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 53 min ago

Spontaneous low frequency BOLD signal variations from resting-state fMRI are decreased in Alzheimer disease.

Tue, 06/06/2017 - 17:40

Spontaneous low frequency BOLD signal variations from resting-state fMRI are decreased in Alzheimer disease.

PLoS One. 2017;12(6):e0178529

Authors: Kazemifar S, Manning KY, Rajakumar N, Gómez FA, Soddu A, Borrie MJ, Menon RS, Bartha R, Alzheimer’s Disease Neuroimaging Initiative

Abstract
Previous studies have demonstrated altered brain activity in Alzheimer's disease using task based functional MRI (fMRI), network based resting-state fMRI, and glucose metabolism from 18F fluorodeoxyglucose-PET (FDG-PET). Our goal was to define a novel indicator of neuronal activity based on a first-order textural feature of the resting state functional MRI (RS-fMRI) signal. Furthermore, we examined the association between this neuronal activity metric and glucose metabolism from 18F FDG-PET. We studied 15 normal elderly controls (NEC) and 15 probable Alzheimer disease (AD) subjects from the AD Neuroimaging Initiative. An independent component analysis was applied to the RS-fMRI, followed by template matching to identify neuronal components (NC). A regional brain activity measurement was constructed based on the variation of the RS-fMRI signal of these NC. The standardized glucose uptake values of several brain regions relative to the cerebellum (SUVR) were measured from partial volume corrected FDG-PET images. Comparing the AD and NEC groups, the mean brain activity metric was significantly lower in the accumbens, while the glucose SUVR was significantly lower in the amygdala and hippocampus. The RS-fMRI brain activity metric was positively correlated with cognitive measures and amyloid β1-42 cerebral spinal fluid levels; however, these did not remain significant following Bonferroni correction. There was a significant linear correlation between the brain activity metric and the glucose SUVR measurements. This proof of concept study demonstrates that this novel and easy to implement RS-fMRI brain activity metric can differentiate a group of healthy elderly controls from a group of people with AD.

PMID: 28582450 [PubMed - in process]

Abnormal baseline brain activity in Alzheimer's disease patients with depression: a resting-state functional magnetic resonance imaging study.

Tue, 06/06/2017 - 17:40

Abnormal baseline brain activity in Alzheimer's disease patients with depression: a resting-state functional magnetic resonance imaging study.

Neuroradiology. 2017 Jun 03;:

Authors: Liu X, Guo Z, Ding Y, Li J, Wang G, Hou H, Chen X, Yu E

Abstract
PURPOSE: As one of the most common mental disorders and the most important precursor of suicide in Alzheimer's disease (AD), depression is associated with a decline in both well-being and daily functioning. At present, the diagnosis of AD patients with depression (D-AD) is largely dependent on clinical signs and symptoms, and the precise neural correlate underlying D-AD is still not fully understood.
METHODS: The current study sought to investigate low-frequency oscillations at the voxel level in D-AD patients based on the amplitude of low-frequency fluctuations (ALFF) measured using resting-state functional magnetic resonance imaging. We examined 22 D-AD patients and 21 non-depressed AD (nD-AD) patients.
RESULTS: The results revealed that D-AD patients exhibited increased ALFF values in the left caudate and thalamus and decreased ALFF values in the left middle temporal pole compared with nD-AD patients.
CONCLUSION: These findings may provide further insight into the underlying neuropathophysiology of AD with depression.

PMID: 28580529 [PubMed - as supplied by publisher]

Acupuncture modulates the abnormal brainstem activity in migraine without aura patients.

Tue, 06/06/2017 - 17:40

Acupuncture modulates the abnormal brainstem activity in migraine without aura patients.

Neuroimage Clin. 2017;15:367-375

Authors: Li Z, Zeng F, Yin T, Lan L, Makris N, Jorgenson K, Guo T, Wu F, Gao Y, Dong M, Liu M, Yang J, Li Y, Gong Q, Liang F, Kong J

