Effects of Fronto-Temporal Transcranial Direct Current Stimulation on Auditory Verbal Hallucinations and Resting-State Functional Connectivity of the Left Temporo-Parietal Junction in Patients With Schizophrenia.
Schizophr Bull. 2015 Aug 24;
Authors: Mondino M, Jardri R, Suaud-Chagny MF, Saoud M, Poulet E, Brunelin J
Auditory verbal hallucinations (AVH) in patients with schizophrenia are associated with abnormal hyperactivity in the left temporo-parietal junction (TPJ) and abnormal connectivity between frontal and temporal areas. Recent findings suggest that fronto-temporal transcranial Direct Current stimulation (tDCS) with the cathode placed over the left TPJ and the anode over the left prefrontal cortex can alleviate treatment-resistant AVH in patients with schizophrenia. However, brain correlates of the AVH reduction are unclear. Here, we investigated the effect of tDCS on the resting-state functional connectivity (rs-FC) of the left TPJ. Twenty-three patients with schizophrenia and treatment-resistant AVH were randomly allocated to receive 10 sessions of active (2 mA, 20min) or sham tDCS (2 sessions/d for 5 d). We compared the rs-FC of the left TPJ between patients before and after they received active or sham tDCS. Relative to sham tDCS, active tDCS significantly reduced AVH as well as the negative symptoms. Active tDCS also reduced rs-FC of the left TPJ with the left anterior insula and the right inferior frontal gyrus and increased rs-FC of the left TPJ with the left angular gyrus, the left dorsolateral prefrontal cortex and the precuneus. The reduction of AVH severity was correlated with the reduction of the rs-FC between the left TPJ and the left anterior insula. These findings suggest that the reduction of AVH induced by tDCS is associated with a modulation of the rs-FC within an AVH-related brain network, including brain areas involved in inner speech production and monitoring.
PMID: 26303936 [PubMed - as supplied by publisher]
Learning to live without the cerebellum.
Neuroreport. 2015 Sep 30;26(14):809-813
Authors: Arrigoni F, Romaniello R, Nordio A, Gagliardi C, Borgatti R
The near-total absence of the cerebellum is a rare congenital condition with a wide phenotypic heterogeneity ranging from a severe to mild impairment of motor, cognitive, and behavioral functions. In this study, the case of a 48-year-old right-handed man with a near-total absence of the cerebellum was examined with the aim of understanding the long-term reorganization of a brain developed without a cerebellum. Clinical, neuropsychological evaluation and a neuroimaging study on a 3-T scanner were carried out. Both conventional structural diffusion tensor imaging (DTI) and functional (resting-state fMRI) data were acquired. A severe neuropsychomotor delay in infancy and adolescence involving motor skills, cognitive, and affective competencies was observed, which improved over the years. Conventional MRI findings confirmed the complete absence of the cerebellum. Analysis of DTI and resting-state fMRI data showed an impairment of the executive-control network, involving areas strongly connected with the cerebellum through the frontopontine fibers. The neuroimaging findings excluded the involvement of the extracerebellar structure. In conclusion, our data support the vascular genesis hypothesis for this rare pathology, consistent with an acquired embryonic cerebellar insult. This case also shows that it is possible to learn to live without the cerebellum over time.
PMID: 26302158 [PubMed - as supplied by publisher]
Considerations for resting state functional MRI and functional connectivity studies in rodents.
Front Neurosci. 2015;9:269
Authors: Pan WJ, Billings JC, Grooms JK, Shakil S, Keilholz SD
Resting state functional MRI (rs-fMRI) and functional connectivity mapping have become widely used tools in the human neuroimaging community and their use is rapidly spreading into the realm of rodent research as well. One of the many attractive features of rs-fMRI is that it is readily translatable from humans to animals and back again. Changes in functional connectivity observed in human studies can be followed by more invasive animal experiments to determine the neurophysiological basis for the alterations, while exploratory work in animal models can identify possible biomarkers for further investigation in human studies. These types of interwoven human and animal experiments have a potentially large impact on neuroscience and clinical practice. However, impediments exist to the optimal application of rs-fMRI in small animals, some similar to those encountered in humans and some quite different. In this review we identify the most prominent of these barriers, discuss differences between rs-fMRI in rodents and in humans, highlight best practices for animal studies, and review selected applications of rs-fMRI in rodents. Our goal is to facilitate the integration of human and animal work to the benefit of both fields.
