New resting-state fMRI related studies at PubMed

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Perceiving Rejection by Others: Relationship between Rejection Sensitivity and the Spontaneous Neuronal Activity of the Brain.

Fri, 06/09/2017 - 13:35
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Perceiving Rejection by Others: Relationship between Rejection Sensitivity and the Spontaneous Neuronal Activity of the Brain.

Soc Neurosci. 2017 Jun 08;:

Authors: Sun J, Zhuang K, Li H, Wei D, Zhang Q, Qiu J

Abstract
Rejection sensitivity (RS) can be defined as the disposition of a person to anxiously expect, readily perceive, and intensely react to rejection. Individuals with high RS are likely to suffer from mental disorders. The association between individual differences in RS and spontaneous neuronal activity at resting state has not yet been investigated. In this study, resting state data were used to investigate the relationship between RS and spontaneous neuronal activity in a large sample of healthy men (137) and women (172). The participants completed the rejection sensitivity questionnaire and underwent resting-state magnetic resonance imaging scan. Multiple regression analysis was conducted to examine the correlation between the regional amplitude of low-frequency fluctuations (ALFF) and rejection sensitivity scores adjusted for age and sex. Results showed that the ALFF value in the subgenual anterior cingulate cortex (sgACC) was positively associated with RS. Furthermore, functional connectivity with the middle frontal gyrus was negatively correlated with RS when sgACC was used as the seed region. These findings suggest that the spontaneous neuronal activity of sgACC and its functional connectivity with the lateral prefrontal cortex which are involved in experiencing social exclusion and regulating negative emotions are associated with individual differences in RS.

PMID: 28592189 [PubMed - as supplied by publisher]

Age-Related Differences in Dynamic Interactions Among Default Mode, Frontoparietal Control, and Dorsal Attention Networks during Resting-State and Interference Resolution.

Thu, 06/08/2017 - 13:00
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Age-Related Differences in Dynamic Interactions Among Default Mode, Frontoparietal Control, and Dorsal Attention Networks during Resting-State and Interference Resolution.

Front Aging Neurosci. 2017;9:152

Authors: Avelar-Pereira B, Bäckman L, Wåhlin A, Nyberg L, Salami A

Abstract
Resting-state fMRI (rs-fMRI) can identify large-scale brain networks, including the default mode (DMN), frontoparietal control (FPN) and dorsal attention (DAN) networks. Interactions among these networks are critical for supporting complex cognitive functions, yet the way in which they are modulated across states is not well understood. Moreover, it remains unclear whether these interactions are similarly affected in aging regardless of cognitive state. In this study, we investigated age-related differences in functional interactions among the DMN, FPN and DAN during rest and the Multi-Source Interference task (MSIT). Networks were identified using independent component analysis (ICA), and functional connectivity was measured during rest and task. We found that the FPN was more coupled with the DMN during rest and with the DAN during the MSIT. The degree of FPN-DMN connectivity was lower in older compared to younger adults, whereas no age-related differences were observed in FPN-DAN connectivity in either state. This suggests that dynamic interactions of the FPN are stable across cognitive states. The DMN and DAN were anti correlated and age-sensitive during the MSIT only, indicating variation in a task-dependent manner. Increased levels of anticorrelation from rest to task also predicted successful interference resolution. Additional analyses revealed that the degree of DMN-DAN anticorrelation during the MSIT was associated to resting cerebral blood flow (CBF) within the DMN. This suggests that reduced DMN neural activity during rest underlies an impaired ability to achieve higher levels of anticorrelation during a task. Taken together, our results suggest that only parts of age-related differences in connectivity are uncovered at rest and thus, should be studied in the functional connectome across multiple states for a more comprehensive picture.

PMID: 28588476 [PubMed - in process]

Functional Network Connectivity Patterns between Idiopathic Generalized Epilepsy with Myoclonic and Absence Seizures.

Thu, 06/08/2017 - 13:00
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Functional Network Connectivity Patterns between Idiopathic Generalized Epilepsy with Myoclonic and Absence Seizures.

