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Differences in interregional brain connectivity in children with unilateral hearing loss.

Fri, 04/21/2017 - 15:20
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Differences in interregional brain connectivity in children with unilateral hearing loss.

Laryngoscope. 2017 Apr 20;:

Authors: Jung ME, Colletta M, Coalson R, Schlaggar BL, Lieu JEC

Abstract
OBJECTIVES: To identify functional network architecture differences in the brains of children with unilateral hearing loss (UHL) using resting-state functional-connectivity magnetic resonance imaging (rs-fcMRI).
STUDY DESIGN: Prospective observational study.
METHODS: Children (7 to 17 years of age) with severe to profound hearing loss in one ear, along with their normal hearing (NH) siblings, were recruited and imaged using rs-fcMRI. Eleven children had right UHL; nine had left UHL; and 13 had normal hearing. Forty-one brain regions of interest culled from established brain networks such as the default mode (DMN); cingulo-opercular (CON); and frontoparietal networks (FPN); as well as regions for language, phonological, and visual processing, were analyzed using regionwise correlations and conjunction analysis to determine differences in functional connectivity between the UHL and normal hearing children.
RESULTS: When compared to the NH group, children with UHL showed increased connectivity patterns between multiple networks, such as between the CON and visual processing centers. However, there were decreased, as well as aberrant connectivity patterns with the coactivation of the DMN and FPN, a relationship that usually is negatively correlated.
CONCLUSION: Children with UHL demonstrate multiple functional connectivity differences between brain networks involved with executive function, cognition, and language comprehension that may represent adaptive as well as maladaptive changes. These findings suggest that possible interventions or habilitation, beyond amplification, might be able to affect some children's requirement for additional help at school.
LEVEL OF EVIDENCE: 3b. Laryngoscope, 2017.

PMID: 28425563 [PubMed - as supplied by publisher]

Modafinil-Induced Changes in Functional Connectivity in the Cortex and Cerebellum of Healthy Elderly Subjects.

Fri, 04/21/2017 - 15:20
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Modafinil-Induced Changes in Functional Connectivity in the Cortex and Cerebellum of Healthy Elderly Subjects.

Front Aging Neurosci. 2017;9:85

Authors: Punzi M, Gili T, Petrosini L, Caltagirone C, Spalletta G, Sensi SL

Abstract
In the past few years, cognitive enhancing drugs (CEDs) have gained growing interest and the focus of investigations aimed at exploring their use to potentiate the cognitive performances of healthy individuals. Most of this exploratory CED-related research has been performed on young adults. However, CEDs may also help to maintain optimal brain functioning or compensate for subtle and or subclinical deficits associated with brain aging or early-stage dementia. In this study, we assessed effects on resting state brain activity in a group of healthy elderly subjects undergoing acute administration of modafinil, a wakefulness-promoting agent. To that aim, participants (n = 24) were investigated with resting state functional Magnetic Resonance Imaging (rs-fMRI) before and after the administration of a single dose (100 mg) of modafinil. Effects were compared to age and size-matched placebo group. Rs-fMRI effects were assessed, employing a graph-based approach and Eigenvector Centrality (EC) analysis, by taking in account topological changes occurring in functional brain networks. The main finding of the study is that modafinil promotes enhanced centrality, a measure of the importance of nodes within functional networks, of the bilateral primary visual (V1) cortex. EC analysis also revealed that modafinil-treated subjects show increased functional connectivity between the V1 and specific cerebellar (Crus I, Crus II, VIIIa lobule) and frontal (right inferior frontal sulcus and left middle frontal gyrus) regions. Present findings provide functional data supporting the hypothesis that modafinil can modulate the cortico-cerebellar connectivity of the aging brain.

PMID: 28424611 [PubMed - in process]

Longitudinal recovery of local neuronal activity and consciousness level in acquired brain injury.

Fri, 04/21/2017 - 02:40

Longitudinal recovery of local neuronal activity and consciousness level in acquired brain injury.

