New resting-state fMRI related studies at PubMed

Subscribe to New resting-state fMRI related studies at PubMed feed New resting-state fMRI related studies at PubMed
NCBI: db=pubmed; Term=resting state fMRI
Updated: 1 hour 22 min ago

Human Neural Stem Cell Induced Functional Network Stabilization After Cortical Stroke: A Longitudinal Resting-State fMRI Study in Mice.

Thu, 04/23/2020 - 12:40
Related Articles

Human Neural Stem Cell Induced Functional Network Stabilization After Cortical Stroke: A Longitudinal Resting-State fMRI Study in Mice.

Front Cell Neurosci. 2020;14:86

Authors: Minassian A, Green C, Diedenhofen M, Vogel S, Hess S, Stoeber M, Radmilovic MD, Wiedermann D, Kloppenburg P, Hoehn M

Abstract
Most stroke studies dealing with functional deficits and assessing stem cell therapy produce extensive hemispheric damage and can be seen as a model for severe clinical strokes. However, mild strokes have a better prospect for functional recovery. Recently, anatomic and behavioral changes have been reported for distal occlusion of the middle cerebral artery (MCA), generating a well-circumscribed and small cortical lesion, which can thus be proposed as mild to moderate cortical stroke. Using this cortical stroke model of moderate severity in the nude mouse, we have studied the functional networks with resting-state functional magnetic resonance imaging (fMRI) for 12 weeks following stroke induction. Further, human neural stem cells (hNSCs) were implanted adjacent to the ischemic lesion, and the stable graft vitality was monitored with bioluminescence imaging (BLI). Differentiation of the grafted neural stem cells was analyzed by immunohistochemistry and by patch-clamp electrophysiology. Following stroke induction, we found a pronounced and continuously rising hypersynchronicity of the sensorimotor networks including both hemispheres, in contrast to the severe stroke filament model where profound reduction of the functional connectivity had been reported by us earlier. The vitality of grafted neural stem cells remained stable throughout the whole 12 weeks observation period. In the stem cell treated animals, functional connectivity did not show hypersynchronicity but was globally slightly reduced below baseline at 2 weeks post-stroke, normalizing thereafter completely. Our resting-state fMRI (rsfMRI) studies on cortical stroke reveal for the first time a hypersynchronicity of the functional brain networks. This hypersynchronicity appears as a hallmark of mild cortical strokes, in contrast to severe strokes with striatal involvement where exclusively hyposynchronicity has been reported. The effect of the stem cell graft was an early and persistent normalization of the functional sensorimotor networks across the whole brain. These novel functional results may help interpret future outcome investigations after stroke and demonstrate the highly promising potential of stem cell treatment for functional outcome improvement after stroke.

PMID: 32317940 [PubMed]

Topological Data Analysis reveals robust alterations in the whole-brain and frontal lobe functional connectomes in Attention-Deficit/Hyperactivity Disorder.

Thu, 04/23/2020 - 12:40
Related Articles

Topological Data Analysis reveals robust alterations in the whole-brain and frontal lobe functional connectomes in Attention-Deficit/Hyperactivity Disorder.

eNeuro. 2020 Apr 13;:

Authors: Gracia-Tabuenca Z, Díaz-Patiño JC, Arelio I, Alcauter S

Abstract
Attention Deficit Hyperactivity Disorder (ADHD) is a developmental disorder characterized by difficulty to control the own behavior. Neuroimaging studies have related ADHD with the interplay of fronto-parietal attention systems with the default mode network (DMN) (Castellanos and Aoki, 2016). However, some results have been inconsistent, potentially due to methodological differences in the analytical strategies when defining the brain functional network, i.e., the functional connectivity threshold and/or the brain parcellation scheme. Here, we make use of Topological Data Analysis to explore the brain connectome as a function of the filtration value (i.e., the connectivity threshold), instead of using a static connectivity threshold. Specifically, we characterized the transition from all nodes being isolated to being connected into a single component as a function of the filtration value. We explored the utility of such a method to identify differences between 81 children with attention-deficit/hyperactivity disorder (ADHD; 45 male, age: 7.26 - 17.61 years old) and 96 typically developing children (TDC; 59 male, age: 7.17 - 17.96 years old), using a public dataset of resting state fMRI in human subjects. Results were highly congruent when using four different brain segmentations (atlases), and exhibited significant differences for the brain topology of children with ADHD, both at the whole brain network and the functional sub-network levels, particularly involving the frontal lobe and the default mode network. Therefore, this is a solid approach that complements connectomics-related methods and may contribute to identify the neurophysio-pathology of ADHD.Significant Statement Topological Data Analysis investigates the topology of interacting nodes. It may model the connectomes as a topological process instead of a static graph, exploring the transition of all nodes being isolated to binding together, as a function of the connectivity threshold. Here, we explored three parameters to characterize the algebraic topology of individual connectomes using four different brain atlases, further exploring the subnetwork levels. Our findings showed that the area under the curve robustly differentiates children with attention-deficit/hyperactivity disorder and typically-developing children, suggesting decreased functional segregation, with the greatest effects on the frontal lobe and the default-mode network. Overall, these results support the use of the proposed methods to robustly explore topological differences in the brain connectome.

