Greater Connectivity Research Articles

Contextualizing connectivity: how internet connection type and parental factors influence technology use among lower-income children

ABSTRACTThis project links research on digital inequality, which focuses on connection quality and its outcomes for under-connected individuals, and parental mediation, which focuses on the influence of parents on children’s technology experiences. We examine the internet connection type used by families, the technology experiences of lower-income parents, and their perceptions of opportunities that technology use offers their children. We then determine how these factors influence the frequency and scope of their school-age children’s technology use. Findings show that contextualizing children’s connectivity to account for infrastructural, socio-demographic, and relational influences provides new insights into the technology experiences of lower-income children. One set of findings suggests that direct benefit from increased connectivity is most evident for lower-income parents – those with the lowest household incomes, lowest levels of education, and whose dominant language is not English. These effects remain after controlling for other socio-demographic factors. The second set of results shows that greater connectivity increases how frequently both children and parents use the internet, but is associated only with a greater scope of internet activities for parents. Parents’ online activity scope is important for their children’s online experiences, directly predicting the scope of their online activities. High-scope parents were also significantly more likely to see digital opportunities in their children’s internet use, which in turn also predicted more frequent and broader internet use by their children. We conclude by considering the practical implications of these findings for digital equity initiatives targeting lower-income families.

Sensory overload and imbalance: Resting-state vestibular connectivity in PTSD and its dissociative subtype

BackgroundThe vestibular system integrates multisensory information to monitor one's bodily orientation in space, and is influenced by interoceptive awareness. Post-traumatic stress disorder (PTSD) involves typically alterations in interoceptive and bodily self-awareness evidenced by symptoms of hyperarousal, as well as of emotional detachment, including emotional numbing, depersonalization, and derealization. These alterations may disrupt vestibular multisensory integration between the brainstem (vestibular nuclei) and key vestibular cortical regions (parieto-insular vestibular cortex, prefrontal cortex). Accordingly, this study examined functional connectivity of the vestibular system in PTSD and its dissociative subtype. MethodsUsing resting-state fMRI data in SPM12 and PickAtlas, a seed-based analysis was employed to examine vestibular nuclei functional connectivity differences among PTSD (n = 60), PTSD dissociative subtype (PTSD + DS, n = 41) and healthy controls (n = 40). ResultsIncreased vestibular nuclei functional connectivity with the parieto-insular vestibular cortex and the dorsolateral prefrontal cortex (dlPFC) was observed in PTSD and in controls as compared to PTSD + DS, and greater connectivity with the posterior insula was observed in controls as compared to PTSD. Interestingly, whereas PTSD symptom severity correlated negatively with dlPFC connectivity, clinical measures of depersonalization/derealization correlated negatively with right supramarginal gyrus connectivity. DiscussionTaken together, decreased vestibular nuclei functional connectivity with key cortical vestibular regions in the PTSD + DS as compared to PTSD group, and its negative correlations with PTSD and dissociative symptoms, suggest that dysregulation of vestibular multisensory integration may contribute to the unique symptom profiles of each group. Further research examining disruption of vestibular system neural circuitry in PTSD and its dissociative subtype will be critical in capturing the neurophenomenology of PTSD symptoms and in identifying psychotherapeutic techniques that target dysfunction related to the vestibular system.

Building a Smart City

This article focuses on the need of creating a digital infrastructure to make smart cities and life better. According to a report by Navigant Research, smart cities are a global phenomenon. There are 250 projects underway in 178 cities worldwide, with Europe leading the way because of its aggressive climate change policies. With digital infrastructure evolving so quickly, municipal officials need to update software frequently to improve capabilities. Cities will need new types of professionals to manage and interpret the data. The buildout of a private digital infrastructure points the way toward even greater connectivity, and it is happening rapidly whether cities are leading the way or not. New security standards are emerging to bring better security to every device on the smart network. The recently released ISO/IEC 18598 standard mandates secure but interoperable interfaces for software from different vendors. Experts suggest that cities must learn to master those flows of traffic, energy, and information to create a smarter city that makes life better for those who are connected and those who are not.