Abstract
Migraine is a common neurological disease with a high prevalence and unsatisfactory treatment options. The specific pathophysiological mechanisms of migraine remain unclear, which restricts the development of effective treatments for this prevalent disorder. The aims of this study were to 1) compare the spontaneous brain activity differences between Migraine without Aura (MwoA) patients and healthy controls (HCs), using amplitude of low-frequency fluctuations (ALFF) calculation method, and 2) explore how an effective treatment (verum acupuncture) could modulate the ALFF of MwoA patients. One hundred MwoA patients and forty-six matched HCs were recruited. Patients were randomized to four weeks' verum acupuncture, sham acupuncture, and waiting list groups. Patients had resting state BOLD-fMRI scan before and after treatment, while HCs only had resting state BOLD-fMRI scan at baseline. Headache intensity, headache frequency, self-rating anxiety and self-rating depression were used for clinical efficacy evaluation. Compared with HCs, MwoA patients showed increased ALFF in posterior insula and putamen/caudate, and reduced ALFF in rostral ventromedial medulla (RVM)/trigeminocervical complex (TCC). After longitudinal verum acupuncture treatment, the decreased ALFF of the RVM/TCC was normalized in migraine patients. Verum acupuncture and sham acupuncture have different modulation effects on ALFF of RVM/TCC in migraine patients. Our results suggest that impairment of the homeostasis of the trigeminovascular nociceptive pathway is involved in the neural pathophysiology of migraines. Effective treatments, such as verum acupuncture, could help to restore this imbalance.

PMID: 28580293 [PubMed - in process]

Altered Default Mode Network on Resting-State fMRI in Children with Infantile Spasms.

Tue, 06/06/2017 - 17:40

Altered Default Mode Network on Resting-State fMRI in Children with Infantile Spasms.

Front Neurol. 2017;8:209

Authors: Wang Y, Li Y, Wang H, Chen Y, Huang W

Abstract
Infantile spasms (IS) syndrome is an age-dependent epileptic encephalopathy, which occurs in children characterized by spasms, impaired consciousness, and hypsarrhythmia. Abnormalities in default mode network (DMN) might contribute to the loss of consciousness during seizures and cognitive deficits in children with IS. The purpose of the present study was to investigate the changes in DMN with functional connectivity (FC) and amplitude of low-frequency fluctuation (ALFF), the two methods to discover the potential neuronal underpinnings of IS. The consistency of the two calculate methods of DMN abnormalities in IS patients was also our main focus. To avoid the disturbance of interictal epileptic discharge, our testing was performed within the interictal durations without epileptic discharges. Resting-state fMRI data were collected from 13 patients with IS and 35 sex- and age-matched healthy controls. FC analysis with seed in posterior cingulate cortex (PCC) was used to compare the differences between two groups. We chose PCC as the seed region because PCC is the only node in the DMN that directly interacts with virtually all other nodes according to previous studies. Furthermore, the ALFF values within the DMN were also calculated and compared between the two groups. The FC results showed that IS patients exhibited markedly reduced connectivity between posterior seed region and other areas within DMN. In addition, part of the brain areas within the DMN showing significant difference of FC had significantly lower ALFF signal in the patient group than that in the healthy controls. The observed disruption in DMN through the two methods showed that the coherence of brain signal fluctuation in DMN during rest was broken in IS children. Neuronal functional impairment or altered integration in DMN would be one neuroimaging characteristic, which might help us to understand the underlying neural mechanism of IS. Further studies are needed to determine whether the disturbed FC and ALFF observed in the DMN are related to cognitive performance in IS patients.

PMID: 28579971 [PubMed - in process]

Comparison of IVA and GIG-ICA in Brain Functional Network Estimation Using fMRI Data.

Tue, 06/06/2017 - 17:40

Comparison of IVA and GIG-ICA in Brain Functional Network Estimation Using fMRI Data.

Front Neurosci. 2017;11:267

Authors: Du Y, Lin D, Yu Q, Sui J, Chen J, Rachakonda S, Adali T, Calhoun VD

Abstract
Spatial group independent component analysis (GICA) methods decompose multiple-subject functional magnetic resonance imaging (fMRI) data into a linear mixture of spatially independent components (ICs), some of which are subsequently characterized as brain functional networks. Group information guided independent component analysis (GIG-ICA) as a variant of GICA has been proposed to improve the accuracy of the subject-specific ICs estimation by optimizing their independence. Independent vector analysis (IVA) is another method which optimizes the independence among each subject's components and the dependence among corresponding components of different subjects. Both methods are promising in neuroimaging study and showed a better performance than the traditional GICA. However, the difference between IVA and GIG-ICA has not been well studied. A detailed comparison between them is demanded to provide guidance for functional network analyses. In this work, we employed multiple simulations to evaluate the performances of the two approaches in estimating subject-specific components and time courses under conditions of different data quality and quantity, varied number of sources generated and inaccurate number of components used in computation, as well as the presence of spatially subject-unique sources. We also compared the two methods using healthy subjects' test-retest resting-state fMRI data in terms of spatial functional networks and functional network connectivity (FNC). Results from simulations support that GIG-ICA showed better recovery accuracy of both components and time courses than IVA for those subject-common sources, and IVA outperformed GIG-ICA in component and time course estimation for the subject-unique sources. Results from real fMRI data suggest that GIG-ICA resulted in more reliable spatial functional networks and yielded higher and more robust modularity property of FNC, compared to IVA. Taken together, GIG-ICA is appropriate for estimating networks which are consistent across subjects, while IVA is able to estimate networks with great inter-subject variability or subject-unique property.

