Multiscale heterogeneity of white matter morphometry in psychiatric disorders.

Background: Inter-individual variability in neurobiological and clinical characteristics in mental illness is often overlooked by classical group-mean case-control studies. Studies using normative modelling to infer person-specific deviations of grey matter volume have indicated that group means are not representative of most individuals. The extent to which this variability is present in white matter morphometry, which is integral to brain function, remains unclear.

Individuals with problem gambling and obsessive-compulsive disorder learn through distinct reinforcement mechanisms.

Obsessive-compulsive disorder (OCD) and pathological gambling (PG) are accompanied by deficits in behavioural flexibility. In reinforcement learning, this inflexibility can reflect asymmetric learning from outcomes above and below expectations. In alternative frameworks, it reflects perseveration independent of learning.

Out of sight, but not out of mind: a case study of the collaborative development of a university-wide orientation resource for online students.

The global online education sector has been rising rapidly, particularly during and after the events of 2020, and is becoming mainstream much sooner than expected. Despite this, research studies report higher levels of perceived isolation, difficulties with engagement, and higher attrition rates in online compared to equivalent on-campus programs. Reasons include restrictions to the type of institutional support accessible by online students, and the lack of comprehensiveness of orientation resources.

Neural correlates of symptom severity in obsessive-compulsive disorder using magnetization transfer and diffusion tensor imaging.

Recent neuroimaging studies in OCD have reported structural alterations in the brain, not limited to frontostriatal regions. While Diffusion Tensor Imaging (DTI) is typically used to interrogate WM microstructure in OCD, additional imaging metric, such as Magnetization Transfer Imaging (MTI), allows for further identification of subtle but important structural changes across both GM and WM. In this study, both MTI and DTI were utilised to investigate the structural integrity of the brain, in OCD in relation to healthy controls.

Transdiagnostic variations in impulsivity and compulsivity in obsessive-compulsive disorder and gambling disorder correlate with effective connectivity in cortical-striatal-thalamic-cortical circuits.

Individual differences in impulsivity and compulsivity is thought to underlie vulnerability to a broad range of disorders and are closely tied to cortical-striatal-thalamic-cortical function. However, whether impulsivity and compulsivity in clinical disorders is continuous with the healthy population and explains cortical-striatal-thalamic-cortical dysfunction across different disorders remains unclear. Here, we characterized the relationship between cortical-striatal-thalamic-cortical effective connectivity, estimated using dynamic causal modelling of resting-state functional magnetic resonance imaging data, and dimensional phenotypes of impulsivity and compulsivity in two symptomatically distinct but phenotypically related disorders, obsessive-compulsive disorder and gambling disorder.

A neutron diffraction study of the headgroup conformation of phosphatidylglycerol from Escherichia coli membranes.

By using neutron diffraction, the headgroup conformation of purified phosphatidylglycerol from Escherichia coli membranes has been investigated. Measurements at 25 degrees C and 15% relative humidity on oriented multilayers of lipid selectively deuterated at the sn-3-position of the glycerol backbone and of the gamma-position of the glycerol headgroup show that the labels are at a mean distance of 23.0 A and 27.

Structural changes in lipid bilayers and biological membranes caused hydrostatic pressure.

By use of neutron diffraction, the structural parameters of oriented multilayers of 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine with deuteriocarbon chains/cholesterol (molar ratio 70:30), multilamellar lipid vesicles composed of pure lipids and lipid/cholesterol mixtures, and crystalline purple membrane patches from Halobacterium halobium have been measured at pressures up to 2 kbar. Pressurization of the oriented 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine/cholesterol multilayers results in an in-plane compression with the mean deuteriocarbon chain spacing of 4.44 A obtained under ambient conditions decreasing by 3-7% at 1.

Hydrostatic pressure induces hydrocarbon chain interdigitation in single-component phospholipid bilayers.

By use of neutron diffraction for structural analysis, the temperature-pressure phase diagrams of several fully hydrated single-component phospholipid bilayers have been explored up to hydrostatic pressures of 2 kbars. The gel to liquid-crystalline phase transition temperature Tm increases linearly with pressure over a 10(-3)-2 kbar range in accordance with the Clausius-Clapeyron relationship giving dTm/dP values of 23.0 degrees C/kbar for 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) and 28.

The superdiamagnetic effect of magnetic fields on one and two component multilamellar liposomes.

For multilamella vesicles of DMPC, DPPC, DSPC, binary mixtures of DMPC-DPPC, DMPC-DSPC, DMPC-DPPE, DOPC and egg lecithin, the optical turbidity decreases significantly on the application of a magnetic field in excess of about 0.2 T, provided that the temperature is above the pretransition value. The turbidity reaches a limiting value for magnetic fields of about 2 T.

Dye permeability at phase transitions in single and binary component phospholipid bilayers.

By encapsulating a pH-sensitive dye, phenol red, in multilamellar liposomes of DMPC, DPPC and DMPC/DPPC mixtures, the permeability of these phospholipid bilayers to dye as a function of temperature has been studied. For both DMPC and DPPC liposomes, dye release begins well below the main gel-to-liquid-crystalline phase transition (24 degrees C and 42 degrees C, respectively) at temperatures corresponding to the onset of the pretransition (about 14 degrees C and 36 degrees C, respectively) with DPPC liposomes exhibiting a permeability anomaly at the main phase transition (42 degrees C). The perturbation occurring in the bilayer structure that allows the release of encapsulated phenol red (approx.