Network Structure and Consolidation in the US Airline Industry, 1990-2015

We study the effect of consolidation on airline network connectivity using three measures of centrality from graph theory: Degree, Closeness, and Betweenness. Changes in these measures from 1990 to 2015 imply: i) the average airport services a greater proportion of possible routes, ii) the average origin airport is fewer stops away from any given destination, and iii) the average hub is less often along the shortest route between two other airports. Yet, we find the trend toward greater connectivity in the national network structure is largely unaffected by consolidation, in the form of mergers and codeshare agreements, during this period.

Semanticized autobiographical memory and the default – executive coupling hypothesis of aging

As we age, the architecture of cognition undergoes a fundamental transition. Fluid intellectual abilities decline while crystalized abilities remain stable or increase. This shift has a profound impact across myriad cognitive and functional domains, yet the neural mechanisms remain under-specified. We have proposed that greater connectivity between the default network and executive control regions in lateral prefrontal cortex may underlie this shift, as older adults increasingly rely upon accumulated knowledge to support goal-directed behavior. Here we provide direct evidence for this mechanism within the domain of autobiographical memory. In a large sample of healthy adult participants (n = 103 Young; n = 80 Old) the strength of default – executive coupling reliably predicted more semanticized, or knowledge-based, recollection of autobiographical memories in the older adult cohort. The findings are consistent with the default – executive coupling hypothesis of aging and identify this shift in network dynamics as a candidate neural mechanism associated with crystalized cognition in later life that may signal adaptive capacity in the context of declining fluid cognitive abilities.

Deciding where to attend: Large-scale network mechanisms underlying attention and intention revealed by graph-theoretic analysis

The neural mechanisms by which intentions are transformed into actions remain poorly understood. We investigated the network mechanisms underlying spontaneous voluntary decisions about where to focus visual-spatial attention (willed attention). Graph-theoretic analysis of two independent datasets revealed that regions activated during willed attention form a set of functionally-distinct networks corresponding to the frontoparietal network, the cingulo-opercular network, and the dorsal attention network. Contrasting willed attention with instructed attention (where attention is directed by external cues), we observed that the dorsal anterior cingulate cortex was allied with the dorsal attention network in instructed attention, but shifted connectivity during willed attention to interact with the cingulo-opercular network, which then mediated communications between the frontoparietal network and the dorsal attention network. Behaviorally, greater connectivity in network hubs, including the dorsolateral prefrontal cortex, the dorsal anterior cingulate cortex, and the inferior parietal lobule, was associated with faster reaction times. These results, shown to be consistent across the two independent datasets, uncover the dynamic organization of functionally-distinct networks engaged to support intentional acts.

Sex differences in the influence of body mass index on anatomical architecture of brain networks.

Background/ObjectiveThe brain plays a central role in regulating ingestive behavior in obesity. Analogous to addiction behaviors, an imbalance in the processing of rewarding and salient stimuli results in maladaptive eating behaviors that override homeostatic needs. We performed network analysis based on graph theory to examine the association between body mass index (BMI) and network measures of integrity, information flow, and global communication (centrality) in reward, salience and sensorimotor regions, and to identify sex-related differences in these parameters.Subjects/MethodsStructural and diffusion tensor imaging were obtained in a sample of 124 individuals (61 males and 63 females). Graph theory was applied to calculate anatomical network properties (centrality) for regions of the reward, salience, and sensorimotor networks. General linear models with linear contrasts were performed to test for BMI and sex-related differences in measures of centrality, while controlling for age.ResultsIn both males and females, individuals with high BMI (obese and overweight) had greater anatomical centrality (greater connectivity) of reward (putamen) and salience (anterior insula) network regions. Sex differences were observed both in individuals with normal and elevated BMI. In individuals with high BMI, females compared to males showed greater centrality in reward (amygdala, hippocampus, nucleus accumbens) and salience (anterior mid cingulate cortex) regions, while males compared to females had greater centrality in reward (putamen) and sensorimotor (posterior insula) regions.ConclusionsIn individuals with increased BMI, reward, salience, and sensorimotor network regions are susceptible to topological restructuring in a sex related manner. These findings highlight the influence of these regions on integrative processing of food-related stimuli and increased ingestive behavior in obesity, or in the influence of hedonic ingestion on brain topological restructuring. The observed sex differences emphasize the importance of considering sex differences in obesity pathophysiology.

