New resting-state fMRI related studies at PubMed

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Assessment of brain functional connectome alternations and correlation with depression and anxiety in major depressive disorders.

Wed, 11/29/2017 - 11:20
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Assessment of brain functional connectome alternations and correlation with depression and anxiety in major depressive disorders.

PeerJ. 2017;5:e3147

Authors: Chen VC, Shen CY, Liang SH, Li ZH, Hsieh MH, Tyan YS, Lu ML, Lee Y, McIntyre RS, Weng JC

Abstract
Major depressive disorder (MDD) is highly prevalent, recurrent, and associated with functional impairment, morbidity, and mortality. Herein, we aimed to identify disruptions in functional connectomics among subjects with MDD by using resting-state functional magnetic resonance imaging (rs-fMRI). Sixteen subjects with MDD and thirty health controls completed resting-state fMRI scans and clinical assessments (e.g., Hamilton Depression Rating Scale (HAMD) and Hospital Anxiety and Depression Scale (HADS)). We found higher amplitude of low frequency fluctuations (ALFF) bilaterally in the hippocampus and amygdala among MDD subjects when compared to healthy controls. Using graph theoretical analysis, we found decreased clustering coefficient, local efficiency, and transitivity in the MDD patients. Our findings suggest a potential biomarker for differentiating individuals with MDD from individuals without MDD.

PMID: 29181274 [PubMed]

High-fidelity measures of whole-brain functional connectivity and white matter integrity mediate relationships between TBI and PTSD symptoms.

Wed, 11/29/2017 - 11:20
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High-fidelity measures of whole-brain functional connectivity and white matter integrity mediate relationships between TBI and PTSD symptoms.

J Neurotrauma. 2017 Nov 27;:

Authors: Gordon EM, Scheibel R, Zambrano-Vazquez L, Jia-Richards M, May GJ, Meyer EC, Nelson SM

Abstract
Traumatic brain injury (TBI) disrupts brain communication and increases risk for posttraumatic stress disorder (PTSD). However, mechanisms by which TBI-related disruption of brain communication confers PTSD risk have not been successfully elucidated in humans. This may be in part because fMRI, the most common technique for measuring brain function, is unreliable for characterizing individual patients. However, this unreliability can be overcome with sufficient within-individual data. Here, we examined whether relationships could be observed between TBI, structural and functional brain connectivity, and PTSD severity by collecting ~3.5 hours of resting-state fMRI and DTI data in each of 26 US military veterans. We observed that a TBI history was associated with decreased whole-brain resting-state functional connectivity (RSFC), while the number of lifetime TBIs was associated with reduced whole-brain fractional anisotropy (FA). Both RSFC and FA explained independent variance in PTSD severity, with RSFC mediating the TBI-PTSD relationship. Finally, we showed that large amounts of per-individual data produced highly reliable RSFC measures, and that relationships between TBI, RSFC/FA, and PTSD could not be observed with typical data quantities. These results demonstrate links between TBI, brain connectivity, and PTSD severity, and illustrate the need for precise characterization of individual patients using high-data fMRI scanning.

PMID: 29179667 [PubMed - as supplied by publisher]

Spinal Cord Injury Disrupts Resting-State Networks in the Human Brain.

Wed, 11/29/2017 - 11:20
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Spinal Cord Injury Disrupts Resting-State Networks in the Human Brain.

J Neurotrauma. 2017 Nov 27;:

Authors: Hawasli A, Rutlin J, Roland JL, Murphy R, Song SK, Leuthardt E, Shimony J, Ray WZ

Abstract
Despite 253,000 spinal cord injury (SCI) patients in America, little is known about how SCI affects brain networks. Spinal magnetic resonance imaging (MRI) provides only structural information with no insight into functional connectivity. Resting-state functional MRI (RS-fMRI) quantifies network connectivity through the identification of resting-state networks (RSNs) and allows detection of functionally-relevant changes during disease. Given the robust network of spinal cord afferents to the brain, we hypothesized SCI produces meaningful changes in brain RSNs. RS-fMRIs and functional assessments were performed on 10 SCI subjects. Blood oxygen-dependent RS-fMRI sequences were acquired. Seed-based correlation mapping was performed using five RSNs: default-mode (DMN), dorsal-attention (DAN) , salience (SAL), control (CON) and somatomotor (SMN). RSNs were compared to normal control subjects using false-discovery rate-corrected two-way t-tests. SCI reduced brain network connectivity within the SAL, SMN and DMN and disrupted anti-correlated connectivity between CON and SMN. When divided into separate cohorts, complete but not incomplete SCI disrupted connectivity within SAL, DAN, SMN and DMN and between CON and SMN. Finally, connectivity changed over time after SCI: primary motor cortex decreased connectivity with primary somatosensory cortex, visual cortex decreased connectivity with primary motor cortex and visual cortex decreased connectivity with sensory parietal cortex. These unique findings demonstrate the functional network plasticity that occurs in the brain as a result of injury to the spinal cord. Connectivity changes after SCI may serve as biomarkers to predict functional recovery following a SCI and guide future therapy.

