This study examined the relationship between five neurocognitive domains, including memory, visual-spatial skills, executive functioning, language, and attention, and three instrumental activities of daily living (IADLs), (financial management, medication management, and driving), as well as three basic activities of daily living (ADLs), including dressing, feeding, and grooming. Subjects were community dwelling older adults diagnosed with Alzheimer's Disease (AD) ranging in severity from mild to severe. Correlation and regression models were used to analyze the relationship between neurocognitive domains and self-care activities. All of the neurocognitive domains were significantly but mildly correlated with declines in IADLs, and all of the neurocognitive domains, except memory, were significantly but mildly correlated with ADL decline. None of the regression models, except driving, produced significant results. The hypotheses were based on the belief that overlap occurs between declines in cognitive domains and self-care skills. The results of this study support the assertion that global cognitive decline occurs followed by declines in IADLs and later declines in ADLs. Thus, instead of specific neurocognitive domains predicting decline in individual self-care skills, this research indicates that the degree of severity of cognitive decline is predictive of impairments in IADLs or ADLs with milder global impairment predicting IADLs and more pronounced decline predicting declines in ADLs. Degree of severity may have been more predictive because while individuals vary in cognitive symptom presentation, the course of AD always progresses from mild to more severe. The role of over-learning also potentially impacted the results of the study. Individuals learn and daily practice ADLs at a young age causing them to require less higher level cognitive skills (over-learned). Since over-learned IADLs require less higher level cognition, they were preserved longer in AD course, thus declining after global cognitive impairment. Clinicians need to thoroughly assess the degree to which an individual has over-learned a task in order to make the most accurate recommendations. If an individual has milder global decline, IADLs are likely to be impaired, and if an individual has moderate global decline with memory reaching a floor, ADLs are likely to be impaired.

The aims of this project were (1) to investigate two forms of event perception: perception of movement and perception of sudden appearance, (2) to develop event perception procedures which could be applied to testing clinical populations, and (3) to relate event perception to abnormalities shown by neuroimaging. In addition issues relevant to each of the particular clinical populations involved were addressed. Event perception tasks used stimuli consisting of a background of randomly selected dots of light. In one task a dot was added to the display (appearance), in the other a dot started to move (movement onset). Four laboratory experiments were conducted examining the ability to detect and locate these events under varying conditions in healthy controls. Results indicated that neuronal coding strategies were different for appearances and movement onset. Laboratory tasks were adapted for clinical application and administered to groups of patients with different neurological conditions. Five studies were conducted to assess sensitivity and specificity of the Event Perception tasks in clinical settings. The groups studied were chronic solvent abusers, detoxified alcoholics, patients suffering from optic neuritis, and patients with traumatic brain injury. Event Perception tasks were found to be differentially sensitive to neurological conditions and showed dissociations and double dissociations both within and between neurological conditions. Relationships with Magnetic Resonance Imaging (MRI) and Single Photon Emission Computed Tomography (SPECT) were investigated in patients with head injury. Patterns of brain damage differed significantly for patients with impaired performance on the movement task. It is concluded that Event Perception tasks are of value in the assessment of neurological patients: They allow assessment of functions which are not usually evaluated in neuropsychological examinations, facilitate detection of subtle deficits and deficits which may present at an early stage, and offer greater specificity and sensitivity than many traditional neuropsychological test procedures. Event Perception tasks are easy to administer and do not suffer from training effects on repeated administration to the same degree as many traditional measures. It is also argued that tests with a theoretical basis are better suited to clinical research in neuropsychology than many traditional tasks because they potentially allow a more precise explanation and assessment of the abnormal processes under investigation.

