New resting-state fMRI related studies at PubMed

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Resting-state Functional Magnetic Resonance Imaging Analysis of Brain Functional Activity in Rats with Ischemic Stroke Treated by Electro-acupuncture.

Sun, 07/09/2017 - 14:00
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Resting-state Functional Magnetic Resonance Imaging Analysis of Brain Functional Activity in Rats with Ischemic Stroke Treated by Electro-acupuncture.

J Stroke Cerebrovasc Dis. 2017 Jul 04;:

Authors: Liang S, Lin Y, Lin B, Li J, Liu W, Chen L, Zhao S, Tao J

Abstract
OBJECTIVE: To evaluate whether electro-acupuncture (EA) treatment at acupoints of Zusanli (ST 36) and Quchi (LI 11) could reduce motor impairments and enhance brain functional recovery in rats with ischemic stroke.
MATERIALS AND METHODS: A rat model of middle cerebral artery occlusion (MCAO) was established. EA at ST 36 and LI 11was started at 24 hours (MCAO + EA group) after ischemic stroke. The nontreatment (MCAO) and sham-operated control (SC) groups were included as controls. The neurologic deficits of all groups were assessed by Zea Longa scores and the modified neurologic severity scores on 24 hours and 8 days after MCAO. To further investigate the effect of EA on infract volume and brain function, magnetic resonance imaging was used to estimate the brain lesion and brain neural activities of each group at 8 days after ischemic stroke.
RESULTS: Within 1 week after EA treatment, the neurologic deficits were significantly alleviated, and the cerebral infarctions were improved, including visual cortex, motor cortex, striatum, dorsal thalamus, and hippocampus. Furthermore, whole brain neural activities of auditory cortex, lateral nucleus group of dorsal thalamus, hippocampus, motor cortex, orbital cortex, sensory cortex, and striatum were decreased in MCAO group, whereas that of brain neural activities were increased after EA treatment, suggesting these brain regions are in accordance with the brain structure analysis.
CONCLUSION: EA at ST 36 and LI 11 could enhance the neural activity of motor function-related brain regions, including motor cortex, dorsal thalamus, and striatum in rats, which is a potential treatment for ischemia stroke.

PMID: 28687422 [PubMed - as supplied by publisher]

Influence of physiological noise on accelerated 2D and 3D resting state functional MRI data at 7 T.

Sat, 07/08/2017 - 13:00

Influence of physiological noise on accelerated 2D and 3D resting state functional MRI data at 7 T.

Magn Reson Med. 2017 Jul 07;:

Authors: Reynaud O, Jorge J, Gruetter R, Marques JP, van der Zwaag W

Abstract
PURPOSE: Physiological noise often dominates the blood-oxygen level-dependent (BOLD) signal fluctuations in high-field functional MRI (fMRI) data. Therefore, to optimize fMRI protocols, it becomes crucial to investigate how physiological signal fluctuations impact various acquisition and reconstruction schemes at different acquisition speeds. In particular, further differences can arise between 2D and 3D fMRI acquisitions due to different encoding strategies, thereby impacting fMRI sensitivity in potentially significant ways.
METHODS: The amount of physiological noise to be removed from the BOLD fMRI signal acquired at 7 T was quantified for different sampling rates (repetition time from 3300 to 350 ms, acceleration 1 to 8) and techniques dedicated to fast fMRI (simultaneous multislice echo planar imaging [EPI] and 3D EPI). Resting state fMRI (rsfMRI) performances were evaluated using temporal signal-to-noise ratio (tSNR) and network characterization based on seed correlation and independent component analysis.
RESULTS: Overall, acceleration enhanced tSNR and rsfMRI metrics. 3D EPI benefited the most from physiological noise removal at long repetition times. Differences between 2D and 3D encoding strategies disappeared at high acceleration factors (6- to 8-fold).
CONCLUSION: After physiological noise correction, 2D- and 3D-accelerated sequences provide similar performances at high fields, both in terms of tSNR and resting state network identification and characterization. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine.

PMID: 28686788 [PubMed - as supplied by publisher]

Altered Spontaneous Brain Activity in Children with Early Tourette Syndrome: a Resting-state fMRI Study.

Sat, 07/08/2017 - 13:00
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Altered Spontaneous Brain Activity in Children with Early Tourette Syndrome: a Resting-state fMRI Study.

