New resting-state fMRI related studies at PubMed

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Tau Pathology Distribution in Alzheimer's disease Corresponds Differentially to Cognition-Relevant Functional Brain Networks.

Sat, 04/15/2017 - 15:20
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Tau Pathology Distribution in Alzheimer's disease Corresponds Differentially to Cognition-Relevant Functional Brain Networks.

Front Neurosci. 2017;11:167

Authors: Hansson O, Grothe MJ, Strandberg TO, Ohlsson T, Hägerström D, Jögi J, Smith R, Schöll M

Abstract
Neuropathological studies have shown that the typical neurofibrillary pathology of hyperphosphorylated tau protein in Alzheimer's disease (AD) preferentially affects specific brain regions whereas others remain relatively spared. It has been suggested that the distinct regional distribution profile of tau pathology in AD may be a consequence of the intrinsic network structure of the human brain. The spatially distributed brain regions that are most affected by the spread of tau pathology may hence reflect an interconnected neuronal system. Here, we characterized the brain-wide regional distribution profile of tau pathology in AD using (18)F-AV 1451 tau-sensitive positron emission tomography (PET) imaging, and studied this pattern in relation to the functional network organization of the human brain. Specifically, we quantified the spatial correspondence of the regional distribution pattern of PET-evidenced tau pathology in AD with functional brain networks characterized by large-scale resting state functional magnetic resonance imaging (rs-fMRI) data in healthy subjects. Regional distribution patterns of increased PET-evidenced tau pathology in AD compared to controls were characterized in two independent samples of prodromal and manifest AD cases (the Swedish BioFINDER study, n = 44; the ADNI study, n = 35). In the BioFINDER study we found that the typical AD tau pattern involved predominantly inferior, medial, and lateral temporal cortical areas, as well as the precuneus/posterior cingulate, and lateral parts of the parietal and occipital cortex. This pattern overlapped primarily with the dorsal attention, and to some extent with higher visual, limbic and parts of the default-mode network. PET-evidenced tau pathology in the ADNI replication sample, which represented a more prodromal group of AD cases, was less pronounced but showed a highly similar spatial distribution profile, suggesting an earlier-stage snapshot of a consistently progressing regional pattern. In conclusion, the present study indicates that the regional deposition of tau aggregates in AD predominantly affects higher-order cognitive over primary sensory-motor networks, but does not appear to be specific for the default-mode or related limbic networks.

PMID: 28408865 [PubMed - in process]

Functional network-based statistics in depression: Theory of mind subnetwork and importance of parietal region.

Fri, 04/14/2017 - 14:20

Functional network-based statistics in depression: Theory of mind subnetwork and importance of parietal region.

J Affect Disord. 2017 Apr 07;217:132-137

Authors: Lai CH, Wu YT, Hou YM

Abstract
OBJECTIVE: The functional network analysis of whole brain is an emerging field for research in depression. We initiated this study to investigate which subnetwork is significantly altered within the functional connectome in major depressive disorder (MDD).
METHODS: The study enrolled 52 first-episode medication-naïve patients with MDD and 40 controls for functional network analysis. All participants received the resting-state functional imaging using a 3-Tesla magnetic resonance scanner. After preprocessing, we calculated the connectivity matrix of functional connectivity in whole brain for each subject. The network-based statistics of connectome was used to perform group comparisons between patients and controls. The correlations between functional connectivity and clinical parameters were also performed.
RESULTS: MDD patients had significant alterations in the network involving "theory of mind" regions, such as the left precentral gyrus, left angular gyrus, bilateral rolandic operculums and left inferior frontal gyrus. The center node of significant network was the left angular gyrus. No significant correlations of functional connectivity within the subnetwork and clinical parameters were noted.
CONCLUSION: Functional connectivity of "theory of mind" subnetwork may be the core issue for pathophysiology in MDD. In addition, the center role of parietal region should be emphasized in future study.

PMID: 28407556 [PubMed - as supplied by publisher]

Thalamocortical connectivity in major depressive disorder.

Fri, 04/14/2017 - 14:20

Thalamocortical connectivity in major depressive disorder.

