New resting-state fMRI related studies at PubMed

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Multi-band SWIFT enables quiet and artefact-free EEG-fMRI and awake fMRI studies in rat.

Sat, 11/16/2019 - 19:00
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Multi-band SWIFT enables quiet and artefact-free EEG-fMRI and awake fMRI studies in rat.

Neuroimage. 2019 Nov 12;:116338

Authors: Paasonen J, Laakso H, Pirttimäki T, Stenroos P, Salo RA, Zhurakovskaya E, Lehto LJ, Tanila H, Garwood M, Michaeli S, Idiyatullin D, Mangia S, Gröhn O

Abstract
Functional magnetic resonance imaging (fMRI) studies in animal models provide invaluable information regarding normal and abnormal brain function, especially when combined with complementary stimulation and recording techniques. The echo planar imaging (EPI) pulse sequence is the most common choice for fMRI investigations, but it has several shortcomings. EPI is one of the loudest sequences and very prone to movement and susceptibility-induced artefacts, making it suboptimal for awake imaging. Additionally, the fast gradient-switching of EPI induces disrupting currents in simultaneous electrophysiological recordings. Therefore, we investigated whether the unique features of Multi-Band SWeep Imaging with Fourier Transformation (MB-SWIFT) overcome these issues at a high 9.4 T magnetic field, making it a potential alternative to EPI. MB-SWIFT had 32-dB and 20-dB lower peak and average sound pressure levels, respectively, than EPI with typical fMRI parameters. Body movements had little to no effect on MB-SWIFT images or functional connectivity analyses, whereas they severely affected EPI data. The minimal gradient steps of MB-SWIFT induced significantly lower currents in simultaneous electrophysiological recordings than EPI, and there were no electrode-induced distortions in MB-SWIFT images. An independent component analysis of the awake rat functional connectivity data obtained with MB-SWIFT resulted in near whole-brain level functional parcellation, and simultaneous electrophysiological and fMRI measurements in isoflurane-anesthetized rats indicated that MB-SWIFT signal is tightly linked to neuronal resting-state activity. Therefore, we conclude that the MB-SWIFT sequence is a robust preclinical brain mapping tool that can overcome many of the drawbacks of conventional EPI fMRI at high magnetic fields.

PMID: 31730923 [PubMed - as supplied by publisher]

Effects of Motion Related Outliers in Dynamic Functional Connectivity Using the Sliding Window Method.

Sat, 11/16/2019 - 19:00
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Effects of Motion Related Outliers in Dynamic Functional Connectivity Using the Sliding Window Method.

J Neurosci Methods. 2019 Nov 12;:108519

Authors: Savva AD, Kassinopoulos M, Smyrnis N, Matsopoulos GK, Mitsis GD

Abstract
BACKGROUND: It has been suggested that the use of window functions, other than the rectangular, in the sliding window method, may be beneficial for reducing the effects of motion-related outliers in the time-series, when assessing dynamic functional connectivity (dFC) in resting-state fMRI (rs-fMRI).
METHODOLOGY: Ten window functions for a wide range of window lengths (20-150 s) combined with Pearson and Kendall correlation metrics, were investigated. One hundred high quality rs-fMRI datasets from healthy controls, were used to systematically assess the effect of varying the window function and length on dFC assessment. To this end, two approaches were implemented: a) simulated outliers were added to the experimental data and b) the experimental data were divided into low and high motion subgroups.
RESULTS: The presence of experimental motion-noise tended to inflate the number of dynamic connections for longer (≥100 s) wide-shaped windows, while shorter (20-30 s) narrow-shaped windows exhibited increased sensitivity in the presence of simulated outliers. Moreover, window sizes from 60 s to 90 s were mildly affected by motion-related effects. In most cases, the number of dynamic connections increased, and gradually lower frequencies were captured, with an increasing window size.
CONCLUSIONS: Subject motion considerably affects the obtained dFC patterns; thus, it is preferable to perform motion artefact removal in the pre-processing stage rather than using alternative window functions to mitigate their effects. Provided that motion-noise is not excessive, the choice of a rectangular window is adequate. Finally, low frequency oscillations in functional connectivity seem to play an important role in the context of dFC assessment.

PMID: 31730872 [PubMed - as supplied by publisher]

Increased soluble amyloid-beta causes early aberrant brain network hypersynchronisation in a mature-onset mouse model of amyloidosis.

Sat, 11/16/2019 - 19:00
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Increased soluble amyloid-beta causes early aberrant brain network hypersynchronisation in a mature-onset mouse model of amyloidosis.