PMID: 26300718 [PubMed]
The Relevance of Fractional Amplitude of Low-Frequency Fluctuation to Interference Effect.
Behav Brain Res. 2015 Aug 20;
Authors: Deng Y, Wang Y, Ding X, Tang YY
Growing evidence has indicated a potential connection between resting-state functional magnetic resonance imaging (RS-fMRI) signal and cognitive performance. However, the relationship between intrinsic neural activity and behavioral interference effect on cognitive control has been poorly understood. In the present study, seventy-eight healthy subjects underwent RS-fMRI and performed Multi-Source Interference Task (MSIT). The fractional amplitude of low-frequency fluctuation (fALFF) was measured as an indicator of intrinsic brain activity. The difference in reaction times between interference and control conditions in MSIT was evaluated as interference effect. Then we examined the associations between fALFF and interference effect using partial correlation analysis controlling for age, gender and mean framewise displacement. The results demonstrated that fALFF values in orbital prefrontal cortex (OPFC) and right inferior frontal cortex (IFC) were negatively correlated with the interference effect in MSIT. The findings manifest that OPFC and right IFC may influence the processing efficiency of cognitive conflict and play a crucial role in cognitive control.
PMID: 26300450 [PubMed - as supplied by publisher]
Auditory-limbic interactions in chronic tinnitus: challenges for neuroimaging research.
Hear Res. 2015 Aug 20;
Authors: Leaver AM, Seydell-Greenwald A, Rauschecker JP
Tinnitus is a widespread auditory disorder affecting approximately 10-15% of the population, often with debilitating consequences. Although tinnitus commonly begins with damage to the auditory system due to loud-noise exposure, aging, or other etiologies, the exact neurophysiological basis of chronic tinnitus remains unknown. Many researchers point to a central auditory origin of tinnitus; however, a growing body of evidence also implicates other brain regions, including the limbic system. Correspondingly, we and others have proposed models of tinnitus in which the limbic and auditory systems both play critical roles and interact with one another. Specifically, we argue that damage to the auditory system generates an initial tinnitus signal, consistent with previous research. In our model, this "transient" tinnitus is suppressed when a limbic frontostriatal network, comprised of ventromedial prefrontal cortex and ventral striatum, successfully modulates thalamocortical transmission in the auditory system. Thus, in chronic tinnitus, limbic-system damage and resulting inefficiency of auditory-limbic interactions prevents proper compensation of the tinnitus signal. Neuroimaging studies utilizing connectivity methods like resting-state fMRI and diffusion MRI continue to uncover tinnitus-related anomalies throughout auditory, limbic, and other brain systems. However, directly assessing interactions between these brain regions and networks has proved to be more challenging. Here, we review existing empirical support for models of tinnitus stressing a critical role for involvement of "non-auditory" structures in tinnitus pathophysiology, and discuss the possible impact of newly refined connectivity techniques from neuroimaging on tinnitus research.
PMID: 26299843 [PubMed - as supplied by publisher]
Functional connectivity MRI tracks memory networks after maze learning in rodents.
Neuroimage. 2015 Aug 20;
Authors: Nasrallah FA, To XV, Chen DY, Routtenberg A, Chuang KH
Learning and memory employs a series of cognitive processes which require the coordination of multiple areas across the brain. However in vivo imaging of cognitive function has been challenging in rodents. Since these processes involve synchronous firing among different brain loci we explored functional connectivity imaging with resting-state fMRI. After 5-day training on a hidden platform watermaze task, notable signal correlations were seen between the hippocampal CA3 and other structures, including thalamus, septum and cingulate cortex, compared to swim control or naïve animals. The connectivity sustained 7 days after training and was reorganized towards the cortex, consistent with views of memory trace distribution leading to memory consolidation. These data demonstrates that, after a cognitive task, altered functional connectivity can be detected in the subsequently sedated rodent using in vivo imaging. This approach paves the way to understand dynamics of area-dependent distribution processes in animal models of cognition.
