed in the estimation of the nodule’s depth during haptic exploration. The results from the experiments have confirmed the hypothesis that by allowing the probe to vary its internal stiffness and behavioral variables, the estimation process can enhance the accuracy in haptic perception. Using artificial system as an abstraction of biological counterparts, this thesis has, for the first time, explained the possible reason as to why biological systems, humans, for instance, actuate both internal parameter (like stiffness of the joint) and the behavioral variables during haptic exploration of the environment.

Running shoes are designed to reduce injury risk and enhance performance. In line with traditional running injury paradigms running shoes aim to reduce the magnitude and/or rate of foot motion and impact loading. While numerous studies have explored the influence of different shoe modifications upon these parameters, limited work has explored how different types of conventional running shoe influence foot and lower limb kinematics. Therefore the overarching aim of this thesis was to determine the influence of different types of running shoe on shod foot and lower limb motion during running. Twenty-eight active males (26 ± 7years, 1.77 ± 0.05m, 79 ± 9kg) participated in the main phase of testing. Participants ran in three types of running shoe (motion control, neutral and cushioned) at a self-selected pace, on a treadmill. Three-dimensional lower limb and inter-segmental foot kinematics were calculated from the position of retro-reflective markers tracked by a VICON motion analysis system. Incisions were made within the right shoe to accommodate direct tracking of shod foot motion. The incision parameters were validated in preliminary work. One-way repeated measures analysis of variance (ANOVA) and Freidman’s ANOVA were used to explore differences between footwear conditions. Significant differences in lower limb and foot kinematics were reported at the knee, ankle, midfoot-rearfoot, forefoot-rearfoot and medial longitudinal arch (MLA). Motion control shoes significantly reduced midfoot-rearfoot eversion and MLA deformation compared to neutral and cushioned shoes. Cushioned shoes significantly reduced ankle joint eversion compared to the motion control shoe. The findings of this thesis provide novel information regarding the influence of motion control, neutral and cushioned running shoes upon foot and lower limb kinematics, and further develop means of modelling the shod foot. Overall the findings of this thesis demonstrate the efficacy of running shoes to reduce the magnitude of foot motion.

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The steps involved in early bone mineralisation have been extensively studied. Studies have suggested various means by which bone mineralisation occurs: (1) a cell-independent (protein-assisted) process where non-collagenous proteins mediate soluble ions to form mineral on the collagen fibril; (2) a cell-controlled mechanism where mineral seeds formed within intracellular vesicles released from the plasma membrane would subsequently rupture and disperse their contents on the extracellular matrix; and (3) an acellular route in which amorphous calcium phosphate mineral precursors are produced and deposited in collagen fibrils where they transform into more crystalline apatite platelets. Despite extensive studies, there are still unanswered questions about how bone becomes bone. The first series of experiments in this thesis are aimed at studying the mineral characteristics of early in vitro osteoblast mineralisation at the extracellular matrix. These experiments seek to determine the sequence of possible mineralisation events that take place during mineral nucleation and growth on collagen. Transmission electron microscopy was used to provide high spatial resolution, which was compounded with chemical analysis of energy dispersive x-ray and electron energy-loss spectroscopies. We identified carbonate-rich calcium phosphate dense granules in the extracellular matrix that may act as seeds for growth into larger, submicron-sized, globular aggregates of apatite mineral with a different stoichiometry. These globules appear to mineralise the collagen fibrils forming crystalline textured crystals with higher calcium-to-phosphate ratio and lower carbonate content as the mineral phase of bone. We provide new evidence that the use of a carbonate rich, amorphous calcium phosphate spherical bioseed could be a process by which a soluble calcium phosphate phase is stabilised and delivered to the collagen for subsequent maturation and collagen mineralisation. We also examined the effect of strontium ion supplementation to bone mineralisation as a translational study. Previous studies showed the positive effects of in vivo strontium supplementation as an anti-osteoporotic drug. Strontium is able to: (1) stimulate bone formation; (2) increase osteoid surface, osteoblast surface, and bone forming surfaces; (3) decrease bone resorbing cells; (4) increase bone strength and mass; and (5) reduce the risk of fractures. In the in vitro system, studies have focused on how strontium ions increase bone mineral's a- and c-axis lattice parameters. The effect of strontium ions on the matrix component of bone is the aim for the second part of this thesis. Using Raman spectroscopy, TEM imaging, and biochemical quantification, we studied the effect of strontium ion supplementation on in vitro MC3T3 osteoblasts, with close focus on the osteoblast matrix. We observed that cultures treated with high strontium supplementation had impaired mineralisation, where nodules were formed but failed to mineralise. Periodic collagen banding was seen on TEM micrograph from all treatments. Collagen organisation was quantified using image analysis of TEM micrograph, and strontium supplementation seemed to affect fibril organisation. A slight addition of 0.1 mM strontium seemed to result in the less random organisation of collagen fibril, while 3 mM supplementation seemed to increase the random organisation. Only cultures treated with the highest amount of strontium supplementation showed an abundance of matrix vesicles around the collagen fibrils. Raman spectroscopy showed an increase in lipid detection on strontium supplemented groups, which may be due to the increased presence of matrix vesicles. Taken together, high strontium supplementation may decrease the rate of degradation of matrix vesicles and lead to altered mineralisation whereby nodules form but fail to mineralise. The relative amounts of collagen were also explored by Raman spectroscopy and hydroxyproline analysis; however, our findings were not statistically significant. Further experiments are needed to more completely elucidate the molecular mechanisms at play in strontium's effect on bone mineralisation.

