New resting-state fMRI related studies at PubMed

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Abnormal regional spontaneous neural activity in visual pathway in retinal detachment patients: a resting-state functional MRI study.

Tue, 12/05/2017 - 12:00

Abnormal regional spontaneous neural activity in visual pathway in retinal detachment patients: a resting-state functional MRI study.

Neuropsychiatr Dis Treat. 2017;13:2849-2854

Authors: Huang X, Li D, Li HJ, Zhong YL, Freeberg S, Bao J, Zeng XJ, Shao Y

Abstract
Objective: The aim of the study was to investigate changes of brain neural homogeneity in retinal detachment (RD) patients using the regional homogeneity (ReHo) method to understand their relationships with clinical features.
Materials and methods: A total of 30 patients with RD (16 men and 14 women), and 30 healthy controls (HCs) (16 men and 14 women) closely matched in age and sex were recruited. Resting-state functional magnetic resonance imaging scans were performed for all subjects. The ReHo method was used to investigate the brain regional neural homogeneity. Patients with RD were distinguished from HCs by receiver operating characteristic curve. The relationships between the mean ReHo signal values in many brain regions and clinical features in RD patients were calculated by Pearson correlation analysis.
Results: Compared with HCs, RD patients had significantly decreased ReHo values in the right occipital lobe, right superior temporal gyrus, bilateral cuneus and left middle frontal gyrus. Moreover, we found that the mean ReHo signal of the bilateral cuneus showed positive relationships with the duration of the RD (r=0.392, P=0.032).
Conclusion: The RD patients showed brain neural homogeneity dysfunction in the visual pathway, which may underline the pathological mechanism of RD patients with acute vision loss. Besides, the ReHo values can reflect the progress of the RD disease.

PMID: 29200859 [PubMed]

PROCEDURAL PAIN AND ORAL GLUCOSE IN PRETERM NEONATES: BRAIN DEVELOPMENT AND SEX-SPECIFIC EFFECTS.

Tue, 12/05/2017 - 12:00

PROCEDURAL PAIN AND ORAL GLUCOSE IN PRETERM NEONATES: BRAIN DEVELOPMENT AND SEX-SPECIFIC EFFECTS.

Pain. 2017 Dec 01;:

Authors: Schneider J, Duerden EG, Guo T, Ng K, Hagmann P, Graz MB, Grunau RE, Chakravarty MM, Hüppi PS, Truttmann AC, Miller SP

Abstract
Our objectives were to determine whether procedural pain and glucose exposure are associated with altered structural and functional brain development differently in preterm males and females, and neurodevelopment at 18-months corrected age. Fifty-one very-preterm neonates (22 males; median[IQR] gestational age 27.6[2.0] weeks) underwent three serial scans including T1-weighted and resting-state functional magnetic resonance imaging (MRI) at median postmenstrual weeks: 29.4, 31.9, and 41.1. Thalamus, basal ganglia, and total brain volumes were segmented. Functional resting-state MRI data were extracted from the independent-components maps. Pain was operationalized as the total number of NICU-administered invasive procedures. Neurodevelopmental outcomes at 18-months corrected age were assessed with the Bayley Scales of Infant Development, second edition. Generalized estimating equations assessed the association of pain and glucose exposure with brain structural and functional development. More invasive procedures were independently associated with slower growth of thalamic (p<0.001), basal ganglia (p=0.028), and total brain volumes (p=0.001), particularly in females. Similar relationships were observed between glucose exposure and brain volumes. Functional connectivity between thalamus and sensorimotor cortices was negatively associated with number of invasive procedures. Greater procedural pain and higher glucose exposure were related to poorer neurodevelopmental outcomes. These findings suggest that structural and functional brain development is vulnerable to procedural pain. Glucose used for analgesia does not appear to mitigate the adverse impact of pain on brain development. The vulnerability of brain development in females towards early pain is distinct from other neonatal morbidities. The link between pain and glucose with neurodevelopment suggests that these factors have long-lasting impact.

PMID: 29200180 [PubMed - as supplied by publisher]

Same same but different: processing words in the aging brain.

Tue, 12/05/2017 - 12:00

Same same but different: processing words in the aging brain.