RNA Seq analysis for transcriptome profiling in response to classical swine fever vaccination in indigenous and crossbred pigs

In present investigation, differential expression of transcriptome after classical swine fever (CSF) vaccination has been explored at the cellular level in crossbred and indigenous (desi) piglets. RNA Sequencing by Expectation-Maximization (RSEM) package was used to quantify gene expression from RNA Sequencing data, and differentially expressed genes (DEGs) were identified using EBSeq, DESeq2, and edgeR softwares. After analysis, 5222, 6037, and 6210 common DEGs were identified in indigenous post-vaccinated verses pre-vaccinated, crossbred post-vaccinated verses pre-vaccinated, and post-vaccinated crossbred verses indigenous pigs, respectively. Functional annotation of these DEGs showed enrichment of antigen processing-cross presentation, B cell receptor signaling, T cell receptor signaling, NF-κB signaling, and TNF signaling pathways. The interaction network among the immune genes included more number of genes with greater connectivity in vaccinated crossbred than the indigenous piglets. Higher expression of IRF3, IL1β, TAP1, CSK, SLA2, SLADM, and NF-kB in crossbred piglets in comparison to indigenous explains the better humoral response observed in crossbred piglets. Here, we predicted that the processed CSFV antigen through the T cell receptor signaling cascade triggers the B cell receptor-signaling pathway to finally activate MAPK kinase and NF-κB signaling pathways in B cell. This activation results in expression of genes/transcription factors that lead to B cell ontogeny, auto immunity and immune response through antibody production. Further, immunologically important genes were validated by qRT-PCR.

77. Thalamic Dysconnectivity in Individuals at Clinically High Risk for Schizophrenia and During Early Illness

Abstract Background: Schizophrenia has been associated with thalamic hyperconnectivity with sensory regions, including the middle and superior temporal gyrus, and hypoconnectivity with cerebellar and prefrontal regions. While thalamic dysconnectivity has been consistently replicated in chronic schizophrenia samples, less is known about when these abnormalities emerge in the illness course and if they are present prior to illness onset. Methods: Resting-state fMRI data were collected from clinical high-risk youth (n = 45; CHR), early illness schizophrenia (n = 74; ESZ) patients, and healthy controls (n = 85; HC). Age-adjusted whole-brain functional connectivity, seeded from the thalamus, was compared among the three groups. Main effects of group (FDR-corrected, p = .01) were followed up with Tukey-corrected pairwise comparisons. Results: Significant main effects of group were observed in 8 regions: 2 left middle temporal regions, 2 right middle temporal regions, a left superior temporal region, a right superior temporal region, a left cerebellar region, and a bilateral thalamic region. Pairwise follow-up tests (P < .05) conducted on extracted mean connectivity values revealed that, consistent with data comparing chronic schizophrenia patients to HCs, ESZ patients demonstrated greater thalamic connectivity with all middle and superior temporal regions, and reduced connectivity with cerebellar and thalamic regions. Compared to HCs, CHR youth demonstrated greater thalamic connectivity with 1 left and 1 right middle temporal region, and displayed reduced connectivity with cerebellar and thalamic regions. Compared to CHR participants, ESZ participants displayed significantly greater connectivity in all but one middle and superior temporal region, but did not differ from CHR participants in connectivity with cerebellar and thalamic regions. Conclusion: In conclusion, like chronic samples, individuals in the early stages of schizophrenia demonstrate hyperconnectivity between the thalamus and sensory regions, and hypoconnectivity with the cerebellum. Further, individuals at elevated risk for schizophrenia appear to demonstrate an intermediate level of dysconnectivity, with mean values falling between those of the early illness schizophrenia group and the healthy control group. These findings suggest that thalamic dysconnectivity occurs prior to illness onset, but is more pronounced in the early stages of schizophrenia.

Cortical plasticity after brachial plexus injury and repair: a resting-state functional MRI study.

