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Disrupted Neural Activity in Unilateral Vascular Pulsatile Tinnitus Patients in the Early Stage of Disease: Evidence from Resting-state fMRI.

Thu, 02/05/2015 - 16:30

Disrupted Neural Activity in Unilateral Vascular Pulsatile Tinnitus Patients in the Early Stage of Disease: Evidence from Resting-state fMRI.

Prog Neuropsychopharmacol Biol Psychiatry. 2015 Jan 30;

Authors: Han L, Zhaohui L, Fei Y, Pengfei Z, Ting L, Cheng D, Zhenchang W

Abstract
Numerous studies have shown that neurological changes are important findings of tinnitus patients. Previous studies on tinnitus have indicated that patients with pulsatile tinnitus (PT) often show altered baseline brain activity in the resting state. This study used resting-state functional magnetic resonance imaging (rs-fMRI) to investigate changes in spontaneous brain activity among patients with unilateral pulsatile tinnitus in the early stage of disease (less than forty-eight months) and determined the relationship of these changes with clinical data. PT patients (n=34) and matched normal control subjects (n=34) were enrolled in this study. Spontaneous brain activity was revealed by the regional homogeneity (ReHo) and amplitude of low-frequency fluctuation (ALFF) values. Compared with normal controls, patients with PT had significantly increased ReHo and ALFF in the posterior cingulate cortex, right inferior parietal lobule (IPL) and right cerebellum posterior lobe. The PT group showed increased ReHo in the posterior cingulate cortex (PCC), precuneus, right IPL, right superior frontal gyrus, some occipital areas and part of the right cerebellum posterior lobe. For ALFF, the increased clusters were in the PCC and precuneus and in some areas of the cerebellum posterior lobe, bilateral IPL and inferior frontal gyrus (IFG). Increased PT duration was correlated with increased ALFF in the bilateral inferior frontal gyrus (IFG) and precuneus. An increased THI score was correlated with ReHo and ALFF values in the precuneus. Taken together, the combined study of ReHo and ALFF measurements may yield a more comprehensive neurological pathophysiology framework for PT patients in the early stage of disease.

PMID: 25645870 [PubMed - as supplied by publisher]

Default-mode network functional connectivity is closely related to metabolic activity.

Thu, 02/05/2015 - 16:30

Default-mode network functional connectivity is closely related to metabolic activity.

Hum Brain Mapp. 2015 Feb 3;

Authors: Passow S, Specht K, Adamsen TC, Biermann M, Brekke N, Craven AR, Ersland L, Grüner R, Kleven-Madsen N, Kvernenes OH, Schwarzlmüller T, Olesen RA, Hugdahl K

Abstract
Over the last decade, the brain's default-mode network (DMN) and its function has attracted a lot of attention in the field of neuroscience. However, the exact underlying mechanisms of DMN functional connectivity, or more specifically, the blood-oxygen level-dependent (BOLD) signal, are still incompletely understood. In the present study, we combined 2-deoxy-2-[(18) F]fluoroglucose positron emission tomography (FDG-PET), proton magnetic resonance spectroscopy ((1) H-MRS), and resting-state functional magnetic resonance imaging (rs-fMRI) to investigate more directly the association between local glucose consumption, local glutamatergic neurotransmission and DMN functional connectivity during rest. The results of the correlation analyzes using the dorsal posterior cingulate cortex (dPCC) as seed region showed spatial similarities between fluctuations in FDG-uptake and fluctuations in BOLD signal. More specifically, in both modalities the same DMN areas in the inferior parietal lobe, angular gyrus, precuneus, middle, and medial frontal gyrus were positively correlated with the dPCC. Furthermore, we could demonstrate that local glucose consumption in the medial frontal gyrus, PCC and left angular gyrus was associated with functional connectivity within the DMN. We did not, however, find a relationship between glutamatergic neurotransmission and functional connectivity. In line with very recent findings, our results lend further support for a close association between local metabolic activity and functional connectivity and provide further insights towards a better understanding of the underlying mechanism of the BOLD signal. Hum Brain Mapp, 2015. © 2014 Wiley Periodicals, Inc.

PMID: 25644693 [PubMed - as supplied by publisher]

A meta-analysis of changes in brain activity in clinical depression.

Wed, 02/04/2015 - 15:30

A meta-analysis of changes in brain activity in clinical depression.

