Grounded in the self-determination (SDT; Deci & Ryan, 1985, 2000) and achievement goal (Nicholls, 1989) theories this thesis had the broad aim of expanding current knowledge and theoretical understanding of motivational processes. This was achieved via four studies in dance addressing contemporary conceptual and methodological issues raised in the motivation literature. The studies aimed to progress the conceptualisation and measurement of key motivational constructs (i.e., the teacher-created motivational climate and motivation regulations) by examining their application in dance using quantitative and qualitative methods. Additionally, the studies aimed to enhance understanding of the motivational processes via which the motivational climate, as a multi-dimensional construct, predicts dancers’ psychological well- and ill-being. Specifically, the mediating roles of basic psychological needs and motivation regulations between dancers’ perceptions of the motivational climate and affective states were examined. Collectively the thesis supports the central features of the SDT framework, including Duda’s (2013) conceptualisation of the motivational climate as multi-dimensional, and basic psychological need thwarting (as detailed in Bartholomew, Ntoumanis, Ryan, & Thøgersen-Ntoumani, 2011b). The studies in this thesis will substantiate the need for and inform theoretically-grounded interventions which aim to educate teachers in how they can support dancers’ psychological well-being in a variety of dance settings.

This thesis aimed to increase understanding of the underlying physiological sources of the substantial inter-individual variability in heart rate (HR) and blood pressure (BP) reactions to acute psychological stress. This aim was achieved using a multi-method approach that included meta-analysis, laboratory studies, and prospective secondary analysis of epidemiological data. Chapter 2 implicated beta-adrenergic sympathetic activation and parasympathetic withdrawal in the cardiovascular stress response and showed that autonomic changes vary as a function of stress task, age, and sex. Chapter 3 demonstrated that individual differences in a unique HR complexity marker accounted for a significant amount of the observed variance in HR reactivity and that this effect was independent of task performance and changes in autonomic activity and respiration. Chapter 4 revealed that individual differences in resting physiological allostatic load related to HR reactivity such that higher allostatic load indicated lower reactivity. Finally, in Chapter 5, multivariate cluster analysis of HR, systolic and diastolic BP reactivity resolved a large sample into four homogenous clusters, each displaying significantly different reactivity patterns and risk of hypertension at 5-year follow-up. The research reported in this thesis confirms already suspected physiological sources of individual difference but also reveals novel sources that deserve further inquiry.

Knee instability has been the focus of a large number of studies over the last decade; however, a high incidence rate still exists. The aim of this thesis is to better understand knee joint stability assessment and enhancement of knee function through rehabilitation strategies. A mixed methods approach was used, incorporating both a systematic review of the literature and two experimental studies. Chapter 3 presents evidence that there is no consensus in the literature on a single technique to detect knee instability and provide return-to-play criteria. Chapter 4 demonstrates that the response rate of the anterior cruciate ligament-hamstring reflex is too low for it to be reliably used in a clinical setting, and thus it has limited value in assessing the return of neuromuscular function following knee injuries. Chapter 5 shows that peripheral electrical and magnetic stimulation can be used as an adjunct to resistance training. Overall, the research reported in this thesis provides further evidence that knee stability assessment depends on multiple factors rather than a single measure. In addition, peripheral stimulation may be efficacious to enhancing knee function and a guide to return-to-play following injuries. This thesis highlights important points for future studies on knee stability assessment and rehabilitation; the necessity of a sensorimotor assessment of knee stability and the promising role of peripheral stimulation in knee rehabilitation.

According to self-determination theory (SDT; Ryan & Deci, 2000), the quality of support (autonomy support versus controlling) from important others is an important predictor of psychological need satisfaction, and subsequent engagement in health-conducive behaviours, such as physical activity and healthy eating. In this dissertation, four research studies grounded on SDT are presented. Results from these studies highlighted the important link between autonomy support and psychological need satisfaction. In turn, these studies showed that need satisfaction supported better psychological well-being and health-conducive behaviours. The findings also underscored the detrimental effects of controlling behaviours. For instance, such behaviours were found to be related to the thwarting of psychological needs, and in turn higher psychological ill-being and maladaptive outcomes, such as unhealthy eating behaviours. Motivation contagion effects were also examined in one study. The results suggested that practitioners’ quality of support provided may vary as a function of their perceived motivation of a client. Findings from our studies have implications for researchers and important others (e.g. spouse) of individuals engaging in weight management. Possible areas for future research, such as the design of new interventions based on the tenets of SDT, are discussed.