PMID: 29179629 [PubMed - as supplied by publisher]

Multiparametric MRI changes persist beyond recovery in concussed adolescent hockey players.

Wed, 11/29/2017 - 11:20
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Multiparametric MRI changes persist beyond recovery in concussed adolescent hockey players.

Neurology. 2017 Nov 21;89(21):2157-2166

Authors: Manning KY, Schranz A, Bartha R, Dekaban GA, Barreira C, Brown A, Fischer L, Asem K, Doherty TJ, Fraser DD, Holmes J, Menon RS

Abstract
OBJECTIVE: To determine whether multiparametric MRI data can provide insight into the acute and long-lasting neuronal sequelae after a concussion in adolescent athletes.
METHODS: Players were recruited from Bantam hockey leagues in which body checking is first introduced (male, age 11-14 years). Clinical measures, diffusion metrics, resting-state network and region-to-region functional connectivity patterns, and magnetic resonance spectroscopy absolute metabolite concentrations were analyzed from an independent, age-matched control group of hockey players (n = 26) and longitudinally in concussed athletes within 24 to 72 hours (n = 17) and 3 months (n = 14) after a diagnosed concussion.
RESULTS: There were diffusion abnormalities within multiple white matter tracts, functional hyperconnectivity, and decreases in choline 3 months after concussion. Tract-specific spatial statistics revealed a large region along the superior longitudinal fasciculus with the largest decreases in diffusivity measures, which significantly correlated with clinical deficits. This region also spatially intersected with probabilistic tracts connecting cortical regions where we found acute functional connectivity changes. Hyperconnectivity patterns at 3 months after concussion were present only in players with relatively less severe clinical outcomes, higher choline concentrations, and diffusivity indicative of relatively less axonal disruption.
CONCLUSIONS: Changes persisted well after players' clinical scores had returned to normal and they had been cleared to return to play. Ongoing white matter maturation may make adolescent athletes particularly vulnerable to brain injury, and they may require extended recovery periods. The consequences of early brain injury for ongoing brain development and risk of more serious conditions such as second impact syndrome or neural degenerative processes need to be elucidated.

PMID: 29070666 [PubMed - indexed for MEDLINE]

Loss of Functional Connectivity in Patients with Parkinson Disease and Visual Hallucinations.

Wed, 11/29/2017 - 11:20
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Loss of Functional Connectivity in Patients with Parkinson Disease and Visual Hallucinations.

Radiology. 2017 Dec;285(3):896-903

Authors: Hepp DH, Foncke EMJ, Olde Dubbelink KTE, van de Berg WDJ, Berendse HW, Schoonheim MM

Abstract
Purpose To gain more insight into the pathophysiological mechanisms of visual hallucinations (VHs) in patients with Parkinson disease (PD) by analyzing whole-brain resting-state functional connectivity in PD patients with VH (hereafter, referred to as PD + VH patients) and without VH (hereafter, referred to as PD - VH patients) and control participants. Materials and Methods For this retrospective study, 15 PD + VH patients, 40 PD - VH patients, and 15 control participants from a prospective cohort study were included, which was approved by the local ethics board and written informed consent was obtained from all participants. Functional connectivity was calculated between 47 regions of interests, of which whole-brain and region-specific means were compared by using a general linear model with false discovery rate control for multiple comparisons. Results Whole-brain mean functional connectivity was significantly lower in PD patients compared with control participants, with regional decreases involving paracentral and occipital regions in both PD + VH and PD - VH patients (mean whole-brain functional connectivity in PD + VH vs PD - VH, 0.12 ± 0.01 [standard deviation] vs 0.14 ± 0.03, respectively; control participants, 0.15 ± 0.04; P < .05, corrected). In PD + VH patients, nine additional frontal, temporal, occipital, and striatal regions showed decreased functional connectivity compared with control participants (mean of these nine regions in PD + VH, PD - VH, and control participants: 0.12 ± 0.02, 0.14 ± 0.03, and 0.16 ± 0.04, respectively; P < .05, corrected). Resting-state functional connectivity was unrelated to motor performance (r = 0.182; P = .184) and related to cognitive deficits such as attention and perception (ρ, -0.555 and -0.558, respectively; P < .05). Conclusion The findings show a PD-related effect on resting-state functional connectivity of posterior and paracentral brain regions, whereas the presence of VH is associated with a more global loss of connectivity, related to attention and perception. These findings suggest that the pathophysiological mechanisms of VH in PD may include a global loss of network efficiency, which could drive disturbed attentional and visual processing. © RSNA, 2017 Online supplemental material is available for this article.