Front Hum Neurosci. 2014;8:1045

Authors: Palmer SM, Crewther SG, Carey LM, START Project Team

Abstract
Insights into neurobiological mechanisms of depression are increasingly being sought via brain imaging studies. Our aim was to quantitatively summarize overlap and divergence in regions of altered brain activation associated with depression under emotionally valenced compared to cognitively demanding task conditions, and with reference to intrinsic functional connectivity. We hypothesized differences reflective of task demands. A co-ordinate-based meta-analysis technique, activation likelihood estimation, was used to analyze relevant imaging literature. These studies compared brain activity in depressed adults relative to healthy controls during three conditions: (i) emotionally valenced (cognitively easy) tasks (n = 29); (ii) cognitively demanding tasks (n = 15); and (iii) resting conditions (n = 21). The meta-analyses identified five, eight, and seven significant clusters of altered brain activity under emotion, cognition, and resting conditions, respectively, in depressed individuals compared to healthy controls. Regions of overlap and divergence between pairs of the three separate meta-analyses were quantified. There were no significant regions of overlap between emotion and cognition meta-analyses, but several divergent clusters were found. Cognitively demanding conditions were associated with greater activation of right medial frontal and insula regions while bilateral amygdala was more significantly altered during emotion (cognitively undemanding) conditions; consistent with task demands. Overlap was present in left amygdala and right subcallosal cingulate between emotion and resting meta-analyses, with no significant divergence. Our meta-analyses highlight alteration of common brain regions, during cognitively undemanding emotional tasks and resting conditions but divergence of regions between emotional and cognitively demanding tasks. Regions altered reflect current biological and system-level models of depression and highlight the relationship with task condition and difficulty.

PMID: 25642179 [PubMed]

Resting state functional connectivity of the subthalamic nucleus in Parkinson's disease assessed using arterial spin-labeled perfusion fMRI.

Wed, 02/04/2015 - 15:30

Resting state functional connectivity of the subthalamic nucleus in Parkinson's disease assessed using arterial spin-labeled perfusion fMRI.

Hum Brain Mapp. 2015 Jan 30;

Authors: Fernández-Seara MA, Mengual E, Vidorreta M, Castellanos G, Irigoyen J, Erro E, Pastor MA

Abstract
Neurophysiological changes within the cortico-basal ganglia-thalamocortical circuits appear to be a characteristic of Parkinson's disease (PD) pathophysiology. The subthalamic nucleus (STN) is one of the basal ganglia components showing pathological neural activity patterns in PD. In this study, perfusion imaging data, acquired noninvasively using arterial spin-labeled (ASL) perfusion MRI, were used to assess the resting state functional connectivity (FC) of the STN in 24 early-to-moderate PD patients and 34 age-matched healthy controls, to determine whether altered FC in the very low frequency range of the perfusion time signal occurs as a result of the disease. Our results showed that the healthy STN was functionally connected with other nuclei of the basal ganglia and the thalamus, as well as with discrete cortical areas including the insular cortex and the hippocampus. In PD patients, connectivity of the STN was increased with two cortical areas involved in motor and cognitive processes. These findings suggest that hyperconnectivity of the STN could underlie some of the motor and cognitive deficits often present even at early stages of the disease. The FC measures provided good discrimination between controls and patients, suggesting that ASL-derived FC metrics could be a putative PD biomarker. Hum Brain Mapp, 2015. © 2014 Wiley Periodicals, Inc.

PMID: 25641065 [PubMed - as supplied by publisher]

Disrupted resting-state functional connectivity and its changing trend in migraine suffers.

Wed, 02/04/2015 - 15:30

Disrupted resting-state functional connectivity and its changing trend in migraine suffers.

Hum Brain Mapp. 2015 Jan 30;

Authors: Liu J, Zhao L, Lei F, Zhang Y, Yuan K, Gong Q, Liang F, Tian J

Abstract
Chronic pain has been linked with learning and memory processes and functional changes in brain plasticity in its development and maintenance via neuroimaging studies. However, the principle of reorganization of the migraine brain network as the brain progresses into chronic pain remain poorly understood. Here, using resting-state functional magnetic resonance imaging (rs-fMRI) and graph theory approaches, we aimed to investigate the dynamic dysfunctional connectivity in 108 patients with migraine without aura (MWoA) and 30 gender-matched healthy controls (HC). All patients were divided into 40 groups using a sliding boxcar grouping of subjects in disease duration order. As compared with HC, nonparametric permutation tests were applied for between-group comparisons of functional connectivity strength in each patient group. We focused only on the between-group differences of functional connections in MWoA, and the situation how these different connections were organized along with the changing trend. As the disease duration increased, the presence of chronic headache altered the functional connectivity from the local central nervous system (CNS) to a disruption in the whole-brain networks. These dysfunctional connections integrated into a connected component in relatively longer migraine duration groups, suggesting an abnormal integrated network configuration with ongoing central changes for long-term migraine. Within these between-group differences of the connected component, there were contained a small number of brain regions that had disproportionately numerous connections. Moreover, these brain regions exhibited a tendency to link to each other were organized into a strongly interconnected community. These interconnected brain regions were mainly located in the sensory-discriminative brain areas. Our results exhibited a working model of the central mechanisms of migraine where the brain functional connectivity was altered from the local central nervous system to a densely interconnected center, which may extend our understanding of the role of learning mechanisms which are likely involved in maintenance of chronic pain. Hum Brain Mapp, 2015. © 2014 Wiley Periodicals, Inc.