Sci Rep. 2017 Jul 06;7(1):4808

Authors: Liu Y, Wang J, Zhang J, Wen H, Zhang Y, Kang H, Wang X, Li W, He H, Peng Y

Abstract
Tourette syndrome (TS) is a childhood-onset chronic disorder characterized by the presence of multiple motor and vocal tics. This study investigated the alterations of spontaneous brain activities in children with TS by resting-state functional magnetic resonance imaging (rs-fMRI). We obtained rs-fMRI scans from 21 drug-naïve and pure TS children and 29 demographically matched healthy children. The amplitude of low-frequency fluctuation (ALFF), fractional ALFF (fALFF) and regional homogeneity (ReHo) of rs-fMRI data were calculated to measure spontaneous brain activity. We found significant alterations of ALFF or fALFF in vision-related structures including the calcarine sulcus, the cuneus, the fusiform gyrus, and the left insula in TS children. Decreased ReHo was found in the right cerebellum. Further analysis showed that the ReHo value of the right cerebellum was positively correlated with TS duration. Our study provides empirical evidence for abnormal spontaneous neuronal activity in TS patients, which may implicate the neurophysiological mechanism in TS children. Moreover, the right cerebellum can be potentially used as a biomarker for the pathophysiology of early TS in children.

PMID: 28684794 [PubMed - in process]

Just a thought: How mind-wandering is represented in dynamic brain connectivity.

Sat, 07/08/2017 - 13:00
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Just a thought: How mind-wandering is represented in dynamic brain connectivity.

Neuroimage. 2017 Jul 03;:

Authors: Kucyi A

Abstract
The neuroscience of mind-wandering has begun to flourish, with roles of brain regions and networks being defined for various components of spontaneous thought. However, often underappreciated is that most of brain activity does not represent immediately occurring thoughts. Instead, spontaneous, organized network activity largely reflects "intrinsic" functions that are unrelated to the current experience. There remains no consensus on how brain networks represent mind-wandering in parallel to functioning in other ongoing, predominantly unconscious processes. Commonly, in network analysis of functional neuroimaging data, functional connectivity (FC; correlated time series) between remote brain regions is considered over several minutes or longer. In contrast, dynamic functional connectivity (dFC) is a new, promising approach to characterizing spontaneous changes in neural network communication on the faster time-scale at which intra-individual fluctuations in thought contents may occur. Here I describe how a potential relationship between mind-wandering and FC has traditionally been considered in the literature, and I review methods and results pertaining to the study of the dFC-mind-wandering relationship. While acknowledging challenges to the dFC approach and to behaviorally capturing fluctuations in inner experiences, I describe a framework for describing spontaneous thoughts in terms of brain-network activity patterns that are comprised of connections weighted by time-varying relevance to conscious and unconscious processing. This perspective suggests preferential roles of certain anatomical communication avenues (e.g., via the default mode network) in mind-wandering, while also implying that a region's connectivity fluctuates over time in its immediate degree of relevance to conscious contents, ultimately allowing novelty and diversity of thought.

PMID: 28684334 [PubMed - as supplied by publisher]

Reduced functional connectivity between bilateral precuneus and contralateral parahippocampus in schizotypal personality disorder.

Sat, 07/08/2017 - 13:00
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Reduced functional connectivity between bilateral precuneus and contralateral parahippocampus in schizotypal personality disorder.

BMC Psychiatry. 2017 Feb 02;17(1):48

Authors: Zhu Y, Tang Y, Zhang T, Li H, Tang Y, Li C, Luo X, He Y, Lu Z, Wang J

Abstract
BACKGROUND: Schizotypal personality disorder (SPD) is linked to schizophrenia in terms of shared genetics, biological markers and phenomenological characteristics. In the current study, we aimed to determine whether the previously reported altered functional connectivity (FC) with precuneus in patients with schizophrenia could be extended to individuals with SPD.
METHODS: Twenty subjects with SPD and 19 healthy controls were recruited from 4461 freshmen at a university in Shanghai and received a resting-state scan of MRI. All participants were evaluated by the Chinese version of Schizotypal Personality Questionnaire (SPQ) and the Chinese version of Symptom Checklist (SCL-90). The imaging data were analysed using the seed-based functional connectivity method.
RESULTS: Compared with the controls, SPD subjects exhibited reduced FC between bilateral precuneus and contralateral parahippocampus. In SPD group, SPQ total score was negatively correlated with FC between right precuneus and left parahippocampus (r = -0.603, p = 0.006); there was a negative trend between SPQ subscale score of suspiciousness and FC between left precuneus and right parahippocampus (r = -0.553, p = 0.014); and a positive trend was found between SPQ subscale score of odd or eccentric behaviour and FC between left precuneus and right superior temporal gyrus (r = 0.543, p = 0.016). As for the SCL-90 score, a similar negative trend was found between SCL-90 subscale score of suspiciousness and FC between right precuneus and left parahippocampus (r = -0.535, p = 0.018) in SPD group.
CONCLUSIONS: Our findings suggest that the decreased functional connectivity between precuneus and contralateral parahippocampus might play a key role in the pathophysiology of schizophrenia spectrum disorder.