PMID: 28952907 [PubMed - indexed for MEDLINE]

Alzheimer's disease disrupts alpha and beta-band resting-state oscillatory network connectivity.

Wed, 11/29/2017 - 11:20
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Alzheimer's disease disrupts alpha and beta-band resting-state oscillatory network connectivity.

Clin Neurophysiol. 2017 Nov;128(11):2347-2357

Authors: Koelewijn L, Bompas A, Tales A, Brookes MJ, Muthukumaraswamy SD, Bayer A, Singh KD

Abstract
OBJECTIVE: Neuroimaging studies in Alzheimer's disease (AD) yield conflicting results due to selective investigation. We conducted a comprehensive magnetoencephalography study of connectivity changes in AD and healthy ageing in the resting-state.
METHODS: We performed a whole-brain, source-space assessment of oscillatory neural signalling in multiple frequencies comparing AD patients, elderly and young controls. We compared eyes-open and closed group oscillatory envelope activity in networks obtained through temporal independent component analysis, and calculated whole-brain node-based amplitude and phase connectivity.
RESULTS: In bilateral parietotemporal areas, oscillatory envelope amplitude increased with healthy ageing, whereas both local amplitude and node-to-global connectivity decreased with AD. AD-related decreases were spatially specific and restricted to the alpha and beta bands. A significant proportion of the variance in areas of peak group difference was explained by cognitive integrity, in addition to group. None of the groups differed in phase connectivity. Results were highly similar for eyes-open and closed resting-state.
CONCLUSIONS: These results support the disconnection syndrome hypothesis and suggest that AD shows distinct and unique patterns of disrupted neural functioning, rather than accelerated healthy ageing.
SIGNIFICANCE: Whole-brain assessments show that disrupted regional oscillatory envelope amplitude and connectivity in the alpha and beta bands play a key role in AD.

PMID: 28571910 [PubMed - indexed for MEDLINE]

Cerebral blood flow and its connectivity features of auditory verbal hallucinations in schizophrenia: A perfusion study.

Wed, 11/29/2017 - 11:20
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Cerebral blood flow and its connectivity features of auditory verbal hallucinations in schizophrenia: A perfusion study.

Psychiatry Res. 2017 Feb 28;260:53-61

Authors: Cui LB, Chen G, Xu ZL, Liu L, Wang HN, Guo L, Liu WM, Liu TT, Qi S, Liu K, Qin W, Sun JB, Xi YB, Yin H

Abstract
The goal of the study was to investigate cerebral blood flow (CBF) and its connectivity (an across-subject covariance measure) patterns of schizophrenia (SZ) patients with auditory verbal hallucinations (AVHs). A total of demographically matched 25 SZ patients with AVHs, 25 without AVHs, and 25 healthy controls (HCs) underwent resting state perfusion imaging using a pulsed arterial spin labeling sequence. CBF and its connectivity were analyzed and then CBF topological properties were calculated. AVHs patients exhibited decreased CBF in the bilateral superior and middle frontal gyri and postcentral gyri, and right supplementary motor area compared with SZ patients without AVHs. SZ patients without AVHs showed reduced CBF in the left middle frontal gyrus relative to HCs. Moreover, AVHs groups showed distinct connectivity pattern, an intermediate level between HCs and patients without AVHs in the global efficiency. Our study demonstrates aberrant CBF in the brain regions associated with inner speech monitoring and language processing in SZ patients with AVHs. The complex network measures showed by CBF-derived functional connectivity indicate dysconnectivity between different functional units within the network of AVHs in SZ. Our findings might shed light on the neural underpinnings behind AVHs in this devastating disease at the level of CBF and its connectivity.

PMID: 28024236 [PubMed - indexed for MEDLINE]

Functional and structural connectivity of the amygdala in obsessive-compulsive disorder.

Wed, 11/29/2017 - 11:20
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Functional and structural connectivity of the amygdala in obsessive-compulsive disorder.

Neuroimage Clin. 2017;13:246-255

Authors: Rus OG, Reess TJ, Wagner G, Zimmer C, Zaudig M, Koch K

Abstract
BACKGROUND: The amygdala is known to be involved in anxiety processing, but its role in the psychopathology of obsessive-compulsive disorder (OCD) is still unclear.
AIMS: In this MRI study we investigated potential alterations in structural and functional connectivity of the amygdala in 42 adult patients with OCD and 37 healthy subjects.
METHOD: Psychophysiological interaction analysis was used to explore amygdala functional connectivity during a negative affective task. Probabilistic tractography was then employed to study structural connectivity and integrity of underlying white matter fiber tracts.
RESULTS: Compared to controls, OCD patients showed a significantly increased functional connectivity of the left amygdala with mostly parieto-occipital regions during task. No structural connectivity differences could be found between the groups. In addition, only patients showed a significant association between functional and structural connectivity of these regions. Moreover, symptom severity was negatively associated with structural integrity of the underlying white matter tracts.
CONCLUSIONS: Present results emphasize the relevance of the amygdala for OCD and may reflect that neuronal alterations in structural connectivity could be associated with functional connectivity alterations in broader networks.