PMID: 25640857 [PubMed - as supplied by publisher]

Long-lasting enhancements of memory and hippocampal-cortical functional connectivity following multiple-day targeted noninvasive stimulation.

Wed, 02/04/2015 - 15:30

Long-lasting enhancements of memory and hippocampal-cortical functional connectivity following multiple-day targeted noninvasive stimulation.

Hippocampus. 2015 Jan 12;

Authors: Wang JX, Voss JL

Abstract
Noninvasive stimulation can alter the function of brain networks, although the duration of neuroplastic changes are uncertain and likely vary for different networks and stimulation parameters. We have previously shown that multiple-day repetitive transcranial magnetic stimulation can influence targeted hippocampal-cortical networks, producing increased functional MRI connectivity of these networks and concomitant improvements in memory that outlast stimulation by ~24 hours. Here we present new analyses showing that multiple-day targeted stimulation of hippocampal-cortical networks produces even longer-lasting enhancement. The ability to learn novel, arbitrary face-word pairings improved over five consecutive daily stimulation sessions, and this improvement remained robust at follow-up testing performed an average of 15 days later. Further, stimulation increased functional MRI connectivity of the targeted portion of the hippocampus with distributed regions of the posterior hippocampal-cortical network, and these changes in connectivity remained robust at follow-up testing. Neuroplastic changes of hippocampal-cortical networks caused by multiple-day noninvasive stimulation therefore persist for extended periods. These findings have implications for the design of multiple-day stimulation experiments and for the development of stimulation-based interventions for memory disorders. This article is protected by copyright. All rights reserved.

PMID: 25639205 [PubMed - as supplied by publisher]

Neural signatures of the interaction between the 5-HTTLPR genotype and stressful life events in healthy women.

Wed, 02/04/2015 - 15:30
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Neural signatures of the interaction between the 5-HTTLPR genotype and stressful life events in healthy women.

Psychiatry Res. 2014 Aug 30;223(2):157-63

Authors: Favaro A, Manara R, Pievani M, Clementi M, Forzan M, Bruson A, Tenconi E, Degortes D, Pinato C, Giannunzio V, Battista Frisoni G, Santonastaso P

Abstract
A change in neural connectivity of brain structures implicated in the memory of negative life events has been hypothesized to explain the enhancement of memory encoding during the processing of negative stimuli in depressed patients. Here, we investigated the effects of the interaction between negative life events and the 5-HTTLPR genotype - a polymorphism of the serotonin transporter gene - on the functional and structural connectivity of the hippocampal area in 34 healthy women. All participants were genotyped for the presence of the 5-HTTLPR short variant and for the A/G single-nucleotide polymorphism; they underwent clinical assessment including structured diagnostic interviews to exclude the presence of psychiatric disorders and to assess the presence of stressful life events. Resting state functional magnetic resonance imaging and diffusion tensor imaging scans were performed. We found significant interactions between stressful events and the 5-HTTLPR genotype in both the functional connectivity of the parahippocampus with the posterior cingulate cortex and the structural connectivity between the hippocampus and both the amygdala and the putamen. In addition, we found several genotype-related differences in the relationship between functional/structural connectivity of the hippocampal area and the ability to update expectations or stress-related phenotypes, such as anxiety symptoms. If confirmed by future studies, these mechanisms may clarify the role of the 5HTTLPR genotype as a risk factor for depression, in interaction with negative events.

PMID: 24914006 [PubMed - indexed for MEDLINE]

Dopamine precursor depletion impairs structure and efficiency of resting state brain functional networks.

Wed, 02/04/2015 - 15:30
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Dopamine precursor depletion impairs structure and efficiency of resting state brain functional networks.

Neuropharmacology. 2014 Sep;84:90-100

Authors: Carbonell F, Nagano-Saito A, Leyton M, Cisek P, Benkelfat C, He Y, Dagher A

Abstract
Spatial patterns of functional connectivity derived from resting brain activity may be used to elucidate the topological properties of brain networks. Such networks are amenable to study using graph theory, which shows that they possess small world properties and can be used to differentiate healthy subjects and patient populations. Of particular interest is the possibility that some of these differences are related to alterations in the dopamine system. To investigate the role of dopamine in the topological organization of brain networks at rest, we tested the effects of reducing dopamine synthesis in 13 healthy subjects undergoing functional magnetic resonance imaging. All subjects were scanned twice, in a resting state, following ingestion of one of two amino acid drinks in a randomized, double-blind manner. One drink was a nutritionally balanced amino acid mixture, and the other was tyrosine and phenylalanine deficient. Functional connectivity between 90 cortical and subcortical regions was estimated for each individual subject under each dopaminergic condition. The lowered dopamine state caused the following network changes: reduced global and local efficiency of the whole brain network, reduced regional efficiency in limbic areas, reduced modularity of brain networks, and greater connection between the normally anti-correlated task-positive and default-mode networks. We conclude that dopamine plays a role in maintaining the efficient small-world properties and high modularity of functional brain networks, and in segregating the task-positive and default-mode networks. This article is part of the Special Issue Section entitled 'Neuroimaging in Neuropharmacology'.