Acta Neuropathol Commun. 2019 Nov 14;7(1):180

Authors: Ben-Nejma IRH, Keliris AJ, Daans J, Ponsaerts P, Verhoye M, Van der Linden A, Keliris GA

Abstract
Alzheimer's disease (AD) is the most common form of dementia in the elderly. According to the amyloid hypothesis, the accumulation and deposition of amyloid-beta (Aβ) peptides play a key role in AD. Soluble Aβ (sAβ) oligomers were shown to be involved in pathological hypersynchronisation of brain resting-state networks in different transgenic developmental-onset mouse models of amyloidosis. However, the impact of protein overexpression during brain postnatal development may cause additional phenotypes unrelated to AD. To address this concern, we investigated sAβ effects on functional resting-state networks in transgenic mature-onset amyloidosis Tet-Off APP (TG) mice. TG mice and control littermates were raised on doxycycline (DOX) diet from 3d up to 3 m of age to suppress transgenic Aβ production. Thereafter, longitudinal resting-state functional MRI was performed on a 9.4 T MR-system starting from week 0 (3 m old mice) up to 28w post DOX treatment. Ex-vivo immunohistochemistry and ELISA analysis was performed to assess the development of amyloid pathology. Functional Connectivity (FC) analysis demonstrated early abnormal hypersynchronisation in the TG mice compared to the controls at 8w post DOX treatment, particularly across regions of the default mode-like network, known to be affected in AD. Ex-vivo analyses performed at this time point confirmed a 20-fold increase in total sAβ levels preceding the apparition of Aβ plaques and inflammatory responses in the TG mice compared to the controls. On the contrary at week 28, TG mice showed an overall hypoconnectivity, coinciding with a widespread deposition of Aβ plaques in the brain. By preventing developmental influence of APP and/or sAβ during brain postnatal development, we demonstrated FC abnormalities potentially driven by sAβ neurotoxicity on resting-state neuronal networks in mature-induced TG mice. Thus, the Tet-Off APP mouse model could be a powerful tool while used as a mature-onset model to shed light into amyloidosis mechanisms in AD.

PMID: 31727182 [PubMed - in process]

Stimulating the hippocampal posterior-medial network enhances task-dependent connectivity and memory.

Fri, 11/15/2019 - 18:20
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Stimulating the hippocampal posterior-medial network enhances task-dependent connectivity and memory.

Elife. 2019 Nov 14;8:

Authors: Warren KN, Hermiller MS, Nilakantan AS, Voss JL

Abstract
Successful episodic memory involves dynamic increases in activity across distributed hippocampal networks, including the posterior-medial (PMN) and the anterior-temporal (ATN) networks. We tested whether this up-regulation of functional connectivity during memory processing can be enhanced within hippocampal networks by noninvasive stimulation, and whether such task-dependent connectivity enhancement predicts memory improvement. Participants received stimulation targeting the PMN or an out-of-network control location. We compared the effects of stimulation on fMRI connectivity during an autobiographical retrieval task versus during rest within the PMN and the ATN. PMN-targeted stimulation significantly increased connectivity during autobiographical retrieval versus rest within the PMN. This effect was not observed in the ATN, or in either network following control stimulation. Task-dependent increases in connectivity within the medial temporal lobe predicted improved performance of a separate episodic memory test. It is therefore possible to enhance the task-dependent regulation of hippocampal network connectivity that supports memory processing using noninvasive stimulation.

PMID: 31724946 [PubMed - in process]

Temporal stability of fMRI in medetomidine-anesthetized rats.

Fri, 11/15/2019 - 18:20
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Temporal stability of fMRI in medetomidine-anesthetized rats.

Sci Rep. 2019 Nov 13;9(1):16673

Authors: Sirmpilatze N, Baudewig J, Boretius S

Abstract
Medetomidine has become a popular choice for anesthetizing rats during long-lasting sessions of blood-oxygen-level dependent (BOLD) functional magnetic resonance imaging (fMRI). Despite this, it has not yet been thoroughly established how commonly reported fMRI readouts evolve over several hours of medetomidine anesthesia and how they are affected by the precise timing, dose, and route of administration. We used four different protocols of medetomidine administration to anesthetize rats for up to six hours and repeatedly evaluated somatosensory stimulus-evoked BOLD responses and resting state functional connectivity. We found that the temporal evolution of fMRI readouts strongly depended on the method of administration. Intravenous administration of a medetomidine bolus (0.05 mg/kg), combined with a subsequent continuous infusion (0.1 mg/kg/h), led to temporally stable measures of stimulus-evoked activity and functional connectivity throughout the anesthesia. Deviating from the above protocol-by omitting the bolus, lowering the medetomidine dose, or using the subcutaneous route-compromised the stability of these measures in the initial two-hour period. We conclude that both an appropriate protocol of medetomidine administration and a suitable timing of fMRI experiments are crucial for obtaining consistent results. These factors should be considered for the design and interpretation of future rat fMRI studies.