PMID: 28018851 [PubMed - indexed for MEDLINE]

Executive attention networks show altered relationship with default mode network in PD.

Wed, 11/29/2017 - 11:20
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Executive attention networks show altered relationship with default mode network in PD.

Neuroimage Clin. 2017;13:1-8

Authors: Boord P, Madhyastha TM, Askren MK, Grabowski TJ

Abstract
Attention dysfunction is a common but often undiagnosed cognitive impairment in Parkinson's disease that significantly reduces quality of life. We sought to increase understanding of the mechanisms underlying attention dysfunction using functional neuroimaging. Functional MRI was acquired at two repeated sessions in the resting state and during the Attention Network Test, for 25 non-demented subjects with Parkinson's disease and 21 healthy controls. Behavioral and MRI contrasts were calculated for alerting, orienting, and executive control components of attention. Brain regions showing group differences in attention processing were used as seeds in a functional connectivity analysis of a separate resting state run. Parkinson's disease subjects showed more activation during increased executive challenge in four regions of the dorsal attention and frontoparietal networks, namely right frontal eye field, left and right intraparietal sulcus, and precuneus. In three regions we saw reduced resting state connectivity to the default mode network. Further, whereas higher task activation in the right intraparietal sulcus correlated with reduced resting state connectivity between right intraparietal sulcus and the precuneus in healthy controls, this relationship was absent in Parkinson's disease subjects. Our results suggest that a weakened interaction between the default mode and task positive networks might alter the way in which the executive response is processed in PD.

PMID: 27896064 [PubMed - indexed for MEDLINE]

The Effects of Acetazolamide on the Evaluation of Cerebral Hemodynamics and Functional Connectivity Using Blood Oxygen Level-Dependent MR Imaging in Patients with Chronic Steno-Occlusive Disease of the Anterior Circulation.

Wed, 11/29/2017 - 11:20
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The Effects of Acetazolamide on the Evaluation of Cerebral Hemodynamics and Functional Connectivity Using Blood Oxygen Level-Dependent MR Imaging in Patients with Chronic Steno-Occlusive Disease of the Anterior Circulation.

AJNR Am J Neuroradiol. 2017 Jan;38(1):139-145

Authors: Wu J, Dehkharghani S, Nahab F, Allen J, Qiu D

Abstract
BACKGROUND AND PURPOSE: Measuring cerebrovascular reactivity with the use of vasodilatory stimuli, such as acetazolamide, is useful for chronic cerebrovascular steno-occlusive disease. The purpose of this study was to evaluate the effects of acetazolamide on the assessment of hemodynamic impairment and functional connectivity by using noninvasive resting-state blood oxygen level-dependent MR imaging.
MATERIALS AND METHODS: A 20-minute resting-state blood oxygen level-dependent MR imaging scan was acquired with infusion of acetazolamide starting at 5 minutes after scan initiation. A recently developed temporal-shift analysis technique was applied on blood oxygen level-dependent MR imaging data before and after acetazolamide infusion to identify regions with hemodynamic impairment, and the results were compared by using contrast agent-based DSC perfusion imaging as the reference standard. Functional connectivity was compared with and without correction on the signal by using information from temporal-shift analysis, before and after acetazolamide infusion.
RESULTS: Visually, temporal-shift analysis of blood oxygen level-dependent MR imaging data identified regions with compromised hemodynamics as defined by DSC, though performance deteriorated in patients with bilateral disease. The Dice similarity coefficient between temporal-shift and DSC maps was higher before (0.487 ± 0.150 by using the superior sagittal sinus signal as a reference for temporal-shift analysis) compared with after acetazolamide administration (0.384 ± 0.107) (P = .006, repeated-measures ANOVA). Functional connectivity analysis with temporal-shift correction identified brain network nodes that were otherwise missed. The accuracy of functional connectivity assessment decreased after acetazolamide administration (P = .015 for default mode network, repeated-measures ANOVA).
CONCLUSIONS: Temporal-shift analysis of blood oxygen level-dependent MR imaging can identify brain regions with hemodynamic compromise in relation to DSC among patients with chronic cerebrovascular disease. The use of acetazolamide reduces the accuracy of temporal-shift analysis and network connectivity evaluation.

PMID: 27758776 [PubMed - indexed for MEDLINE]

Resting-state functional connectivity of the amygdala and longitudinal changes in depression severity in adolescent depression.