PMID: 32317343 [PubMed - as supplied by publisher]

Functional differentiation in the human ventromedial frontal lobe: A data-driven parcellation.

Wed, 04/22/2020 - 11:40
Related Articles

Functional differentiation in the human ventromedial frontal lobe: A data-driven parcellation.

Hum Brain Mapp. 2020 Apr 21;:

Authors: Chase HW, Grace AA, Fox PT, Phillips ML, Eickhoff SB

Abstract
Ventromedial regions of the frontal lobe (vmFL) are thought to play a key role in decision-making and emotional regulation. However, aspects of this area's functional organization, including the presence of a multiple subregions, their functional and anatomical connectivity, and the cross-species homologies of these subregions with those of other species, remain poorly understood. To address this uncertainty, we employed a two-stage parcellation of the region to identify six distinct structures within the region on the basis of data-driven classification of functional connectivity patterns obtained using the meta-analytic connectivity modeling (MACM) approach. From anterior to posterior, the derived subregions included two lateralized posterior regions, an intermediate posterior region, a dorsal and ventral central region, and a single anterior region. The regions were characterized further by functional connectivity derived using resting-state fMRI and functional decoding using the Brain Map database. In general, the regions could be differentiated on the basis of different patterns of functional connectivity with canonical "default mode network" regions and/or subcortical regions such as the striatum. Together, the findings suggest the presence of functionally distinct neural structures within vmFL, consistent with data from experimental animals as well prior demonstrations of anatomical differences within the region. Detailed correspondence with the anterior cingulate, medial orbitofrontal cortex, and rostroventral prefrontal cortex, as well as specific animal homologs are discussed. The findings may suggest future directions for resolving potential functional and structural correspondence of subregions within the frontal lobe across behavioral contexts, and across mammalian species.

PMID: 32314470 [PubMed - as supplied by publisher]

Abnormalities in the thalamo-cortical network in patients with functional constipation.

Wed, 04/22/2020 - 11:40
Related Articles

Abnormalities in the thalamo-cortical network in patients with functional constipation.

Brain Imaging Behav. 2020 Apr 20;:

Authors: Liu L, Hu C, Hu Y, Zhang W, Zhang Z, Ding Y, Wang Y, von Deneen KM, Sun L, Wang H, Duan S, Mao K, Wang F, Cui G, Liu J, Nie Y, Zhang Y

Abstract
Functional constipation (FCon) is a common functional gastrointestinal disorder (FGID); neuroimaging studies have shown brain functional abnormalities in thalamo-cortical regions in patients with FGID. However, association between FCon and topological characteristics of brain networks remains largely unknown. We employed resting-state functional magnetic resonance imaging (RS-fMRI) and graph theory approach to investigate functional brain topological organization in 42 patients with FCon and 41 healthy controls (HC) from perspectives of global, regional and modular levels. Results showed patients with FCon had a significantly lower normalized clustering coefficient and small-worldness, implying decreased brain functional connectivity. Regions showed altered nodal degree and efficiency mainly located in the thalamus, rostral anterior cingulate cortex (rACC), and supplementary motor area (SMA), which are involved in somatic/sensory, emotional processing and motor-control. For the modular analysis, thalamus, rACC and SMA had an aberrant within-module nodal degree and nodal efficiency, and thalamus-related network exhibited abnormal interaction with the limbic network (amygdala and hippocampal gyrus). Nodal degree in the thalamus was negatively correlated with difficulty of defecation, and nodal degree in the rACC was negatively correlated with sensation of incomplete evacuation. These findings indicated that FCon was associated with abnormalities in the thalamo-cortical network.

PMID: 32314199 [PubMed - as supplied by publisher]

Altered resting-state functional networks in patients with hemodialysis: a graph-theoretical based study.

Wed, 04/22/2020 - 11:40
Related Articles

Altered resting-state functional networks in patients with hemodialysis: a graph-theoretical based study.

Brain Imaging Behav. 2020 Apr 20;:

Authors: Jin M, Wang L, Wang H, Han X, Diao Z, Guo W, Yang Z, Ding H, Wang Z, Zhang P, Zhao P, Lv H, Liu W, Wang Z