PMID: 28579940 [PubMed - in process]

Compensatory Hyperconnectivity in Developing Brains of Young Children With Type 1 Diabetes.

Tue, 06/06/2017 - 17:40
Related Articles

Compensatory Hyperconnectivity in Developing Brains of Young Children With Type 1 Diabetes.

Diabetes. 2017 Mar;66(3):754-762

Authors: Saggar M, Tsalikian E, Mauras N, Mazaika P, White NH, Weinzimer S, Buckingham B, Hershey T, Reiss AL, Diabetes Research in Children Network (DirecNet)

Abstract
Sustained dysregulation of blood glucose (hyper- or hypoglycemia) associated with type 1 diabetes (T1D) has been linked to cognitive deficits and altered brain anatomy and connectivity. However, a significant gap remains with respect to how T1D affects spontaneous at-rest connectivity in young developing brains. Here, using a large multisite study, resting-state functional MRI data were examined in young children with T1D (n = 57; mean age = 7.88 years; 27 females) as compared with age-matched control subjects without diabetes (n = 26; mean age = 7.43 years; 14 females). Using both model-driven seed-based analysis and model-free independent component analysis and controlling for age, data acquisition site, and sex, converging results were obtained, suggesting increased connectivity in young children with T1D as compared with control subjects without diabetes. Further, increased connectivity in children with T1D was observed to be positively associated with cognitive functioning. The observed positive association of connectivity with cognitive functioning in T1D, without overall group differences in cognitive function, suggests a putative compensatory role of hyperintrinsic connectivity in the brain in children with this condition. Altogether, our study attempts to fill a critical gap in knowledge regarding how dysglycemia in T1D might affect the brain's intrinsic connectivity at very young ages.

PMID: 27702833 [PubMed - indexed for MEDLINE]

Functional Brain Networks Are Altered in Type 2 Diabetes and Prediabetes: Signs for Compensation of Cognitive Decrements? The Maastricht Study.

Tue, 06/06/2017 - 17:40
Related Articles

Functional Brain Networks Are Altered in Type 2 Diabetes and Prediabetes: Signs for Compensation of Cognitive Decrements? The Maastricht Study.

Diabetes. 2016 Aug;65(8):2404-13

Authors: van Bussel FC, Backes WH, van Veenendaal TM, Hofman PA, van Boxtel MP, Schram MT, Sep SJ, Dagnelie PC, Schaper N, Stehouwer CD, Wildberger JE, Jansen JF

Abstract
Type 2 diabetes is associated with cognitive decrements, accelerated cognitive decline, and increased risk for dementia. Patients with the metabolic syndrome, a major risk factor for diabetes, may display comparable cognitive decrements as seen in type 2 diabetes. Currently, the impact of diabetes and prediabetes on cognition and the underlying organization of functional brain networks still remain to be elucidated. This study investigated whether functional brain networks are affected in type 2 diabetes and prediabetes. Forty-seven participants with diabetes, 47 participants with prediabetes, and 45 control participants underwent detailed cognitive testing and 3-Tesla resting state functional MRI. Graph theoretical network analysis was performed to investigate alterations in functional cerebral networks. Participants with diabetes displayed altered network measures, characterized by a higher normalized cluster coefficient and higher local efficiency, compared with control participants. The network measures of the participants with prediabetes fell between those with diabetes and control participants. Lower processing speed was associated with shorter path length and higher global efficiency. Participants with type 2 diabetes have altered functional brain networks. This alteration is already apparent in the prediabetic stage to a somewhat lower level, hinting at functional reorganization of the cerebral networks as a compensatory mechanism for cognitive decrements.

PMID: 27217484 [PubMed - indexed for MEDLINE]

Leptin Substitution in Patients With Lipodystrophy: Neural Correlates for Long-term Success in the Normalization of Eating Behavior.

Tue, 06/06/2017 - 17:40
Related Articles

Leptin Substitution in Patients With Lipodystrophy: Neural Correlates for Long-term Success in the Normalization of Eating Behavior.