Wed, 11/29/2017 - 11:20
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Resting-state functional connectivity of the amygdala and longitudinal changes in depression severity in adolescent depression.

J Affect Disord. 2017 Jan 01;207:86-94

Authors: Connolly CG, Ho TC, Blom EH, LeWinn KZ, Sacchet MD, Tymofiyeva O, Simmons AN, Yang TT

Abstract
BACKGROUND: The incidence of major depressive disorder (MDD) rises during adolescence, yet the neural mechanisms of MDD during this key developmental period are unclear. Altered amygdala resting-state functional connectivity (RSFC) has been associated with both adolescent and adult MDD, as well as symptom improvement in response to treatment in adults. However, no study to date has examined whether amygdala RSFC is associated with changes in depressive symptom severity in adolescents.
METHOD: We examined group differences in amygdala RSFC between medication-naïve depressed adolescents (N=48) and well-matched healthy controls (N=53) cross-sectionally. We then longitudinally examined whether baseline amygdala RSFC was associated with change in depression symptoms three months later in a subset of the MDD group (N=24).
RESULTS: Compared to healthy controls, depressed adolescents showed reduced amygdala-based RSFC with the dorsolateral prefrontal cortex (DLPFC)and the ventromedial prefrontal cortex (VMPFC). Within the depressed group, more positive baseline RSFC between the amygdala and insulae was associated with greater reduction in depression symptoms three months later.
LIMITATIONS: Only a subset of depressed participants was assessed at follow-up and treatment type and delivery were not standardized.
CONCLUSIONS: Adolescent depression may be characterized by dysfunction of frontolimbic circuits (amygdala-DLPFC, amygdala-VMPFC) underpinning emotional regulation, whereas those circuits (amygdala-insula) subserving affective integration may index changes in depression symptom severity and may therefore potentially serve as a candidate biomarker for treatment response. Furthermore, these results suggest that the biomarkers of MDD presence are distinct from those associated with change in depression symptoms over time.

PMID: 27716542 [PubMed - indexed for MEDLINE]

Default mode network coherence in treatment-resistant major depressive disorder during electroconvulsive therapy.

Wed, 11/29/2017 - 11:20
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Default mode network coherence in treatment-resistant major depressive disorder during electroconvulsive therapy.

J Affect Disord. 2016 Nov 15;205:130-137

Authors: Mulders PC, van Eijndhoven PF, Pluijmen J, Schene AH, Tendolkar I, Beckmann CF

Abstract
BACKGROUND: Functional connectivity in the "default mode network" (DMN) is changed in depression, and evidence suggests depression also affects the DMN's spatial topography and might cause a dissociation between its anterior and posterior regions. As antidepressive treatment affects anterior and posterior regions of the network differently, how depression and treatment change DMN-organization is crucial for understanding their mechanisms. We present a novel way of assessing the coherence of a network's regions to the network as a whole, and apply this to investigate treatment-resistant depression and the effects of electroconvulsive therapy (ECT).
METHODS: Resting-state functional MRI was collected from 16 patients with treatment-resistant depression before and after ECT and 16 healthy controls matched for age and sex. For each subject, the mean time series of the DMN was used as a regressor for each voxel within the DMN, creating a map of "network coherence" (NC). The obtained maps were compared across groups using permutation testing.
RESULTS: NC was significantly decreased in depressed subjects in the precuneus and the angular gyrus. With ECT the NC normalized in responders (n=8), but not in non-responders (n=8).
CONCLUSIONS: We present a novel method of investigating within-network coherence and apply this to show that in depression, a large area of the DMN shows a decrease in coherence to the network as a whole. Although tentative due to the small sample size, we find that this effect is not present after ECT in those improving clinically, but persists in patients not responding to ECT.

PMID: 27434117 [PubMed - indexed for MEDLINE]

Sleep disturbance in mild cognitive impairment is associated with alterations in the brain's default mode network.

Wed, 11/29/2017 - 11:20
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Sleep disturbance in mild cognitive impairment is associated with alterations in the brain's default mode network.