PMID: 26299794 [PubMed - as supplied by publisher]
Nodal centrality of functional network in the differentiation of schizophrenia.
Schizophr Res. 2015 Aug 20;
Authors: Cheng H, Newman S, Goñi J, Kent JS, Howell J, Bolbecker A, Puce A, O'Donnell BF, Hetrick WP
A disturbance in the integration of information during mental processing has been implicated in schizophrenia, possibly due to faulty communication within and between brain regions. Graph theoretic measures allow quantification of functional brain networks. Functional networks are derived from correlations between time courses of brain regions. Group differences between SZ and control groups have been reported for functional network properties, but the potential of such measures to classify individual cases has been little explored. We tested whether the network measure of betweenness centrality could classify persons with schizophrenia and normal controls. Functional networks were constructed for 19 schizophrenic patients and 29 non-psychiatric controls based on resting state functional MRI scans. The betweenness centrality of each node, or fraction of shortest-paths that pass through it, was calculated in order to characterize the centrality of the different regions. The nodes with high betweenness centrality agreed well with hub nodes reported in previous studies of structural and functional networks. Using a linear support vector machine algorithm, the schizophrenia group was differentiated from non-psychiatric controls using the ten nodes with the highest betweenness centrality. The classification accuracy was around 80%, and stable against connectivity thresholding. Better performance was achieved when using the ranks as feature space as opposed to the actual values of betweenness centrality. Overall, our findings suggest that changes in functional hubs are associated with schizophrenia, reflecting a variation of the underlying functional network and neuronal communications. In addition, a specific network property, betweenness centrality, can classify persons with SZ with a high level of accuracy.
PMID: 26299706 [PubMed - as supplied by publisher]
Intrinsic brain indices of verbal working memory capacity in children and adolescents.
Dev Cogn Neurosci. 2015 Aug 4;
Authors: Yang Z, Jutagir DR, Koyama MS, Craddock RC, Yan CG, Shehzad Z, Castellanos FX, Di Martino A, Milham MP
Working memory (WM) is central to the acquisition of knowledge and skills throughout childhood and adolescence. While numerous behavioral and task-based functional magnetic resonance imaging (fMRI) studies have examined WM development, few have used resting-state fMRI (R-fMRI). Here, we present a systematic R-fMRI examination of age-related differences in the neural indices of verbal WM performance in a cross-sectional pediatric sample (ages: 7-17; n=68), using data-driven approaches. Verbal WM capacity was measured with the digit span task, a commonly used educational and clinical assessment. We found distinct neural indices of digit span forward (DSF) and backward (DSB) performance, reflecting their unique neuropsychological demands. Regardless of age, DSB performance was related to intrinsic properties of brain areas previously implicated in attention and cognitive control, while DSF performance was related to areas less commonly implicated in verbal WM storage (precuneus, lateral visual areas). From a developmental perspective, DSF exhibited more robust age-related differences in brain-behavior relationships than DSB, and implicated a broader range of networks (ventral attention, default, somatomotor, limbic networks) - including a number of regions not commonly associated with verbal WM (angular gyrus, subcallosum). These results highlight the importance of examining the neurodevelopment of verbal WM and of considering regions beyond the "usual suspects".
PMID: 26299314 [PubMed - as supplied by publisher]
Aberrant orbitofrontal connectivity in marijuana smoking adolescents.
Dev Cogn Neurosci. 2015 Aug 9;
Authors: Lopez-Larson MP, Rogowska J, Yurgelun-Todd D
INTRODUCTION: Orbitofrontal (OFC) circuits have been implicated in the pathophysiology of substance use disorders. The current study examined OFC functional connectivity differences in marijuana-using adolescents (MJ) and non-using healthy controls (HC).