Diabetes. 2016 Aug;65(8):2179-86

Authors: Schlögl H, Müller K, Horstmann A, Miehle K, Püschel J, Villringer A, Pleger B, Stumvoll M, Fasshauer M

Abstract
Lipodystrophy (LD) is a rare disease with a paucity of subcutaneous adipocytes and leptin deficiency. Patients often develop severe diabetes and, additionally, show a disturbed eating behavior with reduced satiety. The disturbed eating behavior can be restored by substitution with the leptin analog metreleptin. Long-term effects of metreleptin on resting state brain connectivity in treatment-naive patients with LD have not been assessed. In this study, resting state functional MRI scans and extensive behavioral testing assessing changes in hunger/satiety regulation were performed during the first 52 weeks of metreleptin treatment in nine patients with LD. Resting state connectivity significantly increased over the course of metreleptin treatment in three brain areas (i.e., hypothalamus, insula/superior temporal gyrus, medial prefrontal cortex). Behavioral tests demonstrated that perceived hunger, importance of eating, eating frequencies, and liking ratings of food pictures significantly decreased during metreleptin therapy. Taken together, leptin substitution was accompanied by long-term changes of hedonic and homeostatic central nervous networks regulating eating behavior as well as decreased hunger feelings and diminished incentive value of food. Future studies need to assess whether metreleptin treatment in LD restores physiological processes important for the development of satiety.

PMID: 27207511 [PubMed - indexed for MEDLINE]

A proof-of-concept study for developing integrated two-photon microscopic and magnetic resonance imaging modality at ultrahigh field of 16.4 tesla.

Mon, 06/05/2017 - 11:15

A proof-of-concept study for developing integrated two-photon microscopic and magnetic resonance imaging modality at ultrahigh field of 16.4 tesla.

Sci Rep. 2017 Jun 02;7(1):2733

Authors: Cui M, Zhou Y, Wei B, Zhu XH, Zhu W, Sanders MA, Ugurbil K, Chen W

Abstract
Functional magnetic resonance imaging (fMRI) based on the blood oxygen level dependent (BOLD) contrast has gained a prominent position in neuroscience for imaging neuronal activity and studying effective brain connectivity under working state and functional connectivity at resting state. However, the fundamental questions in regards to fMRI technology: how the BOLD signal inferences the underlying microscopic neuronal activity and physiological changes and what is the ultimate specificity of fMRI for functional mapping of microcircuits, remain unanswered. The capability of simultaneous fMRI measurement and functional microscopic imaging in a live brain thus holds the key to link the microscopic and mesoscopic neural dynamics to the macroscopic brain activity at the central nervous system level. Here we report the first demonstration to integrate high-resolution two-photon fluorescence microscopy (TPM) with a 16.4 tesla MRI system, which proves the concept and feasibility for performing simultaneous high-resolution fMRI and TPM imaging at ultrahigh magnetic field.

PMID: 28578390 [PubMed - in process]

Assessing dynamic functional connectivity in heterogeneous samples.

Mon, 06/05/2017 - 11:15

Assessing dynamic functional connectivity in heterogeneous samples.

Neuroimage. 2017 May 31;:

Authors: Lehmann BCL, White SR, Henson RN, -Can C, Geerligs L

Abstract
Several methods have been developed to measure dynamic functional connectivity (dFC) in fMRI data. These methods are often based on a sliding-window analysis, which aims to capture how the brain's functional organization varies over the course of a scan. The aim of many studies is to compare dFC across groups, such as younger versus older people. However, spurious group differences in measured dFC may be caused by other sources of heterogeneity between people. For example, the shape of the haemodynamic response function (HRF) and levels of measurement noise have been found to vary with age. We use a generic simulation framework for fMRI data to investigate the effect of such heterogeneity on estimates of dFC. Our findings show that, despite no differences in true dFC, individual differences in measured dFC can result from other (non-dynamic) features of the data, such as differences in neural autocorrelation, HRF shape, connectivity strength and measurement noise. We also find that common dFC methods such as k-means and multilayer modularity approaches can detect spurious group differences in dynamic connectivity due to inappropriate setting of their hyperparameters. fMRI studies therefore need to consider alternative sources of heterogeneity across individuals before concluding differences in dFC.

PMID: 28578129 [PubMed - as supplied by publisher]

Reduced fronto-amygdalar connectivity in adolescence is associated with increased depression symptoms over time.

Sun, 06/04/2017 - 10:55

Reduced fronto-amygdalar connectivity in adolescence is associated with increased depression symptoms over time.

