Cognitive complaints in older adults at risk for Alzheimer's disease are associated with altered resting-state networks.
Alzheimers Dement (Amst). 2017;6:40-49
Authors: Contreras JA, Goñi J, Risacher SL, Amico E, Yoder K, Dzemidzic M, West JD, McDonald BC, Farlow MR, Sporns O, Saykin AJ
INTRODUCTION: Pathophysiological changes that accompany early clinical symptoms in prodromal Alzheimer's disease (AD) may have a disruptive influence on brain networks. We investigated resting-state functional magnetic resonance imaging (rsfMRI), combined with brain connectomics, to assess changes in whole-brain functional connectivity (FC) in relation to neurocognitive variables.
METHODS: Participants included 58 older adults who underwent rsfMRI. Individual FC matrices were computed based on a 278-region parcellation. FastICA decomposition was performed on a matrix combining all subjects' FC. Each FC pattern was then used as a response in a multilinear regression model including neurocognitive variables associated with AD (cognitive complaint index [CCI] scores from self and informant, an episodic memory score, and an executive function score).
RESULTS: Three connectivity independent component analysis (connICA) components (RSN, VIS, and FP-DMN FC patterns) associated with neurocognitive variables were identified based on prespecified criteria. RSN-pattern, characterized by increased FC within all resting-state networks, was negatively associated with self CCI. VIS-pattern, characterized by an increase in visual resting-state network, was negatively associated with CCI self or informant scores. FP-DMN-pattern, characterized by an increased interaction of frontoparietal and default mode networks (DMN), was positively associated with verbal episodic memory.
DISCUSSION: Specific patterns of FC were differently associated with neurocognitive variables thought to change early in the course of AD. An integrative connectomics approach relating cognition to changes in FC may help identify preclinical and early prodromal stages of AD and help elucidate the complex relationship between subjective and objective indices of cognitive decline and differences in brain functional organization.
PMID: 28149942 [PubMed - in process]
Brain changes associated with cognitive and emotional factors in chronic pain: A systematic review.
Eur J Pain. 2017 Feb 01;:
Authors: Malfliet A, Coppieters I, Van Wilgen P, Kregel J, De Pauw R, Dolphens M, Ickmans K
An emerging technique in chronic pain research is MRI, which has led to the understanding that chronic pain patients display brain structure and function alterations. Many of these altered brain regions and networks are not just involved in pain processing, but also in other sensory and particularly cognitive tasks. Therefore, the next step is to investigate the relation between brain alterations and pain related cognitive and emotional factors. This review aims at providing an overview of the existing literature on this subject. Pubmed, Web of Science and Embase were searched for original research reports. Twenty eight eligible papers were included, with information on the association of brain alterations with pain catastrophizing, fear-avoidance, anxiety and depressive symptoms. Methodological quality of eligible papers was checked by two independent researchers. Evidence on the direction of these associations is inconclusive. Pain catastrophizing is related to brain areas involved in pain processing, attention to pain, emotion and motor activity, and to reduced top-down pain inhibition. In contrast to pain catastrophizing, evidence on anxiety and depressive symptoms shows no clear association with brain characteristics. However, all included cognitive or emotional factors showed significant associations with resting state fMRI data, providing that even at rest the brain reserves a certain activity for these pain-related factors. Brain changes associated with illness perceptions, pain attention, attitudes and beliefs seem to receive less attention in literature.
SIGNIFICANCE: This review shows that maladaptive cognitive and emotional factors are associated with several brain regions involved in chronic pain. Targeting these factors in these patients might normalize specific brain alterations.
PMID: 28146315 [PubMed - as supplied by publisher]
Biomarkers, designs, and interpretations of resting-state fMRI in translational pharmacological research: A review of state-of-the-Art, challenges, and opportunities for studying brain chemistry.
