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Journal articleGoldstone AP, Miras AD, Scholtz S, et al., 2015,
Link between increased satiety gut hormones and reduced food reward following gastric bypass surgery for obesity
, Journal of Clinical Endocrinology & Metabolism, Vol: 101, Pages: 599-609, ISSN: 1945-7197Context: Roux-en-Y gastric bypass (RYGB) surgery is an effective long-term intervention for weightloss maintenance, reducing appetite, and also food reward, via unclear mechanisms.Objective: To investigate the role of elevated satiety gut hormones after RYGB, we examined foodhedonic-reward responses following their acute post-prandial suppression.Design: Randomised placebo-controlled double-blind cross-over experimental medicine studies.Patients: Two groups, over 5 months after RYGB for obesity (n7–11), compared with non-obesecontrols (n10), or patients after gastric banding (BAND) surgery (n9).Intervention: Studies were performed after acute administration of the somatostatin analogueOctreotide or saline. In one study, patients after RYGB, and non-obese controls, performed abehavioral progressive ratio task (PRT) for chocolate sweets. In another study, patients after RYGB,and controls after BAND surgery, performed a functional magnetic resonance imaging (fMRI) foodpicture evaluation task.Main outcome measures: Octreotide increased both appetitive food reward (breakpoint) in thePRT (n9), and food appeal (n9) and reward system blood oxygen level dependent (BOLD) signal(n7) in the fMRI task, in the RYGB group, but not in control groups.ISSN
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Journal articleLi LM, Leech R, Scott GT, et al., 2015,
The effect of oppositional parietal transcranial direct current stimulation on lateralized brain functions
, European Journal of Neuroscience, Vol: 42, Pages: 2904-2914, ISSN: 1460-9568Cognitive functions such as numerical processing and spatial attention show varying degrees of lateralization. Transcranial direct current stimulation (tDCS) can be used to investigate how modulating cortical excitability affects performance of these tasks. This study investigated the effect of bi-parietal tDCS on numerical processing, spatial and sustained attention. It was hypothesized that tDCS would have distinct effects on these tasks because of varying lateralization (numerical processing left, spatial attention right) and that these effects are partly mediated by modulation of sustained attention. A single-blinded, crossover, sham-controlled study was performed. Eighteen healthy right-handed participants performed cognitive tasks during three sessions of oppositional parietal tDCS stimulation: sham; right anodal with left cathodal (RA/LC); and right cathodal with left anodal (RC/LA). Participants performed a number comparison task, a modified Posner task, a choice reaction task (CRT) and the rapid visual processing task (RVP). RA/LC tDCS impaired number comparison performance compared with sham, with slower responses to numerically close numbers pairs. RA/LC and RC/LA tDCS had distinct effects on CRT performance, specifically affecting vigilance level during the final block of the task. No effect of stimulation on the Posner task or RVP was found. It was demonstrated that oppositional parietal tDCS affected both numerical performance and vigilance level in a polarity-dependent manner. The effect of tDCS on numerical processing may partly be due to attentional effects. The behavioural effects of tDCS were specifically observed under high task demands, demonstrating the consequences of an interaction between stimulation type and cognitive load.
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Journal articleLi L, Leech R, Seemungal B, et al., 2015,
A SENSE OF DIRECTION: BRAIN STIMULATION IN LATERALISED BRAIN FUNCTION
, JOURNAL OF NEUROLOGY NEUROSURGERY AND PSYCHIATRY, Vol: 86, ISSN: 0022-3050 -
Journal articleCorbett A, Owen A, Hampshire A, et al., 2015,
The Effect of an Online Cognitive Training Package in Healthy Older Adults: An Online Randomized Controlled Trial
, Journal of the American Medical Directors Association, Vol: 16, Pages: 990-997, ISSN: 1525-8610- Author Web Link
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- Citations: 114
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Conference paperGorgoraptis N, Zaw-Linn J, Feeney C, et al., 2015,
THE IMPACT OF TRAUMATIC BRAIN INJURY ON PATIENT-REPORTED PHYSICAL AND MENTAL HEALTH
, Annual Meeting of the Association-of-British-Neurologists (ABN), Publisher: BMJ PUBLISHING GROUP, ISSN: 0022-3050 -
Conference paperJenkins P, Fleminger J, De-Simoni S, et al., 2015,
HOME COMPUTERISED COGNITIVE TESTING FOR TBI IS FEASIBLE AND POPULAR
, Annual Meeting of the Association-of-British-Neurologists (ABN), Publisher: BMJ PUBLISHING GROUP, ISSN: 0022-3050- Author Web Link
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- Citations: 1
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Journal articleGoldstone AP, 2015,
Changes in Reward after Gastric Bypass: the Advantages and Disadvantages
, Current Atherosclerosis Reports, Vol: 17, ISSN: 1534-6242Gastric bypass surgery is an effective long-term weight loss intervention. Key to its success appears a putative shift in food preference away from high-energy-density foods associated with a reduced appetitive drive and loss of neural reactivity in the reward system of the brain towards food. Post-prandial exaggerated satiety gut hormone responses have been implicated as mediators. Whilst the positive impact of bariatric surgery on both physical and psychological outcomes for many patients is clearly evident, a subset of patients appear to be detrimentally affected by this loss of reward from food and by a lack of alternative strategies for regulating affect after surgery. Mindfulness training has emerged as a potential tool in reducing the need for immediate reward that underpins much of eating behaviour. Further research is needed to help identify patients who may be more vulnerable after gastric bypass and which forms of support may be most beneficial.