Psychiatry Res. 2017 May 25;266:35-41

Authors: Scheuer H, Alarcón G, Demeter DV, Earl E, Fair DA, Nagel BJ

Abstract
Depression is common among adolescents, affecting greater than 12% of youth in a given year. Studies have shown aberrant amygdala connectivity in depressed adolescents, compared with controls; however, no studies have examined whether these abnormalities precede and heighten risk for depressive symptom expression. This study used resting state functional connectivity (RSFC) magnetic resonance imaging to examine neurobiological markers of escalating depression symptoms in adolescents (ages 12-16 years; free from psychopathology at baseline). Of a large sample of adolescents, 18 showed ≥ 1 S.D. increase in depression scale t-scores over time ("escalators"; time to escalation ranging from 6 to 54 months in follow up) and were matched and compared to 19 youth showing stable CDI scores over time ("controls"). Whole-brain analyses on baseline RSFC data using an amygdala seed region-of-interest (ROI) showed that controls had greater RSFC, relative to escalators, between the right amygdala and left inferior frontal and supramarginal gyrus and right mid-cingulate cortex. Additionally, relative to escalators, control youth had less RSFC between the left amygdala and cerebellum. Findings suggest a possible neurobiological marker of increasing depressive symptoms during adolescence, characterized in part by reduced fronto-limbic connectivity, suggesting a premorbid deficiency in top-down emotional regulation.

PMID: 28577433 [PubMed - as supplied by publisher]

D2/D3 dopamine receptor binding with [F-18]fallypride correlates of executive function in medication-naïve patients with schizophrenia.

Sun, 06/04/2017 - 10:55
Related Articles

D2/D3 dopamine receptor binding with [F-18]fallypride correlates of executive function in medication-naïve patients with schizophrenia.

Schizophr Res. 2017 May 30;:

Authors: Vyas NS, Buchsbaum MS, Lehrer DS, Merrill BM, DeCastro A, Doninger NA, Christian BT, Mukherjee J

Abstract
Converging evidence indicates that the prefrontal cortex is critically involved in executive control and that executive dysfunction is implicated in schizophrenia. Reduced dopamine D2/D3 receptor binding potential has been reported in schizophrenia, and the correlations with neuropsychological test scores have been positive and negative for different tasks. The aim of this study was to examine the relation between dopamine D2/D3 receptor levels with frontal and temporal neurocognitive performance in schizophrenia. Resting-state (18)F-fallypride positron emission tomography was performed on 20 medication-naïve and 5 previously medicated for brief earlier periods patients with schizophrenia and 19 age- and sex-matched healthy volunteers. Striatal and extra-striatal dopamine D2/D3 receptor levels were quantified as binding potential using fallypride imaging. Magnetic resonance images in standard Talairach position and segmented into gray and white matter were co-registered to the fallypride images, and the AFNI stereotaxic atlas was applied. Two neuropsychological tasks known to activate frontal and temporal lobe function were chosen, specifically the Wisconsin Card Sorting Test (WCST) and the California Verbal Learning Test (CVLT). Images of the correlation coefficient between fallypride binding and WCST and CVLT performance showed a negative correlation in contrast to positive correlations in healthy volunteers. The results of this study demonstrate that lower fallypride binding potential in patients with schizophrenia may be associated with better performance. Our findings are consistent with previous studies that failed to find cognitive improvements with typical dopamine-blocking medications.

PMID: 28576546 [PubMed - as supplied by publisher]

Abnormal amplitude of low-frequency fluctuations associated with rapid-eye movement in chronic primary insomnia patients.

Sat, 06/03/2017 - 10:20

Abnormal amplitude of low-frequency fluctuations associated with rapid-eye movement in chronic primary insomnia patients.

Oncotarget. 2017 May 17;:

Authors: Ran Q, Chen J, Li C, Wen L, Yue F, Shu T, Mi J, Wang G, Zhang L, Gao D, Zhang D

