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Intersubject information mapping: revealing canonical representations of complex natural stimuli

Abstract Real-world time-continuous stimuli such as video promise greater naturalism for studies of brain function. However, modeling the stimulus variation is challenging and introduces a bias in favor of particular descriptive dimensions. Alternatively, we can look for brain regions whose signal is correlated between subjects, essentially using one subject to model another. Intersubject correlation mapping (ICM) allows us to find brain regions driven in a canonical manner across subjects by a complex natural stimulus. However, it requires a direct voxel-to-voxel match between the spatiotemporal activity patterns and is thus only sensitive to common activations sufficiently extended to match up in Talairach space (or in an alternative, e.g. cortical-surface-based, common brain space). Here we introduce the more general approach of intersubject information mapping (IIM). For each brain region, IIM determines how much information is shared between the subjects' local spatiotemporal activity patterns. We estimate the intersubject mutual information using canonical correlation analysis applied to voxels within a spherical searchlight centered on each voxel in turn. The intersubject information estimate is invariant to linear transforms including spatial rearrangement of the voxels within the searchlight. This invariance to local encoding will be crucial in exploring fine-grained brain representations, which cannot be matched up in a common space and, more fundamentally, might be unique to each individual – like fingerprints. IIM yields a continuous brain map, which reflects intersubject information in fine-grained patterns. Performed on data from functional magnetic resonance imaging (fMRI) of subjects viewing the same television show, IIM and ICM both highlighted sensory representations, including primary visual and auditory cortices. However, IIM revealed additional regions in higher association cortices, namely temporal pole and orbitofrontal cortex. These regions appear to encode the same information across subjects in their fine-grained patterns, although their spatial-average activation was not significantly correlated between subjects.

Biventricular Arrhythmogenic Cardiomyopathy: a paradigmatic case

We present a case of arrhythmogenic cardiomyopathy with biventricular involvement and strong arrhythmic substrate, highlighting the need to consider more than a single diagnostic option when facing arrhythmic presentations in young patients and the growing contribution provided by the genetic laboratory and contrast CMR to clinical management.

Review of ‘Active and Stable Platinum/Ionic Liquid/Carbon Nanotube Electrocatalysts for Oxidation of Methanol’

ScienceOpen SO Reviews Review    Rated 3 of 5. Marianna Barberio on 2015-04-30 (2014)
Noteworthy results. An easy method for growth of Pt/IL/CNTs nano-hybrids

Review of ‘The neighbouring effect of isosorbide and its epimers in their reactions with dimethyl carbonate’

ScienceOpen SO Reviews Review    Rated 5 of 5. Jiayu Xin on 2015-04-30 (2014)

The authors studied the reactions of isosorbide, isomannide and isoidide, with dimethyl carbonate under various conditions. As a whole, this manuscript is well written. The manuscript would benefit from improved a consideration of the following points. First, in the experiment concerning …

Patterns of somatic distress among conflict-affected persons in the Republic of Georgia

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Background There are substantial risk factors for somatic distress (SD) among civilian populations affected by armed conflict in low and middle income countries. However, the evidence is very limited. Our aim was to examine patterns of SD among conflict-affected persons in the Republic of Georgia, which has over 200,000 internally displaced persons (IDPs) from the wars over separatists regions in the 1990s and with Russia in 2008. Methods A cross-sectional household survey was conducted with 3600 randomly selected IDPs and former IDPs (returnees). SD was measured using the Patient Health Questionnaire (PHQ-15). Post-traumatic stress disorder (PTSD), depression, anxiety, and disability were measured using the Trauma Screening Questionnaire, Patient Health Questionnaire 9, Generalised Anxiety Disorder 7, and WHO Disability Assessment Schedule 2.0, respectively. Descriptive, tetrachoric and multivariate regression analyses were used. Results Forty-two percent of respondents (29% men; 48% women) were recorded as at risk of SD (PHQ-15 score > 5). In tetrachoric analysis, SD scores were highly correlated with depression (r = 0.60; p < 0.001), PTSD (r = 0.54; p < 0.001), and anxiety (r = 0.49; p < 0.001). Factors significantly associated with SD in the multivariate regression analysis were depression, PTSD, anxiety, individual trauma event exposure, cumulative trauma exposure, female gender, older age, bad household economic status, and being a returnee compared to an IDP. SD was also associated with increased levels of functional disability (b = 6.73; p < 0.001). Conclusions The high levels of SD among IDPs and returnees in Georgia indicate significant suffering. The findings have implications for both mental and physical health services in Georgia.

Gray matter correlates of creative potential: A latent variable voxel-based morphometry study

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There is increasing research interest in the structural and functional brain correlates underlying creative potential. Recent investigations found that interindividual differences in creative potential relate to volumetric differences in brain regions belonging to the default mode network, such as the precuneus. Yet, the complex interplay between creative potential, intelligence, and personality traits and their respective neural bases is still under debate. We investigated regional gray matter volume (rGMV) differences that can be associated with creative potential in a heterogeneous sample of N = 135 individuals using voxel-based morphometry (VBM). By means of latent variable modeling and consideration of recent psychometric advancements in creativity research, we sought to disentangle the effects of ideational originality and fluency as two independent indicators of creative potential. Intelligence and openness to experience were considered as common covariates of creative potential. The results confirmed and extended previous research: rGMV in the precuneus was associated with ideational originality, but not with ideational fluency. In addition, we found ideational originality to be correlated with rGMV in the caudate nucleus. The results indicate that the ability to produce original ideas is tied to default-mode as well as dopaminergic structures. These structural brain correlates of ideational originality were apparent throughout the whole range of intellectual ability and thus not moderated by intelligence. In contrast, structural correlates of ideational fluency, a quantitative marker of creative potential, were observed only in lower intelligent individuals in the cuneus/lingual gyrus.