Hum Brain Mapp. 2017 Feb 01;:
Authors: Khalili-Mahani N, Rombouts SA, van Osch MJ, Duff EP, Carbonell F, Nickerson LD, Becerra L, Dahan A, Evans AC, Soucy JP, Wise R, Zijdenbos AP, van Gerven JM
A decade of research and development in resting-state functional MRI (RSfMRI) has opened new translational and clinical research frontiers. This review aims to bridge between technical and clinical researchers who seek reliable neuroimaging biomarkers for studying drug interactions with the brain. About 85 pharma-RSfMRI studies using BOLD signal (75% of all) or arterial spin labeling (ASL) were surveyed to investigate the acute effects of psychoactive drugs. Experimental designs and objectives include drug fingerprinting dose-response evaluation, biomarker validation and calibration, and translational studies. Common biomarkers in these studies include functional connectivity, graph metrics, cerebral blood flow and the amplitude and spectrum of BOLD fluctuations. Overall, RSfMRI-derived biomarkers seem to be sensitive to spatiotemporal dynamics of drug interactions with the brain. However, drugs cause both central and peripheral effects, thus exacerbate difficulties related to biological confounds, structured noise from motion and physiological confounds, as well as modeling and inference testing. Currently, these issues are not well explored, and heterogeneities in experimental design, data acquisition and preprocessing make comparative or meta-analysis of existing reports impossible. A unifying collaborative framework for data-sharing and data-mining is thus necessary for investigating the commonalities and differences in biomarker sensitivity and specificity, and establishing guidelines. Multimodal datasets including sham-placebo or active control sessions and repeated measurements of various psychometric, physiological, metabolic and neuroimaging phenotypes are essential for pharmacokinetic/pharmacodynamic modeling and interpretation of the findings. We provide a list of basic minimum and advanced options that can be considered in design and analyses of future pharma-RSfMRI studies. Hum Brain Mapp, 2017. © 2017 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.
PMID: 28145075 [PubMed - as supplied by publisher]
Abnormal regional homogeneity and functional connectivity in adjustment disorder of new recruits: a resting-state fMRI study.
Jpn J Radiol. 2017 Jan 31;:
Authors: Li H, Lin Y, Chen J, Wang X, Wu Q, Li Q, Chen Z
PURPOSE: To explore the regional spontaneous neural activity and functional connectivity alterations of adjustment disorder (AD) in new recruits with in vivo resting-state functional MR (rs-fMRI).
MATERIALS AND METHODS: Resting-state fMRI was performed in 31 recruits with AD and in 31 control recruits. Regional homogeneity (ReHo) was used to detect the regional synchronizing features of neuronal activations. Correlative analysis was performed to investigate the relationship between the Symptom Check List-90 (SCL-90) score and ReHo in regions with significant group differences. Regions with significant correlation were then defined as regions of interest (ROIs), and seed-ROI based whole-brain functional connectivity was performed.
RESULTS: Compared with the controls, patients with AD had significantly lower ReHo in the left posterior cerebellar lobe, bilateral medial orbitofrontal cortex, bilateral caudate and left middle temporal gyrus, whereas regions with enhanced ReHo were confined to bilateral posterior cingulate gyrus/precuneus. Only the left posterior cerebellar lobe showed significant correlation between ReHo and the SCL-90 score, and was defined as the seed ROI. Decreased functional connectivity was found between the ROI and bilateral supplementary motor area.
CONCLUSION: This study reveals abnormalities in recruits with AD in baseline brain function activities, which could further improve our understanding of the neural substrates of cognitive impairment in AD.
PMID: 28144895 [PubMed - as supplied by publisher]
Increased insular connectivity with emotional regions in primary insomnia patients: a resting-state fMRI study.
Eur Radiol. 2017 Jan 31;:
Authors: Wang T, Yan J, Li S, Zhan W, Ma X, Xia L, Li M, Lin C, Tian J, Li C, Jiang G
OBJECTIVE: To explore the abnormal connectivity patterns between the insular and the voxels of the brain in primary insomnia (PI) with insular-based functional connectivity (FC).
METHODS: With the resting-state fMRI data acquired from 57 PI patients and 46 healthy controls, a two-sample t test was performed on individual FC correlation maps from two groups. The person correlation analysis was used to evaluate the relationship between the abnormal FC and clinical features.
RESULTS: PI patients show enhanced connectivity between the left insula with the right anterior cingulate cortex (p < 0.05 and p < 0.001, AlphaSim-corrected), right frontal sup orb, bilateral thalamus and left precuneus,as well as decreased connectivity with the left middle temporal gyrus and right fusiform (p < 0.05, AlphaSim-corrected). Correlation analysis indicated the enhanced connectivities in the PI patients have significant negative correlations with Self-Rating Depression Scale(SDS)and Self-Rating Anxiety Scale(SAS)scores. In addition, the decreased functional connectivities showed positive correlations with SDS and SAS scores.