METHODS: Functional magnetic resonance imaging (fMRI) resting-state data were obtained on a 3T MRI scanner on 31 HC and 43 heavy MJ smokers. Image analyses were performed between groups (MJ, HC) for the left and right OFC separately. Regression analyses between OFC functional connectivity and lifetime MJ use, age of first MJ use and impulsivity also were performed.
RESULTS: Increased OFC functional connectivity to frontal and motor regions was observed in heavy MJ users compared to HC. Earlier age of first MJ use was associated with increased functional connectivity of the right OFC to motor regions. High lifetime MJ use was associated with increased OFC functional connectivity to posterior brain regions in MJ youth.
DISCUSSION: Findings indicate atypical OFC functional connectivity patterns in attentional/executive, motor and reward networks in adolescents with heavy MJ use. These anomalies may be related to suboptimal decision making capacities and increased impulsivity. Results also suggest different OFC connectivity patterns may be present in adolescents with early onset of MJ use and high lifetime exposure to MJ.
PMID: 26296778 [PubMed - as supplied by publisher]
Mapping the mouse brain with rs-fMRI: An optimized pipeline for functional network identification.
Neuroimage. 2015 Aug 18;
Authors: Zerbi V, Grandjean J, Rudin M, Wenderoth N
The use of resting-state fMRI (rs-fMRI) in translational research is a powerful tool to assess brain connectivity and investigate neuropathology in mouse models. However, despite encouraging initial results, the characterization of consistent and robust resting state networks in mice remains a methodological challenge. One key reason is that the quality of the measured MR signal is degraded by the presence of structural noise from non-neural sources. Notably, in the current pipeline of the human connectome project a novel approach has been introduced to clean rs-fMRI data, which involves automatic artifact component classification and data cleaning (FIX). FIX does not require any external recordings of physiology or the segmentation of CSF and white matter. In this study we evaluated the performance of FIX for analyzing mouse rs-fMRI data. Our results showed that FIX can be easily applied to mouse datasets and detects true signals with 100% accuracy and true noise components with very high accuracy (>98%), thus reducing both within- and between-subject variability of rs-fMRI connectivity measurements. Using this improved pre-processing pipeline, maps of 23 resting-state circuits in mice were identified including two networks that displayed default-mode-network-like topography. Hierarchical clustering grouped these neural networks into meaningful larger functional circuits. These mouse resting state networks, which are publicly available, might serve as a reference for future work using mouse models of neurological disorders.
PMID: 26296501 [PubMed - as supplied by publisher]
Default mode network connectivity in patients with idiopathic normal pressure hydrocephalus.
J Neurosurg. 2015 Aug 21;:1-9
Authors: Khoo HM, Kishima H, Tani N, Oshino S, Maruo T, Hosomi K, Yanagisawa T, Kazui H, Watanabe Y, Shimokawa T, Aso T, Kawaguchi A, Yamashita F, Saitoh Y, Yoshimine T
OBJECT Idiopathic normal pressure hydrocephalus (iNPH) is a neurological disorder characterized by gait disturbance, cognitive impairment, and incontinence. It is unclear whether the pathophysiology of iNPH is associated with alterations in the default mode network (DMN). The authors investigated alterations in the DMN of patients with iNPH and sought to determine whether a relationship exists between the resting-state functional connectivity of the DMN and a patient's clinical symptoms. METHODS Resting-state functional MRI (rs-fMRI) was performed in 16 preoperative patients with iNPH and 15 neurologically healthy control subjects of a similar age. Independent component and dual-regression analyses were used to quantify DMN connectivity. The patients' clinical symptoms were rated according to the iNPH grading scale (iNPHGS). Each of their specific clinical symptoms were rated according to the cognitive, gait, and urinary continence domains of iNPHGS, and neurocognitive status was assessed using the Mini-Mental State Examination, Frontal Assessment Battery (FAB), and Trail Making Test Part A. The strength of DMN connectivity was compared between patients and controls, and the correlation between DMN connectivity and iNPHGS was examined using both region of interest (ROI)-based analysis and voxel-based analysis. The correlation between DMN connectivity and each of the specific clinical symptoms, as well as neurocognitive status, was examined using voxel-based analysis. RESULTS Both ROI-based and voxel-based analyses revealed reduced DMN connectivity in patients with iNPH. ROI-based analysis showed increased DMN connectivity with worsening clinical symptoms of iNPH. Consistently, voxel-based analyses revealed that DMN connectivity correlated positively with the iNPHGS score, as well as the cognitive and urinary continence domain scores, and negatively with the FAB score. The significant peak in correlation in each case was localized to the precuneus. CONCLUSIONS This is the first study to establish alterations in the DMN of patients with iNPH. DMN connectivity may be a useful indicator of the severity of clinical symptoms in patients with iNPH.