J Affect Disord. 2017 Apr 05;217:125-131

Authors: Brown EC, Clark DL, Hassel S, MacQueen G, Ramasubbu R

Abstract
BACKGROUND: Major Depressive Disorder (MDD) is highly prevalent and potentially devastating, with widespread aberrations in brain activity. Thalamocortical networks are a potential candidate marker for psychopathology in MDD, but have not yet been thoroughly investigated. Here we examined functional connectivity between major cortical areas and thalamus.
METHOD: Resting-state fMRI from 54 MDD patients and 40 healthy controls were collected. The cortex was segmented into six regions of interest (ROIs) consisting of frontal, temporal, parietal, and occipital lobes and pre-central and post-central gyri. BOLD signal time courses were extracted from each ROI and correlated with voxels in thalamus, while removing signals from every other ROI.
RESULTS: Our main findings showed that MDD patients had predominantly increased connectivity between medial thalamus and temporal areas, and between medial thalamus and somatosensory areas. Furthermore, a positive correlation was found between thalamo-temporal connectivity and severity of symptoms.
LIMITATIONS: Most of the patients in this study were not medication naïve and therefore we cannot rule out possible long-term effects of antidepressant use on the findings.
CONCLUSION: The abnormal connectivity between thalamus and temporal, and thalamus and somatosensory regions may represent impaired cortico-thalamo-cortical modulation underlying emotional, and sensory disturbances in MDD. In the context of similar abnormalities in thalamocortical systems across major psychiatric disorders, thalamocortical dysconnectivity could be a reliable transdiagnostic marker.

PMID: 28407555 [PubMed - as supplied by publisher]

Transdiagnostic differences in the resting-state functional connectivity of the prefrontal cortex in depression and schizophrenia.

Fri, 04/14/2017 - 14:20

Transdiagnostic differences in the resting-state functional connectivity of the prefrontal cortex in depression and schizophrenia.

J Affect Disord. 2017 Apr 04;217:118-124

Authors: Chen X, Liu C, He H, Chang X, Jiang Y, Li Y, Duan M, Li J, Luo C, Yao D

Abstract
BACKGROUND: Depression and schizophrenia are two of the most serious psychiatric disorders. They share similar symptoms but the pathology-specific commonalities and differences remain unknown. This study was conducted to acquire a full picture of the functional alterations in schizophrenia and depression patients.
METHODS: The resting-state fMRI data from 20 patients with schizophrenia, 20 patients with depression and 20 healthy control subjects were collected. A data-driven approach that included local functional connectivity density (FCD) analysis combined with multivariate pattern analysis (MVPA) was used to compare the three groups.
RESULTS: Based on the results of the MVPA, the local FCD value in the orbitofrontal cortex (OFC) can differentiate depression patients from schizophrenia patients. The patients with depression had a higher local FCD value in the medial and anterior parts of the OFC than the subjects in the other two groups, which suggested altered abstract and reward reinforces processing in depression patients. Subsequent functional connectivity analysis indicated that the connection in the prefrontal cortex was significantly lower in people with schizophrenia compared to people with depression and healthy controls.
LIMITATION: The systematically different medications for schizophrenia and depression may have different effects on functional connectivity.
CONCLUSIONS: These results suggested that the resting-state functional connectivity pattern in the prefrontal cortex may be a transdiagnostic difference between depression and schizophrenia patients.

PMID: 28407554 [PubMed - as supplied by publisher]

Repeatability of Graph Theoretical Metrics Derived from Resting-state Functional Networks in Pediatric Epilepsy Patients.

Fri, 04/14/2017 - 14:20

Repeatability of Graph Theoretical Metrics Derived from Resting-state Functional Networks in Pediatric Epilepsy Patients.

Br J Radiol. 2017 Apr 13;:20160656

Authors: Paldino MJ, Chu ZD, Chapieski ML, Golriz F, Zhang W

Abstract
OBJECTIVES: To measure the repeatability of metrics that quantify brain network architecture derived from resting-state fMRI (rs-fMRI) in a cohort of pediatric epilepsy patients.
METHODS: We identified patients with: 1. epilepsy; 2. brain MRI at 3 Tesla; 3. two identical rs-fMRI acquisitions performed on the same day. Undirected, weighted networks were constructed based on the resting state time series using a range of processing parameters including parcellation size and graph threshold. The following topological properties were calculated: degree, strength, characteristic path length, global efficiency, clustering coefficient, modularity, and small worldness. Based on repeated measures, we then calculated: 1. Pearson correlation coefficient; 2. Intraclass correlation coefficient (ICC); 3. Root mean square coefficient of variation; 4. Repeatability coefficient; 5. Ninety-five percent confidence limits (95%CL) for change.
RESULTS: 26 patients were included (age range: 4-21 yrs). Correlation coefficients demonstrated a highly consistent relationship between repeated observations for all metrics and ICCs were generally in the excellent range. Repeatability in the dataset was not significantly influenced by parcellation size. However, trends toward decreased repeatability were observed at higher graph thresholds.
CONCLUSIONS: These findings demonstrate the reliability of network metrics in a cohort of pediatric patients with epilepsy. Advances in knowledge: Our results point to the potential for graph theoretical analyses of resting state data to provide reliable markers of network architecture in children with epilepsy. At the level of an individual patient, change over time greater than the repeatability coefficient or 95%CL for change is unlikely to be related to intrinsic variability of the method.

