Alterations in amplitude of low frequency fluctuation in treatment-naïve major depressive disorder measured with resting-state fMRI.
Hum Brain Mapp. 2014 Apr 17;
Authors: Liu J, Ren L, Womer FY, Wang J, Fan G, Jiang W, Blumberg HP, Tang Y, Xu K, Wang F
There are limited resting-state functional magnetic resonance imaging (fMRI) studies in major depressive disorder (MDD). Of these studies, functional connectivity analyses are mostly used. However, a new method based on the magnitude of low frequency fluctuation (LFF) during resting-state fMRI may provide important insight into MDD. In this study, we examined the amplitude of LFF (ALFF) within the whole brain during resting-state fMRI in 30 treatment-naïve MDD subjects and 30 healthy control (HC) subjects. When compared with HC, MDD subjects showed increased ALFF in the frontal cortex (including the bilateral ventral/dorsal anterior cingulate cortex, orbitofrontal cortex, premotor cortex, ventral prefrontal cortex, left dorsal lateral frontal cortex, left superior frontal cortex), basal ganglia (including the right putamen and left caudate nucleus), left insular cortex, right anterior entorhinal cortex and left inferior parietal cortex, together with decreased ALFF in the bilateral occipital cortex, cerebellum hemisphere, and right superior temporal cortex. These findings may relate to characteristics of MDD, such as excessive self-referential processing and deficits in cognitive control of emotional processing, which may contribute to the persistent and recurrent nature of the disorder. Hum Brain Mapp, 2014. © 2014 Wiley Periodicals, Inc.
PMID: 24740815 [PubMed - as supplied by publisher]
Resting state functional connectivity of the basal nucleus of Meynert in humans: in comparison to the ventral striatum and the effects of age.
Neuroimage. 2014 Apr 12;
Authors: Li CS, Ide JS, Zhang S, Hu S, Chao HH, Zaborszky L
The basal nucleus of Meynert (BNM) provides the primary cholinergic inputs to the cerebral cortex. Loss of neurons in the BNM is linked to cognitive deficits in Alzheimer's disease and other degenerative conditions. Numerous animal studies described cholinergic and non-cholinergic neuronal responses in the BNM; however, work in humans has been hampered by the difficulty of defining the BNM anatomically. Here, on the basis of a previous study that delineated the BNM of post-mortem human brains in a standard stereotaxic space, we sought to examine functional connectivity of the BNM, as compared to the nucleus accumbens (or ventral striatum, VS), in a large resting state functional magnetic resonance imaging data set. The BNM and VS shared but also showed a distinct pattern of cortical and subcortical connectivity. Compared to the VS, the BNM showed stronger positive connectivity with the putamen, pallidum, thalamus, amygdala and midbrain, as well as the anterior cingulate cortex, supplementary motor area and pre-supplementary motor area, a network of brain regions that respond to salient stimuli and orchestrate motor behavior. In contrast, compared to the BNM, the VS showed stronger positive connectivity with the ventral caudate and medial orbitofrontal cortex, areas implicated in reward processing and motivated behavior. Furthermore, the BNM and VS each showed extensive negative connectivity with visual and lateral prefrontal cortices. Together, the distinct cerebral functional connectivities support the role of the BNM in arousal, saliency responses and cognitive motor control and the VS in reward related behavior. Considering the importance of BNM in age-related cognitive decline, we explored the effects of age on BNM and VS connectivities. BNM connectivity to the visual and somatomotor cortices decreases while connectivity to subcortical structures including the midbrain, thalamus, and pallidum increases with age. These findings of age-related changes of cerebral functional connectivity of the BNM may facilitate research of the neural bases of cognitive decline in health and illness.
PMID: 24736176 [PubMed - as supplied by publisher]
Brain stimulation and functional imaging with fMRI and PET.
Handb Clin Neurol. 2013;116:77-95
Authors: Ko JH, Tang CC, Eidelberg D
The use of functional brain imaging techniques, including positron emission tomography (PET), single-photon emission computed tomography (SPECT), and functional magnetic resonance imaging (fMRI), has allowed for monitoring neuronal and neurochemical activities in the living human brain and identifying abnormal changes in various neurological and psychiatric diseases. Combining these methods with techniques such as deep brain stimulation (DBS) and transcranial magnetic stimulation (TMS) has greatly advanced our understanding of the effects of such treatment on brain activity at targeted regions as well as specific disease-related networks. Indeed, recent network-level analysis focusing on inter-regional covarying activities in data interpretation has unveiled several key mechanisms underlying the therapeutic effects of brain stimulation. However, non-negligible discrepancies have been reported in the literature, attributable in part to the heterogeneity of both imaging and brain stimulation techniques. This chapter summarizes recent studies that combine brain imaging and brain stimulation, and includes discussion of future direction in these lines of research.
