213 research outputs found
Integrating evidence from neuroimaging and neuropsychological studies of obsessive-compulsive disorder: the orbitofronto-striatal model revisited
No full textObsessive-compulsive disorder (OCD) is a common, heritable and disabling neuropsychiatric disorder. Theoretical models suggest that OCD is underpinned by functional and structural abnormalities in orbitofronto-striatal circuits. Evidence from cognitive and neuroimaging studies (functional and structural magnetic resonance imaging (MRI) and positron emission tomography (PET)) have generally been taken to be supportive of these theoretical models; however, results from these studies have not been entirely congruent with each other. With the advent of whole brain-based structural imaging techniques, such as voxel-based morphometry and multivoxel analyses, we consider it timely to assess neuroimaging findings to date, and to examine their compatibility with cognitive studies and orbitofronto-striatal models. As part of this assessment, we performed a quantitative, voxel-level meta-analysis of functional MRI findings, which revealed consistent abnormalities in orbitofronto-striatal and other additional areas in OCD. This review also considers the evidence for involvement of other brain areas outside orbitofronto-striatal regions in OCD, the limitations of current imaging techniques, and how future developments in imaging may aid our understanding of OCD.</p
Brain network analysis : separating cost from topology using cost-integration
No full textA statistically principled way of conducting brain network analysis is still lacking. Comparison of different populations of
brain networks is hard because topology is inherently dependent on wiring cost, where cost is defined as the number of
edges in an unweighted graph. In this paper, we evaluate the benefits and limitations associated with using cost-integrated
topological metrics. Our focus is on comparing populations of weighted undirected graphs that differ in mean association
weight, using global efficiency. Our key result shows that integrating over cost is equivalent to controlling for any
monotonic transformation of the weight set of a weighted graph. That is, when integrating over cost, we eliminate the
differences in topology that may be due to a monotonic transformation of the weight set. Our result holds for any
unweighted topological measure, and for any choice of distribution over cost levels. Cost-integration is therefore helpful in
disentangling differences in cost from differences in topology. By contrast, we show that the use of the weighted version of
a topological metric is generally not a valid approach to this problem. Indeed, we prove that, under weak conditions, the
use of the weighted version of global efficiency is equivalent to simply comparing weighted costs. Thus, we recommend the
reporting of (i) differences in weighted costs and (ii) differences in cost-integrated topological measures with respect to
different distributions over the cost domain. We demonstrate the application of these techniques in a re-analysis of an fMRI
working memory task. We also provide a Monte Carlo method for approximating cost-integrated topological measures.
Finally, we discuss the limitations of integrating topology over cost, which may pose problems when some weights are zero,
when multiplicities exist in the ranks of the weights, and when one expects subtle cost-dependent topological differences,
which could be masked by cost-integration
Broadband criticality of human brain network synchronization
No full textSelf-organized criticality is an attractive model for human brain dynamics, but there has been little direct evidence for its existence in large-scale systems measured by neuroimaging. In general, critical systems are associated with fractal or power law scaling, long-range correlations in space and time, and rapid reconfiguration in response to external inputs. Here, we consider two measures of phase synchronization: the phase-lock interval, or duration of coupling between a pair of (neurophysiological) processes, and the lability of global synchronization of a (brain functional) network. Using computational simulations of two mechanistically distinct systems displaying complex dynamics, the Ising model and the Kuramoto model, we show that both synchronization metrics have power law probability distributions specifically when these systems are in a critical state. We then demonstrate power law scaling of both pairwise and global synchronization metrics in functional MRI and magnetoencephalographic data recorded from normal volunteers under resting conditions. These results strongly suggest that human brain functional systems exist in an endogenous state of dynamical criticality, characterized by a greater than random probability of both prolonged periods of phase-locking and occurrence of large rapid changes in the state of global synchronization, analogous to the neuronal “avalanches” previously described in cellular systems. Moreover, evidence for critical dynamics was identified consistently in neurophysiological systems operating at frequency intervals ranging from 0.05–0.11 to 62.5–125 Hz, confirming that criticality is a property of human brain functional network organization at all frequency intervals in the brain's physiological bandwidth
White matter abnormalities in patients with obsessive-compulsive disorder and their first-degree relatives
No full textObjective: obsessive-compulsive disorder (OCD) is a common, heritable neuropsychiatric disorder, hypothetically underpinned by dysconnectivity of large-scale brain systems. The extent of white matter abnormalities in OCD is unknown, and the genetic basis of this disorder is poorly understood. The authors used diffusion tensor imaging, a magnetic resonance imaging technique, for examining white matter abnormalities in brain structure through quantification of water diffusion, to confirm whether white matter abnormalities exist in OCD. They also explored whether such abnormalities occur in healthy first-degree relatives of patients, indicating they may be endophenotypes representing increased genetic risk for OCD. Method: the authors used diffusion tensor imaging to measure fractional anisotropy of white matter in 30 patients with OCD, 30 unaffected first-degree relatives, and 30 matched healthy comparison subjects. Regions of significantly abnormal fractional anisotropy in patients in relation to healthy comparison subjects were identified by permutation tests. The authors assessed whether these abnormalities were also evident in the first-degree relatives. A secondary region-of-interest analysis was undertaken to assess the extent of replication between our data and previous relevant literature.Results: patients with OCD demonstrated significantly reduced fractional anisotropy in a large region of right inferior parietal white matter and significantly increased fractional anisotropy in a right medial frontal region. Relatives also exhibited significant abnormalities of fractional anisotropy in these regions. Conclusions: these findings indicate that OCD is associated with white matter abnormalities in parietal and frontal regions. Similar abnormalities in unaffected first-degree relatives suggest these may be white matter endophenotypes for OCD.</p