PMID: 28406312 [PubMed - as supplied by publisher]

Alterations of functional connectivity of the motor cortex in Fabry disease: An RS-fMRI study.

Fri, 04/14/2017 - 14:20
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Alterations of functional connectivity of the motor cortex in Fabry disease: An RS-fMRI study.

Neurology. 2017 Apr 12;:

Authors: Cocozza S, Pisani A, Olivo G, Saccà F, Ugga L, Riccio E, Migliaccio S, Brescia Morra V, Brunetti A, Quarantelli M, Tedeschi E

Abstract
OBJECTIVE: To evaluate the presence of functional connectivity (FC) alterations of the motor circuits in patients with Fabry disease (FD) and their possible correlation with clinical variables with a resting-state (RS) fMRI analysis.
METHODS: In our cross-sectional study, 32 patients with FD with genetically confirmed classic diagnosis of FD (12 men, mean age 43.3 ± 12.2 years) were enrolled along with 35 healthy controls (HCs) of comparable age and sex (14 men, mean age 42.1 ± 14.5 years). RS-fMRI data were analyzed with a seed-based approach, with 2 different seeds for right and left motor cortex. Patients with FD underwent a clinical examination for the assessment of different motor functions. Correlations with clinical variables were probed with the Spearman correlation coefficient.
RESULTS: A reduction of FC was found in patients with FD compared to HCs between both motor cortices and 2 clusters encompassing, for each side, the caudate and lenticular nucleus (p < 5 × 10(-4) and p < 10(-8) for right and left motor cortex, respectively) and between the left motor cortex and dentate nuclei (p = 0.01) and Crus 1 in the right cerebellar hemisphere (p = 0.001). No significant results emerged in tests for possible correlations of FC with clinical scores.
CONCLUSIONS: An alteration of the corticostriatal pathway is present in FD, in line with the recently suggested subclinical involvement of motor circuits in this disease. These results shed new light on the pattern of cerebral involvement in FD.

PMID: 28404798 [PubMed - as supplied by publisher]

Cluster success: fMRI inferences for spatial extent have acceptable false-positive rates.

Fri, 04/14/2017 - 14:20
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Cluster success: fMRI inferences for spatial extent have acceptable false-positive rates.

Cogn Neurosci. 2017 Apr 13;:

Authors: Slotnick SD

Abstract
In an editorial (this issue), I argued that Eklund, Nichols, and Knutsson's 'null data' reflected resting-state/default network activity that inflated their false-positive rates. Commentaries on that paper were received by Nichols, Eklund, and Knutsson (this issue), Hopfinger (this issue), and Cunningham and Koscik (this issue). In this author response, I consider these commentaries. Many issues stemming from Nichols et al. are identified including: (1) Nichols et al. did not provide convincing arguments that resting-state fMRI data reflects null data. (2) Eklund et al. presented one-sample results in the main body of their paper showing that their permutation method was acceptable, while their supplementary results showed that this method produced false-positive rates that were similar to other methods. (3) Eklund et al. used the same event protocol for all the participants, which artifactually inflated the one-sample t-test false-positive rates. (4) At p < .001, using two-sample t-tests (which corrected for the flawed analysis), all the methods employed to correct for multiple comparisons had acceptable false-positive rates. (5) Eklund et al. contrasted resting-state periods, which produced many significant clusters of activity, while null data should arguably be associated with few, if any, significant activations. Eklund et al.'s entire set of results show that commonly employed methods to correct for multiple comparisons have acceptable false-positive rates. Following Hopfinger along with Cunningham and Koscik, it is also highlighted that rather than focusing on only type I error, type I error and type II error should be balanced in fMRI analysis.

PMID: 28403749 [PubMed - as supplied by publisher]

Postretinal Structure and Function in Severe Congenital Photoreceptor Blindness Caused by Mutations in the GUCY2D Gene.

Fri, 04/14/2017 - 14:20
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Postretinal Structure and Function in Severe Congenital Photoreceptor Blindness Caused by Mutations in the GUCY2D Gene.