PMID: 24112887 [PubMed - indexed for MEDLINE]
Acupuncture modulates the functional connectivity of the default mode network in stroke patients.
Evid Based Complement Alternat Med. 2014;2014:765413
Authors: Zhang Y, Li K, Ren Y, Cui F, Xie Z, Shin JY, Tan Z, Tang L, Bai L, Zou Y
Abundant evidence from previous fMRI studies on acupuncture has revealed significant modulatory effects at widespread brain regions. However, few reports on the modulation to the default mode network (DMN) of stroke patients have been investigated in the field of acupuncture. To study the modulatory effects of acupuncture on the DMN of stroke patients, eight right hemispheric infarction and stable ischemic stroke patients and ten healthy subjects were recruited to undergo resting state fMRI scanning before and after acupuncture stimulation. Functional connectivity analysis was applied with the bilateral posterior cingulate cortices chosen as the seed regions. The main finding demonstrated that the interregional interactions between the ACC and PCC especially enhanced after acupuncture at GB34 in stroke patients, compared with healthy controls. The results indicated that the possible mechanisms of the modulatory effects of acupuncture on the DMN of stroke patients could be interpreted in terms of cognitive ability and motor function recovery.
PMID: 24734113 [PubMed]
Acupuncture Enhances Effective Connectivity between Cerebellum and Primary Sensorimotor Cortex in Patients with Stable Recovery Stroke.
Evid Based Complement Alternat Med. 2014;2014:603909
Authors: Xie Z, Cui F, Zou Y, Bai L
Recent neuroimaging studies have demonstrated that stimulation of acupuncture at motor-implicated acupoints modulates activities of brain areas relevant to the processing of motor functions. This study aims to investigate acupuncture-induced changes in effective connectivity among motor areas in hemiparetic stroke patients by using the multivariate Granger causal analysis. A total of 9 stable recovery stroke patients and 8 healthy controls were recruited and underwent three runs of fMRI scan: passive finger movements and resting state before and after manual acupuncture stimuli. Stroke patients showed significantly attenuated effective connectivity between cortical and subcortical areas during passive motor task, which indicates inefficient information transmissions between cortical and subcortical motor-related regions. Acupuncture at motor-implicated acupoints showed specific modulations of motor-related network in stroke patients relative to healthy control subjects. This specific modulation enhanced bidirectionally effective connectivity between the cerebellum and primary sensorimotor cortex in stroke patients, which may compensate for the attenuated effective connectivity between cortical and subcortical areas during passive motor task and, consequently, contribute to improvement of movement coordination and motor learning in subacute stroke patients. Our results suggested that further efficacy studies of acupuncture in motor recovery can focus on the improvement of movement coordination and motor learning during motor rehabilitation.
PMID: 24734108 [PubMed]
[Resting-state functional MRI research of the auditory cortex in patients with long-term unilateral hearing loss].
Zhonghua Yi Xue Za Zhi. 2014 Jan 21;94(3):167-70
Authors: Li J, Yang M, Liu B, Zhang G, Qian N
OBJECTIVE: To evaluate functional connectivity in patients with unilateral sensorineural hearing loss(USNHL) using resting-state fMRI.
METHODS: Functional connectivity MRI were employed in 29 patients with SNHL (15 left, 14 right) with averaged hearing level above 70 dB HL for the deaf ear, and matched 15 and 14 normal hearing subjects, respectively, were recruited. Functional connectivity mappings between the SNHL patients and normal hearing subjects were evaluated and the differences were contrasted.