Hum Brain Mapp. 2017 Apr 19;:

Authors: Zou Q, Wu X, Hu J, Tang W, Mao Y, Zhu J, Lu L, Zhang Y, Gao JH

Abstract
Decreased brain activity in the default mode network, particularly in the precuneus (PCU), has been consistently shown in acquired brain injury (ABI) patients. However, it is unclear whether resting-state brain activity recovers longitudinally in ABI patients and whether functional activity restoration is associated with improvements in consciousness level. Here, resting-state fMRI data were acquired from 23 ABI patients and 30 age- and gender-matched controls with two longitudinal observations for each participant. The fMRI data were analyzed using amplitude of low-frequency fluctuation (ALFF) to measure the fluctuation strength of local spontaneous activity, and seed-based functional connectivity was used to measure functional relationship with the seed region in the whole brain. The level of consciousness was assessed using the Glasgow Coma Scale (GCS) and Coma Recovery Scale-Revised (CRS-R) on both scanning days of the patients. Interaction effect between the two groups and two scans in ALFF was observed in the PCU, which was driven by restored ALFF in the ABI, while a stable ALFF in the control group. Moreover, restoration of ALFF in the PCU correlated with improvements in both the CRS-R and GCS. Specifically, recovery of ALFF in the PCU primarily reflected the signals of the slow-4 frequency band (0.027-0.073 Hz). Based on the functional connectivity maps of the PCU, we observed a nonsignificant interaction effect or correlation with consciousness level. These findings suggest local activity in the PCU but possibly not its functional connectivity, is related to the longitudinal changes in behavioral responsiveness in ABI. Hum Brain Mapp, 2017. © 2017 Wiley Periodicals, Inc.

PMID: 28422373 [PubMed - as supplied by publisher]

Mapping Dorsal and Ventral Caudate in Older Adults: Method and Validation.

Fri, 04/21/2017 - 02:40
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Mapping Dorsal and Ventral Caudate in Older Adults: Method and Validation.

Front Aging Neurosci. 2017;9:91

Authors: Huang H, Nguyen PT, Schwab NA, Tanner JJ, Price CC, Ding M

Abstract
The caudate nucleus plays important roles in cognition and affect. Depending on associated connectivity and function, the caudate can be further divided into dorsal and ventral aspects. Dorsal caudate, highly connected to dorsolateral prefrontal cortex (DLPFC), is implicated in executive function and working memory; ventral caudate, more interconnected with the limbic system, is implicated in affective functions such as pain processing. Clinically, certain brain disorders are known to differentially impact dorsal and ventral caudate. Thus, precise parcellation of caudate has both basic and clinical neuroscience significance. In young adults, past work has combined resting-state fMRI functional connectivity with clustering algorithms to define dorsal and ventral caudate. Whether the same approach is effective in older adults and how to validate the parcellation results have not been considered. We addressed these problems by obtaining resting-state fMRI data from 56 older non-demented adults (age: 69.07 ± 5.92 years and MOCA: 25.71 ± 2.46) along with a battery of cognitive and clinical assessments. Connectivity from each voxel of caudate to the rest of the brain was computed using cross correlation. Applying the K-means clustering algorithm to the connectivity patterns with K = 2 yielded two substructures within caudate, which agree well with previously reported dorsal and ventral divisions of caudate. Furthermore, dorsal-caudate-seeded functional connectivity was shown to be more strongly associated with working memory and fluid reasoning composite scores, whereas ventral-caudate-seeded functional connectivity more strongly associated with pain and fatigue severity. These results demonstrate that dorsal and ventral caudate can be reliably identified by combining resting-state fMRI and clustering algorithms in older adults.

PMID: 28420985 [PubMed - in process]

Age-Related Difference in Functional Brain Connectivity of Mastication.

Fri, 04/21/2017 - 02:40
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Age-Related Difference in Functional Brain Connectivity of Mastication.

Front Aging Neurosci. 2017;9:82

Authors: Lin CS, Wu CY, Wu SY, Lin HH, Cheng DH, Lo WL

Abstract
The age-related decline in motor function is associated with changes in intrinsic brain signatures. Here, we investigated the functional connectivity (FC) associated with masticatory performance, a clinical index evaluating general masticatory function. Twenty-six older adults (OA) and 26 younger (YA) healthy adults were recruited and assessed using the masticatory performance index (MPI) and resting-state functional magnetic resonance imaging (rs-fMRI). We analyzed the rs-fMRI FC network related to mastication, which was constructed based on 12 bilateral mastication-related brain regions according to the literature. For the OA and the YA group, we identified the mastication-related hubs, i.e., the nodes for which the degree centrality (DC) was positively correlated with the MPI. For each pair of nodes, we identified the inter-nodal link for which the FC was positively correlated with the MPI. The network analysis revealed that, in the YA group, the FC between the sensorimotor cortex, the thalamus (THA) and the cerebellum was positively correlated with the MPI. Consistently, the cerebellum nodes were defined as the mastication-related hubs. In contrast, in the OA group, we found a sparser connection within the sensorimotor regions and cerebellum and a denser connection across distributed regions, including the FC between the superior parietal lobe (SPL), the anterior insula (aINS) and the dorsal anterior cingulate cortex (dACC). Compared to the YA group, the network of the OA group also comprised more mastication-related hubs, which were spatially distributed outside the sensorimotor regions, including the right SPL, the right aINS, and the bilateral dACC. In general, the findings supported the hypothesis that in OA, higher masticatory performance is associated with a widespread pattern of mastication-related hubs. Such a widespread engagement of multiple brain regions associated with the MPI may reflect an increased demand in sensorimotor integration, attentional control and monitoring for OA to maintain good mastication.

