Resting cerebral blood flow alteration in severe obstructive sleep apnoea: an arterial spin labelling perfusion fMRI study.
Sleep Breath. 2017 Feb 16;:
Authors: Nie S, Peng DC, Gong HH, Li HJ, Chen LT, Ye CL
STUDY OBJECTIVES: The aim of this study is to investigate changes in regional cerebral blood flow (rCBF) in awake people with untreated severe obstructive sleep apnoea (OSAs) compared with good sleepers (GSs).
DESIGN: Arterial spin labelling perfusion imaging was used to quantify cerebral perfusion based on resting-state functional magnetic resonance imaging (MRI).
SETTING: Lying supine in a 3.0-T magnetic resonance imaging scanner in the night was done.
PARTICIPANTS: Included in this study were 30 subjects with OSA (males; mean age 38.4 years, range 25-55) and 30 controls (males; mean age: 38.3 years, range 26-52) matched for age and years of education.
RESULTS: Compared with GSs, participants with severe OSA had reduced rCBF in the left cerebellum posterior lobe, left temporal lobe, right medial frontal gyrus, and bilateral parahippocampal gyrus and increased rCBF in the bilateral superior frontal gyrus. The lower mean CBF in the right parahippocampal gyrus exhibited a significant positive correlation with arousal index (r = 0.365, P = 0.047). The increased mean CBF in the left superior frontal gyrus exhibited a significant positive correlation with the longest apnoea time (r = 0.422, P = 0.020), and the increased mean CBF in the right superior frontal gyrus exhibited a significant positive correlation with the longest apnoea time (r = 0.447, P = 0.013).
CONCLUSIONS: Our results show that the altered rCBF pattern in the left cerebellum posterior lobe, left temporal lobe, left medial frontal gyrus, bilateral parahippocampal gyrus and superior frontal gyrus in patients have with severe OSA. The arterial spin labelling perfusion imaging method is a useful non-invasive imaging tool for detection of early changes in the regional cerebral blood flow in patients with OSA.
PMID: 28210922 [PubMed - as supplied by publisher]
Association of medial prefrontal resting state functional connectivity and metacognitive capacity in early phase psychosis.
Psychiatry Res. 2017 Feb 08;262:8-14
Authors: Francis MM, Hummer TA, Leonhardt BL, Vohs JL, Yung MG, Mehdiyoun NF, Lysaker PH, Breier A
Metacognition refers to a range of cognitive processes that allow one to form complex ideas of self and others and to use this information to navigate psychosocial challenges. Several studies in both early-phase and prolonged schizophrenia have demonstrated not only that significant deficits in metacognitive ability are present, but importantly that they are associated with significant functional impairment and decreased quality of life. In spite of the importance of metacognitive impairment in schizophrenia, relatively little is known about the biological substrates that may contribute to this dysfunction. In this study, we examined the relationship between resting state functional connectivity of the medial prefrontal cortex (mPFC), a structure shown in prior voxel-based morphometry studies to be associated with metacognition, with metacognitive function in an early-phase psychosis cohort (n=18). Analyses revealed a positive association of resting state functional connectivity between the mPFC and precuneus and posterior cingulate structures and metacognitive ability. These results provide evidence of disrupted resting state connectivity in structures relevant to metacognitive dysfunction in early-phase psychosis, which may have implications for pathophysiological models of complex cognitive deficits in this illness.
PMID: 28208070 [PubMed - as supplied by publisher]
Functional connectivity in resting state as a phonemic fluency ability measure.
Neuropsychologia. 2017 Feb 12;:
Authors: Miró-Padilla A, Bueichekú E, Ventura-Campos N, Palomar-García MÁ, Ávila C
There is some evidence that functional connectivity (FC) measures obtained at rest may reflect individual differences in cognitive capabilities. We tested this possibility by using the FAS test as a measure of phonemic fluency. Seed regions of the main brain areas involved in this task were extracted from meta-analysis results (Wagner et al., 2014) and used for pairwise resting-state FC analysis. Ninety-three undergraduates completed the FAS test outside the scanner. A correlation analysis was conducted between the F-A-S scores (behavioral testing) and the pairwise FC pattern of verbal fluency regions of interest. Results showed that the higher FC between the thalamus and the cerebellum, and the lower FCs between the left inferior frontal gyrus and the right insula and between the supplementary motor area and the right insula were associated with better performance on the FAS test. Regression analyses revealed that the first two FCs contributed independently to this better phonemic fluency, reflecting a more general attentional factor (FC between thalamus and cerebellum) and a more specific fluency factor (FC between the left inferior frontal gyrus and the right insula). The results support the Spontaneous Trait Reactivation hypothesis, which explains how resting-state derived measures may reflect individual differences in cognitive abilities.