Abstract
Recent studies have demonstrated that hemodialysis patients exhibit disruptions in functional networks with invisible cerebral alterations. We explored the alterations of functional connectivity in hemodialysis patients using the graph-theory method. A total of 46 hemodialysis patients (53.11 ± 1.58 years, 28 males) and 47 healthy controls (55.57 ± 0.86 years, 22 males) were scanned by using resting-state functional magnetic resonance imaging. The brains of these patients were divided into 90 regions and functional connectivity was constructed with the automatic anatomical labeling atlas. In the defined threshold range, the graph-theory analysis was performed to compare the topological properties including global, regional and edge parameters between the hemodialysis and the healthy control groups. Both hemodialysis patients and healthy control subjects demonstrated common small-world property of the brain functional connections. At the global level, the parameters normalized clustering coefficients and small-worldness were significantly decreased in hemodialysis patients compared with those noted in healthy controls. At the regional level, abnormal nodal metrics (increased or decreased nodal degree, betweenness centrality and efficiency) were widely found in hemodialysis patients compared with those of healthy controls. The network-based statistical method was employed and two disrupted neural circuits with 18 nodes and 19 edges (P = 0.0139, corrected) and 10 nodes and 11 edges (P = 0.0399, corrected) were detected. Of note, the edge-increased functional connectivity was associated with the salience network and the frontal-temporal-basal ganglia connection, whereas the edge-decreased functional connectivity was associated with the frontoparietal network. The graph-theory method may be one of the potential tools to detect disruptions of cerebral functional connectivity and provide important evidence for understanding the neuropathology of hemodialysis patients from the disrupted network organization perspective.

PMID: 32314197 [PubMed - as supplied by publisher]

The changes of brain functional networks in young adult smokers based on independent component analysis.

Wed, 04/22/2020 - 11:40
Related Articles

The changes of brain functional networks in young adult smokers based on independent component analysis.

Brain Imaging Behav. 2020 Apr 20;:

Authors: Wang X, Xue T, Dong F, Li Y, Xie D, Liu C, Zhang M, Bi Y, Yuan K, Yu D

Abstract
Intrinsic functional connectivity (FC) networks, including the default mode network (DMN), central executive network (CEN), and salience network (SN), have been implicated in nicotine addiction. However, litter evidence exists about the abnormalities in the three networks in young adult smokers. Forty-eight young adult smokers and 49 age- and gender-matched non-smokers were recruited in the present study. Resting-state functional magnetic resonance imaging (fMRI) data were analyzed by a combination of independent component analysis (ICA) and dual regression to identify potential differences of FC patterns in the DMN, CEN, and SN. Compared to non-smokers, young adult smokers showed enhanced FC of the left posterior cingulate cortex (LPCC), right medial prefrontal cortex (RMPFC) and right precuneus within the DMN network, of the right dorsolateral prefrontal cortex (DLPFC) within the right CEN, and of the left anterior insula (LAI) within the SN. We also found increased FC between the DMN, CEN and key node of the SN (anterior insula, AI). Correlation analysis showed that the increased FC within the networks was significantly correlated with smoking behaviors (pack-years, smoking duration, FTND, first smoking age, and number of cigarettes per day). Our findings may provide additional evidence for conceptualizing the framework of nicotine addiction as a disease of intercommunicating brain networks.

PMID: 32314196 [PubMed - as supplied by publisher]

Evidence accumulation during perceptual decisions in humans varies as a function of dorsal frontoparietal organization.

Wed, 04/22/2020 - 11:40
Related Articles

Evidence accumulation during perceptual decisions in humans varies as a function of dorsal frontoparietal organization.

Nat Hum Behav. 2020 Apr 20;:

Authors: Brosnan MB, Sabaroedin K, Silk T, Genc S, Newman DP, Loughnane GM, Fornito A, O'Connell RG, Bellgrove MA

Abstract
Animal neurophysiological studies have identified neural signals within dorsal frontoparietal areas that trace a perceptual decision by accumulating sensory evidence over time and trigger action upon reaching a threshold. Although analogous accumulation-to-bound signals are identifiable on extracranial human electroencephalography, their cortical origins remain unknown. Here neural metrics of human evidence accumulation, predictive of the speed of perceptual reports, were isolated using electroencephalography and related to dorsal frontoparietal network (dFPN) connectivity using diffusion and resting-state functional magnetic resonance imaging. The build-up rate of evidence accumulation mediated the relationship between the white matter macrostructure of dFPN pathways and the efficiency of perceptual reports. This association between steeper build-up rates of evidence accumulation and the dFPN was recapitulated in the resting-state networks. Stronger connectivity between dFPN regions is thus associated with faster evidence accumulation and speeded perceptual decisions. Our findings identify an integrated network for perceptual decisions that may be targeted for neurorehabilitation in cognitive disorders.

PMID: 32313233 [PubMed - as supplied by publisher]

Loss of nucleus accumbens low-frequency fluctuations is a signature of chronic pain.

Wed, 04/22/2020 - 11:40
Related Articles

Loss of nucleus accumbens low-frequency fluctuations is a signature of chronic pain.