PMID: 26295919 [PubMed - as supplied by publisher]
Seizure Frequency Can Alter Brain Connectivity: Evidence from Resting-State fMRI.
AJNR Am J Neuroradiol. 2015 Aug 20;
Authors: Bharath RD, Sinha S, Panda R, Raghavendra K, George L, Chaitanya G, Gupta A, Satishchandra P
BACKGROUND AND PURPOSE: The frequency of seizures is an important factor that can alter functional brain connectivity. Analysis of this factor in patients with epilepsy is complex because of disease- and medication-induced confounders. Because patients with hot-water epilepsy generally are not on long-term drug therapy, we used seed-based connectivity analysis in these patients to assess connectivity changes associated with seizure frequency without confounding from antiepileptic drugs.
MATERIALS AND METHODS: Resting-state fMRI data from 36 patients with hot-water epilepsy (18 with frequent seizures [>2 per month] and 18 with infrequent seizures [≤2 per month]) and 18 healthy age- and sex-matched controls were analyzed for seed-to-voxel connectivity by using 106 seeds. Voxel wise paired t-test analysis (P < .005, corrected for false-discovery rate) was used to identify significant intergroup differences between these groups.
RESULTS: Connectivity analysis revealed significant differences between the 2 groups (P < .001). Patients in the frequent-seizure group had increased connectivity within the medial temporal structures and widespread areas of poor connectivity, even involving the default mode network, in comparison with those in the infrequent-seizure group. Patients in the infrequent-seizure group had focal abnormalities with increased default mode network connectivity and decreased left entorhinal cortex connectivity.
CONCLUSIONS: The results of this study suggest that seizure frequency can alter functional brain connectivity, which can be visualized by using resting-state fMRI. Imaging features such as diffuse network abnormalities, involvement of the default mode network, and recruitment of medial temporal lobe structures were seen only in patients with frequent seizures. Future studies in more common epilepsy groups, however, will be required to further establish this finding.
PMID: 26294642 [PubMed - as supplied by publisher]
Image Understanding Applications of Lattice Autoassociative Memories.
IEEE Trans Neural Netw Learn Syst. 2015 Aug 19;
Authors: Grana M, Chyzhyk D
Multivariate mathematical morphology (MMM) aims to extend the mathematical morphology from gray scale images to images whose pixels are high-dimensional vectors, such as remote sensing hyperspectral images and functional magnetic resonance images (fMRIs). Defining an ordering over the multidimensional image data space is a fundamental issue MMM, to ensure that ensuing morphological operators and filters are mathematically consistent. Recent approaches use the outputs of two-class classifiers to build such reduced orderings. This paper presents the applications of MMM built on reduced supervised orderings based on lattice autoassociative memories (LAAMs) recall error measured by the Chebyshev distance. Foreground supervised orderings use one set of training data from a foreground class, whereas background/foreground supervised orderings use two training data sets, one for each relevant class. The first case study refers to the realization of the thematic segmentation of the hyperspectral images using spatial-spectral information. Spectral classification is enhanced by a spatial processing consisting in the spatial correction guided by a watershed segmentation computed by the LAAM-based morphological operators. The approach improves the state-of-the-art hyperspectral spatial-spectral thematic map building approaches. The second case study is the analysis of resting state fMRI data, working on a data set of healthy controls, schizophrenia patients with and without auditory hallucinations. We perform two experiments: 1) the localization of differences in brain functional networks on population-dependent templates and 2) the classification of subjects into each possible pair of cases. In this data set, we find that the LAAM-based morphological features improve over the conventional correlation-based graph measure features often employed in fMRI data classification.