CONCLUSION: Our study showed the increased connectivity regions with insula were mainly in the emotional circle and decreased connectivity was in cognitive-related regions. These provide additional evidence from functional integration view to understand the possible underlying neural- mechanisms of PI.
KEY POINTS: • The aberrant insular-based connectivity pattern of PI patients was detected. • Regions showing increased connectivity with left insular were mainly in emotional circle. • Significant correlations between changed FC and SDS and SAS score were found.
PMID: 28144739 [PubMed - as supplied by publisher]
Disentangling resting-state BOLD variability and PCC functional connectivity in 22q11.2 deletion syndrome.
Neuroimage. 2017 Jan 28;:
Authors: Zöller D, Schaer M, Scariati E, Padula MC, Eliez S, Ville DV
Although often ignored in fMRI studies, moment-to-moment variability of blood oxygenation level dependent (BOLD) signals reveals important information about brain function. Indeed, higher brain signal variability has been associated with better cognitive performance in young adults compared to children and elderly adults. Functional connectivity, a very common approach in resting-state fMRI analysis, is scaled for variance. Thus, alterations might be confounded or driven by BOLD signal variance alterations. Chromosome 22q11.2 deletion syndrome (22q11.2DS) is a neurodevelopmental disorder that is associated with a vast cognitive and clinical phenotype. To date, several resting-state fMRI studies reported altered functional connectivity in 22q11.2DS, however BOLD signal variance has not yet been analyzed. Here, we employed PLS correlation analysis to reveal multivariate patterns of diagnosis-related alterations and age-relationship throughout the cortex of 50 patients between 9 and 25 years old and 50 healthy controls in the same age range. To address how functional connectivity in the default mode network is influenced by BOLD signal fluctuations, we conducted the same analysis on seed-to-voxel connectivity of the posterior cingulate cortex (PCC) and compared resulting brain patterns. BOLD signal variance was lower mainly in regions of the default mode network and in the dorsolateral prefrontal cortex, but higher in large parts of the temporal lobes. In those regions, BOLD signal variance was correlated with age in healthy controls, but not in patients, suggesting deviant developmental trajectories from child- to adulthood. Positive connectivity of the PCC within the default mode network as well as negative connectivity towards the frontoparietal network were weaker in patients with 22q11.2DS. We furthermore showed that lower functional connectivity of the PCC was not driven by higher BOLD signal variability. Our results confirm the strong implication of BOLD variance in aging and give an initial insight in its relationship with functional connectivity in the DMN.
PMID: 28143774 [PubMed - as supplied by publisher]
Transcranial direct current stimulation targeting primary motor versus dorsolateral prefrontal cortices: proof-of-concept study investigating functional connectivity of thalamo-cortical networks specific to sensory-affective information processing.
Brain Connect. 2017 Jan 31;:
Authors: Sankarasubramanian V, Cunningham D, Potter K, Beall E, Roelle S, Varnerin N, Machado A, Jones S, Lowe M, Plow E
Pain matrix is subtended by an extensive cortical network spanning across sensory and affective domains. Transcranial direct current stimulation (tDCS) targeting primary motor (M1) or dorsolateral prefrontal cortices (DLPFC) represent popular methods to modulate such networks. However, differences between their mechanisms remain unknown. Here, in a proof-of-concept study, resting-state functional MRI was used to investigate the effects of stimulating M1 versus DLPFC on functional connectivity (FC) of networks within a healthy pain matrix. FC changes were compared to further investigate its relation with individual's baseline experience of pain. Ten right-handed healthy individuals received anodal tDCS (1mA, 20min) to right M1 and DLPFC in a single blind, sham-controlled, crossover study. FC changes were studied with venteroposterolateral, the sensory nucleus of thalamus, and with medial dorsal, the affective nucleus. Individual's perception to pain at baseline was assessed using cutaneous heat pain stimuli. The main findings were increased FC across sensorimotor networks following tDCS to M1 and DLPFC, though tDCS to M1 had a greater effect on sensory networks. Similarly, increased FC across motor cortices was observed following tDCS to M1 and DLPFC, but only tDCS to DLPFC modulated affective cortices, like DLPFC. These findings suggest that stimulating M1 mainly modulates FC of sensory networks, whereas stimulating DLPFC modulates FC of both sensory and affective networks. While a small sample size limits generalizability of findings, knowledge of such mechanisms may help differentiate between effects of M1 and DLPFC on pain experience in large clinical trials. Notably, the finding that individuals with high baseline pain thresholds experience greater FC changes with tDCS to DLPFC, implies that these individuals could respond more to stimulation of affective cortices.