Invest Ophthalmol Vis Sci. 2017 Feb 01;58(2):959-973

Authors: Aguirre GK, Butt OH, Datta R, Roman AJ, Sumaroka A, Schwartz SB, Cideciyan AV, Jacobson SG

Abstract
Purpose: To examine how severe congenital blindness resulting from mutations of the GUCY2D gene alters brain structure and function, and to relate these findings to the notable preservation of retinal architecture in this form of Leber congenital amaurosis (LCA).
Methods: Six GUCY2D-LCA patients (ages 20-46) were studied with optical coherence tomography of the retina and multimodal magnetic resonance imaging (MRI) of the brain. Measurements from this group were compared to those obtained from populations of normally sighted controls and people with congenital blindness of a variety of causes.
Results: Patients with GUCY2D-LCA had preservation of the photoreceptors, ganglion cells, and nerve fiber layer. Despite this, visual function in these patients ranged from 20/160 acuity to no light perception, and functional MRI responses to light stimulation were attenuated and restricted. This severe visual impairment was reflected in substantial thickening of the gray matter layer of area V1, accompanied by an alteration of resting-state correlations within the occipital lobe, similar to a comparison group of congenitally blind people with structural damage to the retina. In contrast to the comparison blind population, however, the GUCY2D-LCA group had preservation of the size of the optic chiasm, and the fractional anisotropy of the optic radiations as measured with diffusion tensor imaging was also normal.
Conclusions: These results identify dissociable effects of blindness upon the visual pathway. Further, the relatively intact postgeniculate white matter pathway in GUCY2D-LCA is encouraging for the prospect of recovery of visual function with gene augmentation therapy.

PMID: 28403437 [PubMed - in process]

Altered cortical and subcortical connectivity due to infrasound administered near the hearing threshold - Evidence from fMRI.

Fri, 04/14/2017 - 14:20
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Altered cortical and subcortical connectivity due to infrasound administered near the hearing threshold - Evidence from fMRI.

PLoS One. 2017;12(4):e0174420

Authors: Weichenberger M, Bauer M, Kühler R, Hensel J, Forlim CG, Ihlenfeld A, Ittermann B, Gallinat J, Koch C, Kühn S

Abstract
In the present study, the brain's response towards near- and supra-threshold infrasound (IS) stimulation (sound frequency < 20 Hz) was investigated under resting-state fMRI conditions. The study involved two consecutive sessions. In the first session, 14 healthy participants underwent a hearing threshold-as well as a categorical loudness scaling measurement in which the individual loudness perception for IS was assessed across different sound pressure levels (SPL). In the second session, these participants underwent three resting-state acquisitions, one without auditory stimulation (no-tone), one with a monaurally presented 12-Hz IS tone (near-threshold) and one with a similar tone above the individual hearing threshold corresponding to a 'medium loud' hearing sensation (supra-threshold). Data analysis mainly focused on local connectivity measures by means of regional homogeneity (ReHo), but also involved independent component analysis (ICA) to investigate inter-regional connectivity. ReHo analysis revealed significantly higher local connectivity in right superior temporal gyrus (STG) adjacent to primary auditory cortex, in anterior cingulate cortex (ACC) and, when allowing smaller cluster sizes, also in the right amygdala (rAmyg) during the near-threshold, compared to both the supra-threshold and the no-tone condition. Additional independent component analysis (ICA) revealed large-scale changes of functional connectivity, reflected in a stronger activation of the right amygdala (rAmyg) in the opposite contrast (no-tone > near-threshold) as well as the right superior frontal gyrus (rSFG) during the near-threshold condition. In summary, this study is the first to demonstrate that infrasound near the hearing threshold may induce changes of neural activity across several brain regions, some of which are known to be involved in auditory processing, while others are regarded as keyplayers in emotional and autonomic control. These findings thus allow us to speculate on how continuous exposure to (sub-)liminal IS could exert a pathogenic influence on the organism, yet further (especially longitudinal) studies are required in order to substantialize these findings.

PMID: 28403175 [PubMed - in process]

Associating resting-state connectivity with trait impulsivity.

Thu, 04/13/2017 - 13:00
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Associating resting-state connectivity with trait impulsivity.

Soc Cogn Affect Neurosci. 2017 Apr 11;:

Authors: Angelides NH, Gupta J, Vickery TJ

Abstract
Psychometric research has identified stable traits that predict inter-individual differences in appetitive motivation and approach behavior. Behavioral Inhibition System/Behavioral Activation System (BIS/BAS) scales have been developed to quantitatively assess these traits. However, neural mechanisms corresponding to the proposed constructs reflected in BIS/BAS are still poorly defined. The ventral striatum (VS) and orbitofrontal cortex (OFC) are implicated in subserving reward-related functions that are also associated with the BAS. In this study, we examined whether functional connectivity between these regions predicts components of these scales. We employed resting-state functional connectivity and BIS/BAS scores assessed by a personality questionnaire. Participants completed a resting state run and the Behavioral Inhibition and Activation Systems (BIS/BAS) Questionnaire. Using resting-state BOLD, we assessed correlations between two basal ganglia ROIs (caudate and putamen) and bilateral OFC ROIs, establishing single subject connectivity summary scores. Summary scores were correlated with components of BIS/BAS scores. Results demonstrate a novel correlation between BAS-fun seeking and resting-state connectivity between middle OFC and putamen, implying that spontaneous synchrony between reward-processing regions may play a role in defining personality characteristics related to impulsivity.