Behav Neurosci. 2016 06;130(3):305-15

Authors: McKinnon AC, Lagopoulos J, Terpening Z, Grunstein R, Hickie IB, Batchelor J, Lewis SJ, Duffy S, Shine JM, Naismith SL

Abstract
This study aimed to identify default mode network (DMN) functional connectivity deficits in patients with mild cognitive impairment (MCI) and sleep disturbance, relative to those with MCI and no sleep disturbance. A control group was included to aid in identifying DMN changes specific to MCI. A cross-sectional, single-center study was performed at the Brain and Mind Research Centre in Sydney, Australia. Participants (95 adults over the age of 65: 38 controls and 57 meeting criteria for MCI) underwent resting-state functional MRI along with comprehensive neuropsychological, medical, and psychiatric assessment. Self-report data were collected including sleep quality assessment via the Pittsburgh Sleep Quality Index. A total score of greater than 5 on the Pittsburgh Sleep Quality Index was used to signify the presence of significant sleep disturbance, as per commonly used methodology. Using this criterion, 53% (n = 30) of our MCI group were classified as sleep-disturbed. Whereas the total group of MCI subjects and controls demonstrated no significant differences, sleep-disturbed MCIs demonstrated increased connectivity between temporal and parietal regions, and decreased connectivity between the prefrontal cortex and the temporoparietal junction relative to sleep-disturbed controls. Relative to those MCIs without sleep disturbance, sleep-disturbed MCI participants demonstrated significantly diminished DMN connectivity between temporal and parietal regions, a finding that was particularly pronounced in amnestic MCI. Sleep disturbance in MCI is associated with distinct alterations in DMN functional connectivity in brain regions underpinning salient memory and sleep systems. Future studies may build on these results via experimental manipulation and objective measurement of sleep. (PsycINFO Database Record

PMID: 26963234 [PubMed - indexed for MEDLINE]

Distinct neural substrates of visuospatial and verbal-analytic reasoning as assessed by Raven's Advanced Progressive Matrices.

Tue, 11/28/2017 - 16:20

Distinct neural substrates of visuospatial and verbal-analytic reasoning as assessed by Raven's Advanced Progressive Matrices.

Sci Rep. 2017 Nov 24;7(1):16230

Authors: Chen Z, De Beuckelaer A, Wang X, Liu J

Abstract
Recent studies revealed spontaneous neural activity to be associated with fluid intelligence (gF) which is commonly assessed by Raven's Advanced Progressive Matrices, and embeds two types of reasoning: visuospatial and verbal-analytic reasoning. With resting-state fMRI data, using global brain connectivity (GBC) analysis which averages functional connectivity of a voxel in relation to all other voxels in the brain, distinct neural correlates of these two reasoning types were found. For visuospatial reasoning, negative correlations were observed in both the primary visual cortex (PVC) and the precuneus, and positive correlations were observed in the temporal lobe. For verbal-analytic reasoning, negative correlations were observed in the right inferior frontal gyrus (rIFG), dorsal anterior cingulate cortex and temporoparietal junction, and positive correlations were observed in the angular gyrus. Furthermore, an interaction between GBC value and type of reasoning was found in the PVC, rIFG and the temporal lobe. These findings suggest that visuospatial reasoning benefits more from elaborate perception to stimulus features, whereas verbal-analytic reasoning benefits more from feature integration and hypothesis testing. In sum, the present study offers, for different types of reasoning in gF, first empirical evidence of separate neural substrates in the resting brain.

PMID: 29176725 [PubMed - in process]

Brainstem pain control circuitry connectivity in chronic neuropathic pain.

Tue, 11/28/2017 - 16:20

Brainstem pain control circuitry connectivity in chronic neuropathic pain.

J Neurosci. 2017 Nov 23;:

Authors: Mills EP, Di Pietro F, Alshelh Z, Peck CC, Murray GM, Vickers ER, Henderson LA

Abstract
Preclinical investigations have suggested that altered functioning of brainstem pain modulation circuits may be crucial for the maintenance of some chronic pain conditions. Whilst some human psychophysical studies show that patients with chronic pain display altered pain modulation efficacy, it remains unknown if brainstem pain modulation circuits are altered in individuals with chronic pain. The aim of the present investigation was to determine whether, in humans, chronic pain following nerve injury is associated with altered on-going functioning of the brainstem descending modulation systems. Using resting-state functional magnetic resonance imaging (fMRI), we found that male and female patients with chronic neuropathic orofacial pain show increased functional connectivity between the rostral ventromedial medulla (RVM) and other brainstem pain modulatory regions, including the ventrolateral periaqueductal grey (vlPAG) and locus coeruleus. We also identified an increase in RVM functional connectivity with the region that receives orofacial nociceptor afferents, the spinal trigeminal nucleus. In addition, the vlPAG and locus coeruleus displayed increased functional connectivity strengths with higher brain regions including the hippocampus, nucleus accumbens and anterior cingulate cortex in individuals with chronic pain. These data reveal that chronic pain is associated with altered on-going functioning within the endogenous pain modulation network. These changes may underlie enhanced descending facilitation of processing at the primary synapse resulting in increased nociceptive transmission to higher brain centres. Further, our findings show that higher brain regions interact with the brainstem modulation system differently in chronic pain, possibly reflecting top-down engagement of the circuitry alongside altered reward processing in pain conditions.SIGNIFICANCE STATEMENTExperimental animal models and human psychophysical studies suggest that altered functioning of brainstem pain modulation systems contributes to the maintenance of chronic pain. However, the function of this circuitry has not yet been explored in humans with chronic pain. In this study, we report that individuals with orofacial neuropathic pain show altered functional connectivity between regions within the brainstem pain modulation network. We suggest that these changes reflect largely central mechanisms that feed back onto the primary nociceptive synapse and enhance the transfer of noxious information to higher brain regions, thus contributing to the constant perception of pain. Identifying the mechanisms responsible for the maintenance of neuropathic pain is imperative in order to develop more efficacious therapies.