PMID: 28202336 [PubMed - as supplied by publisher]
The value of resting-state functional magnetic resonance imaging for detecting epileptogenic zones in patients with focal epilepsy.
PLoS One. 2017;12(2):e0172094
Authors: Chen Z, An Y, Zhao B, Yang W, Yu Q, Cai L, Ni H, Yin J
OBJECTIVE: To determine the value of resting-state functional magnetic resonance imaging (RS-fMRI) based on the local analysis methods regional homogeneity (ReHo), amplitude of low-frequency fluctuations (ALFF), and fractional ALFF (fALFF), for detecting epileptogenic zones (EZs).
METHODS: A total of 42 consecutive patients with focal epilepsy were enrolled. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of visually assessed RS-fMRI, MRI, magnetic resonance spectroscopy (MRS), video electroencephalography (VEEG), and positron-emission tomography computed tomography (PET-CT) in EZ localization were evaluated to assess their diagnostic abilities. ReHo, ALFF, and fALFF were also compared for their diagnostic values.
RESULTS: RS-fMRI showed comparable sensitivity to PET (83.3%) and specificity to VEEG (66.7%), respectively, for EZ localization in patients with focal epilepsy. There were no significant differences between RS-fMRI and the other localization techniques in terms of sensitivity, specificity, PPV, and NPV. The sensitivities of ReHo, ALFF, and fALFF were 69.4%, 52.8%, and 38.9%, respectively, and for specificities of 66.7%, 83.3%, and 66.7%, respectively. There were no significant differences among ReHo, ALFF, and fALFF, except that ReHo was more sensitive than fALFF.
CONCLUSIONS: RS-fMRI may be an efficient tool for detecting EZs in focal epilepsy patients.
PMID: 28199371 [PubMed - in process]
Local resting state functional connectivity in autism: site and cohort variability and the effect of eye status.
Brain Imaging Behav. 2017 Feb 14;:
Authors: Nair S, Jao Keehn RJ, Berkebile MM, Maximo JO, Witkowska N, Müller RA
Autism spectrum disorder (ASD) is a neurodevelopmental disorder with prominent impairments in sociocommunicative abilities, which have been linked to anomalous brain network organization. Despite ample evidence of atypical long-distance connectivity, the literature on local connectivity remains small and divergent. We used resting-state functional MRI regional homogeneity (ReHo) as a local connectivity measure in comparative analyses across several well-matched low-motion subsamples from the Autism Brain Imaging Data Exchange and in-house data, with a grand total of 147 ASD and 184 typically developing (TD) participants, ages 7-18 years. We tested for group differences in each subsample, with additional focus on the difference between eyes-open and eyes-closed resting states. Despite selection of highest quality data and tight demographic and motion matching between groups and across samples, few effects in exactly identical loci (voxels) were found across samples. However, there was gross consistency across all eyes-open samples of local overconnectivity (ASD > TD) in posterior, visual regions. There was also gross consistency of local underconnectivity (ASD < TD) in cingulate gyrus, although exact loci varied between mid/posterior and anterior sections. While all eyes-open datasets showed the described gross similarities, the pattern of group differences for participants scanned with eyes closed was different, with local overconnectivity in ASD in posterior cingulate gyrus, but underconnectivity in some visual regions. Our findings suggest that fMRI local connectivity measures may be relatively susceptible to site and cohort variability and that some previous inconsistencies in the ASD ReHo literature may be reconciled by more careful consideration of eye status.
PMID: 28197860 [PubMed - as supplied by publisher]
Imaging the up's and down's of emotion regulation in lifetime depression.