Classical Pavlovian conditioning is a relatively simple behavioural experiment where a conditioned stimulus signals the occurrence of a reward. The repeated presentation of the stimulus and the reward leads to the evolution of a conditioned response. However, the electrophysiological correlates of participating brain structures, including the medial prefrontal cortex, that plays a role in decision making, and the central nucleus of the amygdala, that is responsible for reward learning and motivation, have not yet been fully explored. This study explores the electrophysiological properties of the prefrontal cortex and the amygdala in rats during Pavlovian conditioning, extinction and reacquisition. Multisite multichannel recordings showed a significant desynchronization in response to the conditioned stimulus. Additionally, the complex nature and role of a 4Hz activity and theta oscillation in both brain structures in reward conditioning was revealed. We found a consistent power and phase regulatory mechanism coordinating the 4Hz activity, while not affecting the theta oscillation, thus rendering these two distinct oscillations, with complementary roles, to fall out of synchrony. These findings might lay the foundations for further behavioural studies, mostly in the direction of social interaction and social behaviour.

It has been suggested that a failure of angiogenesis (capillary growth) to keep pace with myocyte expansion is the driving force which pushes hypertrophied hearts into a state of failure marked by contractile dysfunction and alterations in the mechanisms governing energy production. The aims of this study were to investigate how alterations in ventricular capillarity affect contractile performance and substrate metabolism in the isolated rat heart. It was hypothesised that, if cardiac contractile performance and substrate utilisation are directly related to ventricular capillarity then methods to alter the number and distribution of capillaries within the ventricle could be utilised to demonstrate this relationship. Treatment regimes were split into those aimed at inducing new capillary growth (e.g. chronic bradycardia and exposure to cold environments) and those aimed at reducing ventricular capillarity (e.g. hypertension and beta-adrenoceptor stimulation). In contrast to previous reports, capillary growth within the ventricle was very limited in animals exposed to a chronic increase in energy demand (e.g. cold environments) and those subjected to extended periods of mechanical stimulation (e.g. bradycardia). Ventricular remodeling appears to accommodate for alterations in the load and/or energy demand without the need for an expansion of the existing capillary network. Experiments conducted in beta-adrenoceptor mediated hypertrophy demonstrate that capillary rarefaction has little effect on cardiac contractile performance and experiments with hypertensive animals show no capillary growth despite the dramatic increase in energy demand placed on the heart in these conditions. In conclusion these data demonstrate surprising plasticity in the response of the myocardium to a number of physiological and pathological stimuli and indicate that adequate compensation occurs without the need for expansion of the existing capillary bed. The limited angiongenic capacity of the myocardium may therefore indicate that the capillary supply of the ventricle is not limiting to the function of the heart.

Whiplash-associated disorder (WAD) causes substantial social and economic burden, with ≥70% patients classified as WADII. Effective management in the acute stage is required to prevent development of chronicity for approximately 60% patients. A novel Active Behavioural Physiotherapy Intervention (ABPI) addressing both physical and psychological components of WAD was developed and evaluated as a complex intervention for acute WADII through a sequential multiphase project. Each phase was conducted using rigorous, precise and transparent methodologies according to pre-defined protocols. A systematic review and meta-analysis found that the combination of active physiotherapy and behavioural interventions may be a useful strategy. A modified Delphi study (international research and UK clinical whiplash experts) identified the underlying principles, and physiotherapy and behavioural treatment components of the ABPI. As no underpinning psychological theory was identified, the ABPI was further developed employing self-efficacy enhancement from social-cognitive theory to enable individualised management. A cluster-randomised, double-blind, parallel two-arm (ABPI: standard physiotherapy) pilot and feasibility trial (evaluating procedures, feasibility and acceptability ABPI) employed both quantitative and qualitative methods. Findings supported that the ABPI was potentially valuable (95% ABPI participants fully recovered with low number treatment sessions) and acceptable to physiotherapists and patients, supporting a definitive trial (with minor modifications).