RESULTS: The positive functional connectivity of auditory cortex with whole brain in USNHL patients is weaker than that in normal subjects both in volume and intensity. Using the affected side AIas a seed, left and right Laterality index(LI)of auditory cortex was 30.14, -31.25, respectively. Using the healthy side as a seed, the LI of auditory cortex was 0.1, 19.37, respectively. Compared to normal subjects, increased activation in bilateral precentral gyrus, left middle frontal gyrus, left superior frontal gyrus and posterior cingulate cortex/precuneus were found in left USNHL patients. Contrasted with normal subjects, no significant difference was found between the normal subjects and right SNHL patients, except the right caudate nucleus using left AIas a seed.
CONCLUSION: The reduced functional connectivity among the affected side and healthy side auditory cortex as well as associated auditory cortex may suggest a result of functional reorganization adaptive to the SNHL.
PMID: 24731454 [PubMed - in process]
Intensive virtual reality-based training for upper limb motor function in chronic stroke: a feasibility study using a single case experimental design and fMRI.
Disabil Rehabil Assist Technol. 2014 Apr 14;
Authors: Schuster-Amft C, Henneke A, Hartog-Keisker B, Holper L, Siekierka E, Chevrier E, Pyk P, Kollias S, Kiper D, Eng K
Abstract Purpose: To evaluate feasibility and neurophysiological changes after virtual reality (VR)-based training of upper limb (UL) movements. Method: Single-case A-B-A-design with two male stroke patients (P1:67 y and 50 y, 3.5 and 3 y after onset) with UL motor impairments, 45-min therapy sessions 5×/week over 4 weeks. Patients facing screen, used bimanual data gloves to control virtual arms. Three applications trained bimanual reaching, grasping, hand opening. Assessments during 2-week baseline, weekly during intervention, at 3-month follow-up (FU): Goal Attainment Scale (GAS), Chedoke Arm and Hand Activity Inventory (CAHAI), Chedoke-McMaster Stroke Assessment (CMSA), Extended Barthel Index (EBI), Motor Activity Log (MAL). Functional magnetic resonance imaging scans (FMRI) before, immediately after treatment and at FU. Results: P1 executed 5478 grasps (paretic arm). Improvements in CAHAI (+4) were maintained at FU. GAS changed to +1 post-test and +2 at FU. P2 executed 9835 grasps (paretic arm). CAHAI improvements (+13) were maintained at FU. GAS scores changed to -1 post-test and +1 at FU. MAL scores changed from 3.7 at pre-test to 5.5 post-test and 3.3 at FU. Conclusion: The VR-based intervention was feasible, safe, and intense. Adjustable application settings maintained training challenge and patient motivation. ADL-relevant UL functional improvements persisted at FU and were related to changed cortical activation patterns. Implications for Rehabilitation YouGrabber trains uni- and bimanual upper motor function. Its application is feasible, safe, and intense. The control of the virtual arms can be done in three main ways: (a) normal (b) virtual mirror therapy, or (c) virtual following. The mirroring feature provides an illusion of affected limb movements during the period when the affected upper limb (UL) is resting. The YouGrabber training led to ADL-relevant UL functional improvements that were still assessable 12 weeks after intervention finalization and were related to changed cortical activation patterns.
PMID: 24730659 [PubMed - as supplied by publisher]
Estimation of resting-state functional connectivity using random subspace based partial correlation: a novel method for reducing global artifacts.
Neuroimage. 2013 Nov 15;82:87-100
Authors: Chen T, Ryali S, Qin S, Menon V
Intrinsic functional connectivity analysis using resting-state functional magnetic resonance imaging (rsfMRI) has become a powerful tool for examining brain functional organization. Global artifacts such as physiological noise pose a significant problem in estimation of intrinsic functional connectivity. Here we develop and test a novel random subspace method for functional connectivity (RSMFC) that effectively removes global artifacts in rsfMRI data. RSMFC estimates the partial correlation between a seed region and each target brain voxel using multiple subsets of voxels sampled randomly across the whole brain. We evaluated RSMFC on both simulated and experimental rsfMRI data and compared its performance with standard methods that rely on global mean regression (GSReg) which are widely used to remove global artifacts. Using extensive simulations we demonstrate that RSMFC is effective in removing global artifacts in rsfMRI data. Critically, using a novel simulated dataset we demonstrate that, unlike GSReg, RSMFC does not artificially introduce anti-correlations between inherently uncorrelated networks, a result of paramount importance for reliably estimating functional connectivity. Furthermore, we show that the overall sensitivity, specificity and accuracy of RSMFC are superior to GSReg. Analysis of posterior cingulate cortex connectivity in experimental rsfMRI data from 22 healthy adults revealed strong functional connectivity in the default mode network, including more reliable identification of connectivity with left and right medial temporal lobe regions that were missed by GSReg. Notably, compared to GSReg, negative correlations with lateral fronto-parietal regions were significantly weaker in RSMFC. Our results suggest that RSMFC is an effective method for minimizing the effects of global artifacts and artificial negative correlations, while accurately recovering intrinsic functional brain networks.