PMID: 26292345 [PubMed - as supplied by publisher]
Frequency of hospitalizations for pain and association with altered brain network connectivity in sickle cell disease.
J Pain. 2015 Aug 17;
Authors: Darbari DS, Hampson JP, Ichesco E, Kadom N, Vezina G, Evangelou I, Clauw DJ, Taylor JG, Harris RE
Sickle cell disease (SCD) is a hemoglobinopathy affecting more than 100,000 individuals in United States. The disease is characterized by presence of sickle hemoglobin and recurrent episodes of pain. Some individuals with SCD experience frequent hospitalizations and high burden of pain. The role of central mechanisms in SCD pain has not been explored. Twenty-five adolescents and young adults with SCD underwent functional MRI (fMRI). Participants were stratified into high or low pain groups based on the number of hospitalizations for pain in preceding 12 months. Resting state functional connectivity was analyzed using seed based and dual-regression independent component analysis. Intrinsic brain connectivity was compared between high and low pain groups and association with fetal hemoglobin, a known modifier of SCD, was explored. Patients in the high pain group displayed an excess of pro-nociceptive connectivity such as anterior cingulate to default-mode-network structures such as the precuneus, whereas patients in low pain group showed more connectivity to anti-nociceptive structures such as the peri- and sub-genual cingulate. Although a similar proportion of patients in both groups reported to be on hydroxyurea, the fetal hemoglobin levels were significantly higher in the low pain group and were associated with greater connectivity to anti-nociceptive structures. These findings support the role of central mechanisms in SCD pain. Intrinsic brain connectivity should be explored as a complementary and objective outcome measure in SCD pain research.
PERSPECTIVE: Altered connectivity patterns associated with higher pain experience in patients with sickle cell disease suggest a possible role of central mechanisms in sickle cell pain. Resting state brain connectivity studies should be explored as an effective methodology to investigate pain in sickle cell disease.
PMID: 26291276 [PubMed - as supplied by publisher]
Resting-state functional connectivity in the baboon model of genetic generalized epilepsy.
Epilepsia. 2015 Aug 20;
Authors: Salinas FS, Szabó CÁ
OBJECTIVE: The baboon provides a natural model of genetic generalized epilepsy (GGE). This study compares the intrinsic connectivity networks of epileptic and healthy control baboons using resting-state functional magnetic resonance imaging (rs-fMRI) and data-driven functional connectivity mapping.
METHODS: Twenty baboons, matched for gender, age, and weight, were classified into two groups (10 epileptic [EPI], 10 control [CTL]) on the basis of scalp electroencephalography (EEG) findings. Each animal underwent one MRI session that acquired one 5-min resting state fMRI scan and one anatomic MRI scan-used for registration and spatial normalization. Using independent component analysis, we identified 14 unique components/networks, which were then used to characterize each group's functional connectivity maps of each brain network.
RESULTS: The epileptic group demonstrated network-specific differences in functional connectivity when compared to the control animals. The sensitivity and specificity of the two groups' functional connectivity maps differed significantly in the visual, motor, amygdala, insular, and default mode networks. Significant increases were found in the occipital gyri of the epileptic group's functional connectivity map for the default mode, cingulate, intraparietal, motor, visual, amygdala, and thalamic regions.
SIGNIFICANCE: This is the first study using resting-state fMRI to demonstrate intrinsic functional connectivity differences between epileptic and control nonhuman primates. These results are consistent with seed-based GGE studies in humans; however, our use of a data-driven approach expands the scope of functional connectivity mapping to include brain regions/networks comprising the whole brain.
PMID: 26290449 [PubMed - as supplied by publisher]
Negative childhood experiences alter a prefrontal-insular-motor cortical network in healthy adults: A preliminary multimodal rsfMRI-fMRI-MRS-dMRI study.