Brain Imaging Behav. 2017 Feb 14;:
Authors: Radke S, Hoffstaedter F, Löffler L, Kogler L, Schneider F, Blechert J, Derntl B
Reappraisal is a particularly effective strategy for influencing emotional experiences, specifically for reducing the impact of negative stimuli. Although depression has repeatedly been linked to dysfunctional behavioral and neural emotion regulation, prefrontal and amygdala engagement seems to vary with clinical characteristics and the specific regulation strategy used. Whereas previous neuroimaging research has focused on down-regulating reactions to emotionally evocative scenes, the current study compared up- and down-regulation in response to angry facial expressions in patients with depression and healthy individuals. During the initial viewing of faces, patients with depression showed hypoactivation particularly in areas implicated in emotion generation, i.e., amygdala, insula and putamen. In contrast, up-regulating negative emotions yielded stronger recruitment of core face processing areas and posterior medial frontal cortex in patients than in controls. However, group differences did not extend to resting-state functional connectivity. Recurrent depression was inversely associated with amygdala activation specifically during down-regulation, but differences in medication status may limit the current findings. Despite a pattern of reduced neural emotional reactivity in mainly medicated patients, their 'successful' recruitment of the regulation network for up-regulation might point toward an effective use of reappraisal when increasing negative emotions. Future studies need to address how patients might benefit from transferring this ability to adaptive goals, such as improving interpersonal emotion regulation.
PMID: 28197859 [PubMed - as supplied by publisher]
Investigating the Role of Glutamate and GABA in the Modulation of Transthalamic Activity: A Combined fMRI-fMRS Study.
Front Physiol. 2017;8:30
Authors: Just N, Sonnay S
The Excitatory-Inhibitory balance (EIB) between glutamatergic and GABAergic neurons is known to regulate the function of thalamocortical neurocircuits. The thalamus is known as an important relay for glutamatergic and GABAergic signals ascending/descending to/from the somatosensory cortex in rodents. However, new investigations attribute a larger role to thalamic nuclei as modulators of information processing within the cortex. In this study, functional Magnetic Resonance Spectroscopy (fMRS) was used to measure glutamate (Glu) and GABA associations with BOLD responses during activation of the thalamus to barrel cortex (S1BF) pathway at 9.4T. In line with previous studies in humans, resting GABA and Glu correlated negatively and positively respectively with BOLD responses in S1BF. Moreover, a significant negative correlation (R = -0.68, p = 0.0024) between BOLD responses in the thalamus and the barrel cortex was found. Rats with low Glu levels and high resting GABA levels in S1BF demonstrated lower BOLD responses in S1BF and high amplitude BOLD responses in the thalamus themselves linked to the release of high GABA levels during stimulation. In addition, early analysis of resting state functional connectivity suggested EIB controlled thalamocortical neuronal synchrony. We propose that the presented approach may be useful for further characterization of diseases affecting thalamocortical neurotransmission.
PMID: 28197105 [PubMed - in process]
Resting-State Brain Anomalies in Type 2 Diabetes: A Meta-Analysis.
Front Aging Neurosci. 2017;9:14
Authors: Xia W, Chen YC, Ma J
Resting-state functional magnetic resonance imaging (fMRI) studies have revealed abnormal neural activity in patients with type 2 diabetes mellitus (T2DM). Nonetheless, these findings are heterogeneous and have not been quantitatively reviewed. Thus, we aimed to conduct a meta-analysis that identified consistent results of existing resting-state fMRI studies to determine concordant resting-state neural brain activity alterations in T2DM patients. A systematic search was conducted for resting-state fMRI studies comparing T2DM patients with healthy controls. Coordinates were extracted from clusters with significant differences. The meta-analysis was performed using the activation likelihood estimation method, and nine studies were included. This meta-analysis identified robustly reduced resting-state brain activity in the whole brain of T2DM patients, including the bilateral lingual gyrus, left postcentral gyrus, right inferior temporal gyrus, right cerebellar culmen, right insula and right posterior cingulate cortex (PCC). The present study demonstrates a characteristic pattern of resting-state brain anomalies that will contribute to the understanding of neuropathophysiological mechanisms underlying T2DM.
PMID: 28197096 [PubMed - in process]
Longitudinal test-retest neuroimaging data from healthy young adults in southwest China.
Sci Data. 2017 Feb 14;4:170017
Authors: Liu W, Wei D, Chen Q, Yang W, Meng J, Wu G, Bi T, Zhang Q, Zuo XN, Qiu J
Multimodal magnetic resonance imaging (mMRI) has been widely used to map the structure and function of the human brain, as well as its behavioral associations. However, to date, a large sample with a long-term longitudinal design and a narrow age-span has been lacking for the assessment of test-retest reliability and reproducibility of brain-behavior correlations, as well as the development of novel causal insights into these correlational findings. Here we describe the SLIM dataset, which includes brain and behavioral data across a long-term retest-duration within three and a half years, mMRI scans provided a set of structural, diffusion and resting-state functional MRI images, along with rich samples of behavioral assessments addressed-demographic, cognitive and emotional information. Together with the Consortium for Reliability and Reproducibility (CoRR), the SLIM is expected to accelerate the reproducible sciences of the human brain by providing an open resource for brain-behavior discovery sciences with big-data approaches.