Abstract
PURPOSE: Chronic primary insomnia (CPI) is the most prevalent sleep disorder worldwide. CPI manifests as difficulties in sleep onset, maintaining sleep, prolonged sleep latency, and daytime impairment and is often accompanied by cognitive problems such as poor academic performance, poor attention, and decreased memory. The most popular explanation of insomnia is hyperarousal or increased activities of neurons. Rapid eye movement (REM) sleep detected by polysomnography (PSG) exhibits a positive relationship with brain homeostasis and can be helpful for optimally preparing an organism for emotional and social function. Limited work has been performed to explore brain function of insomnia patients in combination with PSG analysis.
RESULTS: We observed increased ALFF within areas related to hyperarousal such as the midbrain and bilateral extra-nucleus, whereas decreased ALFF was observed within areas associated with memory and attention involving the parietal and occipital lobule and others. Furthermore, the altered ALFF was associated with the duration of insomnia, sleep efficiency, duration of REM, latency of RME and ratio of REM.
MATERIALS AND METHODS: In this study, we recruited twenty-five CPI patients and twenty-five normal sleep (NS) volunteers as a control group to investigate the amplitude of low-frequency fluctuations (ALFF) and the correlation between those altered ALFF regions through resting-state fMRI and PSG data.
CONCLUSIONS: These findings suggest that hyperarousal reflected by ALFF abnormality within brain areas related to cognition and emotion in insomnia associated with REM sleep.

PMID: 28575872 [PubMed - as supplied by publisher]

Increased Striatal and Reduced Prefrontal Cerebral Blood Flow in Clinical High Risk for Psychosis.

Sat, 06/03/2017 - 10:20

Increased Striatal and Reduced Prefrontal Cerebral Blood Flow in Clinical High Risk for Psychosis.

Schizophr Bull. 2017 May 30;:

Authors: Kindler J, Schultze-Lutter F, Hauf M, Dierks T, Federspiel A, Walther S, Schimmelmann BG, Hubl D

Abstract
Increased striatal dopaminergic activity and decreased prefrontal functioning have been reported in individuals at clinical high risk (CHR) for psychosis. Abnormal metabolic rate might affect resting-state cerebral blood flow (rCBF) in the respective regions. Here, we examined if striatal and prefrontal rCBF differ between patients with CHR, first-episode psychosis (FEP), chronic schizophrenia-spectrum disorder (SZ) and controls. Two cohorts with a total of 122 participants were included and analyzed separately: 32 patients with SZ and 31 healthy controls (HC) from the University Hospital of Psychiatry, and 59 patients from the Bern Early Recognition and Intervention Center (29 with CHR, 12 with FEP, and 18 clinical controls [CC]). Ultra-high risk criteria were assessed with the Structured Interview for Psychosis-Risk Syndromes, basic symptom criteria with the Schizophrenia Proneness Instrument. rCBF was measured with pseudo-continuous arterial spin labeling 3T-Magnetic Resonance Imaging. Striatal rCBF was significantly increased and prefrontal rCBF significantly decreased in the SZ group compared to HC group and in the CHR and FEP groups compared to CC group. Striatal rCBF correlated significantly with positive symptom scores in SZ and CHR. An inverse correlation between striatal and frontal rCBF was found in controls (HC, CC), but not in patient groups (SZ, FEP, CHR). This is the first study to demonstrate increased neuronal activity within the striatum, but reduced prefrontal activity in patients with CHR, FEP, and SZ compared to the respective controls. Our results indicate that alterations in striatal and prefrontal rCBF are reflecting metabolic abnormalities preceding the onset of frank psychosis.

PMID: 28575528 [PubMed - as supplied by publisher]

White Matter Structural Connectivity Is Not Correlated to Cortical Resting-State Functional Connectivity over the Healthy Adult Lifespan.

Sat, 06/03/2017 - 10:20
Related Articles

White Matter Structural Connectivity Is Not Correlated to Cortical Resting-State Functional Connectivity over the Healthy Adult Lifespan.

Front Aging Neurosci. 2017;9:144

Authors: Tsang A, Lebel CA, Bray SL, Goodyear BG, Hafeez M, Sotero RC, McCreary CR, Frayne R

Abstract
Structural connectivity (SC) of white matter (WM) and functional connectivity (FC) of cortical regions undergo changes in normal aging. As WM tracts form the underlying anatomical architecture that connects regions within resting state networks (RSNs), it is intuitive to expect that SC and FC changes with age are correlated. Studies that investigated the relationship between SC and FC in normal aging are rare, and have mainly compared between groups of elderly and younger subjects. The objectives of this work were to investigate linear SC and FC changes across the healthy adult lifespan, and to define relationships between SC and FC measures within seven whole-brain large scale RSNs. Diffusion tensor imaging (DTI) and resting-state functional MRI (rs-fMRI) data were acquired from 177 healthy participants (male/female = 69/108; aged 18-87 years). Forty cortical regions across both hemispheres belonging to seven template-defined RSNs were considered. Mean diffusivity (MD), fractional anisotropy (FA), mean tract length, and number of streamlines derived from DTI data were used as SC measures, delineated using deterministic tractography, within each RSN. Pearson correlation coefficients of rs-fMRI-obtained BOLD signal time courses between cortical regions were used as FC measure. SC demonstrated significant age-related changes in all RSNs (decreased FA, mean tract length, number of streamlines; and increased MD), and significant FC decrease was observed in five out of seven networks. Among the networks that showed both significant age related changes in SC and FC, however, SC was not in general significantly correlated with FC, whether controlling for age or not. The lack of observed relationship between SC and FC suggests that measures derived from DTI data that are commonly used to infer the integrity of WM microstructure are not related to the corresponding changes in FC within RSNs. The possible temporal lag between SC and FC will need to be addressed in future longitudinal studies to better elucidate the links between SC and FC changes in normal aging.