PMID: 31723186 [PubMed - in process]

Quantitative imaging of brain energy metabolisms and neuroenergetics using in vivo X-nuclear 2H, 17O and 31P MRS at ultra-high field.

Fri, 11/15/2019 - 18:20
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Quantitative imaging of brain energy metabolisms and neuroenergetics using in vivo X-nuclear 2H, 17O and 31P MRS at ultra-high field.

J Magn Reson. 2018 07;292:155-170

Authors: Zhu XH, Lu M, Chen W

Abstract
Brain energy metabolism relies predominantly on glucose and oxygen utilization to generate biochemical energy in the form of adenosine triphosphate (ATP). ATP is essential for maintaining basal electrophysiological activities in a resting brain and supporting evoked neuronal activity under an activated state. Studying complex neuroenergetic processes in the brain requires sophisticated neuroimaging techniques enabling noninvasive and quantitative assessment of cerebral energy metabolisms and quantification of metabolic rates. Recent state-of-the-art in vivo X-nuclear MRS techniques, including 2H, 17O and 31P MRS have shown promise, especially at ultra-high fields, in the quest for understanding neuroenergetics and brain function using preclinical models and in human subjects under healthy and diseased conditions.

PMID: 29866434 [PubMed - indexed for MEDLINE]

Altered brain connectivity in sudden unexpected death in epilepsy (SUDEP) revealed using resting-state fMRI.

Thu, 11/14/2019 - 16:20

Altered brain connectivity in sudden unexpected death in epilepsy (SUDEP) revealed using resting-state fMRI.

Neuroimage Clin. 2019 Oct 28;24:102060

Authors: LA A, Rm H, M G, R K, Ja O, Sb V, S O, Ca S, Sd L, L L, B D

Abstract
The circumstances surrounding SUDEP suggest autonomic or respiratory collapse, implying central failure of regulation or recovery. Characterisation of the communication among brain areas mediating such processes may shed light on mechanisms and noninvasively indicate risk. We used rs-fMRI to examine network properties among brain structures in people with epilepsy who suffered SUDEP (n = 8) over an 8-year follow-up period, compared with matched high- and low-risk subjects (n = 16/group) who did not suffer SUDEP during that period, and a group of healthy controls (n = 16). Network analysis was employed to explore connectivity within a 'regulatory-subnetwork' of brain regions involved in autonomic and respiratory regulation, and over the whole-brain. Modularity, the extent of network organization into separate modules, was significantly reduced in the regulatory-subnetwork, and the whole-brain, in SUDEP and high-risk. Increased participation, a local measure of inter-modular belonging, was evident in SUDEP and high-risk groups, particularly among thalamic structures. The medial prefrontal thalamus was increased in SUDEP compared with all other control groups, including high-risk. Patterns of hub topology were similar in SUDEP and high-risk, but were more extensive in low-risk patients, who displayed greater hub prevalence and a radical reorganization of hubs in the subnetwork. SUDEP is associated with reduced functional organization among cortical and sub-cortical brain regions mediating autonomic and respiratory regulation. Living high-risk subjects demonstrated similar patterns, suggesting such network measures may provide prospective risk-indicating value, though a crucial difference between SUDEP and high-risk was altered connectivity of the medial thalamus in SUDEP, which was also elevated compared with all sub-groups. Disturbed thalamic connectivity may reflect a potential non-invasive marker of elevated SUDEP risk.

PMID: 31722289 [PubMed - as supplied by publisher]

Hubs disruption in mesial temporal lobe epilepsy. A resting-state fMRI study on a language-and-memory network.

Thu, 11/14/2019 - 16:20

Hubs disruption in mesial temporal lobe epilepsy. A resting-state fMRI study on a language-and-memory network.

Hum Brain Mapp. 2019 Nov 13;:

Authors: Roger E, Pichat C, Torlay L, David O, Renard F, Banjac S, Attyé A, Minotti L, Lamalle L, Kahane P, Baciu M

Abstract
Mesial temporal lobe epilepsy (mTLE) affects the brain networks at several levels and patients suffering from mTLE experience cognitive impairment for language and memory. Considering the importance of language and memory reorganization in this condition, the present study explores changes of the embedded language-and-memory network (LMN) in terms of functional connectivity (FC) at rest, as measured with functional MRI. We also evaluate the cognitive efficiency of the reorganization, that is, whether or not the reorganizations support or allow the maintenance of optimal cognitive functioning despite the seizure-related damage. Data from 37 patients presenting unifocal mTLE were analyzed and compared to 48 healthy volunteers in terms of LMN-FC using two methods: pairwise correlations (region of interest [ROI]-to-ROI) and graph theory. The cognitive efficiency of the LMN-FC reorganization was measured using correlations between FC parameters and language and memory scores. Our findings revealed a large perturbation of the LMN hubs in patients. We observed a hyperconnectivity of limbic areas near the dysfunctional hippocampus and mainly a hypoconnectivity for several cortical regions remote from the dysfunctional hippocampus. The loss of FC was more important in left mTLE (L-mTLE) than in right (R-mTLE) patients. The LMN-FC reorganization may not be always compensatory and not always useful for patients as it may be associated with lower cognitive performance. We discuss the different connectivity patterns obtained and conclude that interpretation of FC changes in relation to neuropsychological scores is important to determine cognitive efficiency, suggesting the concept of "connectome" would gain to be associated with a "cognitome" concept.