PMID: 23747287 [PubMed - indexed for MEDLINE]
The Spectral Diversity of Resting-State Fluctuations in the Human Brain.
PLoS One. 2014;9(4):e93375
Authors: Kalcher K, Boubela RN, Huf W, Bartova L, Kronnerwetter C, Derntl B, Pezawas L, Filzmoser P, Nasel C, Moser E
In order to assess whole-brain resting-state fluctuations at a wide range of frequencies, resting-state fMRI data of 20 healthy subjects were acquired using a multiband EPI sequence with a low TR (354 ms) and compared to 20 resting-state datasets from standard, high-TR (1800 ms) EPI scans. The spatial distribution of fluctuations in various frequency ranges are analyzed along with the spectra of the time-series in voxels from different regions of interest. Functional connectivity specific to different frequency ranges (<0.1 Hz; 0.1-0.25 Hz; 0.25-0.75 Hz; 0.75-1.4 Hz) was computed for both the low-TR and (for the two lower-frequency ranges) the high-TR datasets using bandpass filters. In the low-TR data, cortical regions exhibited highest contribution of low-frequency fluctuations and the most marked low-frequency peak in the spectrum, while the time courses in subcortical grey matter regions as well as the insula were strongly contaminated by high-frequency signals. White matter and CSF regions had highest contribution of high-frequency fluctuations and a mostly flat power spectrum. In the high-TR data, the basic patterns of the low-TR data can be recognized, but the high-frequency proportions of the signal fluctuations are folded into the low frequency range, thus obfuscating the low-frequency dynamics. Regions with higher proportion of high-frequency oscillations in the low-TR data showed flatter power spectra in the high-TR data due to aliasing of the high-frequency signal components, leading to loss of specificity in the signal from these regions in high-TR data. Functional connectivity analyses showed that there are correlations between resting-state signal fluctuations of distant brain regions even at high frequencies, which can be measured using low-TR fMRI. On the other hand, in the high-TR data, loss of specificity of measured fluctuations leads to lower sensitivity in detecting functional connectivity. This underlines the advantages of low-TR EPI sequences for resting-state and potentially also task-related fMRI experiments.
PMID: 24728207 [PubMed - as supplied by publisher]
Connectomics signatures of prenatal cocaine exposure affected adolescent brains.
Hum Brain Mapp. 2013 Oct;34(10):2494-510
Authors: Li K, Zhu D, Guo L, Li Z, Lynch ME, Coles C, Hu X, Liu T
Recent in vivo neuroimaging studies revealed that several brain networks are altered in prenatal cocaine exposure (PCE) affected adolescent brains. However, due to a lack of dense and corresponding cortical landmarks across individuals, the systematical alterations of functional connectivities in large-scale brain networks and the alteration of structural brain architecture in PCE affected brain are largely unknown. In this article, we adopted a newly developed data-driven strategy to build a large set of cortical landmarks that are consistent and corresponding across PCE adolescents and their matched controls. Based on these landmarks, we constructed large-scale functional connectomes and applied the well-established approaches of deriving genomics signatures in genome-wide gene expression studies to discover functional connectomics signatures for the characterization of PCE adolescent brains. Results derived from experimental data demonstrated that 10 structurally disrupted landmarks were identified in PCE, and more importantly, the discovered informative functional connectomics signatures among consistent landmarks distinctively differentiate PCE brains from their matched controls.
PMID: 22461404 [PubMed - indexed for MEDLINE]
Resting-state functional MRI: functional connectivity analysis of the visual cortex in primary open-angle glaucoma patients.
Hum Brain Mapp. 2013 Oct;34(10):2455-63
Authors: Dai H, Morelli JN, Ai F, Yin D, Hu C, Xu D, Li Y
PURPOSE: To analyze functional connectivity (FC) of the visual cortex using resting-state functional MRI in human primary open-angle glaucoma (POAG) patients.