PMID: 28402539 [PubMed - as supplied by publisher]

Insensitive parenting may accelerate the development of the amygdala-medial prefrontal cortex circuit.

Thu, 04/13/2017 - 13:00
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Insensitive parenting may accelerate the development of the amygdala-medial prefrontal cortex circuit.

Dev Psychopathol. 2017 May;29(2):505-518

Authors: Thijssen S, Muetzel RL, Bakermans-Kranenburg MJ, Jaddoe VW, Tiemeier H, Verhulst FC, White T, Van Ijzendoorn MH

Abstract
This study examined whether the association between age and amygdala-medial prefrontal cortex (mPFC) connectivity in typically developing 6- to 10-year-old children is correlated with parental care. Resting-state functional magnetic resonance imaging scans were acquired from 124 children of the Generation R Study who at 4 years old had been observed interacting with their parents to assess maternal and paternal sensitivity. Amygdala functional connectivity was assessed using a general linear model with the amygdalae time series as explanatory variables. Higher level analyses assessing Sensitivity × Age as well as exploratory Sensitivity × Age × Gender interaction effects were performed restricted to voxels in the mPFC. We found significant Sensitivity × Age interaction effects on amygdala-mPFC connectivity. Age was related to stronger amygdala-mPFC connectivity in children with a lower combined parental sensitivity score (b = 0.11, p = .004, b = 0.06, p = .06, right and left amygdala, respectively), but not in children with a higher parental sensitivity score, (b = -0.07, p = .12, b = -0.06, p = .12, right and left amygdala, respectively). A similar effect was found for maternal sensitivity, with stronger amygdala-mPFC connectivity in children with less sensitive mothers. Exploratory (parental, maternal, paternal) Sensitivity × Age × Gender interaction analyses suggested that this effect was especially pronounced in girls. Amygdala-mPFC resting-state functional connectivity has been shown to increase from age 10.5 years onward, implying that the positive association between age and amygdala-mPFC connectivity in 6- to 10-year-old children of less sensitive parents represents accelerated development of the amygdala-mPFC circuit.

PMID: 28401836 [PubMed - in process]

Modulatory effects of acupuncture on brain networks in mild cognitive impairment patients.

Thu, 04/13/2017 - 13:00
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Modulatory effects of acupuncture on brain networks in mild cognitive impairment patients.

Neural Regen Res. 2017 Feb;12(2):250-258

Authors: Tan TT, Wang D, Huang JK, Zhou XM, Yuan X, Liang JP, Yin L, Xie HL, Jia XY, Shi J, Wang F, Yang HB, Chen SJ

Abstract
Functional magnetic resonance imaging has been widely used to investigate the effects of acupuncture on neural activity. However, most functional magnetic resonance imaging studies have focused on acute changes in brain activation induced by acupuncture. Thus, the time course of the therapeutic effects of acupuncture remains unclear. In this study, 32 patients with amnestic mild cognitive impairment were randomly divided into two groups, where they received either Tiaoshen Yizhi acupuncture or sham acupoint acupuncture. The needles were either twirled at Tiaoshen Yizhi acupoints, including Sishencong (EX-HN1), Yintang (EX-HN3), Neiguan (PC6), Taixi (KI3), Fenglong (ST40), and Taichong (LR3), or at related sham acupoints at a depth of approximately 15 mm, an angle of ± 60°, and a rate of approximately 120 times per minute. Acupuncture was conducted for 4 consecutive weeks, five times per week, on weekdays. Resting-state functional magnetic resonance imaging indicated that connections between cognition-related regions such as the insula, dorsolateral prefrontal cortex, hippocampus, thalamus, inferior parietal lobule, and anterior cingulate cortex increased after acupuncture at Tiaoshen Yizhi acupoints. The insula, dorsolateral prefrontal cortex, and hippocampus acted as central brain hubs. Patients in the Tiaoshen Yizhi group exhibited improved cognitive performance after acupuncture. In the sham acupoint acupuncture group, connections between brain regions were dispersed, and we found no differences in cognitive function following the treatment. These results indicate that acupuncture at Tiaoshen Yizhi acupoints can regulate brain networks by increasing connectivity between cognition-related regions, thereby improving cognitive function in patients with mild cognitive impairment.