OBJECTIVE The authors aimed to understand the alterations of brain resting-state networks (RSNs) in patients with pan-brachial plexus injury (BPI) before and after surgery, which might provide insight into cortical plasticity after peripheral nerve injury and regeneration. METHODS Thirty-five patients with left pan-BPI before surgery, 30 patients after surgery, and 25 healthy controls underwent resting-state functional MRI (rs-fMRI). The 30 postoperative patients were subdivided into 2 groups: 14 patients with improvement in muscle power and 16 patients with no improvement in muscle power after surgery. RSNs were extracted using independent component analysis to evaluate connectivity at a significance level of p < 0.05 (familywise error corrected). RESULTS The patients with BPI had lower connectivity in their sensorimotor network (SMN) and salience network (SN) and greater connectivity in their default mode network (DMN) before surgery than the controls. Connectivity of the left supplementary motor cortex in the SMN and medial frontal gyrus and in the anterior cingulate cortex in the SN increased in patients whose muscle power had improved after surgery, whereas no significant changes were noted in the unimproved patients. There was a trend toward reduction in DMN connectivity in all the patients after surgery compared with that in the preoperative patients; however, this result was not statistically significant. CONCLUSIONS The results of this study highlight the fact that peripheral nerve injury, its management, and successful treatment cause dynamic changes within the brain's RSNs, which includes not only the obvious SMN but also the higher cognitive networks such as the SN and DMN, which indicates brain plasticity and compensatory mechanisms at work.

SA85. White Matter Connectivity as a Predictor of Response to Antipsychotic Treatment: A Diffusion Connectometry Study in Unmedicated Patients With Schizophrenia

Abstract A number of studies have reported decreased white matter integrity in patients with schizophrenia, but little is known the relationship between white matter alterations and response to antipsychotic treatment. We enrolled 30 unmedicated patients with schizophrenia in a 6-week longitudinal trial with risperidone, a commonly used antipsychotic medication. Symptom severity was assessed with the Brief Psychiatric Rating Scale (BPRS). We obtained diffusion-weighted images before treatment was started. Thirty diffusion sampling directions spanning the whole sphere were acquired twice and concatenated (in plane resolution 2.2 mm, slice thickness 2.2 mm, b-value 1000 s/mm, 5 b0 images). Motion and eddy current correction were performed with the FSL EDDY tool. Diffusion data were then reconstructed in MNI space using q-space diffeomorphic reconstruction to obtain the spin distribution function, with a sampling length ratio of 1.25. Group diffusion connectometry was performed to examine the relationship between connectivity and clinical response after 6 weeks of treatment (defined as [BPRS total baseline − BPRS total week 6]/ BPRS total at baseline × −100) with multiple regression analyses using age and sex as covariates. Local connectomes were tracked using a deterministic fiber-tracking algorithm, with seeding density of 100 seeds/ mm, t-threshold of 2.3, and length threshold of 50 mm; all tracks from bootstrap resampling were included. Track trimming was conducted with 5 iterations. A total of 2000 randomized permutations were applied to obtain the null distribution of the track length. Connectometry analysis indicated that greater connectivity in the corpus callosum, external capsule, and cerebellar peduncle at baseline is related to better treatment response after 6 weeks of treatment; no tracks with lower connectivity related to treatment response were found. Our results suggest a relationship between white matter integrity and response to antipsychotic medications. Future studies investigating the pathophysiological mechanisms underlying white matter alterations will be important for targeted drug development and ultimately improvement of outcomes in patients with poor response to conventional antipsychotic medications.

Feel the beat: Music exploits our brain's ability to predict and the dopamine-reward system to instill pleasure.