PMID: 31721361 [PubMed - as supplied by publisher]

Allelic variant in SLC6A3 rs393795 affects cerebral regional homogeneity and gait dysfunction in patients with Parkinson's disease.

Thu, 11/14/2019 - 16:20

Allelic variant in SLC6A3 rs393795 affects cerebral regional homogeneity and gait dysfunction in patients with Parkinson's disease.

PeerJ. 2019;7:e7957

Authors: Wang L, Yuan Y, Wang J, Shen Y, Zhi Y, Li J, Wang M, Zhang K

Abstract
Aims: We sought to explore the role of the SLC6A3 rs393795 allelic variant in cerebral spontaneous activity and clinical features in Parkinson's disease (PD) via imaging genetic approach.
Methods: Our study recruited 50 PD and 45 healthy control (HC) participants to provide clinical, genetic, and resting state functional magnetic resonance imaging (rs-fMRI) data. All subjects were separated into 16 PD-AA, 34 PD-CA/CC, 14 HC-AA, and 31 HC-CA/CC four subgroups according to SLC6A3 rs393795 genotyping. Afterwards, main effects and interactions of groups (PD versus HC) and genotypes (AA versus CA/CC) on cerebral function reflected by regional homogeneity (ReHo) were explored using two-way analysis of covariance (ANCOVA) after controlling age and gender. Finally, Spearman' s correlations were employed to investigate the relationships between significantly interactive brain regions and clinical manifestations in PD subgroups.
Results: Compared with HC subjects, PD patients exhibited increased ReHo signals in left middle temporal gyrus and decreased ReHo signals in left pallidum. Compared with CA/CC carriers, AA genotype individuals showed abnormal increased ReHo signals in right inferior frontal gyrus (IFG) and supplementary motor area (SMA). Moreover, significant interactions (affected by both disease factor and allelic variation) were detected in right inferior temporal gyrus (ITG). Furthermore, aberrant increased ReHo signals in right ITG were observed in PD-AA in comparison with PD-CA/CC. Notably, ReHo values in right ITG were negatively associated with Tinetti Mobility Test (TMT) gait subscale scores and positively related to Freezing of Gait Questionnaire (FOG-Q) scores in PD-AA subgroup.
Conclusions: Our findings suggested that SLC6A3 rs393795 allelic variation might have a trend to aggravate the severity of gait disorders in PD patients by altering right SMA and IFG function, and ultimately result in compensatory activation of right ITG. It could provide us with a new perspective for exploring deeply genetic mechanisms of gait disturbances in PD.

PMID: 31720106 [PubMed]

Dissociable neural substrates of opioid and cocaine use identified via connectome-based modelling.

Thu, 11/14/2019 - 16:20

Dissociable neural substrates of opioid and cocaine use identified via connectome-based modelling.

Mol Psychiatry. 2019 Nov 12;:

Authors: Lichenstein SD, Scheinost D, Potenza MN, Carroll KM, Yip SW

Abstract
Opioid use disorder is a major public health crisis. While effective treatments are available, outcomes vary widely across individuals and relapse rates remain high. Understanding neural mechanisms of treatment response may facilitate the development of personalized and/or novel treatment approaches. Methadone-maintained, polysubstance-using individuals (n = 53) participated in fMRI scanning before and after substance-use treatment. Connectome-based predictive modeling (CPM)-a recently developed, whole-brain approach-was used to identify pretreatment connections associated with abstinence during the 3-month treatment. Follow-up analyses were conducted to determine the specificity of the identified opioid abstinence network across different brain states (cognitive vs. reward task vs. resting-state) and different substance use outcomes (opioid vs. cocaine abstinence). Posttreatment fMRI data were used to assess network changes over time and within-subject replication. To determine further clinical relevance, opioid abstinence network strength was compared with healthy subjects (n = 38). CPM identified an opioid abstinence network (p = 0.018), characterized by stronger within-network motor/sensory connectivity, and reduced connectivity between the motor/sensory network and medial frontal, default mode, and frontoparietal networks. This opioid abstinence network was anatomically distinct from a previously identified cocaine abstinence network. Relationships between abstinence and opioid and cocaine abstinence networks replicated across multiple brain states but did not generalize across substances. Network connectivity measured at posttreatment related to abstinence at 6-month follow-up (p < 0.009). Healthy comparison subjects displayed intermediate network strengths relative to treatment responders and nonresponders. These data indicate dissociable anatomical substrates of opioid vs. cocaine abstinence. Results may inform the development of novel opioid-specific treatment approaches to combat the opioid epidemic.