PMID: 28400807 [PubMed - in process]

Reduced Resting-State Functional Connectivity in Current and Recovered Restrictive Anorexia Nervosa.

Thu, 04/13/2017 - 13:00
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Reduced Resting-State Functional Connectivity in Current and Recovered Restrictive Anorexia Nervosa.

Front Psychiatry. 2017;8:30

Authors: Scaife JC, Godier LR, Filippini N, Harmer CJ, Park RJ

Abstract
Functional connectivity studies based on resting-state functional magnetic resonance imaging (rs-fMRI) have shown alterations in brain networks associated with self-referential processing, cognitive control, and somatosensory processing in anorexia nervosa (AN). This study aimed to further investigate the functional connectivity of resting-state networks (RSNs) in homogenous subsamples of individuals with restrictive AN (current and recovered) and the relationship this has with core eating disorder psychopathology. rs-fMRI scans were obtained from 12 female individuals with restrictive AN, 14 females recovered from restrictive AN, and 16 female healthy controls. Independent components analysis revealed a set of functionally relevant RSNs, previously reported in the literature. Dual regression analysis showed decreased temporal coherence within the lateral visual and auditory RSNs in individuals with current AN and those recovered from AN compared to healthy individuals. This decreased connectivity was also found in regions associated with somatosensory processing, and is consistent with reduced interoceptive awareness and body image perception, characteristic of AN. Widespread gray matter (GM) reductions were also found in both the AN groups, and differences in functional connectivity were no longer significant when GM maps were added as a covariate in the dual regression analysis. This raises the possibility that deficits in somatosensory and interoceptive processing observed in AN may be in part underpinned or exacerbated by GM reductions.

PMID: 28400737 [PubMed - in process]

Listening to Rhythmic Music Reduces Connectivity within the Basal Ganglia and the Reward System.

Thu, 04/13/2017 - 13:00
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Listening to Rhythmic Music Reduces Connectivity within the Basal Ganglia and the Reward System.

Front Neurosci. 2017;11:153

Authors: Brodal HP, Osnes B, Specht K

Abstract
Music can trigger emotional responses in a more direct way than any other stimulus. In particular, music-evoked pleasure involves brain networks that are part of the reward system. Furthermore, rhythmic music stimulates the basal ganglia and may trigger involuntary movements to the beat. In the present study, we created a continuously playing rhythmic, dance floor-like composition where the ambient noise from the MR scanner was incorporated as an additional instrument of rhythm. By treating this continuous stimulation paradigm as a variant of resting-state, the data was analyzed with stochastic dynamic causal modeling (sDCM), which was used for exploring functional dependencies and interactions between core areas of auditory perception, rhythm processing, and reward processing. The sDCM model was a fully connected model with the following areas: auditory cortex, putamen/pallidum, and ventral striatum/nucleus accumbens of both hemispheres. The resulting estimated parameters were compared to ordinary resting-state data, without an additional continuous stimulation. Besides reduced connectivity within the basal ganglia, the results indicated a reduced functional connectivity of the reward system, namely the right ventral striatum/nucleus accumbens from and to the basal ganglia and auditory network while listening to rhythmic music. In addition, the right ventral striatum/nucleus accumbens demonstrated also a change in its hemodynamic parameter, reflecting an increased level of activation. These converging results may indicate that the dopaminergic reward system reduces its functional connectivity and relinquishing its constraints on other areas when we listen to rhythmic music.

PMID: 28400717 [PubMed - in process]

Electrical Stimulation Reduces Smokers' Craving by Modulating the Coupling between Dorsal Lateral Prefrontal Cortex and Parahippocampal Gyrus.

Wed, 04/12/2017 - 12:00
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Electrical Stimulation Reduces Smokers' Craving by Modulating the Coupling between Dorsal Lateral Prefrontal Cortex and Parahippocampal Gyrus.

Soc Cogn Affect Neurosci. 2017 Apr 04;:

Authors: Yang LZ, Shi B, Li H, Liu Y, Zhang W, Wang Y, Lv W, Ji X, Hudak J, Zhou Y, Fallgatter AJ, Zhang X

Abstract
Applying electrical stimulation over the prefrontal cortex can help nicotine dependents reduce cigarette craving. However, the underlying mechanism remains ambiguous. The present study investigates this issue with functional magnetic resonance imaging. Thirty-two male chronic smokers received real and sham stimulation over dorsal lateral prefrontal cortex separated by 1 week. The neuroimaging data of the resting state, the smoking cue reactivity task and the emotion task after stimulation were collected. The craving across the cue reactivity task was diminished during real stimulation as compared to sham stimulation. The whole-brain analysis on the cue reactivity task revealed a significant interaction between the stimulation condition (real vs. sham) and the cue type (smoking vs. neutral) in the left superior frontal gyrus and the left middle frontal gyrus. The functional connectivity between the left dorsal lateral prefrontal cortex and the right parahippocampal gyrus, as revealed by both psychophysical interaction analysis and the resting state functional connectivity, is altered by electrical stimulation. Moreover, the craving change across the real and sham condition is predicted by alteration of functional connectivity revealed by psychophysical interaction analysis. The local and long-distance coupling, altered by the electrical stimulation, might be the underlying neural mechanism of craving regulation.