Neuroscience. 2017 Nov 30;:

Authors: Froehlich E, Liebig J, Morawetz C, Ziegler JC, Braun M, Heekeren HR, Jacobs AM

Abstract
Reading is not only one of the most appreciated leisure activities of the elderly but it clearly helps older people to maintain functional independence, which has a significant impact on life quality. Yet, very little is known about how aging affects the neural circuits of the processes that underlie skilled reading. Therefore, the aim of the present study was to systematically investigate the neural correlates of sublexical, orthographic, phonological and lexico-semantic processing in the aging brain. Using functional magnetic resonance imaging, we recorded brain activity of younger (N = 20; 22-35 years) and older (N = 38; 65-76 years) adults during letter identification, visual lexical decision, phonological decision and semantic categorization. Older and younger adults recruited an identical set of reading-related brain regions suggesting that the general architecture of the reading network is preserved across the lifespan. However, we also observed age-related differences in brain activity in the subcomponents of the reading network. Age-related differences were most prominent during phonological and orthographic processing possibly due to a failure of older adults to inhibit non-optimal reading strategies. Neural effects of aging were also observed outside reading-related circuits, especially in frontal midline regions. These regions might be involved because of their important role in memory, attention and executive control functions and their potential role in resting state networks.

PMID: 29199068 [PubMed - as supplied by publisher]

How Much Is Enough - Can resting state fMRI provide a demarcation for neurosurgical resection in glioma?

Tue, 12/05/2017 - 12:00

How Much Is Enough - Can resting state fMRI provide a demarcation for neurosurgical resection in glioma?

Neurosci Biobehav Rev. 2017 Nov 30;:

Authors: Ghinda DC, Wu JS, Duncan NW, Northoff G

Abstract
This study represents a systematic review of the insights provided by resting state functional MRI (rs-fMRI) use in the glioma population. Following PRISMA guidelines, 45 studies were included in the review and were classified in glioma-related neuronal changes (n=28) and eloquent area localization (n=17). Despite the heterogeneous nature of the studies, there is considerable evidence of diffuse functional reorganization occurring in the setting of gliomas with local and interhemispheric functional connectivity alterations involving different functional networks. The studies showed evidence of decreased long distance functional connectivity and increased global local efficiency occurring in the setting of gliomas. The tumour grade seems to correlate with distinct functional connectivity changes. Overall, there is a potential clinical utility of rs-fMRI for identifying the functional brain network disruptions occurring in the setting of gliomas. Further studies utilizing standardized analytical methods are required to elucidate the mechanism through which gliomas induce global changes in brain connectivity.

PMID: 29198588 [PubMed - as supplied by publisher]

Attention-Deficit/Hyperactivity Disorder: A Historical Neuropsychological Perspective.

Tue, 12/05/2017 - 12:00

Attention-Deficit/Hyperactivity Disorder: A Historical Neuropsychological Perspective.

J Int Neuropsychol Soc. 2017 Oct;23(9-10):916-929

Authors: Mahone EM, Denckla MB

Abstract
The behavior patterns of hyperactivity, impulsivity and inattention that would ultimately become recognized as Attention-Deficit Hyperactivity Disorder (ADHD) have been described for centuries. Nevertheless, in the past 35 years, advances in diagnostic methods, identification of biomarkers, and treatments have advanced at an exponential rate. ADHD is now recognized as the most common behavioral disorder of childhood, with risks extending well into adulthood for both males and females, leading to its identification as a significant public health issue. This historical neuropsychological review of ADHD emphasizes scientific highlights in the past 35 years related to ADHD, including the evolution of the diagnosis (from Hyperkinetic Reaction of Childhood to ADHD), influential theories (executive functions, cognitive-energetic, delay aversion), landmark treatment studies (Multimodal Treatment of ADHD [MTA] and Preschool ADHD Treatment Study [PATS]), and advances in brain mapping techniques (anatomic, functional, and resting state magnetic resonance imaging, diffusion tensor imaging). The review concludes by highlighting the challenges of studying and treating a heterogeneous neurodevelopmental disorder like ADHD, with emphasis on associated disorders and conditions (learning disabilities, sluggish cognitive tempo), special populations (girls, preschoolers, adults), and recommendations for scientific inquiry in the next 35 years. Neuropsychologists are well positioned to address the clinical and research challenges of the next generation of studies, especially involving advances in understanding the sexual dimor.phism, full developmental course, and dynamic risks associated with ADHD. (JINS, 2017, 23, 916-929).