Proc Natl Acad Sci U S A. 2020 Apr 20;:

Authors: Makary MM, Polosecki P, Cecchi GA, DeAraujo IE, Barron DS, Constable TR, Whang PG, Thomas DA, Mowafi H, Small DM, Geha P

Abstract
Chronic pain is a highly prevalent disease with poorly understood pathophysiology. In particular, the brain mechanisms mediating the transition from acute to chronic pain remain largely unknown. Here, we identify a subcortical signature of back pain. Specifically, subacute back pain patients who are at risk for developing chronic pain exhibit a smaller nucleus accumbens volume, which persists in the chronic phase, compared to healthy controls. The smaller accumbens volume was also observed in a separate cohort of chronic low-back pain patients and was associated with dynamic changes in functional connectivity. At baseline, subacute back pain patients showed altered local nucleus accumbens connectivity between putative shell and core, irrespective of the risk of transition to chronic pain. At follow-up, connectivity changes were observed between nucleus accumbens and rostral anterior cingulate cortex in the patients with persistent pain. Analysis of the power spectral density of nucleus accumbens resting-state activity in the subacute and chronic back pain patients revealed loss of power in the slow-5 frequency band (0.01 to 0.027 Hz) which developed only in the chronic phase of pain. This loss of power was reproducible across two cohorts of chronic low-back pain patients obtained from different sites and accurately classified chronic low-back pain patients in two additional independent datasets. Our results provide evidence that lower nucleus accumbens volume confers risk for developing chronic pain and altered nucleus accumbens activity is a signature of the state of chronic pain.

PMID: 32312809 [PubMed - as supplied by publisher]

Glutamate and Dysconnection in the Salience Network: Neurochemical, Effective Connectivity, and Computational Evidence in Schizophrenia.

Wed, 04/22/2020 - 11:40
Related Articles

Glutamate and Dysconnection in the Salience Network: Neurochemical, Effective Connectivity, and Computational Evidence in Schizophrenia.

Biol Psychiatry. 2020 Feb 06;:

Authors: Limongi R, Jeon P, Mackinley M, Das T, Dempster K, Théberge J, Bartha R, Wong D, Palaniyappan L

Abstract
BACKGROUND: Functional dysconnection in schizophrenia is underwritten by a pathophysiology of the glutamate neurotransmission that affects the excitation-inhibition balance in key nodes of the salience network. Physiologically, this manifests as aberrant effective connectivity in intrinsic connections involving inhibitory interneurons. In computational terms, this produces a pathology of evidence accumulation and ensuing inference in the brain. Finally, the pathophysiology and aberrant inference would partially account for the psychopathology of schizophrenia as measured in terms of symptoms and signs. We refer to this formulation as the 3-level hypothesis.
METHODS: We tested the hypothesis in core nodes of the salience network (the dorsal anterior cingulate cortex [dACC] and the anterior insula) of 20 patients with first-episode psychosis and 20 healthy control subjects. We established 3-way correlations between the magnetic resonance spectroscopy measures of glutamate, effective connectivity of resting-state functional magnetic resonance imaging, and correlations between measures of this connectivity and estimates of precision (inherent in evidence accumulation in the Stroop task) and psychopathology.
RESULTS: Glutamate concentration in the dACC was associated with higher and lower inhibitory connectivity in the dACC and in the anterior insula, respectively. Crucially, glutamate concentration correlated negatively with the inhibitory influence on the excitatory neuronal population in the dACC of subjects with first-episode psychosis. Furthermore, aberrant computational parameters of the Stroop task performance were associated with aberrant inhibitory connections. Finally, the strength of connections from the dACC to the anterior insula correlated negatively with severity of social withdrawal.
CONCLUSIONS: These findings support a link between glutamate-mediated cortical disinhibition, effective-connectivity deficits, and computational performance in psychosis.

PMID: 32312577 [PubMed - as supplied by publisher]

N-Acetyl-Cysteine Supplementation Improves Functional Connectivity Within the Cingulate Cortex in Early Psychosis: A Pilot Study.

Wed, 04/22/2020 - 11:40
Related Articles

N-Acetyl-Cysteine Supplementation Improves Functional Connectivity Within the Cingulate Cortex in Early Psychosis: A Pilot Study.

Int J Neuropsychopharmacol. 2019 08 01;22(8):478-487

Authors: Mullier E, Roine T, Griffa A, Xin L, Baumann PS, Klauser P, Cleusix M, Jenni R, Alemàn-Gómez Y, Gruetter R, Conus P, Do KQ, Hagmann P

Abstract
BACKGROUND: There is increasing evidence that redox dysregulation, which can lead to oxidative stress and eventually to impairment of oligodendrocytes and parvalbumin interneurons, may underlie brain connectivity alterations in schizophrenia. Accordingly, we previously reported that levels of brain antioxidant glutathione in the medial prefrontal cortex were positively correlated with increased functional connectivity along the cingulum bundle in healthy controls but not in early psychosis patients. In a recent randomized controlled trial, we observed that 6-month supplementation with a glutathione precursor, N-acetyl-cysteine, increased brain glutathione levels and improved symptomatic expression and processing speed.
METHODS: We investigated the effect of N-acetyl-cysteine supplementation on the functional connectivity between regions of the cingulate cortex, which have been linked to positive symptoms and processing speed decline. In this pilot study, we compared structural connectivity and resting-state functional connectivity between early psychosis patients treated with 6-month N-acetyl-cysteine (n = 9) or placebo (n = 11) supplementation with sex- and age-matched healthy control subjects (n = 74).
RESULTS: We observed that 6-month N-acetyl-cysteine supplementation increases functional connectivity along the cingulum and more precisely between the caudal anterior part and the isthmus of the cingulate cortex. These functional changes can be partially explained by an increase of centrality of these regions in the functional brain network.
CONCLUSIONS: N-acetyl-cysteine supplementation has a positive effect on functional connectivity within the cingulate cortex in early psychosis patients. To our knowledge, this is the first study suggesting that increased brain glutathione levels via N-acetyl-cysteine supplementation may improve brain functional connectivity.