PMID: 28420981 [PubMed - in process]

Resting State fMRI Reveals Increased Subthalamic Nucleus and Sensorimotor Cortex Connectivity in Patients with Parkinson's Disease under Medication.

Fri, 04/21/2017 - 02:40
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Resting State fMRI Reveals Increased Subthalamic Nucleus and Sensorimotor Cortex Connectivity in Patients with Parkinson's Disease under Medication.

Front Aging Neurosci. 2017;9:74

Authors: Shen B, Gao Y, Zhang W, Lu L, Zhu J, Pan Y, Lan W, Xiao C, Zhang L

Abstract
Functional connectivity (FC) between the subthalamic nucleus (STN) and the sensorimotor cortex is increased in off-medication patients with Parkinson's disease (PD). However, the status of FC between STN and sensorimotor cortex in on-medication PD patients remains unclear. In this study, resting state functional magnetic resonance imaging was employed on 31 patients with PD under medication and 31 healthy controls. Two-sample t-test was used to study the change in FC pattern of the STN, the FC strength of the bilateral STN was correlated with overall motor symptoms, while unilateral STN was correlated with offside motor symptoms. Both bilateral and right STN showed increased FC with the right sensorimotor cortex, whereas only right STN FC was correlated with left-body rigidity scores in all PD patients. An additional subgroup analysis was performed according to the ratio of mean tremor scores and mean postural instability and gait difficulty (PIGD) scores, only the PIGD subgroup showed the increased FC between right STN and sensorimotor cortex under medication. Increased FC between the STN and the sensorimotor cortex was found, which was related to motor symptom severity in on-medication PD patients. Anti-PD drugs may influence the hyperdirect pathway to alleviate motor symptoms with the more effect on the tremor subtype.

PMID: 28420978 [PubMed - in process]

Multi-modal, Multi-measure, and Multi-class Discrimination of ADHD with Hierarchical Feature Extraction and Extreme Learning Machine Using Structural and Functional Brain MRI.

Fri, 04/21/2017 - 02:40
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Multi-modal, Multi-measure, and Multi-class Discrimination of ADHD with Hierarchical Feature Extraction and Extreme Learning Machine Using Structural and Functional Brain MRI.

Front Hum Neurosci. 2017;11:157

Authors: Qureshi MNI, Oh J, Min B, Jo HJ, Lee B

Abstract
Structural and functional MRI unveil many hidden properties of the human brain. We performed this multi-class classification study on selected subjects from the publically available attention deficit hyperactivity disorder ADHD-200 dataset of patients and healthy children. The dataset has three groups, namely, ADHD inattentive, ADHD combined, and typically developing. We calculated the global averaged functional connectivity maps across the whole cortex to extract anatomical atlas parcellation based features from the resting-state fMRI (rs-fMRI) data and cortical parcellation based features from the structural MRI (sMRI) data. In addition, the preprocessed image volumes from both of these modalities followed an ANOVA analysis separately using all the voxels. This study utilized the average measure from the most significant regions acquired from ANOVA as features for classification in addition to the multi-modal and multi-measure features of structural and functional MRI data. We extracted most discriminative features by hierarchical sparse feature elimination and selection algorithm. These features include cortical thickness, image intensity, volume, cortical thickness standard deviation, surface area, and ANOVA based features respectively. An extreme learning machine performed both the binary and multi-class classifications in comparison with support vector machines. This article reports prediction accuracy of both unimodal and multi-modal features from test data. We achieved 76.190% (p < 0.0001) classification accuracy in multi-class settings as well as 92.857% (p < 0.0001) classification accuracy in binary settings. In addition, we found ANOVA-based significant regions of the brain that also play a vital role in the classification of ADHD. Thus, from a clinical perspective, this multi-modal group analysis approach with multi-measure features may improve the accuracy of the ADHD differential diagnosis.