MATERIALS AND METHODS: Twenty-two patients with known POAG and 22 age-matched controls were included in this IRB-approved study. Subjects were evaluated by 3 T MR using resting-state blood oxygenation level dependent and three-dimensional brain volume imaging (3D-BRAVO) MRI. Data processing was performed with standard software. FC maps were generated from Brodmann areas (BA) 17/18/19/7 in a voxel-wise fashion. Region of interest analysis was used to specifically examine FC among each pair of BA17/18/19/7.
RESULTS: Voxel-wise analyses demonstrated decreased FC in the POAG group between the primary visual cortex (BA17) and the right inferior temporal, left fusiform, left middle occipital, right superior occipital, left postcentral, right precentral gyri, and anterior lobe of the left cerebellum. Increased FC was found between BA17 and the left cerebellum, right middle cerebellar peduncle, right middle frontal gyrus, and extra-nuclear gyrus (P < 0.05). In terms of the higher visual cortices (BA18/19), positive FC was disappeared with the cerebellar vermis, right middle temporal, and right superior temporal gyri (P < 0.05). Negative FC was disappeared between BA18/19 and the right insular gyrus (P < 0.05). Region of interest analysis demonstrated no statistically significant differences in FC between the POAG patients relative to the controls (P > 0.05).
CONCLUSION: Changes in FC of the visual cortex are found in patients with POAG. These include alterations in connectivity between the visual cortex and associative visual areas along with disrupted connectivity between the primary and higher visual areas.
PMID: 22461380 [PubMed - indexed for MEDLINE]
Meal replacement: calming the hot-state brain network of appetite.
Front Psychol. 2014;5:249
Authors: Paolini BM, Laurienti PJ, Norris J, Rejeski WJ
There is a growing awareness in the field of neuroscience that the self-regulation of eating behavior is driven by complex networks within the brain. These networks may be vulnerable to "hot states" which people can move into and out of dynamically throughout the course of a day as a function of changes in affect or visceral cues. The goal of the current study was to identify and determine differences in the Hot-state Brain Network of Appetite (HBN-A) that exists after a brief period of food restraint followed either by the consumption of a meal replacement (MR) or water. Fourteen overweight/obese adults came to our laboratory on two different occasions. Both times they consumed a controlled breakfast meal and then were restricted from eating for 2.5 h prior to an MRI scan. On one visit, they consumed a meal replacement (MR) liquid meal after this period of food restriction; on the other visit they consumed an equal amount of water. After these manipulations, the participants underwent a resting fMRI scan. Our first study aim employed an exploratory, data-driven approach to identify hubs relevant to the HBN-A. Using data from the water condition, five regions were found to be the hubs or nodes of the HBN-A: insula, anterior cingulated cortex, the superior temporal pole, the amygdala, and the hippocampus. We then demonstrated that the consumption of a liquid MR dampened interconnectivity between the nodes of the HBN-A as compared to water. Importantly and consistent with these network data, the consumption of a MR beverage also lowered state cravings and hunger.
PMID: 24723901 [PubMed]
Analysis of central mechanism of cognitive training on cognitive impairment after stroke: Resting-state functional magnetic resonance imaging study.
J Int Med Res. 2014 Apr 10;
Authors: Lin ZC, Tao J, Gao YL, Yin DZ, Chen AZ, Chen LD
OBJECTIVE: To investigate the central mechanism of cognitive training in patients with stroke, using resting state (RS) functional magnetic resonance imaging (fMRI).
METHODS: Patients with stroke and executive function and memory deficit were randomized to receive computer-assisted cognitive training (treatment group; total 60 h training over 10 weeks) or no training (control group). All participants received neuropsychological assessment and RS fMRI at baseline and 10 weeks.
RESULTS: Patients in the treatment group (n = 16) showed increased functional connectivity (FC) of the hippocampus with the frontal lobe (right inferior, right middle, left middle, left inferior and left superior frontal gyrus) and left parietal lobe at 10 weeks compared with baseline. Patients in the control group (n = 18) showed decreased FC of the left hippocampus-right occipital gyrus, and right hippocampus-right posterior lobe of cerebellum and left superior temporal gyrus. Significant correlations were found between improved neuropsychological scores and increased FC of the hippocampus with the frontal lobe and left parietal lobe in the treatment group only.