PMID: 28398588 [PubMed - as supplied by publisher]

Frequency Specific Effects of ApoE ε4 Allele on Resting-State Networks in Nondemented Elders.

Wed, 04/12/2017 - 12:00
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Frequency Specific Effects of ApoE ε4 Allele on Resting-State Networks in Nondemented Elders.

Biomed Res Int. 2017;2017:9823501

Authors: Liang Y, Li Z, Wei J, Li C, Zhang X, Neuroimaging Initiative AD

Abstract
We applied resting-state functional magnetic resonance imaging (fMRI) to examine the Apolipoprotein E (ApoE) ε4 allele effects on functional connectivity of the default mode network (DMN) and the salience network (SN). Considering the frequency specific effects of functional connectivity, we decomposed the brain network time courses into two bands: 0.01-0.027 Hz and 0.027-0.08 Hz. All scans were acquired by the Alzheimer's Disease Neuroscience Initiative (ADNI). Thirty-two nondemented subjects were divided into two groups based on the presence (n = 16) or absence (n = 16) of the ApoE ε4 allele. We explored the frequency specific effects of ApoE ε4 allele on the default mode network (DMN) and the salience network (SN) functional connectivity. Compared to ε4 noncarriers, the DMN functional connectivity of ε4 carriers was significantly decreased while the SN functional connectivity of ε4 carriers was significantly increased. Many functional connectivities showed significant differences at the lower frequency band of 0.01-0.027 Hz or the higher frequency band of 0.027-0.08 Hz instead of the typical range of 0.01-0.08 Hz. The results indicated a frequency dependent effect of resting-state signals when investigating RSNs functional connectivity.

PMID: 28396874 [PubMed - in process]

A million variables and more: the Fast Greedy Equivalence Search algorithm for learning high-dimensional graphical causal models, with an application to functional magnetic resonance images.

Tue, 04/11/2017 - 10:55
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A million variables and more: the Fast Greedy Equivalence Search algorithm for learning high-dimensional graphical causal models, with an application to functional magnetic resonance images.

Int J Data Sci Anal. 2017 Mar;3(2):121-129

Authors: Ramsey J, Glymour M, Sanchez-Romero R, Glymour C

Abstract
We describe two modifications that parallelize and reorganize caching in the well-known Greedy Equivalence Search (GES) algorithm for discovering directed acyclic graphs on random variables from sample values. We apply one of these modifications, the Fast Greedy Search (FGS) assuming faithfulness, to an i.i.d. sample of 1,000 units to recover with high precision and good recall an average degree 2 directed acyclic graph (DAG) with one million Gaussian variables. We describe a modification of the algorithm to rapidly find the Markov Blanket of any variable in a high dimensional system. Using 51,000 voxels that parcellate an entire human cortex, we apply the FGS algorithm to Blood Oxygenation Level Dependent (BOLD) time series obtained from resting state fMRI.

PMID: 28393106 [PubMed - in process]

Neural substrates of motor and cognitive dysfunctions in SCA2 patients: A network based statistics analysis.

Tue, 04/11/2017 - 10:55
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Neural substrates of motor and cognitive dysfunctions in SCA2 patients: A network based statistics analysis.

Neuroimage Clin. 2017;14:719-725

Authors: Olivito G, Cercignani M, Lupo M, Iacobacci C, Clausi S, Romano S, Masciullo M, Molinari M, Bozzali M, Leggio M

Abstract
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative disease characterized by a progressive cerebellar syndrome, which can be isolated or associated with extracerebellar signs. It has been shown that patients affected by SCA2 present also cognitive impairments and psychiatric symptoms. The cerebellum is known to modulate cortical activity and to contribute to distinct functional networks related to higher-level functions beyond motor control. It is therefore conceivable that one or more networks, rather than isolated regions, may be dysfunctional in cerebellar degenerative diseases and that an abnormal connectivity within specific cerebello-cortical regions might explain the widespread deficits typically observed in patients. In the present study, the network-based statistics (NBS) approach was used to assess differences in functional connectivity between specific cerebellar and cerebral "nodes" in SCA2 patients. Altered inter-nodal connectivity was found between more posterior regions in the cerebellum and regions in the cerebral cortex clearly related to cognition and emotion. Furthermore, more anterior cerebellar lobules showed altered inter-nodal connectivity with motor and somatosensory cerebral regions. The present data suggest that in SCA2 a cerebellar dysfunction affects long-distance cerebral regions and that the clinical symptoms may be specifically related with connectivity changes between motor and non-motor cerebello-cortical nodes.