PMID: 29198277 [PubMed - in process]

Altered orbitofrontal activity and dorsal striatal connectivity during emotion processing in dependent marijuana users after 28 days of abstinence.

Tue, 12/05/2017 - 12:00

Altered orbitofrontal activity and dorsal striatal connectivity during emotion processing in dependent marijuana users after 28 days of abstinence.

Psychopharmacology (Berl). 2017 Dec 02;:

Authors: Zimmermann K, Yao S, Heinz M, Zhou F, Dau W, Banger M, Weber B, Hurlemann R, Becker B

Abstract
RATIONALE: Intact cognitive and emotional functioning is vital for the long-term success of addiction treatment strategies. Accumulating evidence suggests an association between chronic marijuana use and lasting alterations in cognitive brain function. Despite initial evidence for altered emotion processing in dependent marijuana users after short abstinence periods, adaptations in the domain of emotion processing after longer abstinence remain to be determined.
OBJECTIVE AND METHODS: Using task-based and resting state fMRI, the present study investigated emotion processing in 19 dependent marijuana users and 18 matched non-using controls after an abstinence period of > 28 days.
RESULTS: Relative to the control subjects, negative emotional stimuli elicited increased medial orbitofrontal cortex (mOFC) activity and stronger mOFC-dorsal striatal and mOFC-amygdala functional coupling in dependent marijuana users (p < 0.022, FWE-corrected). Furthermore, mOFC-dorsal striatal functional connectivity was increased at rest in marijuana users (p < 0.03, FWE-corrected). Yet, processing of positive stimuli and subjective ratings of valence and arousal were comparable in both groups.
CONCLUSIONS: Together, the present findings provide the first evidence for persisting emotion processing alterations in dependent marijuana users. Alterations might reflect long-term neural adaptations as a consequence of chronic marijuana use or predisposing risk factors for the development of marijuana dependence.

PMID: 29197984 [PubMed - as supplied by publisher]

Disruption of Semantic Network in Mild Alzheimer's Disease Revealed by Resting-State fMRI.

Tue, 12/05/2017 - 12:00

Disruption of Semantic Network in Mild Alzheimer's Disease Revealed by Resting-State fMRI.

Neuroscience. 2017 Nov 29;:

Authors: Mascali D, DiNuzzo M, Serra L, Mangia S, Maraviglia B, Bozzali M, Giove F

Abstract
Subtle semantic deficits can be observed in Alzheimer's disease (AD) patients even in the early stages of the illness. In this work, we tested the hypothesis that the semantic control network is deregulated in mild AD patients. We assessed the integrity of the semantic control system using resting-state functional magnetic resonance imaging in a cohort of patients with mild AD (n = 38; mean Mini-Mental State Examination=20.5) and in a group of age-matched healthy controls (n = 19). Voxel-wise analysis spatially constrained in the left fronto-temporal semantic control network identified two regions with altered functional connectivity in AD patients, specifically in the pars opercularis (POp, BA44) and in the posterior middle temporal gyrus (pMTG, BA21). Using whole-brain seed-based analysis, we demonstrated that these two regions have altered functional connectivity even beyond the semantic control network. In particular, the pMTG displayed a wide-distributed pattern of lower connectivity to several brain regions involved in language-semantic processing, along with a possibly compensatory higher connectivity to the Wernicke's area. We conclude that in mild AD brain regions belonging to the semantic control network are abnormally connected not only within the network, but also to other areas known to be critical for language processing.

PMID: 29197559 [PubMed - as supplied by publisher]

Decreased Regional Cerebral Perfusion at Resting State in Acute Posttraumatic Stress Disorder Resulting From a Single, Prolonged Stress Event.

Tue, 12/05/2017 - 12:00
Related Articles

Decreased Regional Cerebral Perfusion at Resting State in Acute Posttraumatic Stress Disorder Resulting From a Single, Prolonged Stress Event.