PMID: 31283822 [PubMed - indexed for MEDLINE]

The Role of Hippocampal Functional Connectivity on Multisystem Subclinical Abnormalities in Schizophrenia.

Tue, 04/21/2020 - 16:40
Related Articles

The Role of Hippocampal Functional Connectivity on Multisystem Subclinical Abnormalities in Schizophrenia.

Psychosom Med. 2020 Apr 18;:

Authors: Hare S, Chiappelli J, Savransky A, Adhikari BM, Wisner K, Kvarta M, Goldwaser E, Du X, Chen S, Rowland LM, Kochunov P, Hong LE

Abstract
OBJECTIVE: Schizophrenia is associated with excess medical mortality: patients have an average life expectancy one to two decades shorter than the general population. This study investigates the relationship between aberrant hippocampal resting-state functional connectivity in schizophrenia and cumulative subclinical effects of chronic stress on metabolic, cardiovascular and immune function using the allostatic load index.
METHODS: Cumulative stress was estimated using allostatic load total score (range: 0-13) in 46 patients with schizophrenia and 31 controls matched for age and sex (patients, age=36.1±13.7 y, sex=32/14 m/f; controls, age=35.5±14.1, sex=21/10 m/f). Hippocampal functional connectivity was assessed using resting-state fMRI; hippocampal structural connectivity was assessed using fornix fractional anisotropy. Linear regression analysis was used (1) to test the hypothesis that aberrant hippocampal resting state functional connectivity in schizophrenia (identified in analysis of schizophrenia - control differences) is associated with elevated allostatic load scores in patients, and (2) to determine the association between fornix fractional anisotropy with allostatic load.
RESULTS: In patients, higher allostatic load was significantly associated with reduced resting functional connectivity between the left hippocampus and right cingulate cortex and left precentral gyrus, but higher connectivity between the right hippocampus and left cerebellum lobe VI (corrected p values <0.05). In controls, reductions in both hippocampal structural connectivity and hippocampal-cingulate functional connectivity were associated with higher allostatic load scores.
CONCLUSIONS: These findings support basic neuroscience evidence that cumulative stress and hippocampal function are closely connected and suggest that abnormal hippocampal functional communication in schizophrenia may be related to elevated multi-system subclinical medical issues in patients as indexed by allostatic load.

PMID: 32310840 [PubMed - as supplied by publisher]

A Hierarchical Bayesian Mixture Modeling Approach for Analysis of Resting-State Functional Brain Connectivity: An Alternative to Thresholding.

Tue, 04/21/2020 - 16:40
Related Articles

A Hierarchical Bayesian Mixture Modeling Approach for Analysis of Resting-State Functional Brain Connectivity: An Alternative to Thresholding.

Brain Connect. 2020 Apr 19;:

Authors: Gorbach T, Lundquist A, de Luna X, Nyberg L, Salami A

Abstract
This paper proposes a Bayesian hierarchical mixture model to analyze functional brain connectivity where mixture components represent "connected" and "non-connected" brain regions. Such an approach provides a data-informed separation of reliable and spurious connections in contrast to arbitrary thresholding of a connectivity matrix. The hierarchical structure of the model allows simultaneous inferences for the entire population as well as for each individual subject. A new connectivity measure, the posterior probability of a given pair of brain regions of a specific subject to be connected given the observed correlation of regions' activity, can be computed from the model fit. The posterior probability reflects connectivity of a pair of regions relative to the overall connectivity pattern of an individual, which is overlooked in traditional correlation analyses. This paper demonstrates that using the posterior probability might diminish the effect of spurious connections on inferences, which is present when a correlation is used as a connectivity measure. Additionally, simulation analyses reveal that the sparsification of the connectivity matrix using the posterior probabilities might outperform the absolute thresholding based on correlations. Therefore, we suggest that posterior probability might be a beneficial measure of connectivity compared to the correlation. The applicability of the introduced method is exemplified by a study of functional resting-state brain connectivity in older adults.

PMID: 32308015 [PubMed - as supplied by publisher]

Intrinsic connections between thalamic sub-regions and the lateral prefrontal cortex are differentially impacted by acute methylphenidate.

Tue, 04/21/2020 - 16:40
Related Articles

Intrinsic connections between thalamic sub-regions and the lateral prefrontal cortex are differentially impacted by acute methylphenidate.