PMID: 28195583 [PubMed - in process]
Rare damaging variants in DNA repair and cell cycle pathways are associated with hippocampal and cognitive dysfunction: a combined genetic imaging study in first-episode treatment-naive patients with schizophrenia.
Transl Psychiatry. 2017 Feb 14;7(2):e1028
Authors: Yang Z, Li M, Hu X, Xiang B, Deng W, Wang Q, Wang Y, Zhao L, Ma X, Sham PC, Northoff G, Li T
Schizophrenia is a complex neurodevelopmental disorder where changes in both hippocampus and memory-related cognitive functions are central. However, the exact relationship between neurodevelopmental-genetic factors and hippocampal-cognitive dysfunction remains unclear. The general aim of our study is to link the occurrence of rare damaging mutations involved in susceptibility gene pathways to the structure and function of hippocampus in order to define genetically and phenotypically based subgroups in schizophrenia. In the present study, by analyzing the exome sequencing and magnetic resonance imaging data in 94 first-episode treatment-naive schizophrenia patients and 134 normal controls, we identified that a cluster of rare damaging variants (RDVs) enriched in DNA repair and cell cycle pathways was present only in a subgroup including 39 schizophrenic patients. Furthermore, we found that schizophrenic patients with this RDVs show increased resting-state functional connectivity (rsFC) between left hippocampus (especially for left dentate gyrus) and left inferior parietal cortex, as well as decreased rsFC between left hippocampus and cerebellum. Moreover, abnormal rsFC was related to the deficits of spatial working memory (SWM; that is known to recruit the hippocampus) in patients with the RDVs. Taken together, our data demonstrate for the first time, to our knowledge, that damaging rare variants of genes in DNA repair and cell cycle pathways are associated with aberrant hippocampal rsFC, which was further relative to cognitive deficits in first-episode treatment-naive schizophrenia. Therefore, our data provide some evidence for the occurrence of phenotypic alterations in hippocampal and SWM function in a genetically defined subgroup of schizophrenia.
PMID: 28195569 [PubMed - in process]
Source Localization of Brain States Associated with Canonical Neuroimaging Postures.
J Cogn Neurosci. 2017 Feb 14;:1-10
Authors: Lifshitz M, Thibault RT, Roth RR, Raz A
Cognitive neuroscientists rarely consider the influence that body position exerts on brain activity; yet, postural variation holds important implications for the acquisition and interpretation of neuroimaging data. Whereas participants in most behavioral and EEG experiments sit upright, many prominent brain imaging techniques (e.g., fMRI) require participants to lie supine. Here we demonstrate that physical comportment profoundly alters baseline brain activity as measured by magnetoencephalography (MEG)-an imaging modality that permits multipostural acquisition. We collected resting-state MEG data from 12 healthy participants in three postures (lying supine, reclining at 45°, and sitting upright). Source-modeling analysis revealed a broadly distributed influence of posture on resting brain function. Sitting upright versus lying supine was associated with greater high-frequency (i.e., beta and gamma) activity in widespread parieto-occipital cortex. Moreover, sitting upright and reclined postures correlated with dampened activity in prefrontal regions across a range of bandwidths (i.e., from alpha to low gamma). The observed effects were large, with a mean Cohen's d of 0.95 (SD = 0.23). In addition to neural activity, physiological parameters such as muscle tension and eye blinks may have contributed to these posture-dependent changes in brain signal. Regardless of the underlying mechanisms, however, the present results have important implications for the acquisition and interpretation of multimodal imaging data (e.g., studies combining fMRI or PET with EEG or MEG). More broadly, our findings indicate that generalizing results-from supine neuroimaging measurements to erect positions typical of ecological human behavior-would call for considering the influence that posture wields on brain dynamics.
PMID: 28195522 [PubMed - as supplied by publisher]
From "rest" to language task: Task activation selects and prunes from broader resting-state network.