PMID: 28152990 [PubMed - indexed for MEDLINE]

Increased interhemispheric resting-state functional connectivity in healthy participants with insomnia symptoms: A randomized clinical consort study.

Fri, 07/07/2017 - 11:40
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Increased interhemispheric resting-state functional connectivity in healthy participants with insomnia symptoms: A randomized clinical consort study.

Medicine (Baltimore). 2017 Jul;96(27):e7037

Authors: Li X, Guo S, Wang C, Wang B, Sun H, Zhang X

Abstract
BACKGROUND: Abnormalities within the insular cortex of the salience and thalamus of the hyperarousal network have been increasingly reported in healthy participants with insomnia symptoms by recent resting-state functional magnetic resonance imaging (rsfMRI) studies. However, little is known about the changes in functional interaction between the bilateral cerebral hemispheres in healthy participants with insomnia symptoms.
METHODS: In a randomized trial, 27 healthy participants with insomnia symptoms and 27 age-, gender-, and educational level-matched healthy participants without insomnia symptoms underwent rsfMRI. Voxel-mirrored homotopic connectivity (VMHC) was used to measure functional connectivity between any pair of symmetrical interhemispheric voxels (i.e., functional homotopy).
RESULTS: The healthy participants with insomnia symptoms displayed significantly increased VMHC compared to healthy participants without insomnia symptoms in the bilateral thalamus/posterior insula (including anterior insula), fusiform, middle cingulate gyrus, inferior parietal lobe, and postcentral gyrus. No regions of decreased VMHC were detected in healthy participants with insomnia symptoms. There were significantly positive correlations between the VMHC values in the anterior cingulate cortex (ACC) and sleep disturbance scores in all healthy participants.
CONCLUSIONS: Insomnia is associated with substantial impairment of interhemispheric coordination within the default mode (ACC), salience (insula), hyperarousal (thalamus/posterior insula), and visual (fusiform) networks.

PMID: 28682863 [PubMed - in process]

Fused estimation of sparse connectivity patterns from rest fMRI. Application to comparison of children and adult brains.

Fri, 07/07/2017 - 11:40
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Fused estimation of sparse connectivity patterns from rest fMRI. Application to comparison of children and adult brains.

IEEE Trans Med Imaging. 2017 Jun 29;:

Authors: Zille P, Calhoun VD, Stephen JM, Wilson TW, Wang YP

Abstract
In this work, we consider the problem of estimating multiple sparse, co-activated brain regions from functional magnetic resonance imaging (fMRI) observations belonging to different classes. More precisely, we propose a method to analyze similarities and differences in functional connectivity between children and young adults. Often, analysis is conducted on each class separately, and differences across classes are identified with an additional postprocessing step using adequate statistical tools. Here, we propose to rely on a generalized fused Lasso penalty, which allows us to make use of the entire dataset in order to estimate connectivity patterns that are either shared across classes, or specific to a given group. By using the entire population during the estimation, we hope to increase the power of our analysis. The proposed model falls in the category of population-wise matrix decomposition, and a simple and efficient alternating direction method of multipliers (ADMM) algorithm is introduced to solve the associated optimization problem. After validating our approach on simulated data, experiments are performed on resting-state fMRI imaging from the Philadelphia Neurodevelopmental Cohort (PNC) dataset, comprised of normally developing children from ages 8 to 21. Developmental differences were observed in various brain regions, as a total of 3 class-specific resting-state components were identified. Statistical analysis of the estimated subject-specific features, as well as classification results (based on age groups, up to 81% accuracy, n = 583 samples) related to these components demonstrate that the proposed method is able to properly extract meaningful shared and class-specific sub-networks.

PMID: 28682248 [PubMed - as supplied by publisher]

The anatomical scaffold underlying the functional centrality of known cortical hubs.

Fri, 07/07/2017 - 11:40
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The anatomical scaffold underlying the functional centrality of known cortical hubs.

