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The way emotions influence cognition has been a subject of debate for years. Leading theorists in the fields of cognitive neuroscience and cognitive psychology have postulated that emotions are interpretations of visceral bodily states that precede cognition. However, these theories do not take into account that internal visceral states (i .e. faster heartbeat) overlap with other emotional states (i.e. anger, excitement, elation). Thus the direct mapping of an emotional response to cognitions is not clear-cut. This thesis examines the interface of cognition and emotion using a variety of different methodologies (implicit/explicit behavioural tasks, memory recall and electrophysiology). The relationship between strength of cultural affinity and age of acquisition was explored in Chapter 3, using implicit and explicit cultural identity tasks. We demonstrated that cultural affinity and age of second language acquisition differentially modulate implicit and explicit attitudes, indicating an interface between emotional evaluations and cultural context. In Chapter 4, the relationship between language, emotional arousal, and memory retrieval was examined using an autobiographical memory recall task in Welsh and English. This chapter indicated that age of acquisition and proficiency modulates the emotional memories retrieved in the first (Ll) and second (L2) languages, but strength of emotional arousal does not differ between languages.

Individuals' consistent aptitudes in processing information are referred to as cognitive styles (i.e. the wholist-analytic and verbal-imagery cognitive styles). They have been suggested to be relevant to many observed behaviours especially in the learning and teaching circumstances. However, experimental evidence is required to support their validity and further the understanding of their nature. he first stream of inquiry profiled different facets of the nature of the wholist-analytic cognitive style by various strands of evidence. The other stream of investigation examined the verbal-imagery cognitive style, which is concerned with information representation, verbally or pictorially.

Repetitive transcranial magnetic stimulation (rTMS) in motor areas has been shown to induce transient and reversible changes in the corticospinal excitability of healthy individuals' brains. Furthermore, a number of studies have shown that this reorganisation can occur not only at the site of stimulation but also in other areas which might be anatomically or functionally connected to it. These effects are thought to depend on various parameters such as the protocol of stimulation, the site of stimulation and the behavioural paradigm chosen to study the effects. The aim of this thesis was to use functional neuroimaging in order to explore how the effects of long-lasting rTMS protocols (30-60min stimulation) on the motor system depend on specific conditioning parameters such as the frequency, the site and the pattern of stimulation. We examined how the pattern of activity in the brain reorganises depending on the anatomical and effective connectivity of the stimulated area, and on the behavioural task. Initial studies presented in this thesis used Positron Emission Tomography to compare the effects of high (5Hz) versus low (1Hz) frequency of rTMS on activity and motor network connectivity of the primary motor cortex (M1) during performance of a simple finger movement task or at rest. I found that task-related activity of motor area 4p within M1 and its connectivity with non-primary motor areas, such as the ipsilesional dorsal premotor (PMd) cortex could be modulated bidirectionally with low or high frequency rTMS over M1: compared to sham stimulation, 5Hz rTMS reduced task-related activity and network connectivity of that area. The opposite was true for 1Hz rTMS. A further study using the same task examined whether such reorganisation would be observed with 5Hz rTMS over the PMd. The effect of 5Hz rTMS on this site of stimulation revealed a different pattern of regional cerebral blood flow than rTMS over M1. However, a similar reorganisation in task-related activity and network connectivity was observed, particularly within the PMd area caudal to the stimulated site, which increased in activity after 5Hz rTMS. These two studies demonstrated that rTMS leads to widespread activity changes. However, changes in task-related activity and motor network connectivity occur in motor areas adjacent to the stimulated site. Given the lack of any behavioural effects in these studies, it can be hypothesised that these changes occur as compensatory mechanisms to the "virtual lesion" caused by rTMS. A functional magnetic resonance imaging (fMRI) study of the effects of rTMS over the lateral prefrontal cortex showed task-related changes in activity during performance of a cued choice reaction time task. Targeting the dorsolateral prefrontal cortex (DLPFC) with 5Hz rTMS led to task-related decreases in activity in the adjacent ventrolateral prefrontal cortex. This is reminiscent of the task-related decreases in activity of area 4p observed following 5Hz rTMS over M1 (described above). The side of lateral prefrontal conditioning affected behavioural performance in a further study which distinguished motor from spatial attention in the same behavioural paradigm. Left DLPFC stimulation led to a more prominent switch cost in the motor attention version of this task, confirming a left-lateralised dominance for switching motor responses, described in previous studies. These results provide new evidence that reorganisation in the brain observed following rTMS conditioning is very similar to reorganisation observed following lesions in patients. This reorganisation seems to depend on the task that is required to be performed and determines the pattern of activity obtained in functional neuroimaging studies. In addition, whether this will lead to a behavioural effect depends on the role of that particular area during task performance which is a function of its effective connectivity. These factors seem to determine whether the brain can compensate for the "virtual lesion" induced by rTMS.