Psychopharmacology (Berl). 2020 Apr 19;:

Authors: Gorka AX, Lago TR, Balderston N, Torrisi S, Fuchs B, Grillon C, Ernst M

Abstract
BACKGROUND: The thalamus is a major target of dopaminergic projections and is densely connected with the prefrontal cortex. A better understanding of how dopamine changes thalamo-cortical communication may shed light on how dopamine supports cognitive function. Methylphenidate has been shown to facilitate cognitive processing and reduce connectivity between the thalamus and lateral prefrontal cortex.
AIMS: The thalamus is a heterogeneous structure, and the present study sought to clarify how the intrinsic connections of thalamic sub-regions are differentially impacted by acute dopamine transporter blockade.
METHODS: Sixty healthy volunteers were orally administered either 20 mg of methylphenidate (N = 29) or placebo (N = 31) in a double-blind, randomized, between-subject design. Multi-echo fMRI was used to assess intrinsic functional connectivity of sub-regions of the thalamus during a resting state scan. An N-back working-memory paradigm provided a measure of cognitive performance.
RESULTS: Acute methylphenidate significantly reduced connectivity of the lateral prefrontal cortex with the motor and somatosensory sub-regions of the thalamus and reduced connectivity with the parietal and visual sub-regions at a trend level. Connectivity with the premotor, prefrontal, and temporal sub-regions was not impacted. The intrinsic connectivity between the thalamus and the lateral prefrontal cortex was not associated with working-memory performance.
CONCLUSIONS: Methylphenidate decreases functional connections between the lateral prefrontal cortex and thalamus broadly, while sparing intrinsic connectivity with thalamic sub-regions involved with working-memory and language related processes. Collectively, our results suggest that the dopamine transporter regulates functional connections between the prefrontal cortex and non-cognitive areas of the thalamus.

PMID: 32307560 [PubMed - as supplied by publisher]

[Fractional amplitude of low-frequency fluctuations in retinal vein occlusion: a resting-state fMRI study].

Tue, 04/21/2020 - 16:40
Related Articles

[Fractional amplitude of low-frequency fluctuations in retinal vein occlusion: a resting-state fMRI study].

Zhonghua Yan Ke Za Zhi. 2020 Apr 11;56(4):266-271

Authors: Tong Y, Huang X, Gao Q, Qi CX, Shen Y

Abstract
Objective: To investigate the altered spontaneous brain activity in patients with retinal vein occlusion (RVO) during the resting state. Methods: A case-control study. Forty-five patients with RVO [24 males and 21 females; age, (51.24±5.86) years] diagnosed from May 2018 to July 2019 in Renmin Hospital of Wuhan University were recruited in the RVO group. Meanwhile, forty-three healthy controls [19 males and 24 females; age, (49.79±7.31) years] who were closely matched in age and sex to patients with RVO were recruited in the healthy control group. Each subject underwent a whole-brain resting-state functional magnetic resonance imaging scan to detect the values of fractional amplitude of low-frequency fluctuations (fALFF). The altered spontaneous brain activity between RVO patients and healthy controls were analyzed. The intra-and inter-group comparisons of two sets of fALFF values were conducted using one-sample t-test and two-sample t-test, respectively. Results: Compared with the healthy control group, the fALFF values of RVO patients were significantly changed. The fALFF values of left cerebellum (-0.68±0.48, t=3.8081), right cerebellum (-0.79±0.47, t=4.590), right brainstem (-0.57±0.50, t=3.964) and left insula (-0.22±0.27, t=3.587) increased, while the fALFF values of right calcarinesulcus (0.60±0.72, t=-3.521), right thalamus (-0.68±0.43, t=-3.846) and left lingual gyrus (-0.12±0.33, t=-3.876) decreased. The differences were statistically significant (voxel-level P<0.01, Gaussian random field correction, cluster-level P<0.05). Conclusions: Patients with RVO have abnormal spontaneous neural activity in multiple brain areas, including visual pathways and emotion-cognition processing regions. Moreover, there may be compensatory brain function enhancement in local brain areas. The results provide new insights into the understanding of the mechanism for the occurrence and development of RVO.(Chin J Ophthalmol, 2020, 56:266-271).

PMID: 32306618 [PubMed - in process]

Hemodynamic Responses of the Placenta and Brain to Maternal Hyperoxia in Fetuses with Congenital Heart Disease by Using Blood Oxygen-Level Dependent MRI.

Tue, 04/21/2020 - 16:40
Related Articles

Hemodynamic Responses of the Placenta and Brain to Maternal Hyperoxia in Fetuses with Congenital Heart Disease by Using Blood Oxygen-Level Dependent MRI.