Acad Radiol. 2016 Sep;23(9):1083-90

Authors: Zhe X, Liu K, Mu YF, Qi S, Xi YB, Du P, Huan Y, Tan QR, Yin H, Zhao HT, Ge YL, Chang YJ

Abstract
RATIONALE AND OBJECTIVES: This study evaluated the altered regional cerebral blood flow (rCBF) in resting state in patients with acute posttraumatic stress disorder (PTSD) 3 months after trauma.
MATERIALS AND METHODS: The rCBF was measured in 30 patients with acute PTSD and 36 healthy controls.
RESULTS: Survivors with acute PTSD showed decreased rCBF, the Clinician-Administered PTSD Scale score correlated negatively with the rCBF, and rCBF at resting state decreased in acute PTSD.
CONCLUSIONS: PTSD symptom severity was associated with diminished cerebral blood flow in the right insular cortex and right orbital medial frontal gyrus. The rCBF may predict PTSD symptom severity.

PMID: 27283071 [PubMed - indexed for MEDLINE]

Resting-state functional MRI reveals altered brain connectivity and its correlation with motor dysfunction in a mouse model of Huntington's disease.

Mon, 12/04/2017 - 23:40

Resting-state functional MRI reveals altered brain connectivity and its correlation with motor dysfunction in a mouse model of Huntington's disease.

Sci Rep. 2017 Dec 01;7(1):16742

Authors: Li Q, Li G, Wu D, Lu H, Hou Z, Ross CA, Yang Y, Zhang J, Duan W

Abstract
Huntington's disease (HD) is an autosomal dominant inherited neurodegenerative disorder, and no cure is available currently. Treatment of HD is likely to be most beneficial in the early, possibly pre-manifestation stage. The challenge is to determine the best time for intervention and evaluate putative efficacy in the absence of clinical symptoms. Resting-state functional MRI may represent a promising tool to develop biomarker reflecting early neuronal dysfunction in HD brain, because it can examine multiple brain networks without confounding effects of cognitive ability, which makes the resting-state fMRI promising as a translational bridge between preclinical study in animal models and clinical findings in HD patients. In this study, we examined brain regional connectivity and its correlation to brain atrophy, as well as motor function in the 18-week-old N171-82Q HD mice. HD mice exhibited significantly altered functional connectivity in multiple networks. Particularly, the weaker intra-striatum connectivity was positively correlated with striatal atrophy, while striatum-retrosplenial cortex connectivity is negatively correlated with striatal atrophy. The resting-state brain regional connectivity had no significant correlation with motor deficits in HD mice. Our results suggest that altered brain connectivity detected by resting-state fMRI might serve as an early disease biomarker in HD.

PMID: 29196686 [PubMed - in process]

EEG microstates as a tool for studying the temporal dynamics of whole-brain neuronal networks: A review.

Mon, 12/04/2017 - 23:40

EEG microstates as a tool for studying the temporal dynamics of whole-brain neuronal networks: A review.

Neuroimage. 2017 Nov 28;:

Authors: Michel CM, Koenig T

Abstract
The present review discusses a well-established method for characterizing resting-state activity of the human brain using multichannel electroencephalography (EEG). This method involves the examination of electrical microstates in the brain, which are defined as successive short time periods during which the configuration of the scalp potential field remains semi-stable, suggesting quasi-simultaneity of activity among the nodes of large-scale networks. A few prototypic microstates, which occur in a repetitive sequence across time, can be reliably identified across participants. Researchers have proposed that these microstates represent the basic building blocks of the chain of spontaneous conscious mental processes, and that their occurrence and temporal dynamics determine the quality of mentation. Several studies have further demonstrated that disturbances of mental processes associated with neurological and psychiatric conditions manifest as changes in the temporal dynamics of specific microstates. Combined EEG-fMRI studies and EEG source imaging studies have indicated that EEG microstates are closely associated with resting-state networks as identified using fMRI. The scale-free properties of the time series of EEG microstates explain why similar networks can be observed at such different time scales. The present review will provide an overview of these EEG microstates, available methods for analysis, the functional interpretations of findings regarding these microstates, and their behavioral and clinical correlates.

PMID: 29196270 [PubMed - as supplied by publisher]

Electrocorticography and the early maturation of high-frequency suppression within the default mode network.

Sat, 12/02/2017 - 15:00

Electrocorticography and the early maturation of high-frequency suppression within the default mode network.