Music is universally cherished across humanity. Every culture has its songs and dances, everywhere in the world people listen to music; even small children clap their hands and move to the rhythm of the beat. Music moves us in every sense of the word. We just do not know why. The musical abilities of humankind have puzzled scientists for centuries, and Charles Darwin ranked them as “one of the most mysterious with which he is endowed”. Why do we make music, why do we like it, and how do we even perceive it? > The musical abilities of humankind have puzzled scientists for centuries, and Charles Darwin ranked them as “one of the most mysterious with which he is endowed”. “Music is art in time”, said Peter Vuust, a neuroscientist and music theoretician at Aarhus University in Denmark. Perceiving music has much to do with our sense of time and anticipation. Music is never perceived instantly: We need a few notes or beats before we detect a rhythm, and with the last few notes in mind, we anticipate what will happen next. Mostly, these anticipations will be met, but sometimes not. “Music plays with predictions, and this is what makes it so interesting to science”, explained Vuust, because it helps to investigate the brain's predictive timing mechanisms. “Predictive coding” is a conceptual framework of how the brain makes forecasts. It predicts incoming sensory information based on experience and context. This prediction is tightly coupled to the release of dopamine, the neurotransmitter of reward. In addition to predicting what will happen next, it is just as important to know exactly when it will happen, and an analogous system of “predictive timing” takes on this task. A school of fish or a flock of birds all turning at the same time, a dog …

Resting state functional connectivity measures correlate with the response to anodal transcranial direct current stimulation.

Responses to non-invasive brain stimulation are highly variable between subjects. Resting state functional connectivity was investigated as a marker of plasticity induced by anodal transcranial direct current stimulation (tDCS). Twenty-six healthy adults (15 male, 26.4±6.5years) were tested. Experiment 1 investigated whether functional connectivity could predict modulation of corticospinal excitability following anodal tDCS. Experiment 2 determined test-retest reliability of connectivity measures. Three minutes of electroencephalography was recorded and connectivity was quantified with the debiased weighted phase lag index. Anodal (1mA, 20min) or sham tDCS was applied to the left primary motor cortex (M1), with a change in motor evoked potential amplitude recorded from the right first dorsal interosseous used as a marker of tDCS response. Connectivity in the high beta frequency (20-30Hz) between an electrode approximating the left M1 (C3) and electrodes overlying the left parietal cortex was a strong predictor of tDCS response (cross-validated R2 =0.69). Similar relationships were observed for alpha (8-13Hz; R2 =0.64), theta (4-7Hz; R2 =0.53), and low beta (14-19Hz; R2 =0.58) frequencies, however, test-retest reliability of connectivity measures was strongest for the high beta frequency model (ICC=0.65; good reliability). Further investigation of the high beta model found that greater connectivity between C3 and a cluster of electrodes approximately overlying the left parietal cortex was associated with stronger responses to anodal (rho=0.61, P=0.03), but not sham tDCS (rho=0.43, P=0.14). Functional connectivity is a strong predictor of the neuroplastic response to tDCS and may be one important characteristic to assist targeted tDCS application.

Mobile moralities: Ethical consumption in the digital realm

Ethical consumption, as a realm of production and exchange, a framework for purchasing decisions and as political activism, is now well established in a range of nations. As a politics, it points to an interconnected but divergent set of concerns centred on issues of environmental sustainability, local and global economic and social justice, and community and individual wellbeing. While the subject of sustained critique, not least because of its apparent privileging of the ‘consumer’ as the locus of change, ethical consumption has garnered increasing attention. This is most recently evident in the development and widening use of ‘ethical consumption apps’ for mobile devices. These apps allow the user to both access ethical information on products and, potentially, to connect with a broader politics of consumption. However, in entering the digital realm, ethical consumption also becomes embroiled in the complexities of digital technocultures and their ability to allow users of apps to be connected to each other, potentially building communities of interest and/or activism. This article explores this emerging intersection of the ethical and the digital. It examines whether such digital affordances affect the way ethical consumption itself may be conceived and pursued. Does the ethical consumption app work to collectivise or individualise, help to focus or fragment, speak of timidity, or potential in relation to an oppositional politics of consumption? In confronting these issues, this article suggests that contemporary ethical consumption apps – while full of political potential – remain problematic in that the turn to the digital has tended, so far, to accentuate the already individualising tendencies within a politics of ethical consumption. This speaks also, however, to a similar problematic in the politics of digital technocultures; the use of the digital does not automatically enable – merely through greater connectivity and information availability – forms of radical politics.