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Journal articleHampshire A, Sharp DJ, 2015,
Contrasting network and modular perspectives on inhibitory control.
, Trends in Cognitive Sciences, ISSN: 1364-6613A prominent theory proposes that the right inferior frontal cortex of the human brain houses a dedicated region for motor response inhibition. However, there is growing evidence to support the view that this inhibitory control hypothesis is incorrect. Here, we discuss evidence in favour of our alternative hypothesis, which states that response inhibition is one example of a broader class of control processes that are supported by the same set of frontoparietal networks. These domain-general networks exert control by modulating local lateral inhibition processes, which occur ubiquitously throughout the cortex. We propose that to fully understand the neural basis of behavioural control requires a more holistic approach that considers how common network mechanisms support diverse cognitive processes.
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Journal articleAlsters SIM, Goldstone AP, Buxton JL, et al., 2015,
Truncating homozygous mutation of carboxypeptidase E (CPE) in a morbidly obese female with type 2 diabetes mellitus, intellectual disability and hypogonadotrophic hypogonadism
, PLOS One, Vol: 10, ISSN: 1932-6203Carboxypeptidase E is a peptide processing enzyme, involved in cleaving numerous peptide precursors, including neuropeptides and hormones involved in appetite control and glucose metabolism. Exome sequencing of a morbidly obese female from a consanguineous family revealed homozygosity for a truncating mutation of the CPE gene (c.76_98del; p.E26RfsX68). Analysis detected no CPE expression in whole blood-derived RNA from the proband, consistent with nonsense-mediated decay. The morbid obesity, intellectual disability, abnormal glucose homeostasis and hypogonadotrophic hypogonadism seen in this individual recapitulates phenotypes in the previously described fat/fat and Cpe knockout mouse models, evidencing the importance of this peptide/hormone-processing enzyme in regulating body weight, metabolism, and brain and reproductive function in humans.
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Journal articleShanahan MP, Hellyer P, Sharp DJ, et al., 2015,
Cognitive flexibility through metastable neural dynamics is disrupted by damage to the structural connectome
, Journal of Neuroscience, Vol: 35, Pages: 9050-9063, ISSN: 0270-6474Current theory proposes that healthy neural dynamics operate in a metastable regime, where brain regions interact to simultaneously maximize integration and segregation. Metastability may confer important behavioral properties, such as cognitive flexibility. It is increasingly recognized that neural dynamics are constrained by the underlying structural connections between brain regions. An important challenge is, therefore, to relate structural connectivity, neural dynamics, and behavior. Traumatic brain injury (TBI) is a pre-eminent structural disconnection disorder whereby traumatic axonal injury damages large-scale connectivity, producing characteristic cognitive impairments, including slowed information processing speed and reduced cognitive flexibility, that may be a result of disrupted metastable dynamics. Therefore, TBI provides an experimental and theoretical model to examine how metastable dynamics relate to structural connectivity and cognition. Here, we use complementary empirical and computational approaches to investigate how metastability arises from the healthy structural connectome and relates to cognitive performance. We found reduced metastability in large-scale neural dynamics after TBI, measured with resting-state functional MRI. This reduction in metastability was associated with damage to the connectome, measured using diffusion MRI. Furthermore, decreased metastability was associated with reduced cognitive flexibility and information processing. A computational model, defined by empirically derived connectivity data, demonstrates how behaviorally relevant changes in neural dynamics result from structural disconnection. Our findings suggest how metastable dynamics are important for normal brain function and contingent on the structure of the human connectome.
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