Front Comput Neurosci. 2017;11:38

Authors: Li Q, Chen Y, Wei Y, Chen S, Ma L, He Z, Chen Z

Abstract
The extensive cerebral cortex and subcortical structures are considered as the major regions related to the generalized epileptiform discharges in idiopathic generalized epilepsy. However, various clinical syndromes and electroencephalogram (EEG) signs exist across generalized seizures, such as the loss of consciousness during absence seizures (AS) and the jerk of limbs during myoclonic seizures (MS). It is presumed that various functional systems affected by discharges lead to the difference in syndromes of these seizures. Twenty epileptic patients with MS, 21 patients with AS, and 21 healthy controls were recruited in this study. The functional network connectivity was analyzed based on the resting-state functional magnetic resonance imaging scans. The statistical analysis was performed in three groups to assess the difference in the functional brain networks in two types of generalized seizures. Twelve resting-state networks were identified in three groups. Both patient groups showed common abnormalities, including decreased functional connectivity in salience network (SN), cerebellum network, and primary perceptional networks and decreased connection between SN and visual network, compared with healthy controls. Interestingly, the frontal part of high-level cognitive resting-state networks showed increased functional connectivity (FC) in patients with MS, but decreased FC in patients with AS. Moreover, patients with MS showed decreased negative connections between high-level cognitive networks and primary system. The common alteration in both patient groups, including SN, might reflect a similar mechanism associated with the loss of consciousness during generalized seizures. This study provided the evidence of brain network in generalized epilepsy to understand the difference between MS and AS.

PMID: 28588471 [PubMed - in process]

Abnormal regional homogeneity as a potential imaging biomarker for adolescent-onset schizophrenia: A resting-state fMRI study and support vector machine analysis.

Thu, 06/08/2017 - 13:00
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Abnormal regional homogeneity as a potential imaging biomarker for adolescent-onset schizophrenia: A resting-state fMRI study and support vector machine analysis.

Schizophr Res. 2017 Jun 03;:

Authors: Wang S, Zhang Y, Lv L, Wu R, Fan X, Zhao J, Guo W

Abstract
OBJECTIVE: Structural and functional abnormalities have been reported in the brain of patients with adolescent-onset schizophrenia (AOS). The brain regional functional synchronization in patients with AOS remains unclear.
METHODS: We analyzed resting-state functional magnetic resonance scans in 48 drug-naive patients with AOS and 31 healthy controls by using regional homogeneity (ReHo), a measurement that reflects brain local functional connectivity or synchronization and indicates regional integration of information processing. Then, receiver operating characteristic curves and support vector machines were used to evaluate the effect of abnormal regional homogeneity in differentiating patients from controls.
RESULTS: Patients with AOS showed significantly increased ReHo values in the bilateral superior medial prefrontal cortex (MPFC) and significantly decreased ReHo values in the left superior temporal gyrus (STG), right precentral lobule, right inferior parietal lobule (IPL), and left paracentral lobule when compared with controls. A combination of the ReHo values in bilateral superior MPFC, left STG, and right IPL was able to discriminate patients from controls with the sensitivity of 88.24%, specificity of 91.89%, and accuracy of 90.14%.
CONCLUSION: The brain regional functional synchronization abnormalities exist in drug-naive patients with AOS. A combination of ReHo values in these abnormal regions might serve as potential imaging biomarker to identify patients with AOS.

PMID: 28587813 [PubMed - as supplied by publisher]

Increases in Intrinsic Thalamocortical Connectivity and Overall Cognition Following Cognitive Remediation in Chronic Schizophrenia.

Wed, 06/07/2017 - 12:05

Increases in Intrinsic Thalamocortical Connectivity and Overall Cognition Following Cognitive Remediation in Chronic Schizophrenia.