Completing activities of daily life relies on using both cognitive and physical resources efficiently, but these are affected by age. This may be due either to an age-related reduction in the resources we have available for carrying out tasks or to a reduction in our ability to use these resources efficiently. These resources comprise a set of processes called executive functions (EF), which collectively allow us to plan, initiate and monitor our performance of activities. Control and allocation of these resources is attributed to a central mechanism, sometimes called the central executive or executive attention, but the parameters that determine how resources are allocated are not well understood. Even simple or apparently automatic activities, such as walking, require attention, meaning that when task demands increase, for example when walking and speaking on the phone, there is a loss of efficiency in both tasks. The dual-task (DT) paradigm is an empirical means of examining the way attentional resources are allocated between two tasks by comparing their performance together in relation to how well they are carried out singly. Asking people to perform a cognitive task, such as counting backwards or spelling, while walking provides a reasonably naturalistic way to examine how flexibly older adults can divide their attention between the two tasks. Manipulating the demands of the task, either by increasing the difficulty of the cognitive task or instructing the participants to focus on one task or the other (prioritisation) should illuminate the strategies they use to allocate their available attention between the two tasks ask task demands vary. To explore this hypothesis a cohort of physically and cognitively healthy community-dwelling older adults (mean age = 72.3 years) took part in three studies. In the first experiment, 72 participants completed 8 single and dual-task conditions with varying cognitive load (counting back in 3s and 7s) and attention prioritisation (no prioritisation, prioritising walking and prioritising counting). Instructing the participants to prioritise walking in the DT when counting back in 7s produced the best walking and counting performance and this was predicted their score on a standardised measure of cognitive flexibility. In second part of the study, 68 of the participants were tested 12 months later when there was improvement in both their single and dual-task performances. There was also decline in concurrent walking and counting performance, but only when attention was allocated to walking in preference to the cognitive task. Both the improvements and the decline in performance after the 12-month period were predicted by a standardised test for EF at T1. In the third study a separate group of older adults (73.2 years) was trained to walk rhythmically to music, to further investigate the external manipulation of resource-allocation during concurrent walking and counting. Their performances were compared to 2 control groups who did not receive the same intervention procedures. Overall findings from this doctoral research demonstrate that explicitly manipulating attention-allocation during concurrent walking and cognitive activity improved healthy older adults' walking and counting performance and this was strongly associated with better cognitive flexibility. After 12 months, subtle decline in ability to allocate attention to walking during the DT, when attentional-demands were high, was also predicted by cognitive flexibility in an EF task. Together, these findings illuminated the role of executive attention in a rapidly-changing complex task when the ‘wrong' prioritisation could result in a fall. Observing healthy older adults' cognitive flexibility in allocating attention to walking, when required, revealed that executive attention was key to the future maintenance of their current functional well-being.

published_or_final_version / Psychiatry / Master / Master of Philosophy

Research has paid little attention to clients’ experience of the psychological assessment process, particularly in regard to the experiences of children and their parents. Advocates of collaborative assessment have long espoused the therapeutic benefits of providing feedback that can help clients better understand themselves and improve their lives (Finn & Tonsager, 1992; Fischer, 1970, 1985/1994). Finn, Tharinger, and colleagues (2007; 2009) have extended a semi-structured form of collaborative assessment, Therapeutic Assessment (TA), with children. One important aspect of their method, drawn from Fischer’s (1985/1994) example, is the creation of individualized fables that incorporate assessment findings into a child-friendly format. The fables are then shared with the child and parents as assessment feedback. This study evaluated whether receiving this type of individualized, developmentally appropriate feedback would affect how children and their parents report experiencing the assessment process. The assessment process, with the exception of child feedback, was standard for the setting. Participants were 32 children who underwent a neuropsychological evaluation at a private outpatient clinic, along with their parents. Multivariate and univariate statistics were used to test differences between two groups: an experimental group that received individualized fables as child-focused feedback and a control group. Children in the experimental group reported a greater sense of learning about themselves, a more positive relationship with their assessor, a greater sense of collaboration with the assessment process, and a sense that their parents learned more about them because of the assessment than did children in the control group. Parents in the experimental group reported a more positive relationship between their child and the assessor, a greater sense of collaboration with the assessment process, and higher satisfaction with clinic services compared to the control group. Limitations to the study, implications for assessment practice with children, and future directions for research are discussed. / text