PMID: 28142257 [PubMed - as supplied by publisher]
A defense of using resting state fMRI as null data for estimating false positive rates.
Cogn Neurosci. 2017 Jan 31;:
Authors: Nichols TE, Eklund A, Knutsson H
A recent Editorial by Slotnick (2017) reconsiders the findings of our paper on the accuracy of false positive rate control with cluster inference in fMRI (Eklund et al, 2016), in particular criticising our use of resting state fMRI data as a source for null data in the evaluation of task fMRI methods. We defend this use of resting fMRI data, as while there is much structure in this data, we argue it is representative of task data noise and such analysis software should be able to accommodate this noise. We also discuss a potential problem with Slotnick's own method.
PMID: 28140785 [PubMed - as supplied by publisher]
The value of resting-state functional MRI in subacute ischemic stroke: comparison with dynamic susceptibility contrast-enhanced perfusion MRI.
Sci Rep. 2017 Jan 31;7:41586
Authors: Ni L, Li J, Li W, Zhou F, Wang F, Schwarz CG, Liu R, Zhao H, Wu W, Zhang X, Li M, Yu H, Zhu B, Villringer A, Zang Y, Zhang B, Lv Y, Xu Y
To evaluate the potential clinical value of the time-shift analysis (TSA) approach for resting-state fMRI (rs-fMRI) blood oxygenation level-dependent (BOLD) data in detecting hypoperfusion of subacute stroke patients through comparison with dynamic susceptibility contrast perfusion weighted imaging (DSC-PWI). Forty patients with subacute stroke (3-14 days after neurological symptom onset) underwent MRI examination. Cohort A: 31 patients had MRA, DSC-PWI and BOLD data. Cohort B: 9 patients had BOLD and MRA data. The time delay between the BOLD time course in each voxel and the mean signal of global and contralateral hemisphere was calculated using TSA. Time to peak (TTP) was employed to detect hypoperfusion. Among cohort A, 14 patients who had intracranial large-vessel occlusion/stenosis with sparse collaterals showed hypoperfusion by both of the two approaches, one with abundant collaterals showed neither TTP nor TSA time delay. The remaining 16 patients without obvious MRA lesions showed neither TTP nor TSA time delay. Among cohort B, eight patients showed time delay areas. The TSA approach was a promising alternative to DSC-PWI for detecting hypoperfusion in subacute stroke patients who had obvious MRA lesions with sparse collaterals, those with abundant collaterals would keep intact local perfusion.
PMID: 28139701 [PubMed - in process]
Altered amplitude of low frequency fluctuations in schizophrenia patients with persistent auditory verbal hallucinations.
Schizophr Res. 2017 Jan 28;:
Authors: Alonso-Solís A, Vives-Gilabert Y, Portella MJ, Rabella M, Grasa EM, Roldán A, Keymer-Gausset A, Molins C, Núñez-Marín F, Gómez-Ansón B, Alvarez E, Corripio I
The aim of this study is to analyze the differences in low frequency fluctuation (LFF) values between schizophrenia patients with and without auditory verbal hallucinations (AVH). Nineteen schizophrenia patients with persistent AVH (HP), fourteen non-hallucinating schizophrenia patients (nHP) and twenty healthy controls (HC) underwent R-fMRI. LFF values were calculated in the slow frequency band (0.01-0.08Hz). By means of group level contrasts, we performed direct voxel-wise group comparisons. Both groups of patients showed decreased amplitude LFF (ALFF) values in the occipital pole and lingual gyrus compared to HC, whereas increased ALFF values were found in the temporal pole and fusifom gyrus. Schizophrenia patients exhibited decreased fractional ALFF (fALFF) values in the precuneus, occipital pole and bilateral occipital cortex, and increased fALFF in the insula compared to HC. There were also differences between patients with and without AVH. (Ok to start with lower case?) fALFF values were higher in the putamen and insular cortex and lower in the frontal pole in HP compared to nHP and HC. ALFF increased in HP patients in the bilateral thalamus and bilateral parahippocampal gyrus, compared to nHP patients and HC. Our results suggest that altered dynamics in low-frequency fluctuations may play a key role in the neurophysiology of auditory hallucinations.
