The work presented in the present thesis investigated the neural, behavioural and genetic markers that may be associated with the manifestation of behavioural problems during the early years of life. Across four different empirical studies, and by incorporating, behavioural, neurophysiological and genetic investigations, it was demonstrated that: (1) there are neurophysiological signatures that may be associated with the manifestation of behavioural problems early in life; (2) common genetic variations that determine serotonin variability are strongly associated with affectivity-related patterns of frontal brain activation; and that (3) normal genetic variations that modulate serotonin availability and neuroplasticity are each associated with affectivity-related patterns of visual scanning behaviours in response to faces and aversive scenes. Taken together, the results illustrate the existence of robust neural, genetic and behavioural markers that may be associated with the manifestation of behavioural problems in early childhood and prompt further investigation of the area by generating novel hypotheses. Together, the empirical findings of the thesis provide a first stage contribution to the complex mechanisms that may yield risk and resilience for behavioural problems during the early years of life by generating a more comprehensive insight on the field of affectivity.

In 5 experiments neurologically damaged patients’ counterfactual reasoning, decision making (DM) and experience of counterfactually mediated emotions (CME) was explored. 17 patients, with varying lesion sites resulting from a stroke, (7 female) aged between 31 and 84 (M=64.5 years) and 17 controls (12 female) aged between 28 and 74 (M= 59 years) participated in the project. The project was conducted with three aims in mind; to establish if regret itself is experienced in brain damaged individuals; to explore the component processes of CMEs and widen the search for the brain areas that supports these; to conduct research that points to how the experience of regret directly impacts on future DM and underpins adaptive behavioural change. Through exploring the link between regret and adaptive choice switching, investigating counterfactual reasoning abilities, CME responses, emotional responses to The Regret Gambling Task (RGT) and responses in a task designed to measure risk taking, this project sheds new light on how neurological damage affects counterfactual reasoning, emotions and DM. In addition, two experiments were conducted with undergraduate students to explore whether CMEs are produced slowly, through deliberative processes, or quickly and effortlessly. Results were interpreted as evidence for fast and effortless CME production.

The integration of signals from electro-encephalography (EEG) and functional magnetic resonance imaging (fMRI), acquired simultaneously from the same observer, holds great potential for the elucidation of the neurobiological underpinnings of human brain function. However, the most appropriate way in which to combine the data in order to achieve this goal is not clear. In this thesis, a symmetric and data-driven route to the integration of multimodal functional brain imaging data based on information theory is proposed. As a proof of principle, the framework, which was originally developed in the study of neuronal population codes, is applied in the experimental context of visually evoked responses and the neural underpinnings of visual perceptual decisions. The implications, benefits, and limitations of this theoretical framework for the analysis of simultaneously acquired EEG and fMRI data are discussed.

The aim of the present thesis was to investigate the role of cerebellum in motor learning and action acquisition. This question was pursued by means of behavioural studies on healthy population. In a first study, the role of cerebellum in motor skill learning was explored by perturbing cerebellar activation with transcranial direct current stimulation. The involvement of cerebellum in action acquisition was studied in a paradigm that combined a visuomotor tracking task and an exploration task. The results of this study lead to chapter 4, where we investigated the impact of the tracking task in proprioceptive uncertainty. In a final study, the role of cerebellum, motor cortex and dorsolateral prefrontal cortex in action acquisition were investi- gated by modulating these brain areas using transcranial direct current stimulation. The results suggested that the cerebellum could be contributing in motor learning, not just by providing a state estimation but also by providing the uncertainty related to the estimates. However, based on the results of the final experimental chapter, we can conclude that, at least in the framework of the exploration task, motor cortex is more heavily involved than the cerebellum, perhaps via the cortico–basal–ganglia pathway, in reinforcement learning.

This thesis explores the neural mechanisms underlying the observation of touch and tactile processing in adults and typically developing children and speech versus computerized speech processing in children with autism spectrum disorders (ASD). Chapter 1 reviews the literature on mirror functioning, embodied cognition and typical and atypical development of social and speech processing in infancy and childhood. Chapter 2 investigates the neural mechanisms underlying hand and object touch observation in adults. In Chapter 3, a similar procedure is employed to investigate tactile mirroring mechanisms in children. The findings demonstrate that these mechanisms are relatively developed in 4- to 5- year old children. Chapter 4 further explores somatosensory activity during touch in adults and children. The findings reveal the modulation of somatosensory beta (15-24 Hz) activity during touch in adults, but not in children. Chapter 5 examines the neural mechanisms underlying speech versus computerized speech perception in children with ASD. These results suggest an impaired classification of speech sounds preceded by computerized speech, and atypical lateralization of speech processing in children with ASD. Together, these findings make a notable contribution to our understanding of typical development of tactile mirroring and touch processing mechanisms, and social processing dysfunctions in children with ASD.