J Neurosurg Pediatr. 2017 Dec 01;:1-8

Authors: Weaver KE, Poliakov A, Novotny EJ, Olson JD, Grabowski TJ, Ojemann JG

Abstract
OBJECTIVE The acquisition and refinement of cognitive and behavioral skills during development is associated with the maturation of various brain oscillatory activities. Most developmental investigations have identified distinct patterns of low-frequency electrophysiological activity that are characteristic of various behavioral milestones. In this investigation, the authors focused on the cross-sectional developmental properties of high-frequency spectral power from the brain's default mode network (DMN) during goal-directed behavior. METHODS The authors contrasted regionally specific, time-evolving high gamma power (HGP) in the lateral DMN cortex between 3 young children (age range 3-6 years) and 3 adults by use of electrocorticography (ECoG) recordings over the left perisylvian cortex during a picture-naming task. RESULTS Across all participants, a nearly identical and consistent response suppression of HGP, which is a functional signature of the DMN, was observed during task performance recordings acquired from ECoG electrodes placed over the lateral DMN cortex. This finding provides evidence of relatively early maturation of the DMN. Furthermore, only HGP relative to evoked alpha and beta band power showed this level of consistency across all participants. CONCLUSIONS Regionally specific, task-evoked suppression of the high-frequency components of the cortical power spectrum is established early in brain development, and this response may reflect the early maturation of specific cognitive and/or computational mechanisms.

PMID: 29192865 [PubMed - as supplied by publisher]

Linking functional connectivity and dynamic properties of resting-state networks.

Sat, 12/02/2017 - 15:00

Linking functional connectivity and dynamic properties of resting-state networks.

Sci Rep. 2017 Nov 30;7(1):16610

Authors: Lee WH, Frangou S

Abstract
Spontaneous brain activity is organized into resting-state networks (RSNs) involved in internally-guided, higher-order mental functions (default mode, central executive and salience networks) and externally-driven, specialized sensory and motor processing (auditory, visual and sensorimotor networks). RSNs are characterized by their functional connectivity in terms of within-network cohesion and between-network integration, and by their dynamic properties in terms of synchrony and metastability. We examined the relationship between functional connectivity and dynamic network features using fMRI data and an anatomically constrained Kuramoto model. Extrapolating from simulated data, synchrony and metastability across the RSNs emerged at coupling strengths of 5 ≤ k ≤ 12. In the empirical RSNs, higher metastability and synchrony were respectively associated with greater cohesion and lower integration. Consistent with their dual role in supporting both sustained and diverse mental operations, higher-order RSNs had lower metastability and synchrony. Sensory and motor RSNs showed greater cohesion and metastability, likely to respectively reflect their functional specialization and their greater capacity for altering network states in response to multiple and diverse external demands. Our findings suggest that functional and dynamic RSN properties are closely linked and expand our understanding of the neural architectures that support optimal brain function.

PMID: 29192157 [PubMed - in process]

Resting-state functional connectivity of the dorsal frontal cortex predicts subcortical vascular cognition impairment.

Sat, 12/02/2017 - 15:00

Resting-state functional connectivity of the dorsal frontal cortex predicts subcortical vascular cognition impairment.

Oncotarget. 2017 Nov 03;8(54):93079-93086

Authors: Hu X, Zhou X, Zhang C, Wang H, Yu Y, Sun Z

Abstract
Functional magnetic resonance imaging (fMRI) studies have revealed group differences in the frontal area between the subcortical vascular cognition impairment (SVCI) patients and the controls. However, most of the existing research focused on average differences between the two groups, and therefore had limited clinical applicability. The aim of our study was to investigate whether inter-regions functional connectivity of the dorsal frontal cortex (DFC) can be used to discriminate the SVCI from the controls at the level of the individual. Thirty-two SVCI patients and 32 demographically similar healthy individuals underwent resting-state functional magnetic resonance imaging. The DFC, derived from a prior atlas, was divided into 10 clusters. Features based on DFC were obtained through functional connectivity analysis between pairs of DFC. A nonlinear kernel support vector machine was used for classification and validated using 8-fold cross validation. An excellent classification accuracy was obtained from both the left and the right DFC functional connectivity (accuracy=75.07%, sensitivity=81.57% and specificity=61.71%; accuracy=45.38%, sensitivity=60.74% and specificity=39.48%; P<0.001). These findings shed further light on the pathogenesis of SVCI and showed promising classification performance using machine learning analysis based on DFC fMRI data, which may be useful for the differentiation of SVCI.