PMID: 28420972 [PubMed - in process]

A Fall in the Workplace Leads to a Diagnosis of Parkinson's Disease.

Fri, 04/21/2017 - 02:40
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A Fall in the Workplace Leads to a Diagnosis of Parkinson's Disease.

Workplace Health Saf. 2016 Aug;64(8):348-9

Authors: Lurati AR

Abstract
A 62 year old male worker sustained a head contusion from a fall in the workplace. When assessing the mechanism of the fall, it was noted that the worker stated that his feet became "stuck" and would not move. He also stated that he could not move fast enough to break his fall. Upon physical examination, a resting tremor was noted as well as upper and lower body rigidity, and a festinating gait. The worker was evaluated by a neurologist and diagnosed with early Parkinson's disease.

PMID: 27026277 [PubMed - indexed for MEDLINE]

Intranasal oxytocin enhances intrinsic corticostriatal functional connectivity in women.

Wed, 04/19/2017 - 13:20

Intranasal oxytocin enhances intrinsic corticostriatal functional connectivity in women.

Transl Psychiatry. 2017 Apr 18;7(4):e1099

Authors: Bethlehem RAI, Lombardo MV, Lai MC, Auyeung B, Crockford SK, Deakin J, Soubramanian S, Sule A, Kundu P, Voon V, Baron-Cohen S

Abstract
Oxytocin may influence various human behaviors and the connectivity across subcortical and cortical networks. Previous oxytocin studies are male biased and often constrained by task-based inferences. Here, we investigate the impact of oxytocin on resting-state connectivity between subcortical and cortical networks in women. We collected resting-state functional magnetic resonance imaging (fMRI) data on 26 typically developing women 40 min following intranasal oxytocin administration using a double-blind placebo-controlled crossover design. Independent components analysis (ICA) was applied to examine connectivity between networks. An independent analysis of oxytocin receptor (OXTR) gene expression in human subcortical and cortical areas was carried out to determine plausibility of direct oxytocin effects on OXTR. In women, OXTR was highly expressed in striatal and other subcortical regions, but showed modest expression in cortical areas. Oxytocin increased connectivity between corticostriatal circuitry typically involved in reward, emotion, social communication, language and pain processing. This effect was 1.39 standard deviations above the null effect of no difference between oxytocin and placebo. This oxytocin-related effect on corticostriatal connectivity covaried with autistic traits, such that oxytocin-related increase in connectivity was stronger in individuals with higher autistic traits. In sum, oxytocin strengthened corticostriatal connectivity in women, particularly with cortical networks that are involved in social-communicative, motivational and affective processes. This effect may be important for future work on neurological and psychiatric conditions (for example, autism), particularly through highlighting how oxytocin may operate differently for subsets of individuals.

PMID: 28418398 [PubMed - in process]

S100A10 identified in a genome-wide gene × cannabis dependence interaction analysis of risky sexual behaviours.

Wed, 04/19/2017 - 13:20

S100A10 identified in a genome-wide gene × cannabis dependence interaction analysis of risky sexual behaviours.

J Psychiatry Neurosci. 2017 Apr 13;42(4):160189

Authors: Polimanti R, Meda SA, Pearlson GD, Zhao H, Sherva R, Farrer LA, Kranzler HR, Gelernter J

Abstract
BACKGROUND: We conducted a genome-wide gene × environment interaction analysis to identify genetic variants that interact with cannabis dependence (CaD) in influencing risky sexual behaviours (RSB).
METHODS: Our sample included cannabis-exposed and sexually experienced African-American and European-American participants. A DSM-IV CaD diagnosis and RSB were evaluated using the Semi-Structured Assessment for Drug Dependence and Alcoholism. We analyzed RSBs as a score that takes into account experiences of unprotected sex and multiple sexual partners.
RESULTS: A total of 3350 people participated in our study; 43% had a CaD diagnosis, 56% were African-American and 33% were women. We identified a genome-wide significant locus in African-American participants (S100A10 rs72993629, p = 2.73 × 10(-8)) and a potential transpopulation signal in women (CLTC rs12944716, p = 5.27 × 10(-8)). A resting-state fMRI follow-up analysis of S100A10 rs72993629 conducted in an independent cohort showed 2 significant associations: reduced power of the left paracentral lobule in amplitude of low frequency fluctuations (ALFF) analysis (p = 7.8 × 10(-3)) and reduced power of the right pallidum in fractional ALFF analysis (p = 4.6 × 10(-3)). The activity of these brain regions is known to be involved in sexual functions and behaviours. The S100A10 result functionally recapitulated our S100B finding observed in our previous genome-wide association study of CaD. The probability of identifying 2 S100 genes in 2 independent genome-wide investigations by chance is approximately 1 in 1.1 million.
LIMITATIONS: We were not able to identify any African-American cohort with appropriate sample size, and phenotypic assessment is available to replicate our findings.
CONCLUSION: The S100A10 and S100B genes, which are located on different chromosomes, encode specialized calcium-binding proteins. These data support a role for calcium homeostasis in individuals with CaD and its induced behaviours.