Hum Brain Mapp. 2017 Jul 06;:

Authors: de Pasquale F, Della Penna S, Sabatini U, Caravasso Falletta C, Peran P

Abstract
Cortical hubs play a fundamental role in the functional architecture of brain connectivity at rest. However, the anatomical scaffold underlying their centrality is still under debate. Certainly, the brain function and anatomy are significantly entwined through synaptogenesis and pruning mechanisms that continuously reshape structural and functional connections. Thus, if hubs are expected to exhibit a large number of direct anatomical connections with the rest of the brain, such a dense wiring is extremely inefficient in energetic terms. In this work, we investigate these aspects on fMRI and DTI data from a set of know resting-state networks, starting from the hypothesis that to promote integration, functional, and anatomical connections link different areas at different scales or hierarchies. Thus, we focused on the role of functional hubs in this hierarchical organization of functional and anatomical architectures. We found that these regions, from a structural point of view, are first linked to each other and successively to the rest of the brain. Thus, functionally central nodes seem to show few strong anatomical connections. These findings suggest an efficient strategy of the investigated cortical hubs in exploiting few direct anatomical connections to link functional hubs among each other that eventually reach the rest of the considered nodes through local indirect tracts. Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc.

PMID: 28681960 [PubMed - as supplied by publisher]

Abnormal Functional Connectivity of Ventral Anterior Insula in Asthmatic Patients with Depression.

Fri, 07/07/2017 - 11:40
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Abnormal Functional Connectivity of Ventral Anterior Insula in Asthmatic Patients with Depression.

Neural Plast. 2017;2017:7838035

Authors: Zhang Y, Yang Y, Bian R, Yin Y, Hou Z, Yue Y, Xu Z, Yuan Y

Abstract
OBJECTIVE: To explore the underlying mechanism of depression in asthmatic patients, the ReHo in the insula and its FC was used to probe the differences between depressed asthmatic (DA) and nondepressed asthmatic (NDA) patients.
METHODS: 18 DA patients, 24 NDA patients, and 60 healthy controls (HCs) received resting-state fMRI scan, severity of depression, and asthma control assessment.
RESULTS: DA patients showed increased FC between the left ventral anterior insula (vAI) and the left middle temporal gyrus compared with both NDA and HC groups. In addition, compared with HCs, the DA and NDA patients both exhibited increased FC between the left vAI and the right anterior cingulate cortex (ACC), decreased FC between the left vAI and the bilateral parietal lobe, and increased FC between the right vAI and the left putamen and the right caudate, respectively. Furthermore, the increased FC between the left vAI and the right ACC could differentiate HCs from both DA and NDA patients, and the increased FC between the right vAI and both the left putamen and the right caudate could separate NDA patients from HCs.
CONCLUSIONS: This study confirmed that abnormal vAI FC may be involved in the neuropathology of depression in asthma. The increased FC between the left vAI and the left MTG could distinguish DA from the NDA and HC groups.

PMID: 28680706 [PubMed - in process]

A Comprehensive Analysis of the Correlations between Resting-State Oscillations in Multiple-Frequency Bands and Big Five Traits.

Fri, 07/07/2017 - 11:40
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A Comprehensive Analysis of the Correlations between Resting-State Oscillations in Multiple-Frequency Bands and Big Five Traits.

Front Hum Neurosci. 2017;11:321

Authors: Ikeda S, Takeuchi H, Taki Y, Nouchi R, Yokoyama R, Kotozaki Y, Nakagawa S, Sekiguchi A, Iizuka K, Yamamoto Y, Hanawa S, Araki T, Miyauchi CM, Sakaki K, Nozawa T, Yokota S, Magistro D, Kawashima R

Abstract
Recently, the association between human personality traits and resting-state brain activity has gained interest in neuroimaging studies. However, it remains unclear if Big Five personality traits are represented in frequency bands (~0.25 Hz) of resting-state functional magnetic resonance imaging (fMRI) activity. Based on earlier neurophysiological studies, we investigated the correlation between the five personality traits assessed by the NEO Five-Factor Inventory (NEO-FFI), and the fractional amplitude of low-frequency fluctuation (fALFF) at four distinct frequency bands (slow-5 (0.01-0.027 Hz), slow-4 (0.027-0.073 Hz), slow-3 (0.073-0.198 Hz) and slow-2 (0.198-0.25 Hz)). We enrolled 835 young subjects and calculated the correlations of resting-state fMRI signals using a multiple regression analysis. We found a significant and consistent correlation between fALFF and the personality trait of extraversion at all frequency bands. Furthermore, significant correlations were detected in distinct brain regions for each frequency band. This finding supports the frequency-specific spatial representations of personality traits as previously suggested. In conclusion, our data highlight an association between human personality traits and fALFF at four distinct frequency bands.

PMID: 28680397 [PubMed - in process]

Altered interhemispheric functional connectivity in remitted bipolar disorder: A Resting State fMRI Study.

Fri, 07/07/2017 - 11:40
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Altered interhemispheric functional connectivity in remitted bipolar disorder: A Resting State fMRI Study.