PMID: 29190979 [PubMed]

Investigating the effects of subconcussion on functional connectivity using mass-univariate and multivariate approaches.

Fri, 12/01/2017 - 14:00

Investigating the effects of subconcussion on functional connectivity using mass-univariate and multivariate approaches.

Brain Imaging Behav. 2017 Nov 29;:

Authors: Reynolds BB, Stanton AN, Soldozy S, Goodkin HP, Wintermark M, Druzgal TJ

Abstract
There are concerns about the effects of subconcussive head impacts in sport, but the effects of subconcussion on brain connectivity are not well understood. We hypothesized that college football players experience changes in brain functional connectivity not found in athletes competing in lower impact sports or healthy controls. These changes may be spatially heterogeneous across participants, requiring analysis methods that go beyond mass-univariate approaches commonly used in functional MRI (fMRI). To test this hypothesis, we analyzed resting-state fMRI data from college football (n = 15), soccer (n = 12), and lacrosse players (n = 16), and controls (n = 29) collected at preseason and postseason time points. Regional homogeneity (ReHo) and degree centrality (DC) were calculated as measures of local and long-range functional connectivity, respectively. Standard voxel-wise analysis and paired support vector machine (SVM) classification studied subconcussion's effects on local and global functional connectivity. Voxel-wise analyses yielded minimal findings, but SVM classification had high accuracy for college football's ReHo (87%, p = 0.009) and no other group. The findings suggest subconcussion results in spatially heterogeneous changes in local functional connectivity that may only be detectible with multivariate analyses. To determine if voxel-wise and SVM analyses had similar spatial patterns, region-average t-statistic and SVM weight values were compared using a measure of ranking distance. T-statistic and SVM weight rankings exhibited significantly low ranking distance values for all groups and metrics, demonstrating that the analyses converged on a similar underlying effect. Overall, this research suggests that subconcussion in football may produce local functional connectivity changes similar to concussion.

PMID: 29188492 [PubMed - as supplied by publisher]

Predicting Long-Term Cognitive Outcome Following Breast Cancer with Pre-Treatment Resting State fMRI and Random Forest Machine Learning.

Fri, 12/01/2017 - 14:00

Predicting Long-Term Cognitive Outcome Following Breast Cancer with Pre-Treatment Resting State fMRI and Random Forest Machine Learning.

Front Hum Neurosci. 2017;11:555

Authors: Kesler SR, Rao A, Blayney DW, Oakley-Girvan IA, Karuturi M, Palesh O

Abstract
We aimed to determine if resting state functional magnetic resonance imaging (fMRI) acquired at pre-treatment baseline could accurately predict breast cancer-related cognitive impairment at long-term follow-up. We evaluated 31 patients with breast cancer (age 34-65) prior to any treatment, post-chemotherapy and 1 year later. Cognitive testing scores were normalized based on data obtained from 43 healthy female controls and then used to categorize patients as impaired or not based on longitudinal changes. We measured clustering coefficient, a measure of local connectivity, by applying graph theory to baseline resting state fMRI and entered these metrics along with relevant patient-related and medical variables into random forest classification. Incidence of cognitive impairment at 1 year follow-up was 55% and was predicted by classification algorithms with up to 100% accuracy (p < 0.0001). The neuroimaging-based model was significantly more accurate than a model involving patient-related and medical variables (p = 0.005). Hub regions belonging to several distinct functional networks were the most important predictors of cognitive outcome. Characteristics of these hubs indicated potential spread of brain injury from default mode to other networks over time. These findings suggest that resting state fMRI is a promising tool for predicting future cognitive impairment associated with breast cancer. This information could inform treatment decision making by identifying patients at highest risk for long-term cognitive impairment.

PMID: 29187817 [PubMed]

Longitudinal Functional Brain Mapping in Supernormals.

Fri, 12/01/2017 - 14:00

Longitudinal Functional Brain Mapping in Supernormals.