PMID: 24412649 [PubMed - indexed for MEDLINE]

Characterization of resting-state fMRI-derived functional connectivity in patients with deficiency versus excess patterns of major depression.

Tue, 02/03/2015 - 14:00

Characterization of resting-state fMRI-derived functional connectivity in patients with deficiency versus excess patterns of major depression.

Complement Ther Med. 2015 Feb;23(1):7-13

Authors: Zhang YF, Han Y, Wang YZ, Zhang YF, Jia HX, Jin EH, Deng LG, Li L

Abstract
OBJECTIVE: Patients with major depression (MD) experience a variety of emotional and mental problems accompanied by characteristic clinical symptoms. Based on traditional Chinese medicine (TCM) notions, the clinical appearance of MD can be divided into two syndromes, namely a deficiency pattern (DP) and an excess pattern (EP), depending on the patient's clinical symptoms, pulse, and lingual signs. Brain functional neuroimaging has demonstrated cerebral activity abnormalities in MD patients. However, such abnormalities have not been linked to particular symptoms of MD. The objective of this work was to compare functional connectivity of the posterior cingulate cortex (PCC) across MD patients with DP, MD patients with EP, and normal control (NC) subjects in a resting-state functional magnetic resonance imaging (rs-fMRI) study.
METHODS: Participants (24 DP patients, 21 EP patients, and 20 NCs) underwent rs-fMRI scans. Whole-brain functional connectivity of a seed in the PCC was then mapped for each subject. Functional connectivity differences among the three studied groups were analyzed statistically.
RESULTS: Compared to the NC group, DP patients had decreased functional connectivity of the PCC with the right middle temporal gyrus and bilateral precuneus, as well as increased functional connectivity of the PCC with the bilateral middle frontal gyrus. Meanwhile, compared to the NC group, the EP group had decreased functional connectivity of the PCC with both the middle temporal gyrus and bilateral precuneus, as well as increased functional connectivity of the PCC with the bilateral superior frontal gyrus. Relative to the DP group, the EP group had reduced functional connectivity of the PCC with the bilateral cerebellum and left superior frontal gyrus.
CONCLUSION: Functional connectivity changes differ between MD patients with different TCM syndrome types, suggesting that the TCM clinical syndromes of MD are associated with correlates in cerebral functional activity.

PMID: 25637147 [PubMed - in process]

Unmasking Language Lateralization in Human Brain Intrinsic Activity.

Tue, 02/03/2015 - 14:00

Unmasking Language Lateralization in Human Brain Intrinsic Activity.

Cereb Cortex. 2015 Jan 30;

Authors: McAvoy M, Mitra A, Coalson RS, Petersen SE, Raichle ME

Abstract
Lateralization of function is a fundamental feature of the human brain as exemplified by the left hemisphere dominance of language. Despite the prominence of lateralization in the lesion, split-brain and task-based fMRI literature, surprisingly little asymmetry has been revealed in the increasingly popular functional imaging studies of spontaneous fluctuations in the fMRI BOLD signal (so-called resting-state fMRI). Here, we show the global signal, an often discarded component of the BOLD signal in resting-state studies, reveals a leftward asymmetry that maps onto regions preferential for semantic processing in left frontal and temporal cortex and the right cerebellum and a rightward asymmetry that maps onto putative attention-related regions in right frontal, temporoparietal, and parietal cortex. Hemispheric asymmetries in the global signal resulted from amplitude modulation of the spontaneous fluctuations. To confirm these findings obtained from normal, healthy, right-handed subjects in the resting-state, we had them perform 2 semantic processing tasks: synonym and numerical magnitude judgment and sentence comprehension. In addition to establishing a new technique for studying lateralization through functional imaging of the resting-state, our findings shed new light on the physiology of the global brain signal.

PMID: 25636911 [PubMed - as supplied by publisher]

Altered thalamic functional connectivity in multiple sclerosis.

Tue, 02/03/2015 - 14:00

Altered thalamic functional connectivity in multiple sclerosis.