Radiology. 2020 01;294(1):141-148

Authors: You W, Andescavage NN, Kapse K, Donofrio MT, Jacobs M, Limperopoulos C

Abstract
Background Impaired brain development in fetuses with congenital heart disease (CHD) may result from inadequate cerebral oxygen supply in utero. Purpose To test whether fetal cerebral oxygenation can be increased by maternal oxygen administration, effects of maternal hyperoxia on blood oxygenation of the placenta and fetal brain were examined by using blood oxygenation level-dependent (BOLD) functional MRI. Materials and Methods In this prospective study, BOLD MRI was performed in 86 fetuses (56 healthy fetuses and 30 fetuses diagnosed with CHD) between 22 and 39 weeks gestational age (GA) from May 2015 to December 2017, with the following study design: phase I, 2-minute resting state at baseline (room air); phase II, 6-minute maternal hyperoxia with 100% oxygen; and phase III, 5.6-minute return to resting state. After motion correction, the signals were averaged over the placenta and fetal brain and converted to the change in R2* (ΔR2*). Fetuses with CHD were categorized into those with a single ventricle (SV) or two ventricles (TVs) and those with aortic obstruction (AO) or non-AO. Data were analyzed by using generalized linear mixed models controlling for GA and sex. Results Placental ΔR2* increased during maternal hyperoxia in healthy fetuses and fetuses with CHD, but it was higher in SV CHD (mean ΔR2*, 1.3 sec-1 ± 0.1 [standard error; P < .01], 1.9 sec-1 ± 0.2 [P < .01], and 1.0 sec-1 ± 0.3 [P < .01], respectively, for control fetuses, fetuses with SV CHD, and fetuses with TV CHD). Placental ΔR2* during maternal hyperoxia changed with GA in healthy control fetuses and fetuses with SV or AO CHD (ΔR2* per week, 0.1 sec-1 ± 0 [P < .01], 0.2 sec-1 ± 0 [P = .01], and 0.2 sec-1 ± 0 [P = .01], respectively), but not in fetuses with CHD and TV or non-AO. Fetal brain ΔR2* was constant across all phases in healthy control fetuses and fetuses with TV CHD but increased during maternal hyperoxia in fetuses with SV or AO CHD (mean ΔR2*, 0.7 sec-1 ± 0.2 [P = .01] and 0.5 sec-1 ± 0.2 [P = .02], respectively). Conclusion Six minutes of maternal hyperoxia increased placental oxygenation in healthy fetuses and fetuses with congenital heart disease, and it selectively increased cerebral blood oxygenation in fetuses with single ventricle or aortic obstruction. © RSNA, 2019 Online supplemental material is available for this article.

PMID: 31687920 [PubMed - indexed for MEDLINE]

Dynamic brain network configurations during rest and an attention task with frequent occurrence of mind wandering.

Tue, 04/21/2020 - 16:40
Related Articles

Dynamic brain network configurations during rest and an attention task with frequent occurrence of mind wandering.

Hum Brain Mapp. 2019 10 15;40(15):4564-4576

Authors: Denkova E, Nomi JS, Uddin LQ, Jha AP

Abstract
Mind wandering (MW) has become a prominent topic of neuroscientific investigation due to the importance of understanding attentional processes in our day-to-day experiences. Emerging evidence suggests a critical role for three large-scale brain networks in MW: the default network (DN), the central executive network (CEN), and the salience network (SN). Advances in analytical methods for neuroimaging data (i.e., dynamic functional connectivity, DFC) demonstrate that the interactions between these networks are not static but dynamically fluctuate over time (Chang & Glover, 2010, NeuroImage, 50(1), 81-98). While the bulk of the evidence comes from studies involving resting-state functional MRI, a few studies have investigated DFC during a task. Direct comparison of DFC during rest and task with frequent MW is scarce. The present study applies the DFC method to neuroimaging data collected from 30 participants who completed a resting-state run followed by two runs of sustained attention to response task (SART) with embedded probes indicating a high prevalence of MW. The analysis identified five DFC states. Differences between rest and task were noted in the frequency of three DFC states. One DFC state characterized by negative DN-CEN/SN connectivity along with positive CEN-SN connectivity was more frequently observed during task vs. rest. Two DFC states, one of which was characterized by weaker connectivity between networks, were more frequently observed during rest than task. These findings suggest that the dynamic relationships between brain networks may vary as a function of whether ongoing cognitive activity unfolds in an "unconstrained" manner during rest or is "constrained" by task demands.

PMID: 31379120 [PubMed - indexed for MEDLINE]

Evaluation of the spatial variability in the major resting-state networks across human brain functional atlases.

Tue, 04/21/2020 - 16:40
Related Articles

Evaluation of the spatial variability in the major resting-state networks across human brain functional atlases.

Hum Brain Mapp. 2019 10 15;40(15):4577-4587

Authors: Doucet GE, Lee WH, Frangou S

Abstract
The human brain is intrinsically organized into resting-state networks (RSNs). Currently, several human brain functional atlases are used to define the spatial constituents of these RSNs. However, there are significant concerns about interatlas variability. In response, we undertook a quantitative comparison of the five major RSNs (default mode [DMN], salience, central executive, sensorimotor, and visual networks) across currently available brain functional atlases (n = 6) in which we demonstrated that (a) similarity between atlases was modest and positively linked to the size of the sample used to construct them; (b) across atlases, spatial overlap among major RSNs ranged between 17 and 76% (mean = 39%), which resulted in variability in their functional connectivity; (c) lower order RSNs were generally spatially conserved across atlases; (d) among higher order RSNs, the DMN was the most conserved across atlases; and (e) voxel-wise flexibility (i.e., the likelihood of a voxel to change network assignment across atlases) was high for subcortical regions and low for the sensory, motor and medial prefrontal cortices, and the precuneus. In order to facilitate RSN reproducibility in future studies, we provide a new freely available Consensual Atlas of REsting-state Networks, based on the most reliable atlases.