PMID: 31719641 [PubMed - as supplied by publisher]

Functional maintenance in the multiple demand network characterizes superior fluid intelligence in aging.

Thu, 11/14/2019 - 16:20

Functional maintenance in the multiple demand network characterizes superior fluid intelligence in aging.

Neurobiol Aging. 2019 Sep 20;:

Authors: Zuo N, Salami A, Liu H, Yang Z, Jiang T

Abstract
The multiple demand network (MDN) is conceptualized as the core processing system for multitasking. Increasing evidence also provides strong support for the involvement of the MDN in fluid intelligence (gF), that is, the ability to solve new problems. However, the underlying neural mechanisms of declining intelligence in old age are poorly explored, particularly whether maintenance of the functional architecture of the MDN can characterize superior intelligence in successful aging. Here, we used eigenvector centrality (EC) to explore the resting-state functional architecture of the MDN in terms of its communication across the entire brain. We found gF to be negatively associated with age and that the MDN EC competitively mediated age-related decline in gF over the aging lifespan, suggesting that excessive cross-talk from the MDN is deleterious for intelligence. Critically, older individuals with comparable MDN EC as younger individuals exhibited superior gF compared with their age-matched counterparts. Taken together, these data provide support for the maintenance of youth-like functional architecture of the MDN and its implication for superior intelligence in successful aging.

PMID: 31718925 [PubMed - as supplied by publisher]

Evidence for Depressogenic Spontaneous Thoughts and Altered Resting-State Connectivity in Adolescents With a Maltreatment History.

Thu, 11/14/2019 - 16:20
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Evidence for Depressogenic Spontaneous Thoughts and Altered Resting-State Connectivity in Adolescents With a Maltreatment History.

J Am Acad Child Adolesc Psychiatry. 2018 09;57(9):687-695.e4

Authors: Hoffmann F, Viding E, Puetz VB, Gerin MI, Sethi A, Rankin G, McCrory EJ

Abstract
OBJECTIVE: Childhood maltreatment has been associated with major depressive disorder (MDD). Atypical self-generated thoughts (SGT), lacking in positive and privileging negative content-a feature of ruminative thinking-might represent one vulnerability factor for developing depression. Rumination in MDD has been linked to alterations in resting-state functional connectivity (RSFC) of the subgenual anterior cingulate cortex (sgACC) to the default mode network and the fronto-parietal network (FPN). This study aimed to investigate online SGT content and its variability, as well as sgACC RSFC, as potential risk markers for depression in adolescents who experienced maltreatment.
METHOD: Adolescents 12 to 16 years old (29 with maltreatment history [MT] and 39 with no maltreatment history [NMT]) performed an established mind-wandering task. Participants made nondemanding number discriminations during which intermittent questions probed their SGTs that were classified as off-task, positive, negative, self-related, other-related, past-oriented, or future-oriented. Resting-state data were acquired separately for 22 of 29 MT and 27 39 NMT adolescents, and seed-based functional connectivity analyses of the sgACC were performed.
RESULTS: MT, relative to the NMT adolescents, generated significantly fewer positively valenced thoughts, and exhibited more extreme ratings for positively valenced thoughts. MT adolescents also showed significantly reduced RSFC between the sgACC and the FPN. Group differences in depressive symptoms between the MT and NMT adolescents were partly accounted by differences in sgACC-FPN RSFC.
CONCLUSION: Adolescents who experienced maltreatment show a reduction in positively valenced spontaneous thoughts and reduced sgACC-FPN RSFC at the neural level. These may contribute to a ruminative thinking style, representing risk factors for developing depression later in life.

PMID: 30196872 [PubMed - indexed for MEDLINE]

X-Chromosome Effects on Attention Networks: Insights from Imaging Resting-State Networks in Turner Syndrome.

Thu, 11/14/2019 - 16:20
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X-Chromosome Effects on Attention Networks: Insights from Imaging Resting-State Networks in Turner Syndrome.