Cereb Cortex. 2017 Nov 23;:1-11

Authors: Wang X, Ren P, Baran TM, Raizada RDS, Mapstone M, Lin F, Alzheimer’s Disease Neuroimaging Initiative

Abstract
Prevention of age-related cognitive decline is an increasingly important topic. Recently, increased attention is being directed at understanding biological models of successful cognitive aging. Here, we examined resting-state brain regional low-frequency oscillations using functional magnetic resonance imaging in 19 older adults with excellent cognitive abilities (Supernormals), 28 older adults with normative cognition, 57 older adults with amnestic mild cognitive impairment, and 26 with Alzheimer's disease. We identified a "Supernormal map", a set of regions whose oscillations were resistant to the aging-associated neurodegenerative process, including the right fusiform gyrus, right middle frontal gyrus, right anterior cingulate cortex, left middle temporal gyrus, left precentral gyrus, and left orbitofrontal cortex. The map was unique to the Supernormals, differentiated this group from cognitive average-ager comparisons, and predicted a 1-year change in global cognition (indexed by the Montreal Cognitive Assessment scores, adjusted R2 = 0.68). The map was also correlated to Alzheimer's pathophysiological features (beta-amyloid/pTau ratio, adjusted R2 = 0.66) in participants with and without cognitive impairment. These findings in phenotypically successful cognitive agers suggest a divergent pattern of brain regions that may either reflect inherent neural integrity that contributes to Supernormals' cognitive success, or alternatively indicate adaptive reorganization to the demands of aging.

PMID: 29186360 [PubMed - as supplied by publisher]

Multimodal connectivity based eloquence score computation and visualisation for computer-aided neurosurgical path planning.

Fri, 12/01/2017 - 14:00

Multimodal connectivity based eloquence score computation and visualisation for computer-aided neurosurgical path planning.

Healthc Technol Lett. 2017 Oct;4(5):152-156

Authors: Bakhshmand SM, Eagleson R, de Ribaupierre S

Abstract
Non-invasive assessment of cognitive importance has been a major challenge for planning of neurosurgical procedures. In the past decade, in vivo brain imaging modalities have been considered for estimating the 'eloquence' of brain areas. In order to estimate the impact of damage caused by an access path towards a target region inside of the skull, multi-modal metrics are introduced in this paper. Accordingly, this estimated damage is obtained by combining multi-modal metrics. In other words, this damage is an aggregate of intervened grey matter volume and axonal fibre numbers, weighted by their importance within the assigned anatomical and functional networks. To validate these metrics, an exhaustive search algorithm is implemented for characterising the solution space and visually representing connectional cost associated with a path initiated from underlying points. In this presentation, brain networks are built from resting state functional magnetic resonance imaging (fMRI) and deterministic tractography. their results demonstrate that the proposed approach is capable of refining traditional heuristics, such as choosing the minimal distance from the lesion, by supplementing connectional importance of the resected tissue. This provides complementary information to help the surgeon in avoiding important functional hubs and their anatomical linkages; which are derived from neuroimaging modalities and incorporated to the related anatomical landmarks.

PMID: 29184656 [PubMed]

On the role of the corpus callosum in interhemispheric functional connectivity in humans.

Fri, 12/01/2017 - 14:00

On the role of the corpus callosum in interhemispheric functional connectivity in humans.

Proc Natl Acad Sci U S A. 2017 Nov 28;:

Authors: Roland JL, Snyder AZ, Hacker CD, Mitra A, Shimony JS, Limbrick DD, Raichle ME, Smyth MD, Leuthardt EC

Abstract
Resting state functional connectivity is defined in terms of temporal correlations between physiologic signals, most commonly studied using functional magnetic resonance imaging. Major features of functional connectivity correspond to structural (axonal) connectivity. However, this relation is not one-to-one. Interhemispheric functional connectivity in relation to the corpus callosum presents a case in point. Specifically, several reports have documented nearly intact interhemispheric functional connectivity in individuals in whom the corpus callosum (the major commissure between the hemispheres) never develops. To investigate this question, we assessed functional connectivity before and after surgical section of the corpus callosum in 22 patients with medically refractory epilepsy. Section of the corpus callosum markedly reduced interhemispheric functional connectivity. This effect was more profound in multimodal associative areas in the frontal and parietal lobe than primary regions of sensorimotor and visual function. Moreover, no evidence of recovery was observed in a limited sample in which multiyear, longitudinal follow-up was obtained. Comparison of partial vs. complete callosotomy revealed several effects implying the existence of polysynaptic functional connectivity between remote brain regions. Thus, our results demonstrate that callosal as well as extracallosal anatomical connections play a role in the maintenance of interhemispheric functional connectivity.