PMID: 28418321 [PubMed - as supplied by publisher]

A posterior-to-anterior shift of brain functional dynamics in aging.

Wed, 04/19/2017 - 13:20
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A posterior-to-anterior shift of brain functional dynamics in aging.

Brain Struct Funct. 2017 Apr 17;:

Authors: Zhang H, Lee A, Qiu A

Abstract
Convergent evidence from task-based functional magnetic resonance imaging (fMRI) studies suggests a posterior-to-anterior shift as an adaptive compensatory scaffolding mechanism for aging. This study aimed to investigate whether brain functional dynamics at rest follow the same scaffolding mechanism for aging using a large Chinese sample aged from 22 to 79 years (n = 277). We defined a probability of brain regions being hubs over a period of time to characterize functional hub dynamic, and defined variability of the functional connectivity to characterize dynamic functional connectivity using resting-state fMRI. Our results revealed that both functional hub dynamics and dynamic functional connectivity posited an age-related posterior-to-anterior shift. Specifically, the posterior brain region showed attenuated dynamics, while the anterior brain regions showed augmented dynamics in aging. Interestingly, our analysis further indicated that the age-related episodic memory decline was associated with the age-related decrease in the brain functional dynamics of the posterior regions. Hence, these findings provided a new dimension to view the scaffolding mechanism for aging based on the brain functional dynamics.

PMID: 28417233 [PubMed - as supplied by publisher]

Treatment effect of methylphenidate on intrinsic functional brain network in medication-naïve ADHD children: A multivariate analysis.

Wed, 04/19/2017 - 13:20
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Treatment effect of methylphenidate on intrinsic functional brain network in medication-naïve ADHD children: A multivariate analysis.

Brain Imaging Behav. 2017 Apr 17;:

Authors: Yoo JH, Kim D, Choi J, Jeong B

Abstract
Methylphenidate is a first-line therapeutic option for treating attention-deficit/hyperactivity disorder (ADHD); however, elicited changes on resting-state functional networks (RSFNs) are not well understood. This study investigated the treatment effect of methylphenidate using a variety of RSFN analyses and explored the collaborative influences of treatment-relevant RSFN changes in children with ADHD. Resting-state functional magnetic resonance imaging was acquired from 20 medication-naïve ADHD children before methylphenidate treatment and twelve weeks later. Changes in large-scale functional connectivity were defined using independent component analysis with dual regression and graph theoretical analysis. The amplitude of low frequency fluctuation (ALFF) was measured to investigate local spontaneous activity alteration. Finally, significant findings were recruited to random forest regression to identify the feature subset that best explains symptom improvement. After twelve weeks of methylphenidate administration, large-scale connectivity was increased between the left fronto-parietal RSFN and the left insula cortex and the right fronto-parietal and the brainstem, while the clustering coefficient (CC) of the global network and nodes, the left fronto-parietal, cerebellum, and occipital pole-visual network, were decreased. ALFF was increased in the bilateral superior parietal cortex and decreased in the right inferior fronto-temporal area. The subset of the local and large-scale RSFN changes, including widespread ALFF changes, the CC of the global network and the cerebellum, could explain the 27.1% variance of the ADHD Rating Scale and 13.72% of the Conner's Parent Rating Scale. Our multivariate approach suggests that the neural mechanism of methylphenidate treatment could be associated with alteration of spontaneous activity in the superior parietal cortex or widespread brain regions as well as functional segregation of the large-scale intrinsic functional network.

PMID: 28417219 [PubMed - as supplied by publisher]

Diffeomorphic Functional Brain Surface Alignment: Functional Demons.

Wed, 04/19/2017 - 13:20
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Diffeomorphic Functional Brain Surface Alignment: Functional Demons.