Biol Psychiatry Cogn Neurosci Neuroimaging. 2017 May;2(4):355-362

Authors: Ramsay IS, Nienow TM, MacDonald AW

Abstract
BACKGROUND: Thalamic projections to the prefrontal cortex (PFC) are critical for cognition, and disruptions in these circuits are thought to underlie the pathophysiology of schizophrenia. Cognitive remediation (REM) is a behavioral intervention that holds promise for improving cognition and functioning in schizophrenia, however the extent to which it affects thalamo-prefrontal connections has not been researched. This study sought to determine whether patients with schizophrenia who undergo a placebo-controlled trial of REM show increased functional connectivity between the thalamus and PFC, and whether these changes correspond to improvements in cognition.
METHODS: Twenty-six patients with chronic schizophrenia were randomized to either 48 hours (over 16 weeks) of a drill-and-practice working memory-focused REM or an active placebo condition. All participants underwent cognitive assessment (MATRICS Consensus Cognitive Battery), as well as both resting and task-based fMRI before and after their respective intervention. All clinicians, technicians, and raters were blind to participant condition.
RESULTS: We observed changes in resting-state connectivity in the PFC for the REM group but not the placebo group. Increased intrinsic connectivity between the thalamus and right middle frontal gyrus correlated with improvements in overall cognition. Additionally, lower baseline cognition correlated with greater increases in connectivity between the thalamus and PFC. Similar findings were observed when patients were scanned during a working memory task.
CONCLUSIONS: These results suggest that increases in thalamo-prefrontal circuitry correspond with training-related improvements of the cognitive deficits associated with schizophrenia.

PMID: 28584882 [PubMed - in process]

Slow-5 dynamic functional connectivity reflects the capacity to sustain cognitive performance during pain.

Wed, 06/07/2017 - 12:05

Slow-5 dynamic functional connectivity reflects the capacity to sustain cognitive performance during pain.

Neuroimage. 2017 Jun 02;:

Authors: Cheng JC, Bosma RL, Hemington KS, Kucyi A, Lindquist MA, Davis KD

Abstract
Some individuals are more distracted by pain during a cognitive task than others, representing poor pain coping. We have characterized individuals as A-type (attention dominates) or P-type (pain dominates) based on how pain interferes with task speed. The ability to optimize behavior during pain may relate to the flexibility in communication at rest between the dorsolateral prefrontal cortex (DLPFC) of the executive control network, and the anterior mid-cingulate cortex (aMCC) of the salience network (SN) - regions involved in cognitive-interference. The aMCC and aIns (SN hub) also signify pain salience; flexible communication at rest between them possibly allowing prioritizing task performance during pain. We tested the hypotheses that pain-induced changes in task performance are related to resting-state dynamic functional connectivity (dFC) between these region pairs (DLPFC-aMCC; aMCC-aIns). We found that 1) pain reduces task consistency/speed in P-type individuals, but enhances performance in A-type individuals, 2) task consistency is related to the FC dynamics within DLPFC-aMCC and aMCC-aIns pairs, 3) brain-behavior relationships are driven by dFC within the slow-5 (0.01-0.027Hz) frequency band, and 4) dFC across the brain decreases at higher frequencies. Our findings point to neural communication dynamics at rest as being associated with prioritizing task performance over pain.

PMID: 28583880 [PubMed - as supplied by publisher]

The Impacts of Pesticide and Nicotine Exposures on Functional Brain Networks in Latino Immigrant workers.

Wed, 06/07/2017 - 12:05

The Impacts of Pesticide and Nicotine Exposures on Functional Brain Networks in Latino Immigrant workers.

Neurotoxicology. 2017 Jun 02;:

Authors: Bahrami M, Laurienti PJ, Quandt SA, Talton J, Pope CN, Summers P, Burdette JH, Chen H, Liu J, Howard TD, Arcury TA, Simpson SL

Abstract
Latino immigrants that work on farms experience chronic exposures to potential neurotoxicants, such as pesticides, as part of their work. For tobacco farmworkers there is the additional risk of exposure to moderate to high doses of nicotine. Pesticide and nicotine exposures have been associated with neurological changes in the brain. Long-term exposure to cholinesterase-inhibiting pesticides, such as organophosphates and carbamates, and nicotine place this vulnerable population at risk for developing neurological dysfunction. In this study we examined whole-brain connectivity patterns and brain network properties of Latino immigrant workers. Comparisons were made between farmworkers and non-farmworkers using resting-state functional magnetic resonance imaging data and a mixed-effects modeling framework. We also evaluated how measures of pesticide and nicotine exposures contributed to the findings. Our results indicate that despite having the same functional connectivity density and strength, brain networks in farmworkers had more clustered and modular structures when compared to non-farmworkers. Our findings suggest increased functional specificity and decreased functional integration in farmworkers when compared to non-farmworkers. Cholinesterase activity was associated with population differences in community structure and the strength of brain network functional connections. Urinary cotinine, a marker of nicotine exposure, was associated with the differences in network community structure. Brain network differences between farmworkers and non-farmworkers, as well as pesticide and nicotine exposure effects on brain functional connections in this study, may illuminate underlying mechanisms that cause neurological implications in later life.