Efficiency Measures for Low-Cost Brain Functional Networks, with <i>K</i> ∼ 0.1, in All Participants
No full text<div><p>(Top row) Within-subject effects of dopamine antagonism (sulpiride 400 mg) on global efficiency (left column), local efficiency (middle column), and maximum cost efficiency (right column): data on younger subjects are denoted by black lines and black triangles, data on older subjects by red lines and red triangles.</p><p>(Bottom row) Box-plots showing median, interquartile range, and range for global efficiency, local efficiency, and maximum-cost efficiency in each age group after each treatment. Each horizontal line and the associated number represent the <i>p</i>-value of a post-hoc <i>t</i>-test: there were consistent pairwise differences in global efficiency related to age (YP–OP and YS–OS), less consistent age-related differences in cost efficiency (YP–OP), and no significant post-hoc effects of age on local efficiency; however, there were consistent pairwise differences in local efficiency related to drug treatment (YP–YS and OP–OS), and a significant effect of drug on global efficiency in young people (YP–YS).</p></div
Author Correction: The impact of the initial COVID-19 outbreak on young adults’ mental health: a longitudinal study of risk and resilience factors
No full textCorrection to: Scientific Reportshttps://doi.org/10.1038/s41598-022-21053-2, published online 05 October 2022. The original version of this Article contained an omission in the Methods section, under the subheading ‘Risk factors’. “A detailed list of pandemic-related questionnaire items is provided in Supplementary Materials 2.” now reads: “The pandemic-related risk factors were adapted from questionnaire items developed as part of the COVID-19 Social Study (for more information, visit www.covidsocialstudy.org/), with a detailed list of items provided in Supplementary Materials 2.” In addition, the Funding section was incomplete. The Funding section now reads: “Data collection was supported by a strategic award from the Wellcome Trust (095844/Z/11/Z) to the University of Cambridge (IMG, ETB, PBJ) and University College London (RJD, PF). Data management was supported by the NIHR Cambridge Bioresource and data analysis by the NIHR ARC East of England. These funders had no role in determining our study design, hypotheses, interpretation, or the writing of this report. AW, JP, and PBJ were supported by the NIHR ARC East of England at Cambridgeshire and Peterborough NHS Foundation Trust. JF was supported by the NIHR Cambridge Biomedical Research Centre; ETB by an NIHR Senior Investigator award. SRC role in this study was funded by a Wellcome Trust Clinical Fellowship (110049/Z/15/Z & 110049/Z/15/A) which also co-supported data collection for the fourth assessment. The NSPN COVID-19 2020 follow-up survey included a collection of items derived from questionnaire material developed as part of the COVID-19 Social Study, which was supported by the Nuffield Foundation (WEL/FR-000022583), the MARCH Mental Health Network funded by the Cross-Disciplinary Mental Health Network Plus initiative supported by UK Research and Innovation (ES/S002588/1), and the Wellcome Trust (221400/Z/20/Z and 205407/Z/16/Z).” The original Article has been corrected.</p
Endogenous human brain dynamics recover slowly following cognitive effort
No full textIn functional magnetic resonance imaging, the brain's response to experimental cognitive tasks is usually assumed to be independent of endogenous oscillations. To test this assumption, we measured fractal scaling of fMRI time-series before and after a working memory task. Prolonged and task difficulty-related changes in post-task 'resting' data suggest that brain dynamics recover slowly from cognitive effort, contrary to the reflexive model that background oscillations are independent of task performance
DEPICT: Depression, epigenetics, and childhood trauma
No full textThe DEPICT study aims to elucidate how early life stress (ELS) reprograms the peripheral immune system, focused on CD4 and CD8 T cell
Fractionation of impulsive and compulsive trans-diagnostic phenotypes and their longitudinal associations
No full textOBJECTIVE: Young adulthood is a crucial neurodevelopmental period during which impulsive and compulsive problem behaviours commonly emerge. While traditionally considered diametrically opposed, impulsive and compulsive symptoms tend to co-occur. The objectives of this study were as follows: (a) to identify the optimal trans-diagnostic structural framework for measuring impulsive and compulsive problem behaviours, and (b) to use this optimal framework to identify common/distinct antecedents of these latent phenotypes. METHOD: In total, 654 young adults were recruited as part of the Neuroscience in Psychiatry Network, a population-based cohort in the United Kingdom. The optimal trans-diagnostic structural model capturing 33 types of impulsive and compulsive problem behaviours was identified. Baseline predictors of subsequent impulsive and compulsive trans-diagnostic phenotypes were characterised, along with cross-sectional associations, using partial least squares. RESULTS: Current problem behaviours were optimally explained by a bi-factor model, which yielded dissociable measures of impulsivity and compulsivity, as well as a general disinhibition factor. Impulsive problem behaviours were significantly explained by prior antisocial and impulsive personality traits, male gender, general distress, perceived dysfunctional parenting and teasing/arguments within friendships. Compulsive problem behaviours were significantly explained by prior compulsive traits and female gender. CONCLUSION: This study demonstrates that trans-diagnostic phenotypes of 33 impulsive and compulsive problem behaviours are identifiable in young adults, utilising a bi-factor model based on responses to a single questionnaire. Furthermore, these phenotypes have different antecedents. The findings yield a new framework for fractionating impulsivity and compulsivity, and suggest different early intervention targets to avert emergence of problem behaviours. This framework may be useful for future biological and clinical dissection of impulsivity and compulsivity
Protecting Peer Review: Correspondence Chronology and Ethical Analysis Regarding Logothetis vs. Shmuel and Leopold
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