PMID: 28572765 [PubMed - in process]

Multifocal tDCS targeting the resting state motor network increases cortical excitability beyond traditional tDCS targeting unilateral motor cortex.

Sat, 06/03/2017 - 10:20
Related Articles

Multifocal tDCS targeting the resting state motor network increases cortical excitability beyond traditional tDCS targeting unilateral motor cortex.

Neuroimage. 2017 May 29;:

Authors: Fischer DB, Fried PJ, Ruffini G, Ripolles O, Salvador R, Banus J, Ketchabaw WT, Santarnecchi E, Pascual-Leone A, Fox MD

Abstract
Scientists and clinicians have traditionally targeted single brain regions with stimulation to modulate brain function and disease. However, brain regions do not operate in isolation, but interact with other regions through networks. As such, stimulation of one region may impact and be impacted by other regions in its network. Here we test whether the effects of brain stimulation can be enhanced by simultaneously targeting a region and its network, identified with resting state functional connectivity MRI. Fifteen healthy participants received two types of transcranial direct current stimulation (tDCS): a traditional two-electrode montage targeting a single brain region (left primary motor cortex [M1]) and a novel eight-electrode montage targeting this region and its associated resting state network. As a control, 8 participants also received multifocal tDCS mismatched to this network. Network-targeted tDCS more than doubled the increase in left M1 excitability over time compared to traditional tDCS and the multifocal control. Modeling studies suggest these results are unlikely to be due to tDCS effects on left M1 itself, however it is impossible to completely exclude this possibility. It also remains unclear whether multifocal tDCS targeting a network selectively modulates this network and which regions within the network are most responsible for observed effects. Despite these limitations, network-targeted tDCS appears to be a promising approach for enhancing tDCS effects beyond traditional stimulation targeting a single brain region. Future work is needed to test whether these results extend to other resting state networks and enhance behavioral or therapeutic effects.

PMID: 28572060 [PubMed - as supplied by publisher]

Decreased middle temporal gyrus connectivity in the language network in schizophrenia patients with auditory verbal hallucinations.

Sat, 06/03/2017 - 10:20
Related Articles

Decreased middle temporal gyrus connectivity in the language network in schizophrenia patients with auditory verbal hallucinations.

Neurosci Lett. 2017 May 29;:

Authors: Zhang L, Li B, Wang H, Li L, Liao Q, Liu Y, Bao X, Liu W, Yin H, Lu H, Tan Q

Abstract
As the most common symptoms of schizophrenia, the long-term persistence of obstinate auditory verbal hallucinations (AVHs) brings about great mental pain to patients. Neuroimaging studies of schizophrenia have indicated that AVHs were associated with altered functional and structural connectivity within the language network. However, effective connectivity that could reflect directed information flow within this network and is of great importance to understand the neural mechanisms of the disorder remains largely unknown. In this study, we utilized stochastic dynamic causal modeling (DCM) to investigate directed connections within the language network in schizophrenia patients with and without AVHs. Thirty-six patients with schizophrenia (18 with AVHs and 18 without AVHs), and 37 healthy controls participated in the current resting-state functional magnetic resonance imaging (fMRI) study. The results showed that the connection from the left inferior frontal gyrus (LIFG) to left middle temporal gyrus (LMTG) was significantly decreased in patients with AVHs compared to those without AVHs. Meanwhile, the effective connection from the left inferior parietal lobule (LIPL) to LMTG was significantly decreased compared to the healthy controls. Our findings suggest aberrant pattern of causal interactions within the language network in patients with AVHs, indicating that the hypoconnectivity or disrupted connection from frontal to temporal speech areas might be critical for the pathological basis of AVHs.

PMID: 28572034 [PubMed - as supplied by publisher]

Fractional amplitude of low-frequency fluctuations is disrupted in Alzheimer's disease with depression.