PMID: 28139359 [PubMed - as supplied by publisher]
Common Dimensional Reward Deficits Across Mood and Psychotic Disorders: A Connectome-Wide Association Study.
Am J Psychiatry. 2017 Jan 31;:appiajp201616070774
Authors: Sharma A, Wolf DH, Ciric R, Kable JW, Moore TM, Vandekar SN, Katchmar N, Daldal A, Ruparel K, Davatzikos C, Elliott MA, Calkins ME, Shinohara RT, Bassett DS, Satterthwaite TD
OBJECTIVE: Anhedonia is central to multiple psychiatric disorders and causes substantial disability. A dimensional conceptualization posits that anhedonia severity is related to a transdiagnostic continuum of reward deficits in specific neural networks. Previous functional connectivity studies related to anhedonia have focused on case-control comparisons in specific disorders, using region-specific seed-based analyses. Here, the authors explore the entire functional connectome in relation to reward responsivity across a population of adults with heterogeneous psychopathology.
METHOD: In a sample of 225 adults from five diagnostic groups (major depressive disorder, N=32; bipolar disorder, N=50; schizophrenia, N=51; psychosis risk, N=39; and healthy control subjects, N=53), the authors conducted a connectome-wide analysis examining the relationship between a dimensional measure of reward responsivity (the reward sensitivity subscale of the Behavioral Activation Scale) and resting-state functional connectivity using multivariate distance-based matrix regression.
RESULTS: The authors identified foci of dysconnectivity associated with reward responsivity in the nucleus accumbens, the default mode network, and the cingulo-opercular network. Follow-up analyses revealed dysconnectivity among specific large-scale functional networks and their connectivity with the nucleus accumbens. Reward deficits were associated with decreased connectivity between the nucleus accumbens and the default mode network and increased connectivity between the nucleus accumbens and the cingulo-opercular network. In addition, impaired reward responsivity was associated with default mode network hyperconnectivity and diminished connectivity between the default mode network and the cingulo-opercular network.
CONCLUSIONS: These results emphasize the centrality of the nucleus accumbens in the pathophysiology of reward deficits and suggest that dissociable patterns of connectivity among large-scale networks are critical to the neurobiology of reward dysfunction across clinical diagnostic categories.
PMID: 28135847 [PubMed - as supplied by publisher]
Pattern of Reduced Functional Connectivity and Structural Abnormalities in Parkinson's Disease: An Exploratory Study.
Front Neurol. 2016;7:243
Authors: Guimarães RP, Arci Santos MC, Dagher A, Campos LS, Azevedo P, Piovesana LG, De Campos BM, Larcher K, Zeighami Y, Scarparo Amato-Filho AC, Cendes F, D'Abreu AC
BACKGROUND: MRI brain changes in Parkinson's disease (PD) are controversial.
OBJECTIVES: We aimed to describe structural and functional changes in PD.
METHODS: Sixty-six patients with PD (57.94 ± 10.25 years) diagnosed according to the UK Brain Bank criteria were included. We performed a whole brain analysis using voxel-based morphometry (VBM-SPM 8 software), cortical thickness (CT) using CIVET, and resting-state fMRI using the Neuroimaging Analysis Kit software to compare patients and controls. For VBM and CT we classified subjects into three groups according to disease severity: mild PD [Hoehn and Yahr scale (HY) 1-1.5], moderate PD (HY 2-2.5), and severe PD (HY 3-5).