Increase of posterior connectivity in aging within the Ventral Attention Network: A functional connectivity analysis using independent component analysis

Multiple studies have found neurofunctional changes in normal aging in a context of selective attention. Furthermore, many articles report intrahemispheric alteration in functional networks. However, little is known about age-related changes within the Ventral Attention Network (VAN), which underlies selective attention. The aim of this study is to examine age-related changes within the VAN, focusing on connectivity between its regions. Here we report our findings on the analysis of 27 participants’ (13 younger and 14 older healthy adults) BOLD signals as well as their performance on a letter-matching task. We identified the VAN independently for both groups using spatial independent component analysis. Three main findings emerged: First, younger adults were faster and more accurate on the task. Second, older adults had greater connectivity among posterior regions (right temporoparietal junction, right superior parietal lobule, right middle temporal gyrus and left cerebellum crus I) than younger adults but lower connectivity among anterior regions (right anterior insula, right medial superior frontal gyrus and right middle frontal gyrus). Older adults also had more connectivity between anterior and posterior regions than younger adults. Finally, correlations between connectivity and response time on the task showed a trend toward connectivity in posterior regions for the older group and in anterior regions for the younger group. Thus, this study shows that intrahemispheric neurofunctional changes in aging also affect the VAN. The results suggest that, in contexts of selective attention, posterior regions increased in importance for older adults, while anterior regions had reduced centrality.

Anything goes? Regulation of the neural processes underlying response inhibition in TBI patients

Despite evidence for beneficial use of methylphenidate in response inhibition, no studies so far have investigated the effects of this drug in the neurobiology of inhibitory control in traumatic brain injury (TBI), even though impulsive behaviours are frequently reported in this patient group. We investigated the neural basis of response inhibition in a group of TBI patients using functional magnetic resonance imaging and a stop-signal paradigm. In a randomised double-blinded crossover study, the patients received either a single 30mg dose of methylphenidate or placebo and performed the stop-signal task. Activation in the right inferior frontal gyrus (RIFG), an area associated with response inhibition, was significantly lower in patients compared to healthy controls. Poor response inhibition in this group was associated with greater connectivity between the RIFG and a set of regions considered to be part of the default mode network (DMN), a finding that suggests the interplay between DMN and frontal executive networks maybe compromised. A single dose of methylphenidate rendered activity and connectivity profiles of the patients RIFG near normal. The results of this study indicate that the neural circuitry involved in response inhibition in TBI patients may be partially restored with methylphenidate. Given the known mechanisms of action of methylphenidate, the effect we observed may be due to increased dopamine and noradrenaline levels.

Cingulate cortex functional connectivity predicts future relapse in alcohol dependent individuals.

Alcohol dependence is a chronic relapsing illness. Alcohol and stress cues have consistently been shown to increase craving and relapse risk in recovering alcohol dependent (AUD) patients. However, differences in functional connectivity in response to these cues have not been studied using data-driven approaches. Here, voxel-wise connectivity is used in a whole-brain investigation of functional connectivity differences associated with alcohol and stress cues and to examine whether these differences are related to subsequent relapse. In Study 1, 45, 4- to 8-week abstinent, recovering AUD patients underwent functional magnetic resonance imaging during individualized imagery of alcohol, stress, and neutral cues. Relapse measures were collected prospectively for 90 days post-discharge from inpatient treatment. AUD patients showed blunted anterior (ACC), mid (MCC) and posterior cingulate cortex (PCC), voxel-wise connectivity responses to stress compared to neutral cues and blunted PCC response to alcohol compared to neutral cues. Using Cox proportional hazard regression, weaker connectivity in ACC and MCC during neutral exposure was associated with longer time to relapse (better recovery outcome). Similarly, greater connectivity in PCC during alcohol-cue compared to stress cue was associated with longer time to relapse. In Study 2, a sub-group of 30 AUD patients were demographically-matched to 30 healthy control (HC) participants for group comparisons. AUD compared to HC participants showed reduced cingulate connectivity during alcohol and stress cues. Using novel data-driven approaches, the cingulate cortex emerged as a key region in the disruption of functional connectivity during alcohol and stress-cue processing in AUD patients and as a marker of subsequent alcohol relapse.