PMID: 28583619 [PubMed - as supplied by publisher]

Functional connectivity in the fronto-parietal network: an indicator of pre-operative cognitive function and cognitive outcome following surgery in patients with glioma.

Wed, 06/07/2017 - 12:05

Functional connectivity in the fronto-parietal network: an indicator of pre-operative cognitive function and cognitive outcome following surgery in patients with glioma.

World Neurosurg. 2017 Jun 02;:

Authors: Lang S, Gaxiola-Valdez I, Opoku-Darko M, Partlo LA, Goodyear BG, Kelly JJP, Federico P

Abstract
BACKGROUND: Patients with diffuse glioma are known to have impaired cognitive functions pre-operatively. However, the mechanism of these cognitive deficits remains unclear. Resting state functional connectivity in the fronto-parietal network (FPN) is associated with cognitive performance in healthy subjects. For this reason, it was hypothesized that functional connectivity of the FPN would be related to cognitive functioning in patients with glioma. To assess this relationship, pre-operative cognitive status was correlated to patient specific connectivity within the FPN. Further, we assessed whether connectivity could predict neuropsychological outcome following surgery.
METHODS: Sixteen patients with diffuse glioma underwent neuropsychological assessment and pre-operative fMRI using task (n-back) and resting state scans. Thirteen patients had post-operative cognitive assessment. An index of patient-specific functional connectivity in the FPN was derived by averaging connectivity values between two prefrontal and two parietal cortex regions defined by activation during the n-back task. The relationship of these indices with cognitive performance was assessed.
RESULTS: Higher average connectivity within the FPN is associated with lower composite cognitive scores. Higher connectivity of the parietal region of the tumor-affected hemisphere is associated specifically with lower fluid cognition. Lower connectivity of the parietal region of the non-tumor hemisphere is associated with worse neuropsychological outcome one month after surgery.
CONCLUSION: Resting state functional connectivity between key regions of the FPN is associated with cognitive performance in patients with glioma and is related to cognitive outcome following surgery.

PMID: 28583454 [PubMed - as supplied by publisher]

Disrupted Olfactory Integration in Schizophrenia: Functional Connectivity Study.

Tue, 06/06/2017 - 17:40

Disrupted Olfactory Integration in Schizophrenia: Functional Connectivity Study.

Int J Neuropsychopharmacol. 2017 Jun 03;:

Authors: Kiparizoska S, Ikuta T

Abstract
Background: Evidence for olfactory dysfunction in schizophrenia has been firmly established. However, in the typical understanding of schizophrenia, olfaction is not recognized to contribute to or interact with the illness. Despite the solid presence of olfactory dysfunction in schizophrenia, its relation to the rest of the illness remains largely unclear. Here, we aimed to examine functional connectivity of the olfactory bulb, olfactory tract, and piriform cortices and isolate the network that would account for the altered olfaction in schizophrenia.
Methods: We examined the functional connectivity of these specific regions associated with olfaction in order to isolate other brain regions that are associated with olfactory processing in schizophrenia. Using the resting state functional MRI data from the Center for Biomedical Research Excellence in Brain Function and Mental Illness, we compared 84 patients of schizophrenia (SZ group) and 90 individuals without schizophrenia (control group).
Results: The SZ group showed disconnectivity between the anterior piriform cortex and the nucleus accumbens, between the posterior piriform cortex and the middle frontal gyrus, and between the olfactory tract and the visual cortices.
Conclusions: The current results suggest functional disconnectivity of olfactory regions in schizophrenia, which may account for olfactory dysfunction and disrupted integration with other sensory modalities in schizophrenia.

PMID: 28582529 [PubMed - as supplied by publisher]

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
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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
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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
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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]

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