RESULTS: We observed gray matter atrophy in the insula and inferior frontal gyrus in the moderate PD and in the insula, frontal gyrus, putamen, cingulated, and paracingulate gyri in the severe groups. In the CT analysis, in mild PD, cortical thinning was restricted to the superior temporal gyrus, gyrus rectus, and olfactory cortex; in the moderate group, the postcentral gyrus, supplementary motor area, and inferior frontal gyrus were also affected; in the severe PD, areas such as the precentral and postentral gyrus, temporal pole, fusiform, and occipital gyrus had reduced cortical thinning. We observed altered connectivity at the default mode, visual, sensorimotor, and cerebellar networks.
CONCLUSION: Subjects with mild symptoms already have cortical involvement; however, further cerebral involvement seems to follow Braak's proposed mechanism. Similar regions are affected both structurally and functionally. We believe the combination of different MRI techniques may be useful in evaluating progressive brain involvement and they may eventually be used as surrogate markers of disease progression.
PMID: 28133455 [PubMed - in process]
Assessing uncertainty in dynamic functional connectivity.
Neuroimage. 2017 Jan 26;:
Authors: Kudela M, Harezlak J, Lindquist MA
Functional connectivity (FC) - the study of the statistical association between time series from anatomically distinct regions (Friston, 1994, 2011) - has become one of the primary areas of research in the field surrounding resting state functional magnetic resonance imaging (rs-fMRI). Although for many years researchers have implicitly assumed that FC was stationary across time in rs-fMRI, it has recently become increasingly clear that this is not the case and the ability to assess dynamic changes in FC is critical for better understanding of the inner workings of the human brain (Hutchison et al., 2013; Chang and Glover, 2010). Currently, the most common strategy for estimating these dynamic changes is to use the sliding-window technique. However, its greatest shortcoming is the inherent variation present in the estimate, even for null data, which is easily confused with true time-varying changes in connectivity (Lindquist et al., 2014). This can have serious consequences as even spurious fluctuations caused by noise can easily be confused with an important signal. For these reasons, assessment of uncertainty in the sliding-window correlation estimates is of critical importance. Here we propose a new approach that combines the multivariate linear process bootstrap (MLPB) method and a sliding-window technique to assess the uncertainty in a dynamic FC estimate by providing its confidence bands. Both numerical results and an application to rs-fMRI study are presented, showing the efficacy of the proposed method.
PMID: 28132931 [PubMed - as supplied by publisher]
Altered degree centrality in childhood absence epilepsy: A resting-state fMRI study.
J Neurol Sci. 2017 Feb 15;373:274-279
Authors: Wang X, Jiao D, Zhang X, Lin X
Modern network studies have suggested that the pathology of many neurological diseases is in fact not equally distributed over the brain but preferentially affects the hub regions. This study aims to investigate how hub regions were affected in Children with Childhood absence epilepsy (CAE) using resting-state fMRI (rs-fMRI). As one important measures obtained from rs-fMRI, degree centrality (DC) calculates the number of direct connections between a given node and the rest of the brain within the entire connectivity matrix of the brain. In this study, twenty-five CAE children and 25 healthy controls were recruited to investigate the DC changes in CAE patients. Compared with healthy controls, children with CAE showed significantly decreased DC in default mode network (DMN, medial prefrontal cortex, posterior cingulate cortex, precuneus and middle temporal cortex) and increased DC in thalamus. Importantly, significant negative correlation between the epilepsy duration and DC was found in precuneus. Our results suggested selective and specific disruption of hub nodes, especially thalamus and the highly connected brain regions within DMN, might underlie the pathophysiological mechanism of CAE.
PMID: 28131205 [PubMed - in process]
Resting state fMRI regional homogeneity correlates with cognition measures in subcortical vascular cognitive impairment.
J Neurol Sci. 2017 Feb 15;373:1-6
Authors: Diciotti S, Orsolini S, Salvadori E, Giorgio A, Toschi N, Ciulli S, Ginestroni A, Poggesi A, De Stefano N, Pantoni L, Inzitari D, Mascalchi M, VMCI Tuscany investigators
BACKGROUND: The hyperintensity of cerebral white matter (WM) in T2-weighted MR images of elderly subjects due to small vessel disease (SVD) is associated with variable clinical features including mild cognitive impairment (MCI), also termed subcortical vascular cognitive impairment (SVCI). The latter is typically characterized by psychomotor slowing, attention deficits, and executive dysfunctions. We hypothesized that functional brain changes might be associated with these distinctive cognitive deficits in patients with SVCI.