Formation of raiding parties for intergroup violence is mediated by social network structure

Intergroup violence is common among humans worldwide. To assess how within-group social dynamics contribute to risky, between-group conflict, we conducted a 3-y longitudinal study of the formation of raiding parties among the Nyangatom, a group of East African nomadic pastoralists currently engaged in small-scale warfare. We also mapped the social network structure of potential male raiders. Here, we show that the initiation of raids depends on the presence of specific leaders who tend to participate in many raids, to have more friends, and to occupy more central positions in the network. However, despite the different structural position of raid leaders, raid participants are recruited from the whole population, not just from the direct friends of leaders. An individual's decision to participate in a raid is strongly associated with the individual's social network position in relation to other participants. Moreover, nonleaders have a larger total impact on raid participation than leaders, despite leaders' greater connectivity. Thus, we find that leaders matter more for raid initiation than participant mobilization. Social networks may play a role in supporting risky collective action, amplify the emergence of raiding parties, and hence facilitate intergroup violence in small-scale societies.

Magnetoencephalographic and functional MRI connectomics in schizophrenia via intra- and inter-network connectivity

Examination of intrinsic functional connectivity using functional MRI (fMRI) has provided important findings regarding dysconnectivity in schizophrenia. Extending these results using a complementary neuroimaging modality, magnetoencephalography (MEG), we present the first direct comparison of functional connectivity between schizophrenia patients and controls, using these two modalities combined. We developed a novel MEG approach for estimation of networks using MEG that incorporates spatial independent component analysis (ICA) and pairwise correlations between independent component timecourses, to estimate intra- and intern-network connectivity. This analysis enables group-level inference and testing of between-group differences. Resting state MEG and fMRI data were acquired from a large sample of healthy controls (n=45) and schizophrenia patients (n=46). Group spatial ICA was performed on fMRI and MEG data to extract intrinsic fMRI and MEG networks and to compensate for signal leakage in MEG. Similar, but not identical spatial independent components were detected for MEG and fMRI. Analysis of functional network connectivity (FNC; i.e., pairwise correlations in network (ICA component) timecourses) revealed a differential between-modalities pattern, with greater connectivity among occipital networks in fMRI and among frontal networks in MEG. Most importantly, significant differences between controls and patients were observed in both modalities. MEG FNC results in particular indicated dysfunctional hyperconnectivity within frontal and temporal networks in patients, while in fMRI FNC was always greater for controls than for patients. This is the first study to apply group spatial ICA as an approach to leakage correction, and as such our results may be biased by spatial leakage effects. Results suggest that combining these two neuroimaging modalities reveals additional disease-relevant patterns of connectivity that were not detectable with fMRI or MEG alone.

Brain activity and connectivity in response to negative affective stimuli: Impact of dysphoric mood and sex across diagnoses

Negative affective stimuli elicit behavioral and neural responses which vary on a continuum from adaptive to maladaptive, yet are typically investigated in a dichotomous manner (healthy controls vs. psychiatric diagnoses). This practice may limit our ability to fully capture variance from acute responses to negative affective stimuli to psychopathology at the extreme end. To address this, we conducted a functional magnetic resonance imaging study to examine the neural responses to negative valence/high arousal and neutral valence/low arousal images as a function of dysphoric mood and sex across individuals (n = 99) who represented traditional categories of healthy controls, major depressive disorder, bipolar psychosis, and schizophrenia. Observation of negative (vs. neutral) stimuli elicited blood oxygen-level dependent responses in the following circuitry: periaqueductal gray, hypothalamus (HYPO), amygdala (AMYG), hippocampus (HIPP), orbitofrontal cortex (OFC), medial prefrontal cortex (mPFC), and greater connectivity between AMYG and mPFC. Across all subjects, severity of dysphoric mood was associated with hyperactivity of HYPO, and, among females, right (R) AMYG. Females also demonstrated inverse relationships between severity of dysphoric mood and connectivity between HYPO - R OFC, R AMYG - R OFC, and R AMYG - R HIPP. Overall, our findings demonstrated sex-dependent deficits in response to negative affective stimuli increasing as a function of dysphoric mood state. Females demonstrated greater inability to regulate arousal as mood became more dysphoric. These findings contribute to elucidating biosignatures associated with response to negative stimuli across disorders and suggest the importance of a sex-dependent lens in determining these biosignatures. Hum Brain Mapp 37:3733-3744, 2016. © 2016 Wiley Periodicals, Inc.