Everyday behaviour requires constant coordination and monitoring in order for our actions to be successful. Within cognitive science such coordination and monitoring of behaviour is termed ‘control’ and refers to a set of functions that serve to configure the mental system for performing specific acts. A system of cognitive control is thought to set high level goals and direct subordinate cognitive systems in order to accomplish those goals. This thesis utilises a cognitive electrophysiological approach to the study of executive control, addressing research questions concerning the mental processes that are modulated by executive control and the mechanisms underlying control-related processing adjustments. The first experimental chapter investigates the process of task switching. More specifically, how demanding is a proposed stage of endogenous task-set reconfiguration in terms of information processing? It was previously reported that the process of task-set reconfiguration constitutes a hard bottleneck delaying even the earliest processing stages (e.g. perceptual) (Oriet & Jolicoeur, 2003). Three experiments investigated this claim by manipulating stimulus contrast and RSI within an alternating runs task switching paradigm. Both RT results and measurements of P1 and N1 ERP component peak latency did not offer support to the claim that task-set reconfiguration delays perceptual processing. Experimental Chapters 3 and 4 used interference paradigms that are common within the study of executive control (e.g. Eriksen Flanker task and a Stroop task, respectively). Within such interference paradigms, separate stimulus dimensions (relevant and irrelevant) are manipulated, with RT being faster when both the relevant and irrelevant stimulus dimensions indicate the same response. This is termed the ‘congruency effect’ and is often attributed to a failure of selective attention, namely, an inability to ignore the irrelevant stimulus dimension. It has been demonstrated that such congruency effects are dependent upon task sequence with the effect being reduced (or absent) after an incongruent trial (Gratton et al., 1992). Such conflict adaptation effects are a popular measure of cognitive control processes. An influential model of cognitive control is the conflict monitoring model of Botvinick et al. (2001), with much evidence for this model being based on the conflict adaptation effect. Specifically, the model proposes that the ACC measures for the occurrence of response conflict within two response channels, and when detected, signals its occurrence to other brain regions (e.g. DLPFC) that are involved in implementing control. Such control may be implemented via a top-down biasing mechanisms of attention toward the task-relevant stimulus feature. Chapter 3 investigated the conflict adaptation effect within the Flanker task and examined, whether after the occurrence of conflict, attention is directed toward the task-relevant central target location. This was done by measuring P1 and N1 ERP component amplitudes. Although behavioural conflict adaptation effects were evident in overt behaviour, these were specific to response repetitions, consistent with a bottom-up priming account that excludes the necessity for a top-down control explanation (e.g. Mayr et al., 2003). In addition, P1 and N1 amplitude did not show any evidence of increased attentional focus toward the central target location after the occurrence of conflict. Chapter 4 investigated the conflict adaptation effect within a modified Stroop task, and again, examined whether after the detection of conflict, attention is directed toward the task relevant stimulus feature. This was done by measuring N170 amplitude - an ERP component proposed to index face processing - when a face stimulus served as the relevant and irrelevant stimulus dimension. Again, conflict adaptation effects were evident in overt behaviour, with this effect being driven by the occurrence of response conflict. Unlike the data from the Flanker task, the conflict adaptation effect within the Stroop task was specific to response alternations, and thus, a bottom-up priming account is not applicable in this instance. However, again the ERP results did not offer any evidence that the processing of the relevant stimulus dimension was enhanced after the occurrence of conflict. Implications of the present results are discussed in the context of executive control and in particular, in relation to models of task switching and models of conflict control.