METHODS: Resting-state fMRI (rsfMRI) signal was assessed in conjunction with performance on the Montreal Cognitive Assessment battery (MoCA) and Stroop test in 67 subjects with MCI and moderate to severe extension of cerebral WM T2 hyperintensities qualifying for SVCI. We performed a whole-brain analysis of regional homogeneity (ReHo) of rsfMRI in conjunction with cognitive test scores.
RESULTS: We observed a significant (p<0.05) negative association between ReHo and MoCA scores, with higher ReHo in the left posterior cerebellum (crus I) of patients with greater global cognitive impairment, and a significant positive association between ReHo and Stroop scores, with higher ReHo in the middle cingulate cortex bilaterally of patients with worse executive functions.
CONCLUSION: ReHo of rsfMRI is significantly correlated with measurements of the cognitive deficits which are distinctive of SVCI. The increased activity could have a maladaptive or compensatory significance towards specific aspects of cognition.
PMID: 28131162 [PubMed - in process]
Dynamic aftereffects in supplementary motor network following inhibitory transcranial magnetic stimulation protocols.
Neuroimage. 2017 Jan 24;:
Authors: Ji GJ, Yu F, Liao W, Wang K
The supplementary motor area (SMA) is a key node of the motor network. Inhibitory repetitive transcranial magnetic stimulation (rTMS) of the SMA can potentially improve movement disorders. However, the aftereffects of inhibitory rTMS on brain function remain largely unknown. Using a single-blind, crossover within-subject design, we investigated the role of aftereffects with two inhibitory rTMS protocols [1800 pulses of either 1-Hz repetitive stimulation or continuous theta burst stimulation (cTBS)] on the left SMA. A total of 19 healthy volunteers participated in the rTMS sessions on 2 separate days. Firstly, short-term aftereffects were estimated at three levels (functional connectivity, local activity, and network properties) by comparing the resting-state functional magnetic resonance imaging datasets (9min) acquired before and after each rTMS session. Local activity and network properties were not significantly altered by either protocol. Functional connectivity within the SMA network was increased (in the left paracentral gyrus) by 1-Hz stimulation and decreased (in the left inferior frontal gyrus and SMA/middle cingulate cortex) by cTBS. The subsequent three-way analysis of variance (site × time × protocol) did not show a significant interaction effect or "protocol" main effect, suggesting that the two protocols share an underlying mechanism. Secondly, sliding-window analysis was used to evaluate the dynamic features of aftereffects in the ~29min after the end of stimulation. Aftereffects were maintained for a maximum of 9.8 and 6.6min after the 1-Hz and cTBS protocols, respectively. In summary, this study revealed topographical and temporal aftereffects in the SMA network following inhibitory rTMS protocols, providing valuable information for their application in future neuroscience and clinical studies.
PMID: 28130194 [PubMed - as supplied by publisher]
Spatial distribution of resting-state BOLD regional homogeneity as a predictor of brain glucose uptake: A study in healthy aging.
Neuroimage. 2017 Jan 24;:
Authors: Bernier M, Croteau E, Castellano CA, Cunnane SC, Whittingstall K
Positron emission tomography using [18F]-fluorodeoxyglucose (PET-FDG) is the primary imaging modality used to measure glucose metabolism in the brain (CMRGlu). CMRGlu has been used as a biomarker of brain aging and neurodegenerative diseases, but the complexity and invasive nature of PET often limits its use in research. There is therefore great interest in developing non-invasive metrics for estimating brain CMRGlu. We therefore investigated resting state fMRI metrics such as regional homogeneity (ReHo), amplitude of low-frequency fluctuations (ALFF) and regional global connectivity (Closeness) with multiple analytical approaches to determine their relationship to CMRGlu. We investigated this relation in two distinct cognitively healthy populations separated by age (27 young adults and 35 older adults). Overall, we found that both regionally and across participants, ReHo strongly correlated with CMRGlu in healthy young and older adults. Moreover, ReHo demonstrated the same age-related differences as CMRGlu throughout all cortical regions, particularly in the default network and frontal areas.