Neuroimage. 2017 Apr 14;:

Authors: Nenning KH, Liu H, Ghosh S, Sabuncu M, Schwartz E, Langs G

Abstract
Aligning brain structures across individuals is a central prerequisite for comparative neuroimaging studies. Typically, registration approaches assume a strong association between the features used for alignment, such as macro-anatomy, and the variable observed, such as functional activation or connectivity. Here, we propose to use the structure of intrinsic resting state fMRI signal correlation patterns as a basis for alignment of the cortex in functional studies. Rather than assuming the spatial correspondence of functional structures between subjects, we have identified locations with similar connectivity profiles across subjects. We mapped functional connectivity relationships within the brain into an embedding space, and aligned the resulting maps of multiple subjects. We then performed a diffeomorphic alignment of the cortical surfaces, driven by the corresponding features in the joint embedding space. Results show that functional alignment based on resting state fMRI identifies functionally homologous regions across individuals with higher accuracy than alignment based on the spatial correspondence of anatomy. Further, functional alignment enables measurement of the strength of the anatomo-functional link across the cortex, and reveals the uneven distribution of this link. Stronger anatomo-functional dissociation was found in higher association areas compared to primary sensory- and motor areas. Functional alignment based on resting state features improves group analysis of task based functional MRI data, increasing statistical power and improving the delineation of task-specific core regions. Finally, a comparison of the anatomo-functional dissociation between cohorts is demonstrated with a group of left and right handed subjects.

PMID: 28416451 [PubMed - as supplied by publisher]

Bipolar mood state reflected in cortico-amygdala resting state connectivity: A cohort and longitudinal study.

Tue, 04/18/2017 - 12:20
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Bipolar mood state reflected in cortico-amygdala resting state connectivity: A cohort and longitudinal study.

J Affect Disord. 2017 Mar 28;217:205-209

Authors: Brady RO, Margolis A, Masters GA, Keshavan M, Öngür D

Abstract
BACKGROUND: Using resting-state functional magnetic resonance imaging (rsfMRI), we previously compared cohorts of bipolar I subjects in a manic state to those in a euthymic state to identify mood state-specific patterns of cortico-amygdala connectivity. Our results suggested that mania is reflected in the disruption of emotion regulation circuits. We sought to replicate this finding in a group of subjects with bipolar disorder imaged longitudinally across states of mania and euthymia METHODS: We divided our subjects into three groups: 26 subjects imaged in a manic state, 21 subjects imaged in a euthymic state, and 10 subjects imaged longitudinally across both mood states. We measured differences in amygdala connectivity between the mania and euthymia cohorts. We then used these regions of altered connectivity to examine connectivity in the longitudinal bipolar group using a within-subjects design.
RESULTS: Our findings in the mania vs euthymia cohort comparison were replicated in the longitudinal analysis. Bipolar mania was differentiated from euthymia by decreased connectivity between the amygdala and pre-genual anterior cingulate cortex. Mania was also characterized by increased connectivity between amygdala and the supplemental motor area, a region normally anti-correlated to the amygdala in emotion regulation tasks.
LIMITATIONS: Stringent controls for movement effects limited the number of subjects in the longitudinal sample.
CONCLUSIONS: In this first report of rsfMRI conducted longitudinally across mood states, we find that previously observed between-group differences in amygdala connectivity are also found longitudinally within subjects. These results suggest resting state cortico-amygdala connectivity is a biomarker of mood state in bipolar disorder.

PMID: 28415008 [PubMed - as supplied by publisher]

Default mode network connectivity and related white matter disruption in type 2 diabetes mellitus patients concurrent with amnestic mild cognitive impairment.

Tue, 04/18/2017 - 12:20
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Default mode network connectivity and related white matter disruption in type 2 diabetes mellitus patients concurrent with amnestic mild cognitive impairment.

Curr Alzheimer Res. 2017 Apr 17;:

Authors: Qi D, Wang A, Chen Y, Chen K, Zhang S, Zhang J, Li X, Ai L, Zhang Z

Abstract
BACKGROUND: As a risk factor for Alzheimer's disease (AD), Type 2 diabetes mellitus (T2DM) itself causes cognitive impairment and has higher prevalence of mild cognitive impairment (MCI).
OBJECTIVE: The aim of this study was to explore the cognition especially the episodic memory difference, the DMN functional connectivity and DMN-related white matter integrity in patients with both T2DM and amnestic MCI (T2DM-MCI) as compared to patients with T2DM only.
METHOD: Focusing especially on T2DM population, we investigated the default mode network (DMN) through resting functional magnetic resonance imaging among 22 elderly T2DM-MCI patients and 24 elderly T2DM patients. Including primarily the bilateral cingulum, hippocampus and uncinate fasciculus, these DMN white matter fibers were also closely associated with episodic memory and the integrity of them was also investigated using diffusion tensor imaging in 19 elderly T2DM-MCI patients and 23 elderly T2DM patients.
RESULTS: Compared with the patients with T2DM, the T2DM-MCI patients performed worse in several areas of cognition besides episodic memory, and showed stronger DMN functional connectivity in the left precuneus and weaker functional connectivity in the left calcarine, as well as decreased integrity of the left cingulate bundle and bilateral uncinate fasciculus. Furthermore, a correlation analysis indicated that higher left calcarine connectivity was associated with better episodic memory performance among the overall group.
CONCLUSION: Our results demonstrated that T2DM patients with comorbid amnestic MCI had abnormal functional connectivity patterns and decreased white matter integrity, which could potentially serve as AD or AD risk biomarkers for early detection of those elderly individuals with T2DM.

PMID: 28413981 [PubMed - as supplied by publisher]

High-dimensional tests for functional networks of brain anatomic regions.

Tue, 04/18/2017 - 12:20
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High-dimensional tests for functional networks of brain anatomic regions.

J Multivar Anal. 2017 Apr;156:70-88

Authors: Xie J, Kang J

Abstract
Exploring resting-state brain functional connectivity of autism spectrum disorders (ASD) using functional magnetic resonance imaging (fMRI) data has become a popular topic over the past few years. The data in a standard brain template consist of over 170,000 voxel specific points in time for each human subject. Such an ultra-high dimensionality makes the voxel-level functional connectivity analysis (involving four billion voxel pairs) both statistically and computationally inefficient. In this work, we introduce a new framework to identify the functional brain network at the anatomical region level for each individual. We propose two pairwise tests to detect region dependence, and one multiple testing procedure to identify global structures of the network. The limiting null distribution of each test statistic is derived. It is also shown that the tests are rate optimal when the alternative block networks are sparse. The numerical studies show that the proposed tests are valid and powerful. We apply our method to a resting-state fMRI study on autism and identify patient-unique and control-unique hub regions. These findings are biologically meaningful and consistent with the existing literature.

PMID: 28413234 [PubMed - in process]

Electroconvulsive therapy changes the regional resting state function measured by regional homogeneity (ReHo) and amplitude of low frequency fluctuations (ALFF) in elderly major depressive disorder patients: An exploratory study.

Mon, 04/17/2017 - 11:00

Electroconvulsive therapy changes the regional resting state function measured by regional homogeneity (ReHo) and amplitude of low frequency fluctuations (ALFF) in elderly major depressive disorder patients: An exploratory study.

Psychiatry Res. 2017 Apr 08;264:13-21

Authors: Kong XM, Xu SX, Sun Y, Wang KY, Wang C, Zhang J, Xia JX, Zhang L, Tan BJ, Xie XH

Abstract
Electroconvulsive therapy (ECT) is the most effective and rapid treatment for severe major depressive disorder (MDD) in elderly patients. The mechanism of ECT is unclear, and studies on ECT in elderly MDD patients by resting-state functional magnetic resonance imaging are rare. Thirteen elderly MDD patients were scanned before and after ECT using a 3.0T MRI scanner. Regional homogeneity (ReHo) and amplitude of low-frequency fluctuations (ALFF) were processed to compare resting-state function before and after treatment. Depression and anxiety symptoms of all patients abated after ECT. Decreased ReHo values in the bilateral superior frontal gyrus (SFG) were observed after ECT, and the values of right SFG significantly correlated with an altered Hamilton depression rating scale score. Increased ALFF values in the left middle frontal gyrus, right middle frontal gyrus, orbital part, and decreased ALFF values in the left midcingulate area, left precentral gyrus, right SFG/middle frontal gyrus after ECT were also observed. These results support the hypothesis that ECT may affect the regional resting state brain function in geriatric MDD patients.

PMID: 28412557 [PubMed - as supplied by publisher]

Human Brain Mapping: A Systematic Comparison of Parcellation Methods for the Human Cerebral Cortex.

Mon, 04/17/2017 - 11:00

Human Brain Mapping: A Systematic Comparison of Parcellation Methods for the Human Cerebral Cortex.