Eur J Radiol. 2015 Jan 19;

Authors: Liu Y, Liang P, Duan Y, Huang J, Ren Z, Jia X, Dong H, Ye J, Shi FD, Butzkueven H, Li K

Abstract
OBJECTIVE: To compare thalamic functional connectivity (FC) in patients with multiple sclerosis (MS) and healthy controls (HC), and correlate these connectivity measures with other MRI and clinical variables.
METHODS: We employed resting-state functional MRI (fMRI) to examine changes in thalamic connectivity by comparing thirty-five patients with MS and 35 age- and sex-matched HC. Thalamic FC was investigated by correlating low frequency fMRI signal fluctuations in thalamic voxels with voxels in all other brain regions. Additionally thalamic volume fraction (TF), T2 lesion volume (T2LV), EDSS and disease duration were recorded and correlated with the FC changes.
RESULTS: MS patients were found to have a significantly lower TF than HC in bilateral thalami. Compared to HC, the MS group showed significantly decreased FC between thalamus and several brain regions including right middle frontal and parahippocampal gyri, and the left inferior parietal lobule. Increased intra- and inter-thalamic FC was observed in the MS group compared to HC. These FC alterations were not correlated with T2LV, thalamic volume or lesions. In the MS group, however, there was a negative correlation between disease duration and inter-thalamic connectivity (r=-0.59, p<0.001).
CONCLUSION: We demonstrated decreased FC between thalamus and several cortical regions, while increased intra- and inter-thalamic connectivity in MS patients. These complex functional changes reflect impairments and/or adaptations that are independent of T2LV, thalamic volume or presence of thalamic lesions. The negative correlation between disease duration and inter-thalamic connectivity could indicate an adaptive role of thalamus that is gradually lost with increasing disease duration.

PMID: 25636387 [PubMed - as supplied by publisher]

Approaching a network connectivity-driven classification of the psychosis continuum: a selective review and suggestions for future research.

Sun, 02/01/2015 - 18:00
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Approaching a network connectivity-driven classification of the psychosis continuum: a selective review and suggestions for future research.

Front Hum Neurosci. 2014;8:1047

Authors: Schmidt A, Diwadkar VA, Smieskova R, Harrisberger F, Lang UE, McGuire P, Fusar-Poli P, Borgwardt S

Abstract
Brain changes in schizophrenia evolve along a dynamic trajectory, emerging before disease onset and proceeding with ongoing illness. Recent investigations have focused attention on functional brain interactions, with experimental imaging studies supporting the disconnection hypothesis of schizophrenia. These studies have revealed a broad spectrum of abnormalities in brain connectivity in patients, particularly for connections integrating the frontal cortex. A critical point is that brain connectivity abnormalities, including altered resting state connectivity within the fronto-parietal (FP) network, are already observed in non-help-seeking individuals with psychotic-like experiences. If we consider psychosis as a continuum, with individuals with psychotic-like experiences at the lower and psychotic patients at the upper ends, individuals with psychotic-like experiences represent a key population for investigating the validity of putative biomarkers underlying the onset of psychosis. This paper selectively addresses the role played by FP connectivity in the psychosis continuum, which includes patients with chronic psychosis, early psychosis, clinical high risk, genetic high risk, as well as the general population with psychotic experiences. We first discuss structural connectivity changes among the FP pathway in each domain in the psychosis continuum. This may provide a basis for us to gain an understanding of the subsequent changes in functional FP connectivity. We further indicate that abnormal FP connectivity may arise from glutamatergic disturbances of this pathway, in particular from abnormal NMDA receptor-mediated plasticity. In the second part of this paper we propose some concepts for further research on the use of network connectivity in the classification of the psychosis continuum. These concepts are consistent with recent efforts to enhance the role of data in driving the diagnosis of psychiatric spectrum diseases.

PMID: 25628553 [PubMed]

Functional Consequences of Neurite Orientation Dispersion and Density in Humans across the Adult Lifespan.

Fri, 01/30/2015 - 20:30

Functional Consequences of Neurite Orientation Dispersion and Density in Humans across the Adult Lifespan.

J Neurosci. 2015 Jan 28;35(4):1753-62

Authors: Nazeri A, Chakravarty MM, Rotenberg DJ, Rajji TK, Rathi Y, Michailovich OV, Voineskos AN

Abstract
As humans age, a characteristic pattern of widespread neocortical dendritic disruption coupled with compensatory effects in hippocampus and other subcortical structures is shown in postmortem investigations. It is now possible to address age-related effects on gray matter (GM) neuritic organization and density in humans using multishell diffusion-weighted MRI and the neurite-orientation dispersion and density imaging (NODDI) model. In 45 healthy individuals across the adult lifespan (21-84 years), we used a multishell diffusion imaging and the NODDI model to assess the intraneurite volume fraction and neurite orientation-dispersion index (ODI) in GM tissues. We also determined the functional correlates of variations in GM microstructure by obtaining resting-state fMRI and behavioral data. We found a significant age-related deficit in neocortical ODI (most prominently in frontoparietal regions), whereas increased ODI was observed in hippocampus and cerebellum with advancing age. Neocortical ODI outperformed cortical thickness and white matter fractional anisotropy for the prediction of chronological age in the same individuals. Higher GM ODI sampled from resting-state networks with known age-related susceptibility (default mode and visual association networks) was associated with increased functional connectivity of these networks, whereas the task-positive networks tended to show no association or even decreased connectivity. Frontal pole ODI mediated the negative relationship of age with executive function, whereas hippocampal ODI mediated the positive relationship of age with executive function. Our in vivo findings align very closely with the postmortem data and provide evidence for vulnerability and compensatory neural mechanisms of aging in GM microstructure that have functional and cognitive impact in vivo.