Sci Rep. 2017 Jul 05;7(1):4698

Authors: Zhao L, Wang Y, Jia Y, Zhong S, Sun Y, Qi Z, Zhang Z, Huang L

Abstract
Abnormalities in structural and functional brain connectivity have been increasingly reported in patients with bipolar disorder (BD). However, alterations of remitted BD (RBD) in functional connectivity between the cerebral hemispheres are still not well understood. This study was designed to analyze the pattern of the interhemispheric functional connectivity of the whole brain in patients with remitted BD during resting state. Twenty patients with RBD and 38 healthy controls (HC) underwent the resting-state functional magnetic resonance imaging. The functional connectivity between any pair of symmetrical interhemispheric voxels (i.e., functional homotopy) was measured by voxel-mirrored homotopic connectivity (VMHC). The patients with RBD showed lower VMHC than HC in the middle frontal gyrus and precentral gyrus. No regions of increased VMHC were detected in the RBD patients. There were no significant correlations between the VMHC values in these regions and the clinical variables. These findings suggest substantial impairment of interhemispheric coordination in RBD and they may represent trait, rather than state, neurobiological feature of brain function in BD.

PMID: 28680123 [PubMed - in process]

Altered brain network centrality in patients with adult comitant exotropia strabismus: A resting-state fMRI study.

Fri, 07/07/2017 - 11:40
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Altered brain network centrality in patients with adult comitant exotropia strabismus: A resting-state fMRI study.

J Int Med Res. 2017 Jan 01;:300060517715340

Authors: Tan G, Dan ZR, Zhang Y, Huang X, Zhong YL, Ye LH, Rong R, Ye L, Zhou Q, Shao Y

Abstract
Objective To investigate the underlying functional network brain-activity changes in patients with adult comitant exotropia strabismus (CES) and the relationship with clinical features using the voxel-wise degree centrality (DC) method. Methods A total of 30 patients with CES (17 men, 13 women), and 30 healthy controls (HCs; 17 men, 13 women) matched in age, sex, and education level participated in the study. DC was used to evaluate spontaneous brain activity. Receiver operating characteristic (ROC) curve analysis was conducted to distinguish CESs from HCs. The relationship between mean DC values in various brain regions and behavioral performance was examined with correlation analysis. Results Compared with HCs, CES patients exhibited decreased DC values in the right cerebellum posterior lobe, right inferior frontal gyrus, right middle frontal gyrus and right superior parietal lobule/primary somatosensory cortex (S1), and increased DC values in the right superior temporal gyrus, bilateral anterior cingulate, right superior temporal gyrus, and left inferior parietal lobule. However, there was no correlation between mean DC values and behavioral performance in any brain regions. Conclusions Adult comitant exotropia strabismus is associated with abnormal brain network activity in various brain regions, possibly reflecting the pathological mechanisms of ocular motility disorders in CES.

PMID: 28679330 [PubMed - as supplied by publisher]

Sample heterogeneity in unipolar depression as assessed by functional connectivity analyses is dominated by general disease effects.

Thu, 07/06/2017 - 10:20

Sample heterogeneity in unipolar depression as assessed by functional connectivity analyses is dominated by general disease effects.

J Affect Disord. 2017 Jun 27;222:79-87

Authors: Feder S, Sundermann B, Wersching H, Teuber A, Kugel H, Teismann H, Heindel W, Berger K, Pfleiderer B

Abstract
OBJECTIVES: Combinations of resting-state fMRI and machine-learning techniques are increasingly employed to develop diagnostic models for mental disorders. However, little is known about the neurobiological heterogeneity of depression and diagnostic machine learning has mainly been tested in homogeneous samples. Our main objective was to explore the inherent structure of a diverse unipolar depression sample. The secondary objective was to assess, if such information can improve diagnostic classification.
MATERIALS AND METHODS: We analyzed data from 360 patients with unipolar depression and 360 non-depressed population controls, who were subdivided into two independent subsets. Cluster analyses (unsupervised learning) of functional connectivity were used to generate hypotheses about potential patient subgroups from the first subset. The relationship of clusters with demographical and clinical measures was assessed. Subsequently, diagnostic classifiers (supervised learning), which incorporated information about these putative depression subgroups, were trained.
RESULTS: Exploratory cluster analyses revealed two weakly separable subgroups of depressed patients. These subgroups differed in the average duration of depression and in the proportion of patients with concurrently severe depression and anxiety symptoms. The diagnostic classification models performed at chance level.
LIMITATIONS: It remains unresolved, if subgroups represent distinct biological subtypes, variability of continuous clinical variables or in part an overfitting of sparsely structured data.
CONCLUSIONS: Functional connectivity in unipolar depression is associated with general disease effects. Cluster analyses provide hypotheses about potential depression subtypes. Diagnostic models did not benefit from this additional information regarding heterogeneity.