PMID: 29175957 [PubMed - as supplied by publisher]

Resting-state functional connectivity remains unaffected by preceding exposure to aversive visual stimuli.

Tue, 11/28/2017 - 16:20

Resting-state functional connectivity remains unaffected by preceding exposure to aversive visual stimuli.

Neuroimage. 2017 Nov 22;:

Authors: Geissmann L, Gschwind L, Schicktanz N, Deuring G, Rosburg T, Schwegler K, Gerhards C, Milnik A, Pflueger MO, Mager R, de Quervain DJF, Coynel D

Abstract
While much is known about immediate brain activity changes induced by the confrontation with emotional stimuli, the subsequent temporal unfolding of emotions has yet to be explored. To investigate whether exposure to emotionally aversive pictures affects subsequent resting-state networks differently from exposure to neutral pictures, a resting-state fMRI study implementing a two-group repeated-measures design in healthy young adults (N = 34) was conducted. We focused on investigating (i) patterns of amygdala whole-brain and hippocampus connectivity in both a seed-to-voxel and seed-to-seed approach, (ii) whole-brain resting-state networks with an independent component analysis coupled with dual regression, and (iii) the amygdala's fractional amplitude of low frequency fluctuations, all while EEG recording potential fluctuations in vigilance. In spite of the successful emotion induction, as demonstrated by stimuli rating and a memory-facilitating effect of negative emotionality, none of the resting-state measures was differentially affected by picture valence. In conclusion, resting-state networks connectivity as well as the amygdala's low frequency oscillations appear to be unaffected by preceding exposure to widely used emotionally aversive visual stimuli in healthy young adults.

PMID: 29175611 [PubMed - as supplied by publisher]

Convergent and Divergent Functional Connectivity Patterns in Patients with Long-term Left-sided and Right-sided Deafness.

Tue, 11/28/2017 - 16:20

Convergent and Divergent Functional Connectivity Patterns in Patients with Long-term Left-sided and Right-sided Deafness.

Neurosci Lett. 2017 Nov 22;:

Authors: Zhang Y, Mao Z, Feng S, Wang W, Zhang J, Yu X

Abstract
Cortical reorganization may be induced in long-term single-sided deafness (SD); however, the influence of the deafness side on the functional changes remains poorly understood. Here, we investigated whole-brain functional connectivity patterns in long-term SD patients. The normalized voxel-based functional connectivity strength (FCS) was determined using resting-state fMRI (rs-fMRI) in 17 left-sided deafness (LD) patients, 21 right-sided deafness (RD) patients and 21 healthy controls (HCs). Relative to the HCs, both the LD and RD patients exhibited a reduction in the FCS in the ipsilateral visual cortex. However, compared to that in the HCs, a significantly higher FCS was observed in some regions in the salience and default-mode networks in the RD patients, but this FCS alternation pattern was not observed in the LD patients. A direct comparison of the two patient groups revealed a significantly increased FCS in the supplemental motor area in the LD group. Altogether, the long-term SD groups with LD and RD exhibited convergent and divergent functional connectivity patterns in whole-brain networks, providing promising evidence that the functional changes in long-term SD are highly deafness-side-dependent.

PMID: 29175032 [PubMed - as supplied by publisher]

Impact on resting-state dynamic functional connectivity following 36 hours of total sleep deprivation.

Tue, 11/28/2017 - 16:20

Impact on resting-state dynamic functional connectivity following 36 hours of total sleep deprivation.

Brain Res. 2017 Nov 22;:

Authors: Xu H, Shen H, Wang L, Zhong Q, Lei Y, Yang L, Zeng LL, Zhou Z, Hu D, Yang Z