Fri, 06/02/2017 - 10:05

Fractional amplitude of low-frequency fluctuations is disrupted in Alzheimer's disease with depression.

Clin Neurophysiol. 2017 May 17;128(7):1344-1349

Authors: Guo Z, Liu X, Li J, Wei F, Hou H, Chen X, Li X, Chen W

Abstract
OBJECTIVE: To explore brain activity in AD with depression (D-AD) based on fractional amplitude of low-frequency fluctuation (fALFF).
METHODS: Twenty-two D-AD and 21 AD without depression patients (nD-AD) were examined by magnetic resonance imaging during resting state. Neuropsychiatric Inventory and Hamilton Depression Rating Scale were employed to assess the severity of depression. We analysed the characteristics of fALFF in D-AD differing from nD-AD. We also examined the correlation between fALFF and the depression severity.
RESULTS: D-AD patients had higher fALFF in right fusiform gyrus, left caudate nucleus, and right middle temporal gyrus (MTG), meanwhile lower fALFF in supplementary motor area (SMA) than nD-AD patients.
CONCLUSIONS: Abnormal fALFF changes in fusiform gyrus, caudate nucleus, MTG and SMA may be important neuropathophysiologic characteristics of depression in AD.
SIGNIFICANCE: We have clarified the potential neuropathological changes of depression in AD based on fALFF method, which is crucial for effective intervention.

PMID: 28570868 [PubMed - as supplied by publisher]

Aberrant Intra- and Internetwork Functional Connectivity in Depressed Parkinson's Disease.

Fri, 06/02/2017 - 10:05

Aberrant Intra- and Internetwork Functional Connectivity in Depressed Parkinson's Disease.

Sci Rep. 2017 May 31;7(1):2568

Authors: Wei L, Hu X, Zhu Y, Yuan Y, Liu W, Chen H

Abstract
Much is known concerning the underlying mechanisms of Parkinson's disease (PD) with depression, but our understanding of this disease at the neural-system level remains incomplete. This study used resting-state functional MRI (rs-fMRI) and independent component analysis (ICA) to investigate intrinsic functional connectivity (FC) within and between large-scale neural networks in 20 depressed PD (dPD) patients, 35 non-depressed PD (ndPD) patients, and 34 healthy controls (HC). To alleviate the influence caused by ICA model order selection, this work reported results from analyses at 2 levels (low and high model order). Within these two analyses, similar results were obtained: 1) dPD and ndPD patients relative to HC had reduced FC in basal ganglia network (BGN); 2) dPD compared with ndPD patients exhibited increased FC in left frontoparietal network (LFPN) and salience network (SN), and decreased FC in default-mode network (DMN); 3) dPD patients compared to HC showed increased FC between DMN and LFPN. Additionally, connectivity anomalies in the DMN, LFPN and SN correlated with the depression severity in patients with PD. Our findings confirm the involvement of BGN, DMN, LFPN and SN in depression in PD, facilitating the development of more detailed and integrative neural models of PD with depression.

PMID: 28566724 [PubMed - in process]

Functional Connectivity Between Somatosensory and Motor Brain Areas Predicts Individual Differences in Motor Learning by Observing.

Fri, 06/02/2017 - 10:05

Functional Connectivity Between Somatosensory and Motor Brain Areas Predicts Individual Differences in Motor Learning by Observing.

J Neurophysiol. 2017 May 31;:jn.00275.2017

Authors: McGregor HR, Gribble PL

Abstract
Action observation can facilitate the acquisition of novel motor skills, however, there is considerable individual variability in the extent to which observation promotes motor learning. Here we tested the hypothesis that individual differences in brain function or structure can predict subsequent observation-related gains in motor learning. Subjects underwent an anatomical MRI scan and resting-state fMRI scans to assess pre-observation grey matter volume and pre-observation resting-state functional connectivity (FC), respectively. On the following day, subjects observed a video of a tutor adapting her reaches to a novel force field. After observation, subjects performed reaches in a force field as a behavioral assessment of gains in motor learning resulting from observation. We found that individual differences in resting-state FC, but not grey matter volume, predicted post-observation gains in motor learning. Pre-observation resting-state FC between left S1 and bilateral PMd, M1, S1 and left SPL was positively correlated with behavioral measures of post-observation motor learning. Sensory-motor resting-state FC can thus predict the extent to which observation will promote subsequent motor learning.

PMID: 28566463 [PubMed - as supplied by publisher]

Pages