PMID: 28679115 [PubMed - as supplied by publisher]

Functional brain MRI in patients complaining of electrohypersensitivity after long term exposure to electromagnetic fields.

Thu, 07/06/2017 - 10:20

Functional brain MRI in patients complaining of electrohypersensitivity after long term exposure to electromagnetic fields.

Rev Environ Health. 2017 Jul 05;:

Authors: Heuser G, Heuser SA

Abstract
INTRODUCTION: Ten adult patients with electromagnetic hypersensitivity underwent functional magnetic resonance imaging (fMRI) brain scans. All scans were abnormal with abnormalities which were consistent and similar. It is proposed that fMRI brain scans be used as a diagnostic aid for determining whether or not a patient has electromagnetic hypersensitivity. Over the years we have seen an increasing number of patients who had developed multi system complaints after long term repeated exposure to electromagnetic fields (EMFs). These complaints included headaches, intermittent cognitive and memory problems, intermittent disorientation, and also sensitivity to EMF exposure. Regular laboratory tests were within normal limits in these patients. The patients refused to be exposed to radioactivity. This of course ruled out positron emission tomography (PET) and single-photon emission computed tomography (SPECT) brain scanning. This is why we ordered fMRI brain scans on these patients. We hoped that we could document objective abnormalities in these patients who had often been labeled as psychiatric cases.
MATERIALS AND METHODS: Ten patients first underwent a regular magnetic resonance imaging (MRI) brain scan, using a 3 Tesla Siemens Verio MRI open system. A functional MRI study was then performed in the resting state using the following sequences: A three-dimensional, T1-weighted, gradient-echo (MPRAGE) Resting state network. The echo-planar imaging (EPI) sequences for this resting state blood oxygenation level dependent (BOLD) scan were then post processed on a 3D workstation and the independent component analysis was performed separating out the various networks. Arterial spin labeling. Tractography and fractional anisotropy.
RESULTS: All ten patients had abnormal functional MRI brain scans. The abnormality was often described as hyper connectivity of the anterior component of the default mode in the medial orbitofrontal area. Other abnormalities were usually found. Regular MRI studies of the brain were mostly unremarkable in these patients.
CONCLUSION: We propose that functional MRI studies should become a diagnostic aid when evaluating a patient who claims electrohypersensitivity (EHS) and has otherwise normal studies. Interestingly, the differential diagnosis for the abnormalities seen on the fMRI includes head injury. It turns out that many of our patients indeed had a history of head injury which was then followed sometime later by the development of EHS. Many of our patients also had a history of exposure to potentially neurotoxic chemicals, especially mold. Head injury and neurotoxic chemical exposure may make a patient more vulnerable to develop EHS.

PMID: 28678737 [PubMed - as supplied by publisher]

Brain network dynamics in high-functioning individuals with autism.

Thu, 07/06/2017 - 10:20

Brain network dynamics in high-functioning individuals with autism.

Nat Commun. 2017 Jul 05;8:16048

Authors: Watanabe T, Rees G

Abstract
Theoretically, autism should be underpinned by aberrant brain dynamics. However, how brain activity changes over time in individuals with autism spectrum disorder (ASD) remains unknown. Here we characterize brain dynamics in autism using an energy-landscape analysis applied to resting-state fMRI data. Whereas neurotypical brain activity frequently transits between two major brain states via an intermediate state, high-functioning adults with ASD show fewer neural transitions due to an unstable intermediate state, and these infrequent transitions predict the severity of autism. Moreover, in contrast to the controls whose IQ is correlated with the neural transition frequency, IQ scores of individuals with ASD are instead predicted by the stability of their brain dynamics. Finally, such brain-behaviour associations are related to functional segregation between brain networks. These findings suggest that atypical functional coordination in the brains of adults with ASD underpins overly stable neural dynamics, which supports both their ASD symptoms and cognitive abilities.

PMID: 28677689 [PubMed - in process]

Functional connectivity density mapping: comparing multiband and conventional EPI protocols.

Thu, 07/06/2017 - 10:20

Functional connectivity density mapping: comparing multiband and conventional EPI protocols.