Cereb Cortex. 2018 09 01;28(9):3176-3183

Authors: Green T, Saggar M, Ishak A, Hong DS, Reiss AL

Abstract
Attention deficit hyperactivity disorder (ADHD) is strongly affected by sex, but sex chromosomes' effect on brain attention networks and cognition are difficult to examine in humans. This is due to significant etiologic heterogeneity among diagnosed individuals. In contrast, individuals with Turner syndrome (TS), who have substantially increased risk for ADHD symptoms, share a common genetic risk factor related to the absence of the X-chromosome, thus serving as a more homogeneous genetic model. Resting-state functional MRI was employed to examine differences in attention networks between girls with TS (n = 40) and age- sex- and Tanner-matched controls (n = 33). We compared groups on resting-state functional connectivity measures from data-driven independent components analysis (ICA) and hypothesis-based seed analysis. Using ICA, reduced connectivity was observed in both frontoparietal and dorsal attention networks. Similarly, using seeds in the bilateral intraparietal sulcus (IPS), reduced connectivity was observed between IPS and frontal and cerebellar regions. Finally, we observed a brain-behavior correlation between IPS-cerebellar connectivity and cognitive attention measures. These findings indicate that X-monosomy contributes affects to attention networks and cognitive dysfunction that might increase risk for ADHD. Our findings not only have clinical relevance for girls with TS, but might also serve as a biological marker in future research examining the effects of the intervention that targets attention skills.

PMID: 28981595 [PubMed - indexed for MEDLINE]

A New Modular Brain Organization of the BOLD Signal during Natural Vision.

Thu, 11/14/2019 - 16:20
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A New Modular Brain Organization of the BOLD Signal during Natural Vision.

Cereb Cortex. 2018 09 01;28(9):3065-3081

Authors: Kim D, Kay K, Shulman GL, Corbetta M

Abstract
The resting blood oxygen level-dependent (BOLD) signal is synchronized in large-scale brain networks (resting-state networks, RSNs) defined by interregional temporal correlations (functional connectivity, FC). RSNs are thought to place strong constraints on task-evoked processing since they largely match the networks observed during task performance. However, this result may simply reflect the presence of spontaneous activity during both rest and task. Here, we examined the BOLD network structure of natural vision, as simulated by viewing of movies, using procedures that minimized the contribution of spontaneous activity. We found that the correlation between resting and movie-evoked FC (ρ = 0.60) was lower than previously reported. Hierarchical clustering and graph-theory analyses indicated a well-defined network structure during natural vision that differed from the resting structure, and emphasized functional groupings adaptive for natural vision. The visual network merged with a network for navigation, scene analysis, and scene memory. Conversely, the dorsal attention network was split and reintegrated into 2 groupings likely related to vision/scene and sound/action processing. Finally, higher order groupings from the clustering analysis combined internally directed and externally directed RSNs violating the large-scale distinction that governs resting-state organization. We conclude that the BOLD FC evoked by natural vision is only partly constrained by the resting network structure.

PMID: 28981593 [PubMed - indexed for MEDLINE]

Dynamic synergetic configurations of resting-state networks in ADHD.

Wed, 11/13/2019 - 21:40

Dynamic synergetic configurations of resting-state networks in ADHD.

Neuroimage. 2019 Nov 09;:116347

Authors: Kaboodvand N, Iravani B, Fransson P

Abstract
Attention deficit hyperactivity disorder (ADHD) is characterized by high distractibility and impaired executive functions. Notably, there is mounting evidence suggesting that ADHD could be regarded as a default mode network (DMN) disorder. In particular, failure in regulating the dynamics of activity and interactions of the DMN and cognitive control networks have been hypothesized as the main source of task interference causing attentional problems. On the other hand, previous studies indicated pronounced fluctuations in the strength of functional connections over time, particularly for the inter-network connections between the DMN and fronto-parietal control networks. Hence, characterization of connectivity disturbances in ADHD requires a thorough assessment of time-varying functional connectivity (FC). In this study, we proposed a dynamical systems perspective to assess how the DMN over time recruits different configurations of network segregation and integration. Specifically, we were interested in configurations for which both intra- and inter-network connections are retained, as opposed to commonly used methods which assess network segregation as a single measure. From resting-state fMRI data, we extracted three different stable configurations of FC patterns for the DMN, namely synergies. We provided evidence supporting our hypothesis that ADHD differs compared to controls, both in terms of recruitment rate and topology of specific synergies between resting-state networks. In addition, we found a relationship between synergetic cooperation patterns of the DMN with cognitive control networks and a behavioral measure which is sensitive to ADHD-related symptoms, namely the Stroop color-word task.

PMID: 31715256 [PubMed - as supplied by publisher]

The spontaneous activity and functional network of the occipital cortex is correlated with state anxiety in healthy adults.

Wed, 11/13/2019 - 21:40
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The spontaneous activity and functional network of the occipital cortex is correlated with state anxiety in healthy adults.