CONCLUSIONS: Increased RS FC of the hippocampus with the frontal and parietal lobes may be an important mechanism of cognitive recovery after stroke.
PMID: 24722262 [PubMed - as supplied by publisher]
Frequency-dependent amplitude alterations of resting-state spontaneous fluctuations in idiopathic generalized epilepsy.
Epilepsy Res. 2014 Mar 26;
Authors: Wang Z, Zhang Z, Liao W, Xu Q, Zhang J, Lu W, Jiao Q, Chen G, Feng J, Lu G
PURPOSE: Amplitude of low-frequency fluctuation (ALFF) of blood-oxygenation level-dependent (BOLD) has proven a promising way to detect disease-related local brain activity. However, routine approach employs an arbitrary frequency band of 0.01-0.08Hz, which lacks frequency specificity and blinds to the information contained in other frequency bands. This study investigated the amplitude of fluctuations in full BOLD frequency bands, and addressed how amplitudes of fluctuations change in each specific frequency range in idiopathic generalized epilepsy (IGE).
METHODS: Thirty-four IGE patients with generalized tonic-clonic seizure and the same number of age- and sex-matched healthy controls were included. Functional MRI data were acquired using a 2s repetition time. Routine amplitude of low-frequency fluctuation analysis was first performed. The regions showing group difference were set as Region-of-interest for analysis of amplitudes of full-frequency. The amplitudes of BOLD fluctuations were consecutively performed at each frequency bin of 0.002Hz, and specific frequency amplitude analyses were performed in five different frequency ranges (0-0.01Hz, 0.01-0.027Hz, 0.027-0.073Hz, 0.073-0.198Hz, and 0.198-0.25Hz).
KEY FINDINGS: The thalamus and prefrontal cortex showed significant group differences in routine amplitude analysis. For amplitude of full-frequency analysis, a reverse pattern was found in the dynamic changes between the thalamus and prefrontal cortex in IGE. Moreover, the prefrontal cortex showed amplitude difference in the 0.01-0.027Hz band, while the thalamus showed amplitude difference in the 0.027-0.073Hz band. Both these two regions showed amplitude differences in 0.198-0.25Hz band.
SIGNIFICANCE: We demonstrated the characteristic alterations of amplitude of BOLD fluctuations in IGE in frequency domain. The amplitude analysis of full frequency may potentially help to select specific frequency range for detecting epilepsy-related brain activity, and provide insights into the pathophysiological mechanism of IGE.
PMID: 24721198 [PubMed - as supplied by publisher]
A novel approach for fMRI data analysis based on the combination of sparse approximation and affinity propagation clustering.
Magn Reson Imaging. 2014 Mar 14;
Authors: Ren T, Zeng W, Wang N, Chen L, Wang C
Clustering analysis has been widely used to detect the functional connectivity from functional magnetic resonance imaging (fMRI) data. However, it has some limitations such as enormous computer memory requirement, and difficulty in estimating the number of clusters. In this study, in order to effectually resolve the deficiencies mentioned above, we have proposed a novel approach (SAAPC) for fMRI data analysis, which combines sparsity, an effective assumption for analyzing fMRI signal, with affinity propagation clustering (APC). The SAAPC method is composed of three parts: to obtain the sparse approximation coefficients set through wavelet packet decomposition and sparsity measuring and selection, which contributes a lot in the brain functional connectivity detection accuracy; to implement a split APC algorithm, which is put forward in this paper to overcome the computer memory shortage problem and to reduce the time cost in basic APC; to reconstruct the source signal by unmixing the mixed fMRI data using the time courses which are derived from the ultimate exemplars. In the task-related experiments, we can see that SAAPC is more accurate to detect the functional networks than basic APC, and it significantly reduces the time cost relative to basic APC. In addition, in the resting-state data experiments, the SAAPC method can successfully identify typical resting-state networks from the resting-state data set, while this performance is seldom reported by the classical cluster method and the basic APC method. This proposed clustering analysis method is expected to have wide applicability.
PMID: 24721006 [PubMed - as supplied by publisher]
Altered Amplitude of Low-Frequency Fluctuations in Early and Late Mild Cognitive Impairment and Alzheimer's Disease.