This thesis aimed to examine whether observation of force based actions could moderate subsequent executed force and behavioural performance, and also brain activity during and following the action observation. There are six chapters, four that present empirical investigations, a general introduction (Chapter 1) and a general discussion (Chapter 6). Chapter 2 presents behavioural data that examined the effects of observing exerted force on an executed force response. The data revealed that the executed force was moderated by the condition observed so that observation of a 100% force caused increased force response compared to observation of a 50% and 0% force. Chapter 3 further examined whether bouts of observation could also moderate subsequent force and dexterity execution. Three experiments were conducted. In Experiments 1 and 2, observation of hand force based actions significantly moderated the executed hand dexterity. In Experiment 3, observation of leg force actions significantly moderated the executed leg force response. Overall, the data revealed that bouts of action force observation moderated the executed force and dexterity responses. Chapter 4 used fMRI to examine the brain activity during action force observation. The data revealed significant activity in the Superior Frontal Gyrus (SMA), part of the mirror neuron system. The finding was consistent with other findings in the literature, supporting the notion that observation of action force activates the same areas of the brain as those used for execution. To examine the relationship between action priming and brain activity, Chapter 5 again used fMRI, but to investigate resting brain activity. The data revealed significant mirror neurone system activity following action force observation compared to pre-observation and control conditions. The thesis is discussed (Chapter 6) in terms of how action observation could be used clinically for rehabilitation, and moreover, how further experimental directions could be added to these findings.

Methionine mutants of Neurospora crassa were isolated by a filtration concentration technique following ultra-violet irradiation. These and other mutants were classified by the physiological tests of precursor utilisation and heterocaryon complementation. Precursor utilisation data are in agreement with the present outline of methionine synthesis from cysteine but provide little information on the pathway of sulphate reduction and incorporation of sulphur within a carbon skeleton to yield cysteine. Seven cysteine and eight methionine loci are represented on the basis of heterocaryon complementation tests. Four of the cysteine loci and either one or two of the methionine loci, associated with the methylation of homocysteine, have not been reported previously. Two of the eight methionine loci had already been located but five of the remainder were associated with definite chromosome regions. No evidence for the tight clustering of either these or the cysteine loci was obtained. Inter-allelic complementation has been observed at two loci and the fine structure of one of these loci (me-2) has been studied in some detail by analysis of prototroph formation in inter-allelic crosses. The use of "outside markers" has facilitated the demonstration of intra-genic recombination and "conversion". Furthermore, these studies provide evidence for a linear arrangement of mutable sites within the locus with additive prototroph frequencies to yield a site map which can be correlated with a complementation map. The results also show that some alleles are more prone to "conversion" than others.

The mammalian skull is a complex ossified structure of multiple embryological tissue origins. It is formed from two distinct forms of ossification: intramembranous ossification that produces the flat dermal bones of the calvaria craniofacial region and the mandible, and endochondral ossification that forms the cranial base. I investigated the patterns of mineralisation in both bone types, in the dermally ossifying frontal bone and the endochondrally ossifying cranial base. I also investigated the cell behaviour within the frontal bone and expansion of chondrocytes clones in the cranial base synchondroses. I find that the intramembranously ossified frontal bone displays complex and novel forms of biomineralisation, including a system of intercalary biomineral thickness growth that cannot be explained by the current accepted model of dermal ossification. I discover that the cells associated with the specialised biomineralised architecture of the dermal bone, contribute to its growth via a novel mechanism of bi-directional cellular invasion from the outer layers of the bone to the intervening mineralising layer. Cell behaviour is found to depend upon the direction of invasion for preosteoblasts, which also show a distinct invasive pattern compared to other cell types. I discover a number of previously unknown cell types that possess invasive behaviour, including a double positive RUNX2+HAND+ population and neural crest derived endothelial cells in the dermal bone, which co-express the endothelial growth factor VEGFA. Ablation of VEGFA and of HAND2 in the neural crest lineage prevents invasion of the frontal bone and a loss of thickness growth of biomineral respectively. My analysis of the cranial base reveals a cryptic modularity of growth of its separate bones and cartilages that varies with time. I also find the synchondroses of the cranial base not to be the origin of biomineral growth as expected but discover a system of radial and longitudinal intercalary biomineral growth similar to that observed in the frontal bone. My findings suggest that the timing of growth and ossification of bone is crucial for proper development, and this may inform the pathophysiology of cranial base syndromes than have complex timing of the onset symptoms. It suggests hints that the ancient mechanisms of biomineral growth in dermal bone are co-opted for use by tissues that ossify in an endochondral fashion.