Brain Imaging Behav. 2017 Jul 04;:

Authors: Cohen AD, Tomasi D, Shokri-Kojori E, Nencka AS, Wang Y

Abstract
Functional connectivity density mapping (FCDM) is a newly developed data-driven technique that quantifies the number of local and global functional connections for each voxel in the brain. In this study, we evaluated reproducibility, sensitivity, and specificity of both local functional connectivity density (lFCD) and global functional connectivity density (gFCD). We compared these metrics using the human connectome project (HCP) compatible high-resolution (2 mm isotropic, TR = 0.8 s) multiband (MB), and more typical, lower resolution (3.5 mm isotropic, TR = 2.0 s) single-band (SB) resting state functional MRI (rs-fMRI) acquisitions. Furthermore, in order to be more clinically feasible, only rs-fMRI scans that lasted seven minutes were tested. Subjects were scanned twice within a two-week span. We found sensitivity and specificity increased and reproducibility either increased or did not change for the MB compared to the SB acquisitions. The MB scans also showed improved gray matter/white matter contrast compared to the SB scans. The lFCD and gFCD patterns were similar across MB and SB scans and confined predominantly to gray matter. We also observed a strong spatial correlation of FCD between MB and SB scans indicating the two acquisitions provide similar information. These findings indicate high-resolution MB acquisitions improve the quality of FCD data, and seven minute rs-fMRI scan can provide robust FCD measurements.

PMID: 28676985 [PubMed - as supplied by publisher]

Joint prediction of multiple scores captures better individual traits from brain images.

Thu, 07/06/2017 - 10:20

Joint prediction of multiple scores captures better individual traits from brain images.

Neuroimage. 2017 Jul 01;:

Authors: Rahim M, Thirion B, Bzdok D, Buvat I, Varoquaux G

Abstract
To probe individual variations in brain organization, population imaging relates features of brain images to rich descriptions of the subjects such as genetic information or behavioral and clinical assessments. Capturing common trends across these measurements is important: they jointly characterize the disease status of patient groups. In particular, mapping imaging features to behavioral scores with predictive models opens the way toward more precise diagnosis. Here we propose to jointly predict all the dimensions (behavioral scores) that make up the individual profiles, using so-called multi-output models. This approach often boosts prediction accuracy by capturing latent shared information across scores. We demonstrate the efficiency of multi-output models on two independent resting-state fMRI datasets targeting different brain disorders (Alzheimer's Disease and schizophrenia). Furthermore, the model with joint prediction generalizes much better to a new cohort: a model learned on one study is more accurately transferred to an independent one. Finally, we show how multi-output models can easily be extended to multi-modal settings, combining heterogeneous data sources for a better overall accuracy.

PMID: 28676298 [PubMed - as supplied by publisher]

Electrographic patterns in patients with posterior reversible encephalopathy syndrome and seizures.

Thu, 07/06/2017 - 10:20
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Electrographic patterns in patients with posterior reversible encephalopathy syndrome and seizures.

J Neurol Sci. 2017 Apr 15;375:294-298

Authors: Kamiya-Matsuoka C, Tummala S

Abstract
INTRODUCTION: Posterior reversible encephalopathy syndrome (PRES) is a neurotoxic encephalopathic state associated with reversible cerebral vasogenic edema. Seizures are a common clinical presentation in PRES, however its electroencephalographic and radiologic pattern correlation is limited in this subset of patients. The aim of this study is to analyze the origin of electrographic dysfunction according to the radiologic pattern in patients with PRES and seizures.
METHODS: We retrospectively identified 46 cancer patients who developed PRES and seizures at The University of Texas MD Anderson Cancer Center between January 2006 and June 2012. Clinical, radiographic and electroencephalographic data were abstracted from their records and reviewed for our analysis.
RESULTS: The average age at presentation was 49.9±19.7years. Thirty-four (73.9%) patients were women. Twenty-two (47.8%) patients had a primary hematological malignancy whereas the rest had a solid tumor. Thirty-three (71.7%) patients had received some form of chemotherapy. The mean systolic blood pressure (SBP) variation was 23.7±16.4mmHg at onset of symptoms. On brain MRI, 32 (69.6%) patients had typical pattern while 14 (30.4%) had an atypical pattern. Thirty-seven (80.4%) patients had scalp electroencephalogram (EEG) evaluation. Thirty-three (89.2%) had abnormal EEG findings: diffuse theta/delta slowing (N=12, 36.4%), followed by diffuse slowing with focal dysfunction (N=8, 24.2%), focal dysfunction with epileptiform discharges (N=4, 12.1%), non-convulsive status epilepticus (N=4, 12.1%), focal seizure activity and burst suppression (N=2, 6.1% each). Lateralized Periodic Discharges (LPDs) were recorded in 1 case. Four patients had focal dysfunction localized to areas without conventional MRI signal changes. Four patients had recurrent seizures, of which 3 had an atypical PRES pattern.
CONCLUSION: PRES appears to be a diffuse neurotoxic encephalopathic state. Origin of seizures seen on scalp EEG may not correlate with the location of vasogenic edema/MRI signal changes raising the possibility of greater degree of dysfunction which may exist beyond those areas.