PMID: 31322303 [PubMed - indexed for MEDLINE]

Longitudinal increases in structural connectome segregation and functional connectome integration are associated with better recovery after mild TBI.

Tue, 04/21/2020 - 16:40
Related Articles

Longitudinal increases in structural connectome segregation and functional connectome integration are associated with better recovery after mild TBI.

Hum Brain Mapp. 2019 10 15;40(15):4441-4456

Authors: Kuceyeski AF, Jamison KW, Owen JP, Raj A, Mukherjee P

Abstract
Traumatic brain injury damages white matter pathways that connect brain regions, disrupting transmission of electrochemical signals and causing cognitive and emotional dysfunction. Connectome-level mechanisms for how the brain compensates for injury have not been fully characterized. Here, we collected serial MRI-based structural and functional connectome metrics and neuropsychological scores in 26 mild traumatic brain injury subjects (29.4 ± 8.0 years, 20 males) at 1 and 6 months postinjury. We quantified the relationship between functional and structural connectomes using network diffusion (ND) model propagation time, a measure that can be interpreted as how much of the structural connectome is being utilized for the spread of functional activation, as captured via the functional connectome. Overall cognition showed significant improvement from 1 to 6 months (t25 = -2.15, p = .04). None of the structural or functional global connectome metrics was significantly different between 1 and 6 months, or when compared to 34 age- and gender-matched controls (28.6 ± 8.8 years, 25 males). We predicted longitudinal changes in overall cognition from changes in global connectome measures using a partial least squares regression model (cross-validated R2 = .27). We observe that increased ND model propagation time, increased structural connectome segregation, and increased functional connectome integration were related to better cognitive recovery. We interpret these findings as suggesting two connectome-based postinjury recovery mechanisms: one of neuroplasticity that increases functional connectome integration and one of remote white matter degeneration that increases structural connectome segregation. We hypothesize that our inherently multimodal measure of ND model propagation time captures the interplay between these two mechanisms.

PMID: 31294921 [PubMed - indexed for MEDLINE]

The atypical social brain network in autism: advances in structural and functional MRI studies.

Tue, 04/21/2020 - 16:40
Related Articles

The atypical social brain network in autism: advances in structural and functional MRI studies.

Curr Opin Neurol. 2019 08;32(4):617-621

Authors: Sato W, Uono S

Abstract
PURPOSE OF REVIEW: To review advances in structural and functional MRI studies regarding the neural underpinnings of social atypicalities in autism spectrum disorder (ASD).
RECENT FINDINGS: According to the hypothesis that the social brain network, which includes brain regions, such as the amygdala and superior temporal sulcus, may be atypical in ASD, recent structural MRI studies have identified regional gray matter volume abnormalities in the social brain regions in ASD groups compared with the typically developing groups. Studies evaluating gray matter volume covariance and white matter volume/integrity suggested network-level abnormalities associated with the social brain regions. Recent functional MRI studies assessing resting-state neural activity showed reduced functional connectivity among the social brain regions in individuals with ASD compared with typically developing groups. Similarly, task-based functional MRI studies recently revealed a reduction in regional activity and intraregional functional coupling in the social brain regions during the processing of social stimuli in individuals with ASD.
SUMMARY: These structural and functional MRI studies provide supportive evidence for the hypothesis that an atypical social brain network underlies behavioral social problems in ASD.

PMID: 31135458 [PubMed - indexed for MEDLINE]

The impact of modern-day neuroimaging on the field of deep brain stimulation.

Tue, 04/21/2020 - 16:40
Related Articles

The impact of modern-day neuroimaging on the field of deep brain stimulation.

Curr Opin Neurol. 2019 08;32(4):511-520

Authors: Horn A

Abstract
PURPOSE OF REVIEW: Deep brain stimulation (DBS) is an established but growing treatment option for multiple brain disorders. Over the last decade, electrode placement and their effects were increasingly analyzed with modern-day neuroimaging methods like spatial normalization, fibertracking, or resting-state functional MRI. Similarly, specialized basal ganglia MRI sequences were introduced and imaging at high field strengths has become increasingly popular.
RECENT FINDINGS: To facilitate the process of precise electrode localizations, specialized software pipelines were introduced. By those means, DBS targets could recently be refined and significant relationships between electrode placement and clinical improvement could be shown. Furthermore, by combining electrode reconstructions with network imaging methods, relationships between electrode connectivity and clinical improvement were investigated. This led to a broad series of imaging-based insights about DBS that are reviewed in the present work.
SUMMARY: The reviewed literature makes a strong case that brain imaging plays an increasingly important role in DBS targeting and programming. Furthermore, brain imaging will likely help to better understand the mechanism of action of DBS.

PMID: 30844863 [PubMed - indexed for MEDLINE]

Pages