Hum Brain Mapp. 2017 Feb 14;:
Authors: Doucet GE, He X, Sperling MR, Sharan A, Tracy JI
Resting-state networks (RSNs) show spatial patterns generally consistent with networks revealed during cognitive tasks. However, the exact degree of overlap between these networks has not been clearly quantified. Such an investigation shows promise for decoding altered functional connectivity (FC) related to abnormal language functioning in clinical populations such as temporal lobe epilepsy (TLE). In this context, we investigated the network configurations during a language task and during resting state using FC. Twenty-four healthy controls, 24 right and 24 left TLE patients completed a verb generation (VG) task and a resting-state fMRI scan. We compared the language network revealed by the VG task with three FC-based networks (seeding the left inferior frontal cortex (IFC)/Broca): two from the task (ON, OFF blocks) and one from the resting state. We found that, for both left TLE patients and controls, the RSN recruited regions bilaterally, whereas both VG-on and VG-off conditions produced more left-lateralized FC networks, matching more closely with the activated language network. TLE brings with it variability in both task-dependent and task-independent networks, reflective of atypical language organization. Overall, our findings suggest that our RSN captured bilateral activity, reflecting a set of prepotent language regions. We propose that this relationship can be best understood by the notion of pruning or winnowing down of the larger language-ready RSN to carry out specific task demands. Our data suggest that multiple types of network analyses may be needed to decode the association between language deficits and the underlying functional mechanisms altered by disease. Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc.
PMID: 28195438 [PubMed - as supplied by publisher]
Altered Insula Connectivity Under MDMA.
Neuropsychopharmacology. 2017 Feb 14;:
Authors: Walpola IC, Nest T, Roseman L, Erritzoe D, Feilding A, Nutt DJ, Carhart-Harris RL
Recent work with noninvasive human brain imaging has started to investigate the effects of 3, 4-methylenedioxymethamphetamine (MDMA) on large-scale patterns of brain activity. MDMA, a potent monoamine-releaser with particularly pronounced serotonin- releasing properties, has unique subjective effects that include: marked positive mood, pleasant/unusual bodily sensations and pro-social, empathic feelings. However, the neurobiological basis for these effects is not properly understood, and the present analysis sought to address this knowledge gap. To do this, we administered MDMA-HCl (100 mg p.o.) and, separately, placebo (ascorbic acid) in a randomized, double-blind, repeated-measures design with twenty-five healthy volunteers undergoing fMRI scanning. We then employed a measure of global resting-state functional brain connectivity and follow-up seed-to-voxel analysis to the fMRI data we acquired. Results revealed decreased right insula/salience network functional connectivity under MDMA. Furthermore, these decreases in right insula/salience network connectivity correlated with baseline trait anxiety and acute experiences of altered bodily sensations under MDMA. The present findings highlight insular disintegration (ie, compromised salience network membership) as a neurobiological signature of the MDMA experience, and relate this brain effect to trait anxiety and acutely altered bodily sensations-both of which are known to be associated with insular functioning.Neuropsychopharmacology accepted article preview online, 14 February 2017. doi:10.1038/npp.2017.35.
PMID: 28195139 [PubMed - as supplied by publisher]
Simultaneous Intracranial EEG-fMRI Shows Inter-Modality Correlation in Time-Resolved Connectivity Within Normal Areas but Not Within Epileptic Regions.
Brain Topogr. 2017 Feb 13;:
Authors: Ridley B, Wirsich J, Bettus G, Rodionov R, Murta T, Chaudhary U, Carmichael D, Thornton R, Vulliemoz S, McEvoy A, Wendling F, Bartolomei F, Ranjeva JP, Lemieux L, Guye M
For the first time in research in humans, we used simultaneous icEEG-fMRI to examine the link between connectivity in haemodynamic signals during the resting-state (rs) and connectivity derived from electrophysiological activity in terms of the inter-modal connectivity correlation (IMCC). We quantified IMCC in nine patients with drug-resistant epilepsy (i) within brain networks in 'healthy' non-involved cortical zones (NIZ) and (ii) within brain networks involved in generating seizures and interictal spikes (IZ1) or solely spikes (IZ2). Functional connectivity (h (2) ) estimates for 10 min of resting-state data were obtained between each pair of electrodes within each clinical zone for both icEEG and fMRI. A sliding window approach allowed us to quantify the variability over time of h (2) (vh (2)) as an indicator of connectivity dynamics. We observe significant positive IMCC for h (2) and vh (2), for multiple bands in the NIZ only, with the strongest effect in the lower icEEG frequencies. Similarly, intra-modal h (2) and vh (2) were found to be differently modified as a function of different epileptic processes: compared to NIZ, [Formula: see text] was higher in IZ1, but lower in IZ2, while [Formula: see text] showed the inverse pattern. This corroborates previous observations of inter-modal connectivity discrepancies in pathological cortices, while providing the first direct invasive and simultaneous comparison in humans. We also studied time-resolved FC variability multimodally for the first time, finding that IZ1 shows both elevated internal [Formula: see text] and less rich dynamical variability, suggesting that its chronic role in epileptogenesis may be linked to greater homogeneity in self-sustaining pathological oscillatory states.