Bone strength is maintained through the continuous process of bone remodelling within which bone cells work together. Mechanical loading is an important regulator of this process with bone cells being particularly sensitive to fluid shear stress (FSS). The aim of this research was to investigate long-term responses by osteoblasts to low FSS using both monolayer and 3D in vitro models. The osteoblast cell lines IDG-SW3 and MLO-A5 were cultured for 28 days or 21 days respectively in 6-well plates and were exposed to low FSS generated with a see-saw rocker (<0.05 Pa) or an orbital shaker (<0.9 Pa). There were no differences in metabolic activity, cell proliferation, alkaline phosphatase (ALP) activity, mineralisation, collagen deposition and osteocytogenic differentiation between static and dynamic groups. Despite not reacting to FSS, IDG-SW3 responded to biochemical stimulation. Deposition of collagen and ALP activation were inhibited when ascorbic acid (50μg/ml) was omitted (p<0.001). Mineralisation was positively related to the concentration of β-glycerophosphate (β-GP) which also regulated osteocytogenesis. Treatment with 1 mM strontium ranelate reduced ALP activity and mineralisation (p<0.001), but enhanced expression of the osteocyte marker Dmp1-GFP (p<0.001). To investigate whether IDG-SW3 were more responsive to low FSS in a 3D environment, cells were embedded in collagen (2 mg/ml). Modification of a transwell insert enabled long-term cell culture under hydrostatic pressure-driven low fluid flow. After 21 days, cells had contracted the collagen by 50% compared to cell-free controls (p<0.001). However, no significant differences in gel contraction, cell distribution and mineralisation were detected between static and flow-stimulated groups, further confirming the results from the monolayer experiments.

Exposures to hot environments and high intensity exercise provide some of the greatest challenges to the thermoregulatory system. Under such conditions evaporation is the greatest avenue of heat loss from the body. Whilst regional sweat rate variations in humans are widely recognised, most studies only measure a small number of sites using a limited surface area, and generalise this data to larger regions. A consensus in the literature indicates that the highest sweat rates are on the forehead and torso, and lowest on the extremities. However, no study has quantitatively measured regional sweat rates over large surface areas of the body. Since sweating is related to the thermal state of the body, comparison of regional sweat rates between studies is further complicated by the use of different environmental conditions, exercise modes and work rates. A good meta-analysis of existing data is therefore problematic. The aim of this thesis was to produce detailed whole body sweat maps for male and female athletes, and untrained males, during two exercise intensities in moderate environmental conditions (25°C, 50% rh) with a 2 m.s-1 air velocity.

This work examines two aspects of bone structure, namely the basic size and form of the bone mineral crystallites, and the three-dimensional orientation of these crystals within the whole bone. X-ray diffraction, and both bright and dark field electron microscopy of bone, strongly suggest the mineral crystals to be irregular plate-like forms, approximately 5. 0nm thick, with a variable maximum dimension; these methods also find no significant difference in the shape, size or composition of crystals in fixed and unfixed rabbit femur. The (002) diffracted beam is used to produce dark field images, the measured c-axial length distributions have mean values of 32.6nm, 36.2nm, and 32.4nm for rabbit, ox and human bones respectively. Using the x-ray method of line broadening, it is shown that c-axial measurements consistent with those of the dark field method are produced, provided that lattice strain is accounted for in the theoretical formulation. The x-ray method is used to examine crystal maturation. Results indicate that the crystals of rabbit bone increase in size and perfection from birth until a stable situation is attained after approximately seven weeks, when the crystals exhibit a mean c-axial length of approximately 34.0nm, and a maximum compressive or tensile lattice strain of 0.3% in the (002) direction. An x-ray goniometer is designed and constructed, and used to produce quantitative (002) pole figures of small samples of secondary type human, and primary type ox bones. Results show secondary bone to have a major fibre axis aligned on average with the femoral axis, and the degree of orientation shows rotational symmetry about this axis. Primary bone exhibits the same major axis, but also shows a planar orientation along the laminar direction. The results of this work, their significance, and suggestions for future developments are discussed in the final chapter.

