1,721,483 research outputs found
Relationships between substance use and hypomanic symptoms in a non-clinical sample
No full textPrevious work has demonstrated high levels of comorbidity between bipolar disorders and substance use disorders. There appears to be a relationship between substance use and hypomanic symptoms within the general population, but there has been little research in the area. The aim of the study was to examine relationships between substance use variables and hypomanic symptoms in a non-clinical sample. An international sample of 400 undergraduate students completed the 32-item hypomania checklist (HCL-32) and an author-constructed measure of substance use. Scores on the HCL-32 were significantly higher for those who were currently using amphetamines, and were approaching signifiance for those currently using cannabis, 3,4-methylenedioxymethamphetamine (MDMA), and cocaine. Those with a lifetime history of cocaine and amphetamine use had significantly higher scores, and there was a non-significant trend for the same effect with lifetime MDMA use. Statistically significant correlations were found between scores on the HCL-32 subscales and age of first use of cannabis and amphetamines. There were significant correlations or non-significant trends for a relationship between higher hypomanic symptoms and greater consumption of cannabis and MDMA in the past year and higher lifetime use of cannabis, cocaine and amphetamines. The present study concluded that substance use is related to hypomania in non-clinical populations. Further research using longitudinal designs is required to understand better the causal mechanisms involved in such a relationship
The role of cognitive and reward processes in substance use : a cognitive neuroscience approach to understanding drugs of addiction
No full textTHESIS 8752Drugs of addiction are widely considered to induce a pathological state which involves the progression of acute drug use to the development of drug-seeking behaviour, the decreased and slowed ability to respond to naturally rewarding stimuli, compromised impulse control and a vulnerability to drug relapse during abstinence. Therefore, it is believed that drug addiction is a disorder of the brain involving alterations in major neural substrates related to reward, motivation and/or drive, learning and memory and cognitive control. Cogent scientifically based research that focuses on distinct, well-characterized cognitive processes, believed to be the product of these neuronal substrates, affords neuroscience the opportunity to elucidate cognitive operations in drug users, and importantly, how changes in neural functioning related to cognition likely promotes continued drug use and ultimately, addiction
Attention and reasoning : a task-switching investigation of the mental model theory
No full textTHESIS 8684Despite the fact that most theories of reasoning agree on the main role played by
limitations in WM capacity in reasoning performance, little research has been directed
to elucidate how the executive processes that deal with these limitations contribute to
complex mental operations such as calculation or deduction. The present thesis aims to
demonstrate how the methods employed in the investigation of one such executive
process, namely, attention switching, may help to shed light on some debated questions
about the way people tackle reasoning problems. Particularly we are interested in those
questions referring to the influence of attentional limitations in the ease with which
reasoning problems can be solved
Neuroanatomy of executive functions, cognitive control processes and their interactions using functional magnetic resonance imaging
No full textTHESIS 7600Human behaviour, though appearing seamless, is comprised of a number of differing
and interacting cognitive processes. In this dissertation I attempted to establish the
anatomical networks subserving a number of different executive functions, which are
crucial for normal human learning and behaviour with the use of functional magnetic
resonance imaging (fMRI). These functions were the maintenance of task set,
sustaining attentional focus, inhibition of prepotent responses and the detection of
errors or situations in which an error is likely to occur
Flexible cognitive control : task, individual difference and practice determinants of functional neuroanatomy
No full textTHESIS 7802A defining feature of cognitive control is that it is reflexive - we can rapidly and
flexibly adjust attentional processes and executive control over our thoughts and
behaviour in response to changing internal or external demands. Working memory
(WM) and inhibitory control are cognitive abilities at the core of this flexible
cognitive capacity. This thesis presents a body of research, conducted with fMRI,
which investigates the functional anatomy of these flexible cognitive control
processes. Specifically, the thesis presents a number of focused examinations of
dimensions on which cognitive control varies, namely: task difficulty; task practice;
and individual differences, with a particular focus on whether and how the functional
anatomy of cognitive control processes might respond to practice
An investigation into the role of impulsivity in addiction
No full textTHESIS 10216Impulsivity typically refers to actions made without sufficient forethought or
consideration of their consequences. This dissertation focuses on the neural
underpinnings of this trait from a perspective of a striatal-based reward
anticipation system interacting with a prefrontal-centred inhibitory control
mechanism. That is to say, impulsivity might stem from the relationship
between reward-seeking drives and behavioural control mechanisms that
attempt to exert control over such drives. Drug-addicted populations tend
to show elevated levels of impulsivity on a number of measures, suggesting
that disruptions to any identified impulsivity neural network might exist
within such populations
Methodological considerations and functional correlates in structural MR image analysis of the brain
No full textTHESIS 8509Structural magnetic resonance imaging is a complex and extremely powerful high
resolution imaging mechanism that yields excellent soft tissue contrast. Recent times
have seen the development numerous structural image analysis techniques that offer the
researcher a means to perform whole brain voxelwise comparisons between various
groups to capture and localize between-group differences. However, the researcher must
be aware of the complexities involved in such analysis techniques and understand the
implications of methodological variations. Addressing some of these concerns and
applying these findings to perform inter-modal comparisons between functional MRI
activation measures and structural volumetric measures to assess structure/function
relations of the brain is the focus of this thesi
Methodological issues in event-related fMRI
No full textTHESIS 7467Functional magnetic resonance imaging (fMRI) is a very powerful tool for localising psychological functions to specific brain areas. Recently, there has been a surge of interest in determining the functional differences that might characterise certain populations. However, the results of event-related fMRI can be questionable due to the complexities of the techniques involved. A researcher must eliminate possible between-group confounds and optimally design experiments to increase confidence in findings. Addressing some of these methodological concerns is the focus of this thesis. Four questions have been chosen that are of particular importance in event- related fMRI, but have been poorly investigated in the literature
Exploring the neural substrates contributing to the risk for psychosis : an MRI investigation
No full textTHESIS 9312Over the last three decades schizophrenia research has shifted its focus from
studying individuals with the established illness to those who have an elevated risk for
developing the disease. Research has suggested that schizophrenia is a
neurodevelopmental disorder which may be negatively affected by genetic and
environmental insults which may contribute to the neurobiological abnormalities and
cognitive deficits observed in schizophrenia patients
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