Hum Brain Mapp. 2015 Aug 19;
Authors: Duncan NW, Hayes DJ, Wiebking C, Tiret B, Pietruska K, Chen DQ, Rainville P, Marjańska M, Ayad O, Doyon J, Hodaie M, Northoff G
Research in humans and animals has shown that negative childhood experiences (NCE) can have long-term effects on the structure and function of the brain. Alterations have been noted in grey and white matter, in the brain's resting state, on the glutamatergic system, and on neural and behavioural responses to aversive stimuli. These effects can be linked to psychiatric disorder such as depression and anxiety disorders that are influenced by excessive exposure to early life stressors. The aim of the current study was to investigate the effect of NCEs on these systems. Resting state functional MRI (rsfMRI), aversion task fMRI, glutamate magnetic resonance spectroscopy (MRS), and diffusion magnetic resonance imaging (dMRI) were combined with the Childhood Trauma Questionnaire (CTQ) in healthy subjects to examine the impact of NCEs on the brain. Low CTQ scores, a measure of NCEs, were related to higher resting state glutamate levels and higher resting state entropy in the medial prefrontal cortex (mPFC). CTQ scores, mPFC glutamate and entropy, correlated with neural BOLD responses to the anticipation of aversive stimuli in regions throughout the aversion-related network, with strong correlations between all measures in the motor cortex and left insula. Structural connectivity strength, measured using mean fractional anisotropy, between the mPFC and left insula correlated to aversion-related signal changes in the motor cortex. These findings highlight the impact of NCEs on multiple inter-related brain systems. In particular, they highlight the role of a prefrontal-insular-motor cortical network in the processing and responsivity to aversive stimuli and its potential adaptability by NCEs. Hum Brain Mapp, 2015. © 2015 Wiley Periodicals, Inc.
PMID: 26287448 [PubMed - as supplied by publisher]
Breakdown of Sensorimotor Network Communication in Leukoaraiosis.
Neurodegener Dis. 2015 Aug 20;
Authors: Wu X, Lai Y, Zhang Y, Yao L, Wen X
BACKGROUND: Leukoaraiosis (LA) patients may suffer from sensorimotor dysfunctions. The relationship between behavioral disturbances and changes in the sensorimotor network (SMN) has not been thoroughly elucidated.
OBJECTIVE: This study investigated the hypothesized breakdown of communication of SMN and its behavioral consequences in LA.
METHODS: Fluid-attenuated inversion recovery (FLAIR) images, resting-state functional magnetic resonance images (fMRI) and behavioral data were collected from 30 LA patients and 26 healthy individuals (normal controls, NC). The subjects were grouped according to LA severity, as indicated by their FLAIR images. Group independent component analysis was applied to the fMRI data to map the functional connectivity of SMN for NC and LA patients. A whole-brain, voxel-wise analysis was employed to investigate the functional connectivity alteration of SMN in LA. The relationships between LA severity, functional connectivity alteration of the SMN and behavioral clinical symptoms were examined by correlation analysis.
RESULTS: The right cingulate motor area (rCMA), left posterior insula and left ventral premotor area showed attenuated functional connectivity in the LA patients. The extent of the attenuation was related to the severity of the disease. Furthermore, the attenuation in the rCMA was associated with worse sensorimotor integration performance.
CONCLUSIONS: These results suggest that LA impairs sensorimotor integration by interfering with the communication or coordination of these aforementioned regions related to the SMN.
PMID: 26287381 [PubMed - as supplied by publisher]
Improvement in Touch Sensation after Stroke is Associated with Resting Functional Connectivity Changes.
Front Neurol. 2015;6:165
Authors: Bannister LC, Crewther SG, Gavrilescu M, Carey LM
BACKGROUND: Distributed brain networks are known to be involved in facilitating behavioral improvement after stroke, yet few, if any, studies have investigated the relationship between improved touch sensation after stroke and changes in functional brain connectivity.
OBJECTIVE: We aimed to identify how recovery of somatosensory function in the first 6 months after stroke was associated with functional network changes as measured using resting-state connectivity analysis of functional magnetic resonance imaging (fMRI) data.