Neuroimage. 2017 Apr 12;:

Authors: Arslan S, Ktena SI, Makropoulos A, Robinson EC, Rueckert D, Parisot S

Abstract
The macro-connectome elucidates the pathways through which brain regions are structurally connected or functionally coupled to perform a specific cognitive task. It embodies the notion of representing and understanding all connections within the brain as a network, while the subdivision of the brain into interacting functional units is inherent in its architecture. As a result, the definition of network nodes is one of the most critical steps in connectivity network analysis. Although brain atlases obtained from cytoarchitecture or anatomy have long been used for this task, connectivity-driven methods have arisen only recently, aiming to delineate more homogeneous and functionally coherent regions. This study provides a systematic comparison between anatomical, connectivity-driven and random parcellation methods proposed in the thriving field of brain parcellation. Using resting-state functional MRI data from the Human Connectome Project and a plethora of quantitative evaluation techniques investigated in the literature, we evaluate 10 subject-level and 24 groupwise parcellation methods at different resolutions. We assess the accuracy of parcellations from four different aspects: (1) reproducibility across different acquisitions and groups, (2) fidelity to the underlying connectivity data, (3) agreement with fMRI task activation, myelin maps, and cytoarchitectural areas, and (4) network analysis. This extensive evaluation of different parcellations generated at the subject and group level highlights the strengths and shortcomings of the various methods and aims to provide a guideline for the choice of parcellation technique and resolution according to the task at hand. The results obtained in this study suggest that there is no optimal method able to address all the challenges faced in this endeavour simultaneously.

PMID: 28412442 [PubMed - as supplied by publisher]

Transient Networks of Spatio-temporal Connectivity Map Communication Pathways in Brain Functional Systems.

Mon, 04/17/2017 - 11:00

Transient Networks of Spatio-temporal Connectivity Map Communication Pathways in Brain Functional Systems.

Neuroimage. 2017 Apr 12;:

Authors: Griffa A, Ricaud B, Benzi K, Bresson X, Daducci A, Vandergheynst P, Thiran JP, Hagmann P

Abstract
The study of brain dynamics enables us to characterize the time-varying functional connectivity among distinct neural groups. However, current methods suffer from the absence of structural connectivity information. We propose to integrate infra-slow neural oscillations and anatomical-connectivity maps, as derived from functional and diffusion MRI, in a multilayer-graph framework that captures transient networks of spatio-temporal connectivity. These networks group anatomically wired and temporary synchronized brain regions and encode the propagation of functional activity on the structural connectome. In a group of 71 healthy subjects, we find that these transient networks demonstrate power-law spatial and temporal size, globally organize into well-known functional systems and describe wave-like trajectories of activation across anatomically connected regions. Within the transient networks, activity propagates through polysynaptic paths that include selective ensembles of structural connections and differ from the structural shortest paths. In the light of the communication-through-coherence principle, the identified spatio-temporal networks could encode communication channels' selection and neural assemblies, which deserves further attention. This work contributes to the understanding of brain structure-function relationships by considering the time-varying nature of resting-state interactions on the axonal scaffold, and it offers a convenient framework to study large-scale communication mechanisms and functional dynamics.

PMID: 28412440 [PubMed - as supplied by publisher]

Directed connectivity of brain default networks in resting state using GCA and motif.

Sat, 04/15/2017 - 15:20

Directed connectivity of brain default networks in resting state using GCA and motif.

Front Biosci (Landmark Ed). 2017 Jun 01;22:1634-1643

Authors: Jiao Z, Wang H, Ma K, Zou L, Xiang J

Abstract
Nowadays, there is a lot of interest in assessing functional interactions between key brain regions. In this paper, Granger causality analysis (GCA) and motif structure are adopted to study directed connectivity of brain default mode networks (DMNs) in resting state. Firstly, the time series of functional magnetic resonance imaging (fMRI) data in resting state were extracted, and the causal relationship values of the nodes representing related brain regions are analyzed in time domain to construct a default network. Then, the network structures were searched from the default networks of controls and patients to determine the fixed connection mode in the networks. The important degree of motif structures in directed connectivity of default networks was judged according to p-value and Z-score. Both node degree and average distance were used to analyze the effect degree an information transfer rate of brain regions in motifs and default networks, and efficiency of the network. Finally, activity and functional connectivity strength of the default brain regions are researched according to the change of energy distributions between the normals and the patients' brain regions. Experimental results demonstrate that, both normal subjects and stroke patients have some corresponding fixed connection mode of three nodes, and the efficiency and power spectrum of the patient's default network is somewhat lower than that of the normal person. In particular, the Right Posterior Cingulate Gyrus (PCG.R) has a larger change in functional connectivity and its activity. The research results verify the feasibility of the application of GCA and motif structure to study the functional connectivity of default networks in resting state.

PMID: 28410136 [PubMed - in process]

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