PMID: 25632148 [PubMed - in process]

Hyperconnectivity of the Right Posterior Temporo-parietal Junction Predicts Social Difficulties in Boys with Autism Spectrum Disorder.

Fri, 01/30/2015 - 20:30

Hyperconnectivity of the Right Posterior Temporo-parietal Junction Predicts Social Difficulties in Boys with Autism Spectrum Disorder.

Autism Res. 2015 Jan 28;

Authors: Chien HY, Lin HY, Lai MC, Gau SS, Tseng WY

Abstract
The posterior right temporo-parietal junction (pRTPJ) is a key brain region representing other's mental status. Despite reports of atypical activation at pRTPJ during mentalizing in individuals with autism spectrum disorder (ASD), the intrinsic functional connectivity (iFC) of the pRTPJ remains under-investigated. We examined whether boys with ASD show altered resting-state iFC of the pRTPJ, and whether atypical iFC of the pRTPJ is associated with social deficits in ASD in a sample of 40 boys with high-functioning ASD (aged 9-17 years, mean age, 12.38 ± 2.17; mean IQ, 105.60 ± 16.06) and 42 typically developing (TD) boys (aged 9-17 years, mean age, 11.64 ± 2.71; mean IQ, 111.29 ± 13.45). Both groups received resting-state fMRI assessment after imaging data quality control for in-scanner head motion and spatial coverage. Seed-based approach was used to investigate iFC of the pRTPJ. TD and ASD boys demonstrated a resting-state pRTPJ iFC pattern comparable to the known spatial involvement of the default-mode network. Boys with ASD showed pRTPJ hyperconnectivity relative to TD boys in the right ventral occipito-temporal cortex. This atypically increased iFC in the ASD group was positively correlated with social deficits assessed by the Chinese version of the Autism Diagnostic Interview-Revised and the Social Responsive Scale. Our findings provide empirical support for functional "dysconnectivity," that is, atypical functional integration among brain regions, as an integral component of the atypical neurobiology of ASD. Autism Res 2015. © 2015 International Society for Autism Research, Wiley Periodicals, Inc.

PMID: 25630517 [PubMed - as supplied by publisher]

Gender differences in cerebral regional homogeneity of adult healthy volunteers: a resting-state FMRI study.

Fri, 01/30/2015 - 20:30
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Gender differences in cerebral regional homogeneity of adult healthy volunteers: a resting-state FMRI study.

Biomed Res Int. 2015;2015:183074

Authors: Xu C, Li C, Wu H, Wu Y, Hu S, Zhu Y, Zhang W, Wang L, Zhu S, Liu J, Zhang Q, Yang J, Zhang X

Abstract
Objective. We sought to use the regional homogeneity (ReHo) approach as an index in the resting-state functional MRI to investigate the gender differences of spontaneous brain activity within cerebral cortex and resting-state networks (RSNs) in young adult healthy volunteers. Methods. One hundred and twelve healthy volunteers (56 males, 56 females) participated in the resting-state fMRI scan. The ReHo mappings in the cerebral cortex and twelve RSNs of the male and female groups were compared. Results. We found statistically significant gender differences in the primary visual network (PVN) (P < 0.004, with Bonferroni correction) and left attention network (LAtN), default mode network (DMN), sensorimotor network (SMN), executive network (EN), and dorsal medial prefrontal network (DMPFC) as well (P < 0.05, uncorrected). The male group showed higher ReHo in the left precuneus, while the female group showed higher ReHo in the right middle cingulate gyrus, fusiform gyrus, left inferior parietal lobule, precentral gyrus, supramarginal gyrus, and postcentral gyrus. Conclusions. Our results suggested that men and women had regional specific differences during the resting-state. The findings may improve our understanding of the gender differences in behavior and cognition from the perspective of resting-state brain function.

PMID: 25629038 [PubMed - in process]

[Intensity of functional connection between bilateral hemispheres of children with attention-deficit hyperactivity disorder by functional magnetic resonance imaging].

Fri, 01/30/2015 - 14:00

[Intensity of functional connection between bilateral hemispheres of children with attention-deficit hyperactivity disorder by functional magnetic resonance imaging].