PMID: 28130193 [PubMed - as supplied by publisher]
A variance components model for statistical inference on functional connectivity networks.
Neuroimage. 2017 Jan 24;:
Authors: Fiecas M, Cribben I, Bahktiari R, Cummine J
We propose a variance components linear modeling framework to conduct statistical inference on functional connectivity networks that directly accounts for the temporal autocorrelation inherent in functional magnetic resonance imaging (fMRI) time series data and for the heterogeneity across subjects in the study. The novel method estimates the autocorrelation structure in a nonparametric and subject-specific manner, and estimates the variance due to the heterogeneity using iterative least squares. We apply the new model to a resting-state fMRI study to compare the functional connectivity networks in both typical and reading impaired young adults in order to characterize the resting state networks that are related to reading processes. We also compare the performance of our model to other methods of statistical inference on functional connectivity networks that do not account for the temporal autocorrelation or heterogeneity across the subjects using simulated data, and show that by accounting for these sources of variation and covariation results in more powerful tests for statistical inference.
PMID: 28130192 [PubMed - as supplied by publisher]
Amygdala-Prefrontal Cortex Resting-State Functional Connectivity Varies with First Depressive or Manic Episode in Bipolar Disorder.
Neurosci Lett. 2017 Jan 24;:
Authors: Wei S, Geng H, Jiang X, Zhou Q, Chang M, Zhou Y, Xu K, Tang Y, Wang F
BACKGROUND: Bipolar disorder (BD) is one of the most complex mental illnesses, characterized by interactive depressive and manic states that are 2 contrary symptoms of disease states. The bilateral amygdala and prefrontal cortex (PFC) appear to play critical roles in BD; however, abnormalities seem to manifest differently in the 2 states and may provide further insight into underlying mechanisms.
METHODS: Sixteen participants with first-episode depressive and 13 participants with first-episode manic states of bipolar disorder as well as 30 healthy control (HC) participants underwent resting-state functional magnetic resonance imaging (fMRI). Resting-state functional connectivity (rsFC) between the bilateral amygdala and PFC was compared among the 3 groups.
RESULTS: Compared with depressive state participants of the BD group, manic state participants of the BD group showed a significant decrease in rsFC between the amygdala and right orbital frontal cortex (p<0.05, corrected). In addition, rsFC between the amygdala and left middle frontal cortex was significantly decreased in depressive and manic state participants of the BD group when compared with the HC group (p<0.05, corrected).
CONCLUSIONS: Our findings suggest that mood state during the first episodes of BD may be related to abnormality in hemispheric lateralization. The abnormalities in amygdala- left PFC functional connectivity might present the trait feature for BD, while deficits in amygdala- right PFC functional connectivity might be specific to manic episode, compared to depressive episode.
PMID: 28130184 [PubMed - as supplied by publisher]
Long-Term Experience of Chinese Calligraphic Handwriting Is Associated with Better Executive Functions and Stronger Resting-State Functional Connectivity in Related Brain Regions.
PLoS One. 2017;12(1):e0170660
Authors: Chen W, He Y, Gao Y, Zhang C, Chen C, Bi S, Yang P, Wang Y, Wang W
Chinese calligraphic handwriting (CCH) is a traditional art form that requires high levels of concentration and motor control. Previous research has linked short-term training in CCH to improvements in attention and memory. Little is known about the potential impacts of long-term CCH practice on a broader array of executive functions and their potential neural substrates. In this cross-sectional study, we recruited 36 practitioners with at least 5 years of CCH experience and 50 control subjects with no more than one month of CCH practice and investigated their differences in the three components of executive functions (i.e., shifting, updating, and inhibition). Valid resting-state fMRI data were collected from 31 CCH and 40 control participants. Compared with the controls, CCH individuals showed better updating (as measured by the Corsi Block Test) and inhibition (as measured by the Stroop Word-Color Test), but the two groups did not differ in shifting (as measured by a cue-target task). The CCH group showed stronger resting-state functional connectivity (RSFC) than the control group in brain areas involved in updating and inhibition. These results suggested that long-term CCH training may be associated with improvements in specific aspects of executive functions and strengthened neural networks in related brain regions.
PMID: 28129407 [PubMed - in process]