PMID: 28393013 [PubMed - in process]

The effect of repetitive subconcussive collisions on brain integrity in collegiate football players over a single football season: A multi-modal neuroimaging study.

Tue, 04/11/2017 - 10:55
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The effect of repetitive subconcussive collisions on brain integrity in collegiate football players over a single football season: A multi-modal neuroimaging study.

Neuroimage Clin. 2017;14:708-718

Authors: Slobounov SM, Walter A, Breiter HC, Zhu DC, Bai X, Bream T, Seidenberg P, Mao X, Johnson B, Talavage TM

Abstract
The cumulative effect of repetitive subconcussive collisions on the structural and functional integrity of the brain remains largely unknown. Athletes in collision sports, like football, experience a large number of impacts across a single season of play. The majority of these impacts, however, are generally overlooked, and their long-term consequences remain poorly understood. This study sought to examine the effects of repetitive collisions across a single competitive season in NCAA Football Bowl Subdivision athletes using advanced neuroimaging approaches. Players were evaluated before and after the season using multiple MRI sequences, including T1-weighted imaging, diffusion tensor imaging (DTI), arterial spin labeling (ASL), resting-state functional MRI (rs-fMRI), and susceptibility weighted imaging (SWI). While no significant differences were found between pre- and post-season for DTI metrics or cortical volumes, seed-based analysis of rs-fMRI revealed significant (p < 0.05) changes in functional connections to right isthmus of the cingulate cortex (ICC), left ICC, and left hippocampus. ASL data revealed significant (p < 0.05) increases in global cerebral blood flow (CBF), with a specific regional increase in right postcentral gyrus. SWI data revealed that 44% of the players exhibited outlier rates (p < 0.05) of regional decreases in SWI signal. Of key interest, athletes in whom changes in rs-fMRI, CBF and SWI were observed were more likely to have experienced high G impacts on a daily basis. These findings are indicative of potential pathophysiological changes in brain integrity arising from only a single season of participation in the NCAA Football Bowl Subdivision, even in the absence of clinical symptoms or a diagnosis of concussion. Whether these changes reflect compensatory adaptation to cumulative head impacts or more lasting alteration of brain integrity remains to be further explored.

PMID: 28393012 [PubMed - in process]

Dynamic abnormalities of spontaneous brain activity in women with primary dysmenorrhea.

Tue, 04/11/2017 - 10:55
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Dynamic abnormalities of spontaneous brain activity in women with primary dysmenorrhea.

J Pain Res. 2017;10:699-707

Authors: Jin L, Yang X, Liu P, Sun J, Chen F, Xu Z, Qin W, Tian J

Abstract
PURPOSE: This study aimed to investigate the regional spontaneous brain activity changes in primary dysmenorrhea (PD) patients in different phases of the menstrual cycle by regional homogeneity (ReHo) analysis.
PATIENTS AND METHODS: Thirty-three PD patients and 32 healthy controls (HCs) separately received resting-state functional magnetic resonance imaging during menstrual phase and follicular phase (non-menstrual phase). Cox retrospective symptom scale (RSS), Self-Rating Anxiety Scale (SAS) and Self-Rating Depression Scale (SDS) were applied to assess related symptoms and emotions.
RESULTS: There was no significant difference between the two groups in demographic data. The PD patients obtained higher RSS score, SAS score and SDS score than HCs. Compared with HCs, the ReHo values of the PD patients were increased in left midbrain and hippocampus, right posterior cingulate cortex (PCC), insula and middle temporal cortex (MTC) and decreased in left dorsolateral prefrontal cortex and right medial prefrontal cortex (mPFC) in menstrual phase. In non-menstrual phase, enhanced ReHo values were found in bilateral S1 and precuneus, left S2 and MTC, and reduced ReHo values were observed in left mPFC and orbital frontal cortex. RSS score positively correlated with ReHo values of midbrain and negatively correlated with mPFC and PCC.
CONCLUSION: Our results suggested that PD is accompanied by dynamic regional spontaneous activity changes across the menstrual cycle, and the altered regions were involved in descending pain modulation, default mode network and sensory modulation. These abnormal activations might contribute to maintain the menstrual pain.

PMID: 28392711 [PubMed - in process]

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