Research has demonstrated that gonadal hormones, including oestrogen, can influence memory and cognitive tasks that show sex differences in animals and humans. Beneficial effects of oestrogen on mood have also been reported in postmenopausal women in association with Oestrogen Replacement Therapy (ERT). Male-to-Female (M-F) transsexuals offer one of the few opportunities for studying the effect of oestrogen and other cross-sex hormones on human cognitive function. The present research examined the effect of gonadal hormones on memory, cognition and mood in a transsexual population. The aim was to determine whether treatment with oestrogen and other cross-sex hormones would influence memory and cognitive abilities that show sex differences, such that males treated with oestrogen and other cross-sex hormones would perform more like females. We also examined the effect of such hormone treatment on mood. In an initial study (Chapter 2), M-F transsexuals undergoing oestrogen treatment for sex re-assignment scored higher on Verbal Paired Associate Learning (PAL) compared to a similar transsexual control group, awaiting oestrogen treatment. No differences between these groups were detected on a control memory task (Digit Span) or on other cognitive tasks that show sex differences, including Mental Rotations and Controlled Associations. In a second study (Chapter 3), an attempt was made to summarise the magnitude and reliability of sex differences in some of the memory tasks previously used in oestrogen and memory research. In a final study (Chapter 4), a more robust design was used to further examine the association between oestrogen, memory, cognition and mood. Additional aspects of memory function and other cognitive abilities that do and do not show sex differences were used, including verbal and visual-spatial abilities. Also, a repeated measures design was used. M-F transsexuals were tested both prior to hormone treatment and after treatment had begun. In addition, some M-F transsexuals were tested both before and during a period of hormone withdrawal prior to surgery. Findings from this study did not replicate the data from the initial study reported in Chapter 2. Few changes in memory or other aspects of cognitive performance were observed and these were not consistent in the two groups of patients. Improvements in mood were observed, particularly at the commencement of oestrogen treatment. However, this improvement could have resulted from progression in the treatment program rather than from the hormone treatment per se.

The original Bio-Rad gene gun was unable to transfect acute or organotypic brain slices, as the amount of helium gas used, the distance for the gold-coated microcarriers to travel to target area were not optimised for fragile tissues, such as the brain. Typically, tissues were severely damaged by a helium shock wave and only a few cells were transfected. It was essential to improve gene gun accuracy by restricting the gold particles from being propelled superficially over a wide area. It was also necessary to increase the amount of DNA or dye delivery into intact tissues. Furthermore, for the gene gun to perform successfully on brain slices the helium gas pressure had to be lowered thereby reducing the degree of cell damage incurred during a biolistic delivery. Without knowing it at the time, the modified gene gun had worked particularly well on a variety of other fragile tissues, and not just the brain. However, the modified gun was not optimised for cultured cells as other transfection methods were available. A particularly notable point of this work was the successful labelling of individual Purkinje dendritic spines from live nerve cells in the cerebellum region of the brain. Biolistic images of Purkinje cells show that the distribution of dendritic spines are not random (O’Brien and Unwin, 2006). Spines were shown to grow in elaborate regular linear arrays, that trace short-pitch helical paths around the dendrites. It was apparent that the spines are arranged to maximize the probability that the dendritic arbour would interact with any afferent axon. This was an important discovery as there has been much debate as to how spines develop on a dendritic shaft. There are three general views to this question, each proposing a theory describing a model for spinogenesis. Classification of the three models in relation to our findings is described in chapter six of this thesis. The Investigation of spine morphology by biolistics was further optimized; gold particles were reduced from a micrometre to forty nanometres (O’Brien and Lummis, 2011), demonstrating that it is possible to use gold-coated DNA nanoparticles of this size to transfect tissue revealing exquisite structural detail. It was possible to observe boutons making synaptic contacts with the pyramidal nerve spines in the hippocampal region of the brain. The findings so far have shown spines from the pyramidal shaft are similar to the spines in the cerebellum, forming regular linear arrays. Recent studies had linked defects in the function of presynaptic boutons to the etiology of several neurodevelopment and neurodegenerative diseases, including autism and Alzheimer’s disease. Our discovery could help to understand why there are abnormalities in dendritic spines which are associated with pathological conditions characterized by cognitive decline, such as mental retardation, Alzheimer’s, stroke and schizophrenia (Yuste and Bonhoeffer, 2001). This thesis provides a synthesis of knowledge about biolistic technology. It is presented as a narrative from improving the gene gun transfection efficiency in brain slices to the development of nano-biolistics. The delivery of DNA and fluorescent dyes into living cells by