PMID: 28194612 [PubMed - as supplied by publisher]
Disrupted Resting-State Default Mode Network in Betel Quid-Dependent Individuals.
Front Psychol. 2017;8:84
Authors: Zhu X, Zhu Q, Jiang C, Shen H, Wang F, Liao W, Yuan F
Recent studies have shown that substance dependence (addiction) is accompanied with altered activity patterns of the default mode network (DMN). However, the neural correlates of the resting-state DMN and betel quid dependence (BQD)-related physiopathological characteristics still remain unclear. Resting-state functional magnetic resonance imaging images were obtained from 26 BQD individuals and 28 matched healthy control subjects. Group independent component analysis was performed to analyze the resting state images into spatially independent components. Gray matter volume was examined as covariate with voxel-based morphometry to rule out its effect on the functional results. The severity of BQD was assessed by the BQD Scale (BQDS). We observed decreased functional connectivity in anterior part of the DMN including ventral medial prefrontal cortex, orbital MPFC (OMPFC)/anterior cingulate cortex (ACC). Furthermore, the functional connectivity within the OMPFC/ACC in BQD individuals was negatively correlated with BQDS (p = 0.01, r = -0.49). We reported decreased functional connectivity within anterior part of the DMN in BQD individuals, which provides new evidence for the role of the DMN in the pathophysiology of BQD.
PMID: 28194128 [PubMed - in process]
Altered Hippocampo-Cerebello-Cortical Circuit in Schizophrenia by a Spatiotemporal Consistency and Causal Connectivity Analysis.
Front Neurosci. 2017;11:25
Authors: Chen X, Jiang Y, Chen L, He H, Dong L, Hou C, Duan M, Yang M, Yao D, Luo C
In the current study, FOur-dimensional Consistency of local neural Activities (FOCA) analysis was used to investigate the local consistency by integrating the temporal and spatial information of the local region. In the current study, resting-state fMRI data of 69 schizophrenia patients and 70 healthy controls were collected. FOCA was utilized to investigate the local consistency. Moreover, Granger causal analysis was used to investigate causal functional connectivity among these areas, which exhibited significantly different local consistency between groups. Compared with the healthy controls, the schizophrenia patients exhibited increased local consistency in hippocampus, basal ganglia and cerebellum regions, and decreased local consistency in sensoriperceptual cortex. In addition, altered causal functional connectivity was observed in hippocampo-cerebello-cortical (occipital) circuit. These findings suggested that this circuit might play a role in the motor dysfunction in schizophrenia, and should be paid more attention in future.
PMID: 28194095 [PubMed - in process]
New developments in brain research of internet and gaming disorder.
Neurosci Biobehav Rev. 2017 Feb 10;:
Authors: Weinstein A, Livny A, Weizman A
There is evidence that the neural mechanisms underlying Internet Gaming Disorder (IGD) resemble those of drug addiction. Functional Magnetic Resonance Imaging (fMRI) studies of the resting state and measures of gray matter volume have shown that Internet game playing was associated with changes to brain regions responsible for attention and control, impulse control, motor function, emotional regulation, sensory-motor coordination. Furthermore, Internet game playing was associated with lower white matter density in brain regions that are involved in decision-making, behavioral inhibition and emotional regulation. Videogame playing involved changes in reward inhibitory mechanisms and loss of control. Structural brain imaging studies showed alterations in the volume of the ventral striatum that is an important part of the brain's reward mechanisms. Finally, videogame playing was associated with dopamine release similar in magnitude to those of drugs of abuse and lower dopamine transporter and dopamine receptor D2 occupancy indicating sub-sensitivity of dopamine reward mechanisms.
