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Disrupted Regional Cerebral Blood Flow, Functional Activity and Connectivity in Alzheimer's Disease: A Combined ASL Perfusion and Resting State fMRI Study.

Sun, 08/11/2019 - 01:00
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Disrupted Regional Cerebral Blood Flow, Functional Activity and Connectivity in Alzheimer's Disease: A Combined ASL Perfusion and Resting State fMRI Study.

Front Neurosci. 2019;13:738

Authors: Zheng W, Cui B, Han Y, Song H, Li K, He Y, Wang Z

Abstract
Recent studies have demonstrated a close relationship between regional cerebral blood flow (rCBF) and resting state functional connectivity changes in normal healthy people. However, little is known about the parameter changes in the most vulnerable regions in Alzheimer's disease (AD). Forty AD patients and 30 healthy controls participated in this study. The data of resting-state perfusion and functional magnetic resonance imaging (fMRI) was collected. By using voxel-wise arterial spin labeling (ASL) perfusion, we identified several regions of altered rCBF in AD patients. Then, by using resting state fMRI analysis, including amplitude low frequency fluctuation (ALFF) and seed-based functional connectivity, we investigated the changes of functional activity and connectivity among the identified rCBF regions. We extracted cognition-related parameters and searched for a sensitive biomarker to differentiate the AD patients from the normal controls (NC). Compared with controls, AD patients showed special disruptions in rCBF, which were mainly located in the left posterior cingulate cortex (PCC), the left and right dorsolateral prefrontal cortex (DLPFC), the left inferior parietal lobule (IPL), the right middle temporal gyrus (MTG), the left middle occipital gyrus (MOG), and the left precuneus (PCu). ALFF was performed based on the seven regions identified by the ASL method, and AD patients presented significantly decreased ALFF in the left PCC, left IPL, right MTG, left MOG, and left PCu and increased ALFF in the bilateral DLPFC. We constituted the network based on the seven regions and found that there was decreased connectivity among the identified regions in the AD patients, which predicted a disruption in the default mode network (DMN), executive control network (ECN) and visual network (VN). Furthermore, these abnormal parameters are closely associated with cognitive performances in AD patients. We combined the rCBF and ALFF value of PCC/PCu as a biomarker to differentiate the two groups and reached a sensitivity of 85.3% and a specificity of 88.5%. Our findings suggested that there was disrupted rCBF, functional activity and connectivity in specific cognition-related regions in Alzheimer's disease, which can be used as a valuable imaging biomarker for the diagnosis of AD.

PMID: 31396033 [PubMed]

Spatiotemporal Empirical Mode Decomposition of Resting-State fMRI Signals: Application to Global Signal Regression.

Sun, 08/11/2019 - 01:00
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Spatiotemporal Empirical Mode Decomposition of Resting-State fMRI Signals: Application to Global Signal Regression.

Front Neurosci. 2019;13:736

Authors: Moradi N, Dousty M, Sotero RC

Abstract
Resting-state functional connectivity MRI (rs-fcMRI) is a common method for mapping functional brain networks. However, estimation of these networks is affected by the presence of a common global systemic noise, or global signal (GS). Previous studies have shown that the common preprocessing steps of removing the GS may create spurious correlations between brain regions. In this paper, we decompose fMRI signals into 5 spatial and 3 temporal intrinsic mode functions (SIMF and TIMF, respectively) by means of the empirical mode decomposition (EMD), which is an adaptive data-driven method widely used to analyze non-linear and non-stationary phenomena. For each SIMF, functional connectivity matrices were computed by means of Pearson correlation between TIMFs of different brain areas. Thus, instead of a single connectivity matrix, we obtained 5 × 3 = 15 functional connectivity matrices. Given the high correlation and global efficiency values of the connectivity matrices related to the low spatial maps (SIMF3, SIMF4, and SIMF5), our results suggest that these maps can be considered as spatial global signal masks. Thus, by summing up the first two SIMFs extracted from the fMRI signals, we have automatically excluded the GS which is now voxel-specific. We compared the performance of our method with the conventional GS regression and to the results when the GS was not removed. While the correlation pattern identified by the other methods suffers from a low level of precision in identifying the correct brain network connectivity, our approach demonstrated expected connectivity patterns for the default mode network and task-positive network.

PMID: 31396032 [PubMed]

Distinct Dynamic Functional Connectivity Patterns of Pain and Touch Thresholds: A Resting-state fMRI Study.

Fri, 08/09/2019 - 21:59
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Distinct Dynamic Functional Connectivity Patterns of Pain and Touch Thresholds: A Resting-state fMRI Study.