Curr Alzheimer Res. 2014 Mar 31;
Authors: Liang P, Xiang J, Liang H, Qi Z, Zhong N, Li K
Purpose: Previous studies have shown that the strength of the low frequency fluctuation in the medial-line brain areas are abnormally reduced in mild cognitive impairment (MCI) and Alzheimer's disease (AD) patients. The purpose of this study was to explore the functional brain changes in early MCI (EMCI) and late MCI (LMCI) patients by measuring the amplitude of the blood oxygenation level dependent (BOLD) functional MRI (fMRI) signals at rest. Materials and methods: 35 elderly normal controls (NC), 24 EMCI, 29 LMCI, and 14 AD patients from the Alzheimer's Disease Neuroimaging Initiative (ADNI2) were included in this study. Resting state fMRI and 3D structural MRI data were acquired. The spatial patterns of spontaneous brain activity were measured by examining the amplitude of low-frequency fluctuations (ALFF) of BOLD signal during rest. A one-way analysis of variance (ANOVA) was then performed on ALFF maps, with age, sex and regional atrophy as covariates. Results: There were widespread ALFF differences among the four groups. As compared with controls, AD, LMCI and EMCI patients showed decreased ALFF mainly in the posterior cingulate cortex, precuneus, right lingual gyrus and thalamus (with a linear trend: NC>EMCI>LMCI>AD), while there was increased activity in the right parahippocampal gyrus (with a linear trend: NC<EMCI<LMCI<AD). Additionally, we also showed that many regions with ALFF changes had significant correlations with the cognitive performance as measured by mini-mental state examination scores (MMSE) and the emotion states as measured by Geriatric Depression Scale (GD scale) for EMCI, LMCI and AD patients, but not for controls. Conclusion: Our results indicated that the significantly altered ALFF activities can be detected at EMCI stage, independent of age, sex and regional atrophy. The present study thus suggest ALFF abnormalities as a potential biomarker for the early diagnosis of AD and further provide insights into biological mechanisms of the diseases.
PMID: 24720892 [PubMed - as supplied by publisher]
Surface-based regional homogeneity in first-episode, drug-naïve major depression: a resting-state FMRI study.
Biomed Res Int. 2014;2014:374828
Authors: Li HJ, Cao XH, Zhu XT, Zhang AX, Hou XH, Xu Y, Zuo XN, Zhang KR
Background. Previous volume-based regional homogeneity (ReHo) studies neglected the intersubject variability in cortical folding patterns. Recently, surface-based ReHo was developed to reduce the intersubject variability and to increase statistical power. The present study used this novel surface-based ReHo approach to explore the brain functional activity differences between first-episode, drug-naïve MDD patients and healthy controls. Methods. Thirty-three first-episode, drug-naïve MDD patients and 32 healthy controls participated in structural and resting-state fMRI scans. MDD patients were rated with a 17-item Hamilton Rating Scale for Depression prior to the scan. Results. In comparison with the healthy controls, MDD patients showed reduced surface-based ReHo in the left insula. There was no increase in surface-based ReHo in MDD patients. The surface-based ReHo value in the left insula was not significantly correlated with the clinical information or the depressive scores in the MDD group. Conclusions. The decreased surface-based ReHo in the left insula in MDD may lead to the abnormal top-down cortical-limbic regulation of emotional and cognitive information. The surface-based ReHo may be a useful index to explore the pathophysiological mechanism of MDD.
PMID: 24719857 [PubMed - in process]
Fine-grained Mapping of Mouse Brain Functional Connectivity with Resting-state fMRI.
Neuroimage. 2014 Apr 6;
Authors: Mechling A, Hübner N, Lee HL, Hennig J, von Elverfeldt D, Harsan LA
Understanding the intrinsic circuit-level functional organization of the brain has benefited tremendously from the advent of resting-state fMRI (rsfMRI). In humans, resting-state functional network has been consistently mapped and its alterations have been shown to correlate with symptomatology of various neurological or psychiatric disorders. To date, deciphering the mouse brain functional connectivity (MBFC) with rsfMRI remains a largely underexplored research area, despite the plethora of human brain disorders that can be modeled in this specie. To pave the way from pre-clinical to clinical investigations we characterized here the intrinsic architecture of mouse brain functional circuitry, based on rsfMRI data acquired at 7T using the Cryoprobe technology. High-dimensional spatial group independent component analysis demonstrated fine-grained segregation of cortical and subcortical networks into functional clusters, overlapping with high specificity onto anatomical structures, down to single gray matter nuclei. These clusters, showing a high level of stability and reliability in their patterning, formed the input elements for computing the MBFC network using partial correlation and graph theory. Its topological architecture conserved the fundamental characteristics described for the human and rat brain, such as small-worldness and partitioning into functional modules. Our results additionally showed inter-modular interactions via "network hubs". Each major functional system (motor, somatosensory, limbic, visual, autonomic) was found to have representative hubs that might play an important input/output role and form a functional core for information integration. Moreover, the rostro-dorsal hippocampus formed the highest number of relevant connections with other brain areas, highlighting its importance as core structure for MBFC.