PMID: 29183973 [PubMed - as supplied by publisher]

Exploring the reproducibility of functional connectivity alterations in Parkinson's disease.

Wed, 11/29/2017 - 11:20

Exploring the reproducibility of functional connectivity alterations in Parkinson's disease.

PLoS One. 2017;12(11):e0188196

Authors: Badea L, Onu M, Wu T, Roceanu A, Bajenaru O

Abstract
Since anatomic MRI is presently not able to directly discern neuronal loss in Parkinson's Disease (PD), studying the associated functional connectivity (FC) changes seems a promising approach toward developing non-invasive and non-radioactive neuroimaging markers for this disease. While several groups have reported such FC changes in PD, there are also significant discrepancies between studies. Investigating the reproducibility of PD-related FC changes on independent datasets is therefore of crucial importance. We acquired resting-state fMRI scans for 43 subjects (27 patients and 16 normal controls, with 2 replicate scans per subject) and compared the observed FC changes with those obtained in two independent datasets, one made available by the PPMI consortium (91 patients, 18 controls) and a second one by the group of Tao Wu (20 patients, 20 controls). Unfortunately, PD-related functional connectivity changes turned out to be non-reproducible across datasets. This could be due to disease heterogeneity, but also to technical differences. To distinguish between the two, we devised a method to directly check for disease heterogeneity using random splits of a single dataset. Since we still observe non-reproducibility in a large fraction of random splits of the same dataset, we conclude that functional heterogeneity may be a dominating factor behind the lack of reproducibility of FC alterations in different rs-fMRI studies of PD. While global PD-related functional connectivity changes were non-reproducible across datasets, we identified a few individual brain region pairs with marginally consistent FC changes across all three datasets. However, training classifiers on each one of the three datasets to discriminate PD scans from controls produced only low accuracies on the remaining two test datasets. Moreover, classifiers trained and tested on random splits of the same dataset (which are technically homogeneous) also had low test accuracies, directly substantiating disease heterogeneity.

PMID: 29182621 [PubMed - in process]

Nicotine-induced activation of caudate and anterior cingulate cortex in response to errors in schizophrenia.

Wed, 11/29/2017 - 11:20
Related Articles

Nicotine-induced activation of caudate and anterior cingulate cortex in response to errors in schizophrenia.

Psychopharmacology (Berl). 2017 Nov 27;:

Authors: Moran LV, Stoeckel LE, Wang K, Caine CE, Villafuerte R, Calderon V, Baker JT, Ongur D, Janes AC, Evins AE, Pizzagalli DA

Abstract
BACKGROUND: Nicotine improves attention and processing speed in individuals with schizophrenia. Few studies have investigated the effects of nicotine on cognitive control. Prior functional magnetic resonance imaging (fMRI) research demonstrates blunted activation of dorsal anterior cingulate cortex (dACC) and rostral anterior cingulate cortex (rACC) in response to error and decreased post-error slowing in schizophrenia.
METHODS: Participants with schizophrenia (n = 13) and healthy controls (n = 12) participated in a randomized, placebo-controlled, crossover study of the effects of transdermal nicotine on cognitive control. For each drug condition, participants underwent fMRI while performing the stop signal task where participants attempt to inhibit prepotent responses to "go (motor activation)" signals when an occasional "stop (motor inhibition)" signal appears. Error processing was evaluated by comparing "stop error" trials (failed response inhibition) to "go" trials. Resting-state fMRI data were collected prior to the task.
RESULTS: Participants with schizophrenia had increased nicotine-induced activation of right caudate in response to errors compared to controls (DRUG × GROUP effect: p corrected < 0.05). Both groups had significant nicotine-induced activation of dACC and rACC in response to errors. Using right caudate activation to errors as a seed for resting-state functional connectivity analysis, relative to controls, participants with schizophrenia had significantly decreased connectivity between the right caudate and dACC/bilateral dorsolateral prefrontal cortices.
CONCLUSIONS: In sum, we replicated prior findings of decreased post-error slowing in schizophrenia and found that nicotine was associated with more adaptive (i.e., increased) post-error reaction time (RT). This proof-of-concept pilot study suggests a role for nicotinic agents in targeting cognitive control deficits in schizophrenia.

PMID: 29181816 [PubMed - as supplied by publisher]

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