The current research project examines the performance of a group of high functioning young adult males with autism spectrum disorders on standardized measures of neurocognitive functioning to determine whether distinct cognitive profiles of strengths and weaknesses emerge. Neuropsychological test data across various domains: general cognitive ability, visuospatial processing, verbal learning and memory, visual learning and memory, working memory, reasoning, cognitive flexibility, attention, receptive language, expressive language, social and emotional processing, and fine motor skills was examined. Data were analyzed using cluster analysis to assess for the presence and nature of unique clusters/subgroups based on neuropsychological test performance. Three unique clusters were derived from the analyses. This study highlights the well-documented heterogeneity across the spectrum of autism and suggests a method for parsing a heterogeneous sample of ASD subjects into smaller and more meaningful homogeneous groups using standardized neuropsychological assessments. / text

This study examined the associations between video gaming, sleep, and neuropsychological functioning. A total of 143 mother-children dyads were included in the study. The children’s neurocognitive functions were measured using the Wechsler Intelligence Scale for Children– Fourth Edition (Hong Kong), the Test of Everyday Attention for Children (TEA-Ch), and the Grooved Pegboard Test. Sleep quality was measured by the Children's Sleep Habits Questionnaire (CSHQ) and the Pittsburgh Sleep Quality Index (PSQI). Problematic behaviors were measured using the Child Behavior Checklist (CBCL). It was found that (1) more video gaming was associated with poorer subjective sleep quality and shorter total bed time, but not any actual reported sleep time or any domains of problematic sleep in children, (2) playing video games before bed was not associated with more sleep problems in children, (3) children with more sleep problems were perceived to have more internalizing and externalizing behaviors, (4) sleep problem was negatively associated with tests of perceptual reasoning abilities, and had a moderating effect on the relationship between video-gaming and a hand-eye coordination task. Results implied video gaming might not be predominantly bad for children, and the use of it as a training tool must target specific cognitive skills in order to be effective. Children’s sleep problems should be part of a clinical computation and adequately addressed. / published_or_final_version / Clinical Psychology / Master / Master of Social Sciences

As we strive to understand the mechanisms underlying neural computation, mathematical models are increasingly being used as a counterpart to biological experimentation. Alongside building such models, there is a need for mathematical techniques to be developed to examine the often complex behaviour that can arise from even the simplest models. There are now a plethora of mathematical models to describe activity at the single neuron level, ranging from one-dimensional, phenomenological ones, to complex biophysical models with large numbers of state variables. Network models present even more of a challenge, as rich patterns of behaviour can arise due to the coupling alone. We first analyse a planar integrate-and-fire model in a piecewise-linear regime. We advocate using piecewise-linear models as caricatures of nonlinear models, owing to the fact that explicit solutions can be found in the former. Through the use of explicit solutions that are available to us, we categorise the model in terms of its bifurcation structure, noting that the non-smooth dynamics involving the reset mechanism give rise to mathematically interesting behaviour. We highlight the pitfalls in using techniques for smooth dynamical systems in the study of non-smooth models, and show how these can be overcome using non-smooth analysis. Following this, we shift our focus onto the use of phase reduction techniques in the analysis of neural oscillators. We begin by presenting concrete examples showcasing where these techniques fail to capture dynamics of the full system for both deterministic and stochastic forcing. To overcome these failures, we derive new coordinate systems which include some notion of distance from the underlying limit cycle. With these coordinates, we are able to capture the effect of phase space structures away from the limit cycle, and we go on to show how they can be used to explain complex behaviour in typical oscillatory neuron models.

Surface chemical modifications are presented for supporting primary neurons in culture. The initial substrates for culture were glass and gold. The surface modifications were based on self assembled monolayer (SAM) approaches. Glass surfaces were initially modified by silanisation with either 3-aminopropyltrimethoxysilane (APTMS) or 3-aminopropyldimethylethoxysilane (APDES), to present amino-terminated surfaces. Gold surfaces were initially modified by thiol SAMs of either 11-amino-1-undecanethiol (AUT) or a peptide fragment of laminin (PA22-2), to present an amino- or peptide-terminated surface respectively. The amine-terminated surfaces of both glass and gold were subject to further modification. A heterobifunctional linker, containing a polyethylene glycol (PEG) spacer, was used to couple the peptide PA22-2 to the amino-terminated surfaces. Surface modifications were characterised using WCA, XPS and ToF-SIMS. The heterobifunctional linker bound homogeneously across the AUT SAM surface, however the linker was not distributed evenly on either of the amino silanisations of glass. Primary neurons from dissociated embryonic rat hippocampi were cultured on the modified glass and gold surfaces. The cell viability was measured during a 3 week long culture using calcein and ethidium homodimer fluorescence. Neuronal cell cultures were viable on all the gold surface modifications. The only viable glass surface was a control surface of adsorbed poly-l-lysine (PLL) on glass. Cell viability on the AUT and the Peptide-PEG-AUT modified gold surfaces was equivalent to the PLL coated glass. Inclusion of the PEG linker reduced protein adsorption from the media to the peptide modified gold surface, allowing cells to recognise the peptide rather than an adsorbed protein layer and improving their viability. The presented gold surface modifications provide suitable substrates for neural cultures which can be used in existing applications for investigating neural activity, such as; multi-electrode arrays, micro-fluidics devices, and surface plasmon resonance.