Zhonghua Yi Xue Za Zhi. 2014 Dec;94(46):3649-51

Authors: Jiang K, Dong X, Gao M, Li H, Zhang Q, Yi Y, Shen H, Chen L, Ding L, Zheng A

Abstract
OBJECTIVE: To explore the neural mechanisms of attention-deficit hyperactivity disorder (ADHD) through analyzing the intensity of functional connection between bilateral hemispheres of children with ADHD by resting-state functional magnetic resonance imaging (rs-fMRI).
METHODS: The approach of voxel-mirrored homotopic connectivity (VMHC) was employed to analyze 31 school-age and 31 ADHD children by rs-fMRI scans.
RESULTS: Positively activated brain regions were visualized when comparing ADHD and normal children, suggesting that ADHD children's VMHC scores were higher in bilateral frontal lobe (t = 5.81), bilateral occipital lobe (t = 5.82) and bilateral cerebellar posterior lobe (t = 6.17). Statistically significant differences existed between two groups (FDR correction, Q<0.01).
CONCLUSIONS: The increased intensity of functional connection between bilateral prefrontal lobes in children with ADHD reflects attention disorder and leads to a decline of working memory . The strengthening of bilateral occipital lobes slows down memory process. And the increased intensity of cerebellar connections may damage neural circuits and aggravate ADHD symptoms.

PMID: 25622957 [PubMed - in process]

[Default mode network in childhood absence epilepsy by 3.0T magnetic resonance imaging].

Fri, 01/30/2015 - 14:00

[Default mode network in childhood absence epilepsy by 3.0T magnetic resonance imaging].

Zhonghua Yi Xue Za Zhi. 2014 Dec;94(45):3540-4

Authors: Li Y, Wang E, Han X, Gao L, Zheng M, Zhang Y, Ren T, He G, Yan X, Zheng H, Xue Z

Abstract
OBJECTIVE: To explore the default mode network (DMN) in childhood absence epilepsy (CAE) patients and examine their correlations between functional connectivity (FC) and clinical characteristics.
METHODS: Fourteen CAE patients and 14 healthy volunteers were prospectively recruited from Henan Provincial People's Hospital from September 2012 to June 2014. FC in DMN of each group, between-group comparison of DMN FC and their relationships with clinical characteristics were respectively analyzed with 3.0T resting-state functional magnetic resonance imaging (fMRI) FC analysis seeding at bilateral precuneus/posterior cingulate cortex (PCC).
RESULTS: Seeding at bilateral precuneus/posterior cingulate cortex (PCC), positive connection was found in bilateral angular gyrus, bilateral superior parietal gyrus, bilateral superior and middle frontal gyrus, bilateral superior medial frontal gyrus, bilateral middle temporal gyrus and bilateral superior and middle occipital gyrus in controls. However, positive connection in CAE patients was observed in bilateral superior parietal gyrus and bilateral superior occipital gyrus. Between-group analysis of DMN connectivity revealed a reduction of DMN FC in bilateral medial orbitofrontal cortex, bilateral anterior cingulate cortex, bilateral superior frontal gyrus, bilateral middle frontal gyrus and left caudate in CAE patients. Moreover, increased DMN FC was present in right paracentral lobule and right middle cingulate gyrus. FC between PCC and bilateral medial orbitofrontal cortex or bilateral superior/middle frontal gyrus correlated negatively with disease duration, but there was no correlation with seizure frequency or initial age.
CONCLUSION: Brain's default mode network in childhood absence epilepsy is impaired, presumably, as a result of unconsciousness and cognitive impairment during absence seizure. Abnormal DMN activities may be a biomaker of disease progress in absence epilepsy.

PMID: 25622829 [PubMed - in process]

The somatosensory link: S1 functional connectivity is altered by sustained pain and associated with clinical/autonomic dysfunction in fibromyalgia.

Fri, 01/30/2015 - 14:00

The somatosensory link: S1 functional connectivity is altered by sustained pain and associated with clinical/autonomic dysfunction in fibromyalgia.

Arthritis Rheumatol. 2015 Jan 26;

Authors: Kim J, Loggia ML, Cahalan CM, Harris RE, Beissner F, Garcia RG, Kim H, Wasan AD, Edwards RR, Napadow V