PMID: 28193454 [PubMed - as supplied by publisher]
Pons to Posterior Cingulate Functional Projections Predict Affective Processing Changes in the Elderly Following Eight Weeks of Meditation Training.
EBioMedicine. 2016 Aug;10:236-48
Authors: Shao R, Keuper K, Geng X, Lee TM
Evidence indicates meditation facilitates affective regulation and reduces negative affect. It also influences resting-state functional connectivity between affective networks and the posterior cingulate (PCC)/precuneus, regions critically implicated in self-referential processing. However, no longitudinal study employing active control group has examined the effect of meditation training on affective processing, PCC/precuneus connectivity, and their association. Here, we report that eight-week meditation, but not relaxation, training 'neutralized' affective processing of positive and negative stimuli in healthy elderly participants. Additionally, meditation versus relaxation training increased the positive connectivity between the PCC/precuneus and the pons, the direction of which was largely directed from the pons to the PCC/precuneus, as revealed by dynamic causal modeling. Further, changes in connectivity between the PCC/precuneus and pons predicted changes in affective processing after meditation training. These findings indicate meditation promotes self-referential affective regulation based on increased regulatory influence of the pons on PCC/precuneus, which new affective-processing strategy is employed across both resting state and when evaluating affective stimuli. Such insights have clinical implications on interventions on elderly individuals with affective disorders.
PMID: 27349456 [PubMed - indexed for MEDLINE]
Time-varying spectral power of resting-state fMRI networks reveal cross-frequency dependence in dynamic connectivity.
PLoS One. 2017;12(2):e0171647
Authors: Yaesoubi M, Miller RL, Calhoun VD
Brain oscillations and synchronicity among brain regions (brain connectivity) have been studied in resting-state (RS) and task-induced settings. RS-connectivity which captures brain functional integration during an unconstrained state is shown to vary with the frequency of oscillations. Indeed, high temporal resolution modalities have demonstrated both between and cross-frequency connectivity spanning across frequency bands such as theta and gamma. Despite high spatial resolution, functional magnetic resonance imaging (fMRI) suffers from low temporal resolution due to modulation with slow-varying hemodynamic response function (HRF) and also relatively low sampling rate. This limits the range of detectable frequency bands in fMRI and consequently there has been no evidence of cross-frequency dependence in fMRI data. In the present work we uncover recurring patterns of spectral power in network timecourses which provides new insight on the actual nature of frequency variation in fMRI network activations. Moreover, we introduce a new measure of dependence between pairs of rs-fMRI networks which reveals significant cross-frequency dependence between functional brain networks specifically default-mode, cerebellar and visual networks. This is the first strong evidence of cross-frequency dependence between functional networks in fMRI and our subject group analysis based on age and gender supports usefulness of this observation for future clinical applications.
PMID: 28192457 [PubMed - in process]
Adaptive testing for multiple traits in a proportional odds model with applications to detect SNP-brain network associations.
Genet Epidemiol. 2017 Feb 13;:
Authors: Kim J, Pan W, Alzheimer's Disease Neuroimaging Initiative
There has been increasing interest in developing more powerful and flexible statistical tests to detect genetic associations with multiple traits, as arising from neuroimaging genetic studies. Most of existing methods treat a single trait or multiple traits as response while treating an SNP as a predictor coded under an additive inheritance mode. In this paper, we follow an earlier approach in treating an SNP as an ordinal response while treating traits as predictors in a proportional odds model (POM). In this way, it is not only easier to handle mixed types of traits, e.g., some quantitative and some binary, but it is also potentially more robust to the commonly adopted additive inheritance mode. More importantly, we develop an adaptive test in a POM so that it can maintain high power across many possible situations. Compared to the existing methods treating multiple traits as responses, e.g., in a generalized estimating equation (GEE) approach, the proposed method can be applied to a high dimensional setting where the number of phenotypes (p) can be larger than the sample size (n), in addition to a usual small P setting. The promising performance of the proposed method was demonstrated with applications to the Alzheimer's Disease Neuroimaging Initiative (ADNI) data, in which either structural MRI driven phenotypes or resting-state functional MRI (rs-fMRI) derived brain functional connectivity measures were used as phenotypes. The applications led to the identification of several top SNPs of biological interest. Furthermore, simulation studies showed competitive performance of the new method, especially for p>n.
PMID: 28191669 [PubMed - as supplied by publisher]