PMID: 28320152 [PubMed - indexed for MEDLINE]

Grey matter abnormalities in methcathinone abusers with a Parkinsonian syndrome.

Thu, 07/06/2017 - 10:20
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Grey matter abnormalities in methcathinone abusers with a Parkinsonian syndrome.

Brain Behav. 2016 Nov;6(11):e00539

Authors: Juurmaa J, Menke RA, Vila P, Müürsepp A, Tomberg T, Ilves P, Nigul M, Johansen-Berg H, Donaghy M, Stagg CJ, Stepens A, Taba P

Abstract
BACKGROUND: A permanent Parkinsonian syndrome occurs in intravenous abusers of the designer psychostimulant methcathinone (ephedrone). It is attributed to deposition of contaminant manganese, as reflected by characteristic globus pallidus hyperintensity on T1-weighted MRI.
METHODS: We have investigated brain structure and function in methcathinone abusers (n = 12) compared to matched control subjects (n = 12) using T1-weighted structural and resting-state functional MRI.
RESULTS: Segmentation analysis revealed significant (p < .05) subcortical grey matter atrophy in methcathinone abusers within putamen and thalamus bilaterally, and the left caudate nucleus. The volume of the caudate nuclei correlated inversely with duration of methcathinone abuse. Voxel-based morphometry showed patients to have significant grey matter loss (p < .05) bilaterally in the putamina and caudate nucleus. Surface-based analysis demonstrated nine clusters of cerebral cortical thinning in methcathinone abusers, with relative sparing of prefrontal, parieto-occipital, and temporal regions. Resting-state functional MRI analysis showed increased functional connectivity within the motor network of patients (p < .05), particularly within the right primary motor cortex.
CONCLUSION: Taken together, these results suggest that the manganese exposure associated with prolonged methcathinone abuse results in widespread structural and functional changes affecting both subcortical and cortical grey matter and their connections. Underlying the distinctive movement disorder caused by methcathinone abuse, there is a more widespread pattern of brain involvement than is evident from the hyperintensity restricted to the basal ganglia as shown by T1-weighted structural MRI.

PMID: 27843694 [PubMed - indexed for MEDLINE]

Effects of levodopa on corticostriatal circuits supporting working memory in Parkinson's disease.

Wed, 07/05/2017 - 15:20

Effects of levodopa on corticostriatal circuits supporting working memory in Parkinson's disease.

Cortex. 2017 Jun 07;93:193-205

Authors: Simioni AC, Dagher A, Fellows LK

Abstract
Working memory dysfunction is common in Parkinson's disease, even in its early stages, but its neural basis is debated. Working memory performance likely reflects a balance between corticostriatal dysfunction and compensatory mechanisms. We tested this hypothesis by examining working memory performance with a letter n-back task in 19 patients with mild-moderate Parkinson's disease and 20 demographically matched healthy controls. Parkinson's disease patients were tested after an overnight washout of their usual dopamine replacement therapy, and again after a standard dose of levodopa. FMRI was used to assess task-related activation and resting state functional connectivity; changes in BOLD signal were related to performance to disentangle pathological and compensatory processes. Parkinson's disease patients off dopamine replacement therapy displayed significantly reduced spatial extent of task-related activation in left prefrontal and bilateral parietal cortex, and poorer working memory performance, compared to controls. Amongst the Parkinson's disease patients off dopamine replacement therapy, relatively better performance was associated with greater activation of right dorsolateral prefrontal cortex compared to controls, consistent with compensatory right hemisphere recruitment. Administration of levodopa remediated the working memory deficit in the Parkinson's disease group, and resulted in a different pattern of performance-correlated activity, with a shift to greater left ventrolateral prefrontal cortex activation in patients on, compared to off dopamine replacement therapy. Levodopa also significantly increased resting-state functional connectivity between caudate and right parietal cortex (within the right fronto-parietal attentional network). The strength of this connectivity contributed to better performance in patients and controls, suggesting a general compensatory mechanism. These findings argue that Parkinson's disease patients can recruit additional neural resources, here, the right fronto-parietal network, to optimize working memory performance despite impaired corticostriatal function. Levodopa seems to both boost engagement of a task-specific prefrontal region, and strengthen a putative compensatory caudate-cortical network to support this executive function.

PMID: 28675834 [PubMed - as supplied by publisher]

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