Psychiatric symptoms are more prevalent in Huntington's disease (HD) than the general population, but reasons for this are unknown. The primary aim of this research was to investigate possible familial influences on the psychiatric phenotype in HD. 96 gene positive and 5 gene negative siblings were recruited from 50 HD families throughout the UK and underwent a lifetime psychiatric history assessment using semi-structured interview and case-note review. Gene positive index individuals had high lifetime rates of depressive (56%) and anxiety (38%) disorders. Their depressive episodes were less severe and more frequent with an older age of onset and fewer biological symptoms than individuals with depression without HD. Within gene positive sibling-pairs (n=53), there was significant familial aggregation of the presence (ĸ=0.46, \(p\)=0.004) and course (ICC=0.47, \(p\)=0.002) of depressive disorders and the presence of irritability (ĸ=0.357, \(p\)=0.024) and aggression (ĸ=OJ84, \(p\)=O.Ol6). Two gene negative siblings had lifetime psychiatric diagnoses. The high prevalence of psychiatric co-morbidity in HD cannot be entirely explained by the HD gene. Familial factors, most likely other genetic factors, are likely to play a role. Further research into the contribution of biological and environmental factors to the psychiatric phenotype in large samples of individuals with HD is warranted.

Patients with pituitary adenoma often report problems with cognitive function. However, the current literature is inconsistent on the types of cognitive deficits that patients experience. Chapter 1 of this thesis reviews the current literature and the questions that are still unanswered concerning the cognitive function of this patient group. Chapter 2 outlines the methodology used to assess the neurocognitive function of a group of patients with non-functioning pituitary adenoma. Chapters 3, 4 and 5 report and discuss the results of this assessment for general intellectual functioning, memory and executive functions. Chapter 6 discusses the physiological correlates of these results and finally, Chapter 7 presents the first fMRI experiment used to assess both content and context abilities in this patient group. The results of this thesis suggest that patients have intact general intellectual functioning and executive functions, in the presence of relative immediate memory impairment. Having hormone levels outside the normal range are a better predictor of dysfunction than treatment received. This thesis does not implicate surgery or radiotherapy as having adverse consequences to patients’ neurocognitive functioning.

This thesis examined potential corollaries of individual differences in cardiovascular and/or cortisol reactions to acute psychological stress, with specific focus upon personality and behavioural characteristics. Chapter 2 reported that a negative constellation of the Big 5 personality traits, higher neuroticism and lower openness and agreeableness, was associated with blunted physiological reactivity. Chapter 3 demonstrated that, in comparison to individuals without Type D personality, Type Ds had greater physiological reactivity during social stress, but lower reactivity when exposed to largely asocial stress. Both these studies also reported dissociation between subjective and physiological stress responses. Chapter 4 reported that individuals with problematic Internet use and/or excessive alcohol consumption did not differ in physiological stress reactivity in comparison to non-dependent controls. Finally, Chapter 5 demonstrated that, compared to exaggerated cardiovascular stress responders, blunted reactors had greater levels of behavioural impulsivity. Overall, the research reported provides evidence that there is dissociation between affective and physiological stress responses, the context in which the stressful situation is experienced is important, and finally, blunted reactivity appears to be related to adverse outcomes which are stable rather than transient, suggesting that it may be a peripheral marker of dysfunction in the brain systems that support motivated behaviour.

This thesis presents two papers. The first is a systematic review of the literature exploring the relationship between perinatal paternal mental health difficulties and child outcomes in preadolescence. Eighteen papers were reviewed. The review found fairly consistent evidence for internalising and externalising problems and mixed evidence for socio-emotional and cognitive difficulties and child temperament. More research is required regarding mental health in fathers during this period more generally as well as how preadolescent child outcomes may be affected. The second paper is an empirical study exploring whether perfectionism was related to experiences of postnatal distress (depression, anxiety and OCD) in first time mothers and whether this relationship could be explained by antenatal maternal orientation. Furthermore, whether the strength of any relationships were affected by participants’ experience of becoming a mother. Eighty-four women completed questionnaires during their third trimester of pregnancy and fifty-nine six-to-twelve weeks after birth. A relationship between socially prescribed perfectionism and postnatal depression and anxiety was observed. Antenatal maternal orientation did not mediate this relationship. Mental health in pregnancy, the impact of sleep deprivation, feelings of control and powerlessness, perceived relationship with baby and levels of social support predicted depression, anxiety and OCD in the postnatal period.

Making a simple journey may appear to require very little planning on behalf of the navigator but it, in fact, utilises multiple cognitive processes, modalities and skills, many of which may be impaired in acquired brain injury. The aim of this thesis was to explore community travel and route learning in this population through a series of studies. The first study explored changes in community travel patterns and showed a reduction in all types of journeys, particularly unaccompanied and leisure trips. Disability and anxiety played some role in the reduction in travel but not as large a role as expected. The results of this study indicated that the reduction in community travel also impacted on quality of life. A virtual environment was developed and tested for use in the final two studies. This was followed by an investigation into the use of proximal and distal landmark strategies in route learning using the virtual environment. Findings suggested that people with traumatic brain injury have more difficulty using distal landmarks than proximal landmarks when learning a route. The final study built upon these results to develop a set of procedures to test whether it was possible to improve route learning in people with traumatic brain injury. Route learning skills were assessed using the virtual environment and then their naturally chosen strategy was supplemented with an additional one in order to improve performance.