Psychiatry - Research Publications
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ItemGenetic Influences on Cost-Efficient Organization of Human Cortical Functional Networks(SOC NEUROSCIENCE, 2011-03-02)The human cerebral cortex is a complex network of functionally specialized regions interconnected by axonal fibers, but the organizational principles underlying cortical connectivity remain unknown. Here, we report evidence that one such principle for functional cortical networks involves finding a balance between maximizing communication efficiency and minimizing connection cost, referred to as optimization of network cost-efficiency. We measured spontaneous fluctuations of the blood oxygenation level-dependent signal using functional magnetic resonance imaging in healthy monozygotic (16 pairs) and dizygotic (13 pairs) twins and characterized cost-efficient properties of brain network functional connectivity between 1041 distinct cortical regions. At the global network level, 60% of the interindividual variance in cost-efficiency of cortical functional networks was attributable to additive genetic effects. Regionally, significant genetic effects were observed throughout the cortex in a largely bilateral pattern, including bilateral posterior cingulate and medial prefrontal cortices, dorsolateral prefrontal and superior parietal cortices, and lateral temporal and inferomedial occipital regions. Genetic effects were stronger for cost-efficiency than for other metrics considered, and were more clearly significant in functional networks operating in the 0.09-0.18 Hz frequency interval than at higher or lower frequencies. These findings are consistent with the hypothesis that brain networks evolved to satisfy competitive selection criteria of maximizing efficiency and minimizing cost, and that optimization of network cost-efficiency represents an important principle for the brain's functional organization.
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ItemThe relationship between Hippocampal asymmetry and working memory processing in combat-related PTSD - a monozygotic twin study(BMC, 2012-12)BACKGROUND: PTSD is associated with reduction in hippocampal volume and abnormalities in hippocampal function. Hippocampal asymmetry has received less attention, but potentially could indicate lateralised differences in vulnerability to trauma. The P300 event-related potential component reflects the immediate processing of significant environmental stimuli and has generators in several brain regions including the hippocampus. P300 amplitude is generally reduced in people with PTSD. METHODS: Our study examined hippocampal volume asymmetry and the relationship between hippocampal asymmetry and P300 amplitude in male monozygotic twins discordant for Vietnam combat exposure. Lateralised hippocampal volume and P300 data were obtained from 70 male participants, of whom 12 had PTSD. We were able to compare (1) combat veterans with current PTSD; (2) their non-combat-exposed co-twins; (3) combat veterans without current PTSD and (4) their non-combat-exposed co-twins. RESULTS: There were no significant differences between groups in hippocampal asymmetry. There were no group differences in performance of an auditory oddball target detection task or in P300 amplitude. There was a significant positive correlation between P300 amplitude and the magnitude of hippocampal asymmetry in participants with PTSD. CONCLUSIONS: These findings suggest that greater hippocampal asymmetry in PTSD is associated with a need to allocate more attentional resources when processing significant environmental stimuli.
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ItemNo Preview AvailableMental Health Informatics(Springer Berlin Heidelberg, 2014)This book introduces approaches that have the potential to transform the daily practice of psychiatrists and psychologists.
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ItemBaseline characteristics of patients in the Reduction of Events with Darbepoetin alfa in Heart Failure trial (RED-HF).(Wiley, 2013-03)AIMS: This report describes the baseline characteristics of patients in the Reduction of Events with Darbepoetin alfa in Heart Failure trial (RED-HF) which is testing the hypothesis that anaemia correction with darbepoetin alfa will reduce the composite endpoint of death from any cause or hospital admission for worsening heart failure, and improve other outcomes. METHODS AND RESULTS: Key demographic, clinical, and laboratory findings, along with baseline treatment, are reported and compared with those of patients in other recent clinical trials in heart failure. Compared with other recent trials, RED-HF enrolled more elderly [mean age 70 (SD 11.4) years], female (41%), and black (9%) patients. RED-HF patients more often had diabetes (46%) and renal impairment (72% had an estimated glomerular filtration rate < 60 mL/min/1.73 m2). Patients in RED-HF had heart failure of longer duration [5.3 (5.4) years], worse NYHA class (35% II, 63% III, and 2% IV), and more signs of congestion. Mean EF was 30% (6.8%). RED-HF patients were well treated at randomization, and pharmacological therapy at baseline was broadly similar to that of other recent trials, taking account of study-specific inclusion/exclusion criteria. Median (interquartile range) haemoglobin at baseline was 112 (106-117) g/L. CONCLUSION: The anaemic patients enrolled in RED-HF were older, moderately to markedly symptomatic, and had extensive co-morbidity.