biolistic delivery should enable a detailed map of the anatomical connections between individual cells and groups of cells to be constructed, providing a “wiring diagram” of connections. The implications of this are discussed in Chapter twelve. The original Bio-Rad gene gun was unable to transfect acute or organotypic brain slices, as the amount of helium gas used, the distance for the gold-coated microcarriers to travel to target area were not optimised for fragile tissues, such as the brain. Typically, tissues were severely damaged by a helium shock wave and only a few cells were transfected. It was essential to improve gene gun accuracy by restricting the gold particles from being propelled superficially over a wide area. It was also necessary to increase the amount of DNA or dye delivery into intact tissues. Furthermore, for the gene gun to perform successfully on brain slices the helium gas pressure had to be lowered thereby reducing the degree of cell damage incurred during a biolistic delivery. Without knowing it at the time, the modified gene gun had worked particularly well on a variety of other fragile tissues, and not just the brain. However, the modified gun was not optimised for cultured cells as other transfection methods were available. A particularly notable point of this work was the successful labelling of individual Purkinje dendritic spines from live nerve cells in the cerebellum region of the brain. Biolistic images of Purkinje cells show that the distribution of dendritic spines are not random (O’Brien and Unwin, 2006). Spines were shown to grow in elaborate regular linear arrays, that trace short-pitch helical paths around the dendrites. It was apparent that the spines are arranged to maximize the probability that the dendritic arbour would interact with any afferent axon. This was an important discovery as there has been much debate as to how spines develop on a dendritic shaft. There are three general views to this question, each proposing a theory describing a model for spinogenesis. Classification of the three models in relation to our findings is described in chapter six of this thesis. The Investigation of spine morphology by biolistics was further optimized; gold particles were reduced from a micrometre to forty nanometres (O’Brien and Lummis, 2011), demonstrating that it is possible to use gold-coated DNA nanoparticles of this size to transfect tissue revealing exquisite structural detail. It was possible to observe boutons making synaptic contacts with the pyramidal nerve spines in the hippocampal region of the brain. The findings so far have shown spines from the pyramidal shaft are similar to the spines in the cerebellum, forming regular linear arrays. Recent studies had linked defects in the function of presynaptic boutons to the etiology of several neurodevelopment and neurodegenerative diseases, including autism and Alzheimer’s disease. Our discovery could help to understand why there are abnormalities in dendritic spines which are associated with pathological conditions characterized by cognitive decline, such as mental retardation, Alzheimer’s, stroke and schizophrenia (Yuste and Bonhoeffer, 2001). This thesis provides a synthesis of knowledge about biolistic technology. It is presented as a narrative from improving the gene gun transfection efficiency in brain slices to the development of nano-biolistics. The delivery of DNA and fluorescent dyes into living cells by biolistic delivery should enable a detailed map of the anatomical connections between individual cells and groups of cells to be constructed, providing a “wiring diagram” of connections. The implications of this are discussed in Chapter twelve.

Flow is a mental state characterised by a feeling of energised focus, complete involvement and success when fully immersed in an activity. The dimensions of and the conditions required for flow to occur have been explored in a broad spectrum of situational contexts. The close relationship between flow and peak performance sparked an interest in ways to induce flow. However, any process of flow induction requires a measure to trace the degree to which flow is in fact occurring. Self-reports of the flow experience are subjective and provide ad hoc information. Psycho-physiological measures, such as EEG, can provide objective and continuous indications of the degree to which flow is occurring. Unfortunately few studies have explored the relationships between psycho-physiological measures and flow. The present study was an attempt to determine the EEG correlates of flow under conditions of peak performance. Twenty participants were asked to perform a continuous visuomotor task 10 times. Time taken per task was used as an indicator of task performance. EEG recordings were done concurrently. Participants completed an Abbreviated Flow Questionnaire (AFQ) after each task and a Game Flow Inventory (GFI) after having finished all 10 tasks. On completion, performance times and associated flow scores were standardised where after the sample was segmented into a high flow - peak performance and a low flow - low performance level. Multi-variate analysis of variance (MANOVA) was conducted on the performance, flow and EEG data to establish that a significant difference existed between the two levels. In addition, a one-way analysis of variance between high and low flow data was conducted for all variables and main effects were established. Inter-correlations of all EEG data at both levels were then conducted across four brain sites (F3, C3, P3, O1). In high flow only, results indicated increased lobeta power in the sensorimotor cortex together with a unique EEG pattern showing beta band synchronisation between the prefrontal and sensori-motor areas and de-synchronisation between all other areas, while all other frequencies (delta, theta, alpha, lobeta, hibeta, and gamma) remained synchronised across all scalp locations. These findings supported a theoretical neuropsychological model of flow. / Psychology / D. Com. (Consulting Psychology)