PMID: 24718287 [PubMed - as supplied by publisher]
Altered network topologies and hub organization in adults with autism: a resting-state FMRI study.
PLoS One. 2014;9(4):e94115
Authors: Itahashi T, Yamada T, Watanabe H, Nakamura M, Jimbo D, Shioda S, Toriizuka K, Kato N, Hashimoto R
Recent functional magnetic resonance imaging (fMRI) studies on autism spectrum condition (ASC) have identified dysfunctions in specific brain networks involved in social and non-social cognition that persist into adulthood. Although increasing numbers of fMRI studies have revealed atypical functional connectivity in the adult ASC brain, such functional alterations at the network level have not yet been fully characterized within the recently developed graph-theoretical framework. Here, we applied a graph-theoretical analysis to resting-state fMRI data acquired from 46 adults with ASC and 46 age- and gender-matched controls, to investigate the topological properties and organization of autistic brain network. Analyses of global metrics revealed that, relative to the controls, participants with ASC exhibited significant decreases in clustering coefficient and characteristic path length, indicating a shift towards randomized organization. Furthermore, analyses of local metrics revealed a significantly altered organization of the hub nodes in ASC, as shown by analyses of hub disruption indices using multiple local metrics and by a loss of "hubness" in several nodes (e.g., the bilateral superior temporal sulcus, right dorsolateral prefrontal cortex, and precuneus) that are critical for social and non-social cognitive functions. In particular, local metrics of the anterior cingulate cortex consistently showed significant negative correlations with the Autism-Spectrum Quotient score. Our results demonstrate altered patterns of global and local topological properties that may underlie impaired social and non-social cognition in ASC.
PMID: 24714805 [PubMed - in process]
Disturbed small-world networks and neurocognitive function in frontal lobe low-grade glioma patients.
PLoS One. 2014;9(4):e94095
Authors: Huang Q, Zhang R, Hu X, Ding S, Qian J, Lei T, Cao X, Tao L, Qian Z, Liu H
BACKGROUND: Brain tumor patients often associated with losses of the small-world configuration and neurocognitive functions before operations. However, few studies were performed on the impairments of frontal lobe low-grade gliomas (LGG) after tumor resection using small-world network features.
METHODOLOGY/PRINCIPAL FINDINGS: To detect differences in the whole brain topology among LGG patients before and after operation, a combined study of neurocognitive assessment and graph theoretical network analysis of fMRI data was performed. We collected resting-state fMRI data of 12 carefully selected frontal lobe LGG patients before and after operation. We calculated the topological properties of brain functional networks in the 12 LGG, and compared with 12 healthy controls (HCs). We also applied Montreal Cognitive Assessment (MoCA) in a subset of patients (n = 12, including before and after operation groups) and HCs (n = 12). The resulting functional connectivity matrices were constructed for all 12 patients, and binary network analysis was performed. In the range of [Formula: see text], the functional networks in preoperative LGG and postoperative one both fitted the definition of small-worldness. We proposed [Formula: see text] as small-world network interval, and the results showed that the topological properties were found to be disrupted in the two LGG groups, meanwhile the global efficiency increased and the local efficiency decreased. [Formula: see text] in the two LGG groups both were longer than HCs. [Formula: see text] in the LGG groups were smaller than HCs. Compared with the Hcs, MoCA in the two LGG groups were lower than HCs with significant difference, and the disturbed networks in the LGG were negatively related to worse MoCA scores.
CONCLUSIONS: Disturbed small-worldness preperty in the two LGG groups was found and widely spread in the strength and spatial organization of brain networks, and the alterated small-world network may be responsible for cognitive dysfunction in frontal lobe LGG patients.
PMID: 24714669 [PubMed - in process]