Abstract
Objective: Fibromyalgia (FM) is a chronic functional pain syndrome characterized by widespread pain, significant pain catastrophizing,sympathovagal dysfunction, and amplified temporal summation for evoked pain. While several studies have found altered resting brain connectivity in FM, studies have not specifically probed the somatosensory system, and its role in both somatic and non-somatic FM symptomatology. Our objective was to evaluate resting primary somatosensory cortex (S1) connectivity, and explore how sustained, evoked deep-tissue pain modulates this connectivity. Methods: We acquired fMRI and electrocardiography data from FM patients and healthy controls (HC) during rest (REST) and sustained mechanical pressure pain (PAIN) over the lower leg.Functional connectivity associated withdifferent S1 subregions was calculated, while S1leg (leg representation) connectivity was contrast between REST and PAIN, and correlated with clinically-relevant measures in FM. Results:At REST, FM showed decreased connectivity between multiple ipsilateral and cross-hemispheric S1 subregions, which was correlated with clinical pain severity. PAIN, compared to REST, produced increased S1leg connectivity to bilateral anterior insula in FM, but not in HC. Moreover, in FM, sustained pain-altered S1leg connectivity to anterior insula was correlated with clinical/behavioral pain measures and autonomic responses. Conclusion: Our study demonstrates that both somatic and non-somatic dysfunction in FM, including clinical pain, pain catastrophizing, autonomic dysfunction, and amplified temporal summation, are all closely linked with the degree to which evoked deep-tissue pain alters S1 connectivity to salience/affective pain processing regions. Additionally, diminished connectivity between S1 subregions at REST in FM may result from ongoing widespread clinical pain. This article is protected by copyright. All rights reserved.

PMID: 25622796 [PubMed - as supplied by publisher]

Temporal lobe epilepsy: Decreased thalamic resting-state functional connectivity and their relationships with alertness performance.

Wed, 01/28/2015 - 17:30

Temporal lobe epilepsy: Decreased thalamic resting-state functional connectivity and their relationships with alertness performance.

Epilepsy Behav. 2015 Jan 23;44C:47-54

Authors: Chen XM, Huang DH, Chen ZR, Ye W, Lv ZX, Zheng JO

Abstract
OBJECTIVES: Studies have provided evidence regarding the pathology of the thalamus in patients with temporal lobe epilepsy (TLE). The thalamus, particularly the right thalamus, is one of the subcortical structures that are most uniformly accepted as being significantly involved in alertness. Moreover, alertness impairment in epilepsy has been reported. This study aimed to investigate alterations in thalamic resting-state functional connectivity (FC) and their relationships with alertness performance in patients with TLE; an issue that has not yet been addressed.
METHODS: A total of 15 patients with right TLE (rTLE) and 16 healthy controls were recruited for the present study. All of the participants underwent a resting-state functional magnetic resonance imaging (fMRI) scan and the attention network test (ANT). Whole-brain voxel-wise FC analyses were applied to extract the thalamic resting-state functional networks in the patients with rTLE and healthy controls, and the differences between the two groups were evaluated. Correlation analyses were employed to examine the relationships between alterations in thalamic FC and alertness performance in patients with rTLE.
RESULTS: Compared to the healthy controls, the FC within and between the bilateral thalamus was decreased in the patients with rTLE. Moreover, in the patient group, the bilateral anterior cingulate cortex (ACC) and subcortical regions, including the bilateral brainstem, cerebellum, putamen, right caudate nucleus, and amygdala, exhibited decreased FC with the ipsilateral thalamus (p<0.05, AlphaSim corrected, cluster size>44) but not with the contralateral thalamus (p<0.05, AlphaSim corrected, cluster size>43). The intrinsic and phasic alertness performances of the patients were impaired (p=0.001 and p<0.001, respectively) but not correlated with decreased thalamic FC. Meanwhile, the alertness performance was not altered in right TLE but was negatively correlated with decreased thalamic FC with ACC (p<0.05).
CONCLUSIONS: Our findings highlight the functional importance of the thalamus in TLE pathology and suggest that damage to the thalamic resting-state functional networks, particularly ipsilateral to the epileptogenic focus, is present in patients with TLE.

PMID: 25622022 [PubMed - as supplied by publisher]

Consolidation in older adults depends upon competition between resting-state networks.

Wed, 01/28/2015 - 17:30

Consolidation in older adults depends upon competition between resting-state networks.

Front Aging Neurosci. 2014;6:344

Authors: Jacobs HI, Dillen KN, Risius O, Göreci Y, Onur OA, Fink GR, Kukolja J

Abstract
Memory encoding and retrieval problems are inherent to aging. To date, however, the effect of aging upon the neural correlates of forming memory traces remains poorly understood. Resting-state fMRI connectivity can be used to investigate initial consolidation. We compared within and between network connectivity differences between healthy young and older participants before encoding, after encoding and before retrieval by means of resting-state fMRI. Alterations over time in the between-network connectivity analyses correlated with retrieval performance, whereas within-network connectivity did not: a higher level of negative coupling or competition between the default mode and the executive networks during the after encoding condition was associated with increased retrieval performance in the older adults, but not in the young group. Data suggest that the effective formation of memory traces depends on an age-dependent, dynamic reorganization of the interaction between multiple, large-scale functional networks. Our findings demonstrate that a cross-network based approach can further the understanding of the neural underpinnings of aging-associated memory decline.

PMID: 25620930 [PubMed]