Neurosci Lett. 2019 Nov 08;:134596

Authors: Li K, Meng Z, Zhang H, Li X, Zou F, Wang Y, Wu X, Zhang H

Abstract
The occipital lobe has been implicated in anxiety disorder, however, its contributions to anxiety in healthy adults remain less clear. We conducted a resting-state functional magnetic resonance imaging study to explore the relationship between the amplitude of low-frequency fluctuation (ALFF), functional connectivity (FC), and state anxiety level in the healthy population. First, the results showed that the ALFF of the left inferior occipital gyrus (IOG) was negatively correlated with state anxiety. Furthermore, state anxiety was positively correlated with the FC between the left IOG and the right medial superior frontal gyrus and right cerebellum 8 area and negatively correlated with the FC between the left IOG and the left superior parietal gyrus. These results indicate that the occipital lobe of healthy individuals is involved in processing of anxiety in part through a frontal-parietal network.

PMID: 31711976 [PubMed - as supplied by publisher]

Neuroimaging correlates of cognitive changes after bariatric surgery.

Wed, 11/13/2019 - 21:40
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Neuroimaging correlates of cognitive changes after bariatric surgery.

Surg Obes Relat Dis. 2019 Oct 11;:

Authors: Saindane AM, Drane DL, Singh A, Wu J, Qiu D

Abstract
BACKGROUND: Obesity has been associated with cognitive deficits and increased risk for developing dementia. Bariatric surgery may result in improved cognitive function; however, the underlying structural and functional brain correlates are unclear.
OBJECTIVES: This longitudinal study explores the hypothesis that specific brain regions and networks underlie cognitive changes after bariatric surgery.
SETTING: University Hospital, United States.
METHODS: Seventeen patients were recruited for this prospective cohort study, including 9 patients undergoing bariatric surgery, and 8 age-, sex-, and education level-matched healthy, nonobese control patients. Bariatric patients underwent longitudinal neuropsychologic tests and magnetic resonance imaging (MRI) scans both before and 6 months after surgery. One patient was lost to follow-up. The same neuropsychologic tests and MRI scans were performed for control patients. Differences in MRI and neuropsychologic testing between bariatric patients and control patients, and longitudinal changes within bariatric patients were assessed.
RESULTS: At baseline, bariatric patients demonstrated deficits in cognitive function relative to control patients, including pattern comparison (P = .009) and picture sequence memory (P = .004), which improved after significant weight loss. Baseline cognitive deficits in bariatric patients were accompanied by significantly lower left executive control network connectivity on resting-state functional MRI relative to control patients (P = .028), but differences resolved or diminished after bariatric surgery. Longitudinal improvements in pattern comparison performance correlated significantly with increases in left executive control network connectivity (r = .819; P = .013). No significant group or longitudinal differences were found in brain perfusion or brain white matter lesions.
CONCLUSIONS: Individuals with obesity undergoing bariatric surgery exhibit deficits in cognitive function and specific alterations of brain networks; however, cognitive performance can improve, and executive control network connectivity can increase after weight loss from bariatric surgery.

PMID: 31711948 [PubMed - as supplied by publisher]

Altered functional connectivity of the red nucleus and substantia nigra in migraine without aura.

Wed, 11/13/2019 - 21:40
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Altered functional connectivity of the red nucleus and substantia nigra in migraine without aura.

J Headache Pain. 2019 Nov 11;20(1):104

Authors: Huang X, Zhang D, Chen Y, Wang P, Mao C, Miao Z, Liu C, Xu C, Wu X, Yin X

Abstract
BACKGROUND: Functional connectivity (FC) has been used to investigate the pathophysiology of migraine. Accumulating evidence is pointing toward malfunctioning of brainstem structures, i.e., the red nucleus (RN) and substantia nigra (SN), as an important factor in migraine without aura (MwoA). We aimed to identify atypical FC between the RN and SN and other brain areas in patients with MwoA and to explore the association between RN and SN connectivity changes and performance on neuropsychological tests in these patients.
METHODS: Resting-state functional magnetic resonance imaging (fMRI) data were obtained from 30 patients with MwoA and 22 age-, sex-, and years of education-matched healthy controls (HC). The FC of the brainstem structures was analyzed using a standard seed-based whole-brain correlation method. The results of the brainstem structure FC were assessed for correlations with other clinical features.
RESULTS: Patients with MwoA exhibited reduced left RN-based FC with the left middle frontal gyrus, reduced right RN-based FC with the ipsilateral superior parietal lobe, and increased FC with the ipsilateral cerebellum. Additionally, patients with MwoA demonstrated significantly decreased right SN-based FC with the right postcentral gyrus, left parietal lobule, and left superior frontal gyrus. Hypo-connectivity between the right SN and right postcentral gyrus was negatively correlated with disease duration (r = - 0.506, P = 0.004). Additionally, increased connectivity of the right RN to the ipsilateral cerebellar lobes was positively correlated with the Headache Impact Test-6 scores (r = 0.437, P = 0.016).
CONCLUSIONS: The present study suggested that patients with MwoA have disruption in their RN and SN resting-state networks, which are associated with specific clinical characteristics. The changes focus on the regions associated with cognitive evaluation, multisensory integration, and modulation of perception and pain, which may be associated with migraine production, feedback, and development. Taken together, these results may improve our understanding of the neuropathological mechanism of migraine.