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ItemN-cadherin mediates plasticity-induced long-term spine stabilization(ROCKEFELLER UNIV PRESS, 2010-05-03)Excitatory synapses on dendritic spines are dynamic structures whose stability can vary from hours to years. However, the molecular mechanisms regulating spine persistence remain essentially unknown. In this study, we combined repetitive imaging and a gain and loss of function approach to test the role of N-cadherin (NCad) on spine stability. Expression of mutant but not wild-type NCad promotes spine turnover and formation of immature spines and interferes with the stabilization of new spines. Similarly, the long-term stability of preexisting spines is reduced when mutant NCad is expressed but enhanced in spines expressing NCad-EGFP clusters. Activity and long-term potentiation (LTP) induction selectively promote formation of NCad clusters in stimulated spines. Although activity-mediated expression of NCad-EGFP switches synapses to a highly stable state, expression of mutant NCad or short hairpin RNA-mediated knockdown of NCad prevents LTP-induced long-term stabilization of synapses. These results identify NCad as a key molecular component regulating long-term synapse persistence.
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ItemAustralian medical students' perceptions of professionalism and ethics in medical television programs.(Springer Science and Business Media LLC, 2011-07-29)BACKGROUND: Medical television programs offer students fictional representations of their chosen career. This study aimed to discover undergraduate medical students' viewing of medical television programs and students' perceptions of professionalism, ethics, realism and role models in the programs. The purpose was to consider implications for teaching strategies. METHODS: A medical television survey was administered to 386 undergraduate medical students across Years 1 to 4 at a university in New South Wales, Australia. The survey collected data on demographics, year of course, viewing of medical television programs, perception of programs' realism, depiction of ethics, professionalism and role models. RESULTS: The shows watched by most students were House, Scrubs, and Grey's Anatomy, and students nominated watching 30 different medical programs in total. There was no statistical association between year of enrolment and perceptions of accuracy. The majority of students reported that friends or family members had asked them for their opinion on an ethical or medical issue presented on a program, and that they discussed ethical and medical matters with their friends. Students had high recall of ethical topics portrayed on the shows, and most believed that medical programs generally portrayed ideals of professionalism well. CONCLUSIONS: Medical programs offer considerable currency and relevance with students and may be useful in teaching strategies that engage students in ethical lessons about practising medicine.
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ItemBig fish in a big pond: a study of academic self concept in first year medical students.(Springer Science and Business Media LLC, 2011-07-27)BACKGROUND: Big-fish-little-pond effect (BFLPE) research has demonstrated that students in high-ability environments have lower academic self-concepts than equally able students in low-ability settings. Research has shown low academic self-concepts to be associated with negative educational outcomes. Social comparison processes have been implicated as fundamental to the BFLPE. METHODS: Twenty first-year students in an Australian medical school completed a survey that included academic self-concept and social comparison measures, before and after their first written assessments. Focus groups were also conducted with a separate group of students to explore students' perceptions of competence, the medical school environment, and social comparison processes. RESULTS: The quantitative study did not reveal any changes in academic self-concept or self-evaluation. The qualitative study suggested that the attributions that students used when discussing performance were those that have been demonstrated to negatively affect self-concept. Students reported that the environment was slightly competitive and they used social comparison to evaluate their performance. CONCLUSIONS: Although the BFLPE was not evident in the quantitative study, results from the qualitative study suggest that the BFLPE might be operating In that students were using attributions that are associated with lower self-concepts, the environment was slightly competitive, and social comparisons were used for evaluation.
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ItemClinical subtypes of core premenstrual disorders: a Delphi survey(SPRINGER WIEN, 2013-06)The purpose of this study was to classify the clinical subtypes of core premenstrual disorders during the International Society for Premenstrual Disorders' second consensus meeting. Multiple iterations were used to achieve consensus between a group of experts; these iterations included a two-generational Delphi technique that was preceded and followed by open group discussions. The first round was to generate a list of all potential clinical subtypes, which were subsequently prioritized using a Delphi methodology and then finalised in a final round of open discussion. On a six-point scale, 4 of the 12 potential clinical subtypes had a mean score of ≥5.0 following the second iteration and only 3 of the 4 still had a mean score of ≥5.0 after the third iteration. The final list consisted of these three subtypes and an additional subtype, which was introduced and agreed upon, in the final iteration. There is consensus amongst experts that core premenstrual disorder is divided into three symptom-based subtypes: predominantly physical, predominantly psychological and mixed. A proportion of psychological and mixed subtypes may meet the DSM-IV diagnostic criteria for premenstrual dysphoric disorder.
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ItemHolding the Heart of Mindfulness-Based Stress Reduction: Balancing Fidelity and Imagination When Adapting MBSR(Springer Science and Business Media LLC, 2014-12)
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