Aberrant neurotransmitter function promotes cognitive deficits in schizophrenia. These abnormalities in functioning are seen as disruptions in attentional and information processing, as well as disruptions in the consolidation and retrieval of information. Tasks of attentional salience and memory that are used to model these disruptions include the latent inhibition (LI) task of attentional salience, prepulse inhibition (PPI) task of sensorimotor gating and an Episodic memory (EM) task, which is an index of memory for episodes at a particular point in time. Aberrant functioning of candidate genes that are associated with risk for schizophrenia may be seen as behavioural alterations in these tasks of schizophrenia relevant phenotypes. dopaminergic hyperactivity and hypofunction have been implicated in mediating disruptions on these cognitive tasks. Increased transmission in the dopamine system in the striatal region promotes schizophrenia symptoms, and indirect dopamine (DA) agonist Amphetamine worsens these symptoms in patients, and disrupts schizophrenia relevant behaviours on these cognitive tasks. We investigated the effects of deletion of two genes relevant to schizophrenia on cognitive tasks known to be disrupted in the disorder. The effect of deletion of the dopamine D2 receptor (D2R) and trans membrane (TM) domain Neuregulin-1 (Nrg-1) receptor were investigated in mediating disruptions in cognitive processes in an animal model of schizophrenia. The role of the D2R in an attentional model of sensorimotor gating was assessed. PPI was attenuated in D2R knock out (KO), in a one day sensorimotor gating task. In a one day PPI test protocol, amphetamine disruptions on PPI were spared in D2R WT and KO mice. Following on from previous reports of disrupted LI by a single low dose amphetamine injection, separated by 24h interval, we established a single vs. two low dose PPI protocol in order to facilitate a direct comparison of amphetamine induced disruption in LI with PPI. A one injection (prior to test only) vs. two injection (prior to habituation and prior to test) task was established. In the two day protocol, a single low dose of amphetamine disrupted PPI in D2R KO mice and reduced startle reactivity to the 120 dB pulse alone trials. Two low dose injections of amphetamine however, do not disrupt PPI in D2R KO or their WT littermates, and do not mimic low dose amphetamine disruptions in the LI task. These findings demonstrate that prior conclusions about the requirement of the D2R for amphetamine effects in PPI does not generalise to all dose regimens. Episodic memory was also investigated as a measure of cognitive impairment in schizophrenia. D2R KO mice show sex specific dissociations on an EM task. Male D2R WT and KO animals show equal exploration of old vs. recent objects on the what-when component of the EM task, and female KO animals show enhanced memory for old vs. recent objects. Both D2R WT and KO mice show intact memory for displaced objects. These deficits were also investigated in the TM domain Nrg-1 model. Nrg-1 has been implicated as a candidate gene for schizophrenia, and behavioural phenotypes assessing its role in cognitive impairment in schizophrenia were established. Intact LI is seen in both Nrg-1 WT and Het animals. Nrg-1 TM domain Het mutants also show deficits on the schizophrenia relevant PPI task. Nrg-1 Het mutants show attenuated % PPI compared to their WT littermates, which reflects interrupted sensorimotor gating in schizophrenia. Lastly, we found some evidence that reduced function of TM-domain of the Nrg-1 gene disrupted episodic-like memory (what- where-when recognition) in males and improved it in females.