Abstract
Resting-state functional magnetic resonance imaging (fMRI) studies using static functional connectivity (FC) measures have shown that the brain function is severely disrupted after long-term sleep deprivation (SD). However, increasing evidence has suggested that resting-state FC is dynamic and exhibits spontaneous fluctuation on a smaller timescale. The process by which long-term SD can influence dynamic functional connectivity (dynFC) remains unclear. In this study, 37 healthy subjects participated in the SD experiment, and they were scanned both during rested wakefulness (RW) and after 36 hours of SD. A sliding-window based approach and a spectral clustering algorithm were used to evaluate the effects of SD on dynFC. The outcomes showed that time-averaging FC across specific regions as well as temporal properties of the FC states, such as the dwell time and transition probability, was strongly influenced after SD in contrast to the RW condition. Based on the occurrences of FC states, we further identified some RW-dominant states characterized by anti-correlation between the DMN and other cortices, and some SD-dominant states marked by significantly decreased thalamocortical connectivity. In particular, the temporal features of these FC states were negatively correlated with the correlation coefficients between the default mode network (DMN) and dorsal attention network (dATN) and demonstrated high potential in classification of sleep state (with leave-one-out cross-validation accuracy of 86.5%). Collectively, our results suggested that the temporal properties of the FC states greatly account for changes in the resting-state brain networks following SD, which provides new insights into the impact of SD on the resting-state functional organization in the human brain.

PMID: 29174693 [PubMed - as supplied by publisher]

Age-related connectivity differences between attention deficit and hyperactivity disorder patients and typically developing subjects: a resting-state functional MRI study.

Sun, 11/26/2017 - 07:20

Age-related connectivity differences between attention deficit and hyperactivity disorder patients and typically developing subjects: a resting-state functional MRI study.

Neural Regen Res. 2017 Oct;12(10):1640-1647

Authors: Hong J, Park BY, Cho HH, Park H

Abstract
Attention deficit and hyperactivity disorder (ADHD) is a disorder characterized by behavioral symptoms including hyperactivity/impulsivity among children, adolescents, and adults. These ADHD related symptoms are influenced by the complex interaction of brain networks which were under explored. We explored age-related brain network differences between ADHD patients and typically developing (TD) subjects using resting state fMRI (rs-fMRI) for three age groups of children, adolescents, and adults. We collected rs-fMRI data from 184 individuals (27 ADHD children and 31 TD children; 32 ADHD adolescents and 32 TD adolescents; and 31 ADHD adults and 31 TD adults). The Brainnetome Atlas was used to define nodes in the network analysis. We compared three age groups of ADHD and TD subjects to identify the distinct regions that could explain age-related brain network differences based on degree centrality, a well-known measure of nodal centrality. The left middle temporal gyrus showed significant interaction effects between disease status (i.e., ADHD or TD) and age (i.e., child, adolescent, or adult) (P < 0.001). Additional regions were identified at a relaxed threshold (P < 0.05). Many of the identified regions (the left inferior frontal gyrus, the left middle temporal gyrus, and the left insular gyrus) were related to cognitive function. The results of our study suggest that aberrant development in cognitive brain regions might be associated with age-related brain network changes in ADHD patients. These findings contribute to better understand how brain function influences the symptoms of ADHD.

PMID: 29171429 [PubMed]

Impact of previous episodes of hepatic encephalopathy on short-term brain function recovery after liver transplantation: a functional connectivity strength study.

Sun, 11/26/2017 - 07:20

Impact of previous episodes of hepatic encephalopathy on short-term brain function recovery after liver transplantation: a functional connectivity strength study.

Metab Brain Dis. 2017 Nov 23;:

Authors: Cheng Y, Zhang G, Shen W, Huang LX, Zhang L, Xie SS, Zhang XD, Liu B

Abstract
Neuropsychological studies have documented an incomplete reversal of pre-existing cognitive dysfunction in cirrhotic patients after liver transplantation (LT) and have found this is more severe in patients with hepatic encephalopathy (HE). In this study, we aimed to investigate the impact of prior HE episodes on post-transplantation brain function recovery. Resting-state functional magnetic resonance imaging data was collected from 30 healthy controls and 33 cirrhotic patients (HE, n = 15 and noHE, n = 18) before and one month after LT. Long- and short-range functional connectivity strength (FCS) analysis indicated that before transplantation both noHE and HE groups showed diffuse FCS abnormalities relative to healthy controls. For the noHE group, the abnormal FCS found before LT largely returned to normal levels after LT, except for in the cerebellum, precuneus, and orbital middle frontal gyrus. However, the abnormal FCS prior to LT was largely preserved in the HE group, including high-level cognition-related (frontal and parietal lobes) and vision-related areas (occipital lobe, cuneus, and precuneus). In addition, comparisons between HE and noHE groups revealed that weaker FCS in default mode network (DMN) in HE group persisted from pre- to post- LT. Correlation analysis showed that changes in FCS in the left postcentral and right middle frontal gyrus correlated with alterations in neuropsychological performance and ammonia levels. In conclusion, the findings in this study demonstrate potential adverse effects of pre-LT episode of HE on post-LT brain function recovery, and reveal that DMN may be the most affected brain region by HE episodes, which can't be reversed by LT.

PMID: 29170933 [PubMed - as supplied by publisher]

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