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Journal articleVijayan R, Scott G, 2013,
An approach to the obstructive colleague
, British Medical Journal, Vol: 347, ISSN: 0007-1447 -
Journal articleKolias AG, Li LM, Guilfoyle MR, et al., 2013,
Decompressive craniectomy for acute subdural hematomas: time for a randomized trial
, Acta Neurochirurgica, Vol: 155, Pages: 187-188, ISSN: 0001-6268 -
Journal articleGrant JE, Odlaug BL, Chamberlain SR, et al., 2013,
A Proof of Concept Study of Tolcapone for Pathological Gambling: Relationships with COMT Genotype and Brain Activation
, European Neuropsychopharmacology -
Journal articleFallon SJ, Williams-Gray CH, Barker RA, et al., 2013,
Prefrontal dopamine levels determine the balance between cognitive stability and flexibility
, Cereb Cortex, Vol: 23, Pages: 361-369, ISSN: 1460-2199A key mechanism by which the prefrontal cortex (PFC) supports goal-oriented behaviors is attentional set formation: the formation and maintenance of an attentional bias toward relevant features. It has previously been proposed that a common single nucleotide polymorphism (val158met) in the gene that codes for the catechol O-methyltransferase (COMT) enzyme may affect an individual's ability to form and maintain an attentional set by modulating PFC dopamine (DA) levels. Here, we present data from a functional magnetic resonance imaging study that investigated the effect of this polymorphism on the tendency for older adults to display set-like behavior, and we compare these results to preexisting data from Parkinson's Disease (PD) patients. Our results demonstrate that putatively different levels of PFC DA predict both attentional set formation and right dorsolateral PFC (DLPFC) activation. More specifically, while for PD patients, val homozygotes showed heightened DLPFC activation and increased set-like behavior, for healthy older adults, the opposite pattern of results was observed. This interaction between COMT genotype and PD accords well with previous studies that have shown an excess of DA in the PFC in early PD patients and, furthermore, supports the hypothesis that there is an inverted-U shaped functional relationship between PFC DA levels and attentional set formation.
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Journal articleCinan S, Özen G, Hampshire A, 2013,
Confirmatory factor analysis on separability of planning and insight constructs
, Journal of Cognitive Psychology -
Journal articleHellyer PJ, Leech R, Ham TE, et al., 2013,
Individual prediction of white matter injury following traumatic brain injury
, Annals of Neurology, ISSN: 1531-8249 -
Journal articleHampshire A, Parkin BL, Cusack R, et al., 2013,
Assessing residual reasoning ability in overtly non-communicative patients using fMRI
, NeuroImage: Clinical, Vol: 2, Pages: 174-183 -
Journal articleGrant JE, Odlaug BL, Hampshire A, et al., 2013,
White matter abnormalities in skin picking disorder: a diffusion tensor imaging study
, Neuropsychopharmacology, Vol: 38, Pages: 763-769, ISSN: 1740-634XSkin picking disorder (SPD) is characterized by the repetitive and compulsive picking of skin, resulting in tissue damage. Neurocognitive findings in SPD implicate difficulty with response inhibition (suppression of pre-potent motor responses). This function is dependent on the integrity of the right frontal gyrus and the anterior cingulate cortices, and white-matter tracts connecting such neural nodes. It was hypothesized that SPD would be associated with reduced fractional anisotropy in regions implicated in top-down response suppression, particularly white-matter tracts in proximity of the bilateral anterior cingulate and right frontal (especially orbitofrontal and inferior frontal) cortices. 13-subjects meeting proposed SPD criteria for DSM-5 free from other current psychiatric comorbidities, and 12 healthy comparison subjects underwent MRI with a 3-T system. Between-group comparisons of imaging data underwent voxelwise analysis with permutation modeling and cluster correction. Fractional anisotropy (measured using diffusion tensor imaging) was the primary outcome measure. Subjects with SPD exhibited significantly reduced fractional anisotropy in tracts distributed bilaterally, which included the anterior cingulate cortices. Fractional anisotropy did not correlate significantly with SPD disease severity, or depressive or anxiety scores. These findings implicate disorganization of white-matter tracts involved in motor generation and suppression in the pathophysiology of SPD, findings remarkably similar to those previously reported in trichotillomania. This study adds considerable support to the notion that-in addition to the phenomenological and comorbid overlap between SPD and trichotillomania-these disorders likely share overlapping neurobiology.
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Journal articleWilson MH, Davagnanam I, Holland G, et al., 2013,
Cerebral venous system and anatomical predisposition to high-altitude headache
, Annals of neurology, Vol: 73, Pages: 381-389 -
Journal articleFallon SJ, Hampshire A, Williams-Gray CH, et al., 2013,
Putative cortical dopamine levels affect cortical recruitment during planning
, Neuropsychologia, ISSN: 1873-3514Planning, the decomposition of an ultimate goal into a number of sub-goals is critically dependent upon fronto-striatal dopamine (DA) levels. Here, we examined the extent to which the val158met polymorphism in the catechol O-methyltransferase (COMT) gene, which is thought to primarily alter cortical DA levels, affects performance and fronto-parietal activity during a planning task (Tower of London). COMT genotype was found to modulate activity in the left superior posterior parietal cortex (SPC) during planning, relative to subtracting, trials. Specifically, left SPC blood oxygenation level-dependent (BOLD) response was reduced in groups with putatively low or high cortical DA levels (COMT homozygotes) relative to those with intermediate cortical DA levels (COMT heterozygotes). These set of results are argued to occur either due to differences in neuronal processing in planning (and perhaps subtracting) caused by the COMT genotype and/or the cognitively heterogeneous nature of the TOL, which allows different cognitive strategies to be used whilst producing indistinguishable behavioural performance in healthy adults. The implications of this result for our understanding of COMT's effect on cognition in health and disease are discussed.
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