METHODS: Ten stroke survivors underwent clinical testing and resting-state fMRI scans at 1 and 6 months post-stroke. Ten age-matched healthy participants were included as controls.
RESULTS: Patients demonstrated a wide range of severity of touch impairment 1 month post-stroke, followed by variable improvement over time. In the stroke group, significantly stronger interhemispheric functional correlations between regions of the somatosensory system, and with visual and frontal areas, were found at 6 months than at 1 month post-stroke. Clinical improvement in touch discrimination was associated with stronger correlations at 6 months between contralesional secondary somatosensory cortex (SII) and inferior parietal cortex and middle temporal gyrus, and between contralesional thalamus and cerebellum.
CONCLUSION: The strength of connectivity between somatosensory regions and distributed brain networks, including vision and attention networks, may change over time in stroke survivors with impaired touch discrimination. Connectivity changes from contralesional SII and contralesional thalamus are associated with improved touch sensation at 6 months post-stroke. These functional connectivity changes could represent future targets for therapy.
PMID: 26284024 [PubMed]
Attentional performance is correlated with the local regional efficiency of intrinsic brain networks.
Front Behav Neurosci. 2015;9:200
Authors: Xu J, Yin X, Ge H, Han Y, Pang Z, Tang Y, Liu B, Liu S
Attention is a crucial brain function for human beings. Using neuropsychological paradigms and task-based functional brain imaging, previous studies have indicated that widely distributed brain regions are engaged in three distinct attention subsystems: alerting, orienting and executive control (EC). Here, we explored the potential contribution of spontaneous brain activity to attention by examining whether resting-state activity could account for individual differences of the attentional performance in normal individuals. The resting-state functional images and behavioral data from attention network test (ANT) task were collected in 59 healthy subjects. Graph analysis was conducted to obtain the characteristics of functional brain networks and linear regression analyses were used to explore their relationships with behavioral performances of the three attentional components. We found that there was no significant relationship between the attentional performance and the global measures, while the attentional performance was associated with specific local regional efficiency. These regions related to the scores of alerting, orienting and EC largely overlapped with the regions activated in previous task-related functional imaging studies, and were consistent with the intrinsic dorsal and ventral attention networks (DAN/VAN). In addition, the strong associations between the attentional performance and specific regional efficiency suggested that there was a possible relationship between the DAN/VAN and task performances in the ANT. We concluded that the intrinsic activity of the human brain could reflect the processing efficiency of the attention system. Our findings revealed a robust evidence for the functional significance of the efficiently organized intrinsic brain network for highly productive cognitions and the hypothesized role of the DAN/VAN at rest.
PMID: 26283939 [PubMed]
Brain system for mental orientation in space, time, and person.
Proc Natl Acad Sci U S A. 2015 Aug 17;
Authors: Peer M, Salomon R, Goldberg I, Blanke O, Arzy S
Orientation is a fundamental mental function that processes the relations between the behaving self to space (places), time (events), and person (people). Behavioral and neuroimaging studies have hinted at interrelations between processing of these three domains. To unravel the neurocognitive basis of orientation, we used high-resolution 7T functional MRI as 16 subjects compared their subjective distance to different places, events, or people. Analysis at the individual-subject level revealed cortical activation related to orientation in space, time, and person in a precisely localized set of structures in the precuneus, inferior parietal, and medial frontal cortex. Comparison of orientation domains revealed a consistent order of cortical activity inside the precuneus and inferior parietal lobes, with space orientation activating posterior regions, followed anteriorly by person and then time. Core regions at the precuneus and inferior parietal lobe were activated for multiple orientation domains, suggesting also common processing for orientation across domains. The medial prefrontal cortex showed a posterior activation for time and anterior for person. Finally, the default-mode network, identified in a separate resting-state scan, was active for all orientation domains and overlapped mostly with person-orientation regions. These findings suggest that mental orientation in space, time, and person is managed by a specific brain system with a highly ordered internal organization, closely related to the default-mode network.
PMID: 26283353 [PubMed - as supplied by publisher]