PMID: 31711434 [PubMed - in process]

Reduced resting-state brain functional network connectivity and poor regional homogeneity in patients with CADASIL.

Wed, 11/13/2019 - 21:40
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Reduced resting-state brain functional network connectivity and poor regional homogeneity in patients with CADASIL.

J Headache Pain. 2019 Nov 11;20(1):103

Authors: Su J, Ban S, Wang M, Hua F, Wang L, Cheng X, Tang Y, Zhou H, Zhai Y, Du X, Liu J

Abstract
BACKGROUND: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) manifests principally as a suite of cognitive impairments, particularly in the executive domain. Executive functioning requires the dynamic coordination of neural activity over large-scale networks. It remains unclear whether changes in resting-state brain functional network connectivity and regional homogeneities (ReHos) underly the mechanisms of executive dysfunction evident in CADASIL patients.
METHODS: In this study, 22 CADASIL patients and 44 matched healthy controls underwent resting-state functional magnetic resonance imaging (fMRI). Independent component analysis (ICA) was used to measure functional brain network connectivity, and ReHos were calculated to evaluate local brain activities. We used seed-based functional connectivity (FC) analyses to determine whether dysfunctional areas (as defined by ReHos) exhibited abnormal FC with other brain areas. Relationships among the mean intra-network connectivity z-scores of dysfunctional areas within functional networks, and cognitive scores were evaluated using Pearson correlation analyses.
RESULTS: Compared to the controls, CADASIL patients exhibited decreased intra-network connectivity within the bilateral lingual gyrus (LG) and the right cuneus (CU) (thus within the visual network [VIN)], and within the right precuneus (Pcu), inferior frontal gyrus (IFG), and precentral gyrus (thus within the frontal network [FRN]). Compared to the controls, patients also exhibited significantly lower ReHos in the right precuneus and cuneus (Pcu/CU), visual association cortex, calcarine gyri, posterior cingulate, limbic lobe, and weaker FC between the right Pcu/CU and the bilateral parahippocampal gyrus (PHG), and between the right Pcu/CU and the right postcentral gyrus. Notably, the mean connectivity z-scores of the bilateral LG and the right CU within the VIN were positively associated with compromised attention, calculation and delayed recall as revealed by tests of the various cognitive domains explored by the Mini-Mental State Examination.
CONCLUSIONS: The decreases in intra-network connectivity within the VIN and FRN and reduced local brain activity in the posterior parietal area suggest that patients with CADASIL may exhibit dysfunctional visuomotor behaviors (a hallmark of executive function), and that all visual information processing, visuomotor planning, and movement execution may be affected.

PMID: 31711415 [PubMed - in process]

Functional Parcellation of the Cerebral Cortex Across the Human Adult Lifespan.

Wed, 11/13/2019 - 21:40
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Functional Parcellation of the Cerebral Cortex Across the Human Adult Lifespan.

Cereb Cortex. 2018 12 01;28(12):4403-4423

Authors: Han L, Savalia NK, Chan MY, Agres PF, Nair AS, Wig GS

Abstract
Adult aging is associated with differences in structure, function, and connectivity of brain areas. Age-based brain comparisons have typically rested on the assumption that brain areas exhibit a similar spatial organization across age; we evaluate this hypothesis directly. Area parcellation methods that identify locations where resting-state functional correlations (RSFC) exhibit abrupt transitions (boundary-mapping) are used to define cortical areas in cohorts of individuals sampled across a large range of the human adult lifespan (20-93 years). Most of the strongest areal boundaries are spatially consistent across age. Differences in parcellation boundaries are largely explained by differences in cortical thickness and anatomical alignment in older relative to younger adults. Despite the parcellation similarities, age-specific parcellations exhibit better internal validity relative to a young-adult parcellation applied to older adults' data, and age-specific parcels are better able to capture variability in task-evoked functional activity. Incorporating age-specific parcels as nodes in RSFC network analysis reveals that the spatial topography of the brain's large-scale system organization is comparable throughout aging, but confirms that the segregation of systems declines with increasing age. These observations demonstrate that many features of areal organization are consistent across adulthood, and reveal sources of age-related brain variation that contribute to the differences.

PMID: 30307480 [PubMed - indexed for MEDLINE]

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