An ongoing subject of research in the field of human motor control is the extent of similarities in neural activity underlying overt movement execution compared with imagination and observation of movement. Previous work in this area has focused mainly on the 'active' phase of movement (i.e. the period during which movements are actually executed, imagined or observed). Activation of motor cortical areas has been demonstrated during the active phase of motor imagery and observation suggesting that these alternative modes of movement share underlying neural mechanisms with overt motor execution. This thesis aimed to extend this work by studying the preparatory phase of movement, known to be an important part of the production of a motor response. Using high-density electroencephalography (EEG) recorded in a response-priming paradigm the effects of providing advance information about an upcoming movement were compared in the context of execution, imagination and observation of movement. For imagined movements, similar effects of advance information on preparatory activity were demonstrated to those shown prior to executed movements, providing further support for the theory that motor imagery activates existing neural representations of movement in motor areas of the brain (the neural simulation theory). For observed movements, by contrast, advance information about the upcoming movement did not invoke motor- related preparatory activity suggesting that similarities in motor execution and observation do not extend into the preparatory phase. This was interpreted as reflecting the passive nature of movement observation compared with the willful generation of a motor action in movement imagery and execution. In conclusion, an investigation into the preparatory phase of movement in this thesis suggests that motor imagery, in comparison to motor observation, provides a closer correlate to actual movement execution in terms of shared underlying neural activation.

MicroRNAs (miRNA/miRs) play a crucial role in a variety of biological processes including stem cell differentiation and function. Foetal femur-derived skeletal stem cells (SSCs) display enhanced proliferation and multipotential capacity, indicating excellent potential as candidates for tissue engineering applications. This thesis has identified and characterised subpopulations of skeletal stem cells found within the foetal femur. Cells isolated from the epiphyseal region of the foetal femur expressed higher levels of genes associated with chondrogenesis while cells from the diaphyseal region expressed higher levels of genes associated with osteogenic differentiation. In addition to the difference in osteogenic and chondrogenic gene expression, epiphyseal and diaphyseal cell populations displayed distinct miRs expression profiles. To examine the role of miRNA during skeletogenesis, a robust cell culture model containing differentiating SSCs and an effective transfection protocol was developed. Spermine-pullulan complex, a potential delivery system for miRNA-based gene therapy, was shown to be able to transfect SSCs with miRNA mimics and inhibitors but with lower efficacy compared to liposome base transfection reagent. Through miRNA gene expression profiling and mRNA targets analysis, miR-146a was found to be expressed by diaphyseal cell populations at a significantly enhanced level compared to epiphyseal populations and was predicted to target various components of the TGF-β pathway. Examination of miR-146a function in foetal femur cells confirmed regulation of protein translation of SMAD2 and SMAD3 following transient overexpression in epiphyseal cells. The down-regulation of SMAD2 and SMAD3 following overexpression of miR-146a resulted in an up-regulation of the osteogenesis-related gene RUNX2 and down-regulation of the chondrogenesis-related gene SOX9.In conclusion, this thesis has identified subpopulations of skeletal stem cells with enhanced osteogenic and chondrogenic potential and has explored new miRNA targets involved in skeletogenesis in the attempt to develop novel treatments for patients requiring reparation of the skeletal system.

Locomotion is vital for vertebrates and invertebrates to survive. However, the mechanisms for locomotion are partially unknown. Central Pattern Generators and reflex systems have been shown to be the basis of most movements performed by arthropods. Much has been investigated lately on Central Pattern Generators, but little work has been done in reflex systems. Locomotion and motor output in feet (or tarsus in arthropods) has also been disregarded in research. Despite that feet are responsible for stability and agility in most animals, research on feet movements is scarce. In this thesis the tarsal intersegmental reflex of the locust hind leg is investigated. The tarsal reflex consists of a response in the tarsus when there is a change in the femoro-tibial joint. The main objective of the thesis is to describe the system and to develop mathematical and experimental methods to study, model and analyse it. Through a set of experiments is shown that as the knee joint is extended, the tarsus is depressed, and as the knee joint flexes, the tarsus levates. The experiments demonstrated that there is a purely neuronal link between the femoro-tibial joint position and the tibio-tarsal joint position. Moreover, it also reveals the effect of neuromodulatory compounds, such as dopamine, serotonin or octopamine. The tarsal reflex responses are fairly consistent across individuals, although significant variability across animals was found. To model a system where variability is an issue, a mathematical model with strong generalisation abilities is used: Artificial Neural Networks (ANNs). To design the ANNs, a metaheuristic algorithm has been implemented. The resulting ANNs are shown to be as accurate as other mathematical models used in physiology when used in a well known reflex system, the FETi responses. This results showed that ANNs are as good as Wiener methods in predicting responses and they outperform them in prediction of Gaussian inputs. Furthermore, they are able to predict responses in different animals, independently of the variability, with a more limited performance. New experimental methods are also designed to obtain accurate recordings of tarsal movements in response to knee joint changes. These experimental methods facilitate the data acquisition and its accuracy, reducing measurement errors. Using the mathematical methods validated, these responses are modelled and studied, showing responses to Gaussian and sinusoidal inputs, variability across individuals and effects of neuromodulators. With the tarsal reflex described and modelled, it can be used as a tool for further research in disciplines such as medicine, in the diagnose and treatment of euromuscular dysfunction or design of prosthesis and orthoses. This model can also be implemented in robotics to aid in stability when walking on irregular terrain.