Overexpression of the NR2B subunit of the NMDA receptor in the forebrain has been shown to improve learning and memory in mice (Tang et al 1999), which provides exciting implications for the enhancement of human cognition. However, it was first essential to establish replicability, and since the Tang et al (1999) study used only male mice we wished to investigate possible sex differences. On the hidden platform watermaze, we found a trend for male NR2BOE mice to learn the task more quickly than male wildtype mice (as observed by Tang et al. 1999), but the opposite trend in female mice; female NR2BOE mice were slower to reach the hidden platform than female wildtype mice. This pattern of results was also observed on the spatial reference Y memory task and open field task (for anxiety), although not on the spatial working memory T maze task (despite a sex difference). However, wildtype and NR2BOE mice performed at similar levels on the novel object recognition task, the spatial novelty preference task, visible platform watermaze and visual discrimination task. A battery of tests considering some species typical behaviours of mice demonstrated that wildtype and NR2BOE mice were comparable on tests of motor ability, strength, co-ordination, anxiety, burrowing and nesting. This suggests that our behavioural results are not due to a general impairment or enhancement of species typical behaviours. We considered the possibility that the difference between the results of Tang et al (1999) and those we observed may be caused by age differences; hence we attempted to replicate our results on the hidden platform watermaze, spatial reference Y maze and open field test in age matched mice. However, the second cohort of NR2BOE mice performed at similar levels to wildtype mice, and at significantly improved levels compared to the mice of the first cohort. We also considered the effects of knocking out the NR2B subunit on learning and memory, and NR1 subunit deletion within the hippocampus. On the spatial working memory T maze, these mouse strains performed similarly to their respective wildtype strains. Similarly, on a two beacon watermaze (with one indicating the platform position), mice lacking the NR2B subunit were able to locate the platform in a similar length of time. To ensure that the null results we had observed in the second cohort were not due to loss of the NR2B protein overexpression in the forebrain, we performed polymerase chain reactions (PCR), quantitative real-time PCR, and Western blots. We ascertained that the transgene was indeed present and that NR2B mRNA and protein levels were elevated in the hippocampi of the NR2BOE mice. In conclusion, it is unclear why the behaviours we observed in the NR2BOE mice are different to those published in the literature. It is possible that they may be due to differences in environmental enrichment, but the cause of the genotype by sex differences observed in the mice of cohort 1 is unclear. Nonetheless, we have advanced our knowledge of the effects of modifications in the levels of the NR2B subunit of the NMDA receptor on learning and behaviour.

Flow is a mental state characterised by a feeling of energised focus, complete involvement and success when fully immersed in an activity. The dimensions of and the conditions required for flow to occur have been explored in a broad spectrum of situational contexts. The close relationship between flow and peak performance sparked an interest in ways to induce flow. However, any process of flow induction requires a measure to trace the degree to which flow is in fact occurring. Self-reports of the flow experience are subjective and provide ad hoc information. Psycho-physiological measures, such as EEG, can provide objective and continuous indications of the degree to which flow is occurring. Unfortunately few studies have explored the relationships between psycho-physiological measures and flow. The present study was an attempt to determine the EEG correlates of flow under conditions of peak performance. Twenty participants were asked to perform a continuous visuomotor task 10 times. Time taken per task was used as an indicator of task performance. EEG recordings were done concurrently. Participants completed an Abbreviated Flow Questionnaire (AFQ) after each task and a Game Flow Inventory (GFI) after having finished all 10 tasks. On completion, performance times and associated flow scores were standardised where after the sample was segmented into a high flow - peak performance and a low flow - low performance level. Multi-variate analysis of variance (MANOVA) was conducted on the performance, flow and EEG data to establish that a significant difference existed between the two levels. In addition, a one-way analysis of variance between high and low flow data was conducted for all variables and main effects were established. Inter-correlations of all EEG data at both levels were then conducted across four brain sites (F3, C3, P3, O1). In high flow only, results indicated increased lobeta power in the sensorimotor cortex together with a unique EEG pattern showing beta band synchronisation between the prefrontal and sensori-motor areas and de-synchronisation between all other areas, while all other frequencies (delta, theta, alpha, lobeta, hibeta, and gamma) remained synchronised across all scalp locations. These findings supported a theoretical neuropsychological model of flow. / Psychology / D. Com. (Consulting Psychology)