Functional connectivity between salience, default mode and frontoparietal networks in post-stroke depression
Previous studies have demonstrated altered resting state functional connectivity (rsFC) in patients with post-stroke depression (PSD). It remains unclear whether rsFC is changed at the network level as was shown for major depressive disorder (MDD). To address this question, we investigated rsFC of resting sate networks (RSNs) in PSD.
Eleven subjects with PSD underwent fMRI scanning at rest before and after treatment. The severity of depression was assessed using the aphasic depression rating scale (ADRS). We performed functional network connectivity (FNC) analysis for RSNs, region of interest - FC analysis (ROI-FC) and calculation of brain matter volumes in ROIs overlapping with RSNs and in other brain regions associated with mood maintenance.
We found positive correlation of FNC between anterior default mode network (aDMN) and salience network (SAL) with depression severity before treatment, the latter accompanied by the increase of white matter in the middle frontal and left angular gyri. FNC of aDMN and left frontoparietal network (LFP) decreased after treatment. ROI-FC and the brain matter volumes of several regions of DMN, LFP and SAL also showed a correlation with ADRS or significant change after treatment.
Limitations include small sample size and methodological issues concerning altered hemodynamics in stroke. However, we took complex preprocessing steps to overcome these issues.
Present results of altered rsFC in PSD are consistent with previous findings in MDD. The convergence of results obtained in PSD and MDD supports the validity of rsFC approach for investigation of brain network dysfunctions underling these psychiatric symptoms.
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The study of cerebral organization of usage of verbs and nouns was carried out by means of functional magnetic resonance imaging. The influence of strategy of word actualization (verbs and nouns extraction on paradigmatic and syntagmatic connections) and the level of automation of these processes on the pattern of cerebral cortex activation was shown.
Key characteristics of non-fluent (Broca, motor) aphasia are, among others, verb finding difficulties and effortful speech output. These characteristics are related to different levels of speech production (lexical retrieval and motor execution). This study was aimed at identifying normative brain activation related to verb production in healthy individuals, as well as patterns of its reorganization depending on the locus of the linguistic deficit in patients with non-fluent aphasia.
We analyzed brain functional connectivity using data from a task-based fMRI study of explicit categorization of neutral and emotional faces. During the perception of emotional faces, the correlation of BOLD signal in the right posterior superior temporal sulcus (STS) with other regions of the core face system increased, as compared to neutral faces. Conversely, during the perception of neutral faces, we found an increased correlation of STS and other core face system regions with brain areas outside the core system. The functional connectivity of STS shows lateralization due to the presence or absence of emotional expression. The obtained results support the key role of STS in facial expression recognition.
The paper will provide examples of computer vision tasks in which topological data analysis gave new effective solutions. Ideas underlying topological data analysis and its basic methods will be briefly described and illustrated with examples of computer vision problems. No prior knowledge in topological data analysis and computational geometry is assumed, a brief introduction to subject is given throughout the text.
Investigations of the neural correlates of face recognition have typically used old/new paradigms where subjects learn to recognize new faces or identify famous faces. Familiar faces, however, include one's own face, partner's and parents' faces. Using event-related fMRI, we examined the neural correlates of these personally familiar faces. Ten participants were presented with photographs of own, partner, parents, famous and unfamiliar faces and responded to a distinct target. Whole brain, two regions of interest (fusiform gyrus and cingulate gyrus), and multiple linear regression analyses were conducted. Compared with baseline, all familiar faces activated the fusiform gyrus; own faces also activated occipital regions and the precuneus; partner faces activated similar areas, but in addition, the parahippocampal gyrus, middle superior temporal gyri and middle frontal gyrus. Compared with unfamiliar faces, only personally familiar faces activated the cingulate gyrus and the extent of activation varied with face category. Partner faces also activated the insula, amygdala and thalamus. Regions of interest analyses and laterality indices showed anatomical distinctions of processing the personally familiar faces within the fusiform and cingulate gyri. Famous faces were right lateralized whereas personally familiar faces, particularly partner and own faces, elicited bilateral activations. Regression analyses show experiential predictors modulated with neural activity related to own and partner faces. Thus, personally familiar faces activated the core visual areas and extended frontal regions, related to semantic and person knowledge and the extent and areas of activation varied with face type.
An increased propensity for risk taking is a hallmark of adolescent behavior with significant health and social consequences. Here, we elucidated cortical and subcortical regions associated with risky and risk-averse decisions and outcome evaluation using the Balloon Analog Risk Task in a large sample of adolescents (n=256, 56% female, age 14 ± 0.6), including the level of risk as a parametric modulator. We also identified sex differences in neural activity. Risky decisions engaged regions that are parts of the salience, dorsal attention, and frontoparietal networks, but only the insula was sensitive to increasing risks in parametric analyses. During risk-averse decisions, the same networks covaried with parametric levels of risk. The dorsal striatum was engaged by both risky and risk-averse decisions, but was not sensitive to escalating risk. Negative-outcome processing showed greater activations than positive-outcome processing. Insula, lateral orbitofrontal cortex, middle, rostral, and superior frontal areas, rostral and caudal anterior cingulate cortex were activated only by negative outcomes, with a subset of regions associated with negative outcomes showing greater activation in females. Taken together, these results suggest that safe decisions are predicted by more accurate neural representation of increasing risk levels, whereas reward-related processes play a relatively minor role.
The distractive effects on attentional task performance in different paradigms are analyzed in this paper. I demonstrate how distractors may negatively affect (interference effect), positively (redundancy effect) or neutrally (null effect). Distractor effects described in literature are classified in accordance with their hypothetical source. The general rule of the theory is also introduced. It contains the formal prediction of the particular distractor effect, based on entropy and redundancy measures from the mathematical theory of communication (Shannon, 1948). Single- vs dual-process frameworks are considered for hypothetical mechanisms which underpin the distractor effects. Distractor profiles (DPs) are also introduced for the formalization and simple visualization of experimental data concerning the distractor effects. Typical shapes of DPs and their interpretations are discussed with examples from three frequently cited experiments. Finally, the paper introduces hierarchical hypothesis that states the level-fashion modulating interrelations between distractor effects of different classes.
This article describes the expierence of studying factors influencing the social well-being of educational migrants as mesured by means of a psychological well-being scale (A. Perrudet-Badoux, G.A. Mendelsohn, J.Chiche, 1988) previously adapted for Russian by M.V. Sokolova. A statistical analysis of the scale's reliability is performed. Trends in dynamics of subjective well-being are indentified on the basis the correlations analysis between the condbtbions of adaptation and its success rate, and potential mechanisms for developing subjective well-being among student migrants living in student hostels are described. Particular attention is paid to commuting as a factor of adaptation.