Behav Brain Res. 2019 Aug 05;:112142

Authors: Yuan Y, Zhang L, Li L, Huang G, Anter A, Liang Z, Zhang Z

Abstract
Dynamic functional connectivity (dFC) analysis based on resting-state functional magnetic resonance imaging (fMRI) has gained popularity in recent years. Despite many studies have linked dFC patterns to various mental diseases and cognitive functions, little research has used dFC in the investigation of low-level sensory perception. The present study is aimed to explore resting-state fMRI dFC patterns correlated with thresholds of two types of perception, pain and touch, on an individual basis. We collected and analyzed resting-state fMRI data and thresholds of pain and touch from 80 healthy participants. dFC states were identified by using independent component analysis, sliding window correlation, and clustering, and then the thresholds of pain and touch are correlated with the occurrence frequencies of dFC states. A new permutation analysis is developed to make identified dFC states more interpretable. We found that the occurrence frequency of a default mode network (DMN)-dominated state was positively correlated with the pain threshold, while the occurrence frequency of a static functional connectivity (sFC)-like state was negatively correlated with the touch threshold. This study showed that the thresholds of pain and touch have distinct dFC correlates, suggesting different influences of baseline brain states on different types of sensory perception. This study also showed that dFC could serve as an indicator of an individual's pain sensitivity, which can be potentially used for pain management.

PMID: 31394144 [PubMed - as supplied by publisher]

Association between dynamic resting-state functional connectivity and ketamine plasma levels in visual processing networks.

Fri, 08/09/2019 - 21:59
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Association between dynamic resting-state functional connectivity and ketamine plasma levels in visual processing networks.

Sci Rep. 2019 Aug 07;9(1):11484

Authors: Spies M, Klöbl M, Höflich A, Hummer A, Vanicek T, Michenthaler P, Kranz GS, Hahn A, Winkler D, Windischberger C, Kasper S, Lanzenberger R

Abstract
Numerous studies demonstrate ketamine's influence on resting-state functional connectivity (rsFC). Seed-based and static rsFC estimation methods may oversimplify FC. These limitations can be addressed with whole-brain, dynamic rsFC estimation methods. We assessed data from 27 healthy subjects who underwent two 3 T resting-state fMRI scans, once under subanesthetic, intravenous esketamine and once under placebo, in a randomized, cross-over manner. We aimed to isolate only highly robust effects of esketamine on dynamic rsFC by using eight complementary methodologies derived from two dynamic rsFC estimation methods, two functionally defined atlases and two statistical measures. All combinations revealed a negative influence of esketamine on dynamic rsFC within the left visual network and inter-hemispherically between visual networks (p < 0.05, corrected), hereby suggesting that esketamine's influence on dynamic rsFC is highly stable in visual processing networks. Our findings may be reflective of ketamine's role as a model for psychosis, a disorder associated with alterations to visual processing and impaired inter-hemispheric connectivity. Ketamine is a highly effective antidepressant and studies have shown changes to sensory processing in depression. Dynamic rsFC in sensory processing networks might be a promising target for future investigations of ketamine's antidepressant properties. Mechanistically, sensitivity of visual networks for esketamine's effects may result from their high expression of NMDA-receptors.

PMID: 31391479 [PubMed - in process]

Neuroimaging adolescents with depression in a middle-income country: feasibility of an fMRI protocol and preliminary results.

Thu, 08/08/2019 - 21:58
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Neuroimaging adolescents with depression in a middle-income country: feasibility of an fMRI protocol and preliminary results.

Braz J Psychiatry. 2019 Aug 05;:

Authors: Battel L, Swartz J, Anes M, Manfro PH, Rohde LA, Viduani A, Mondelli V, Kieling C

Abstract
OBJECTIVE: To test the feasibility and to present preliminary results of a neuroimaging protocol to evaluate adolescent depression in a middle-income setting.
METHODS: We assessed psychotropic medication-free adolescents (age range 14-16 years) with a diagnosis of major depressive disorder (MDD). Participants underwent a comprehensive clinical evaluation and both structural and functional magnetic resonance imaging (fMRI). In this pilot study, a preliminary single-group analysis of resting-state fMRI (rs-fMRI) data was performed, with a focus on the default mode network (DMN), cognitive control network (CCN), and salience network (SN).
RESULTS: The sample included 29 adolescents with MDD (mean age 16.01, SD 0.78) who completed the protocol. Only two participants were excluded due to MRI quality issues (head movement), and were not included in the analyses. The scans showed significant connectivity between the medial prefrontal cortex and posterior cingulate cortex (DMN), the ACC and anterior insula (SN), and the lateral prefrontal cortex and dorsal parietal cortex (CCN).
CONCLUSION: We demonstrated the feasibility of implementing a complex neuroimaging protocol in a middle-income country. Further, our preliminary rs-fMRI data revealed patterns of resting-state connectivity consistent with prior research performed in adolescents from high-income countries.

PMID: 31389498 [PubMed - as supplied by publisher]

Recording brain activity can function as an implied social presence and alter neural connectivity.

Thu, 08/08/2019 - 21:58
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Recording brain activity can function as an implied social presence and alter neural connectivity.

Cogn Neurosci. 2019 Aug 07;:1-8

Authors: Turner BO, Kingstone A, Risko EF, Santander T, Li J, Miller MB

Abstract
People often behave differently when they know they are being watched. Here, we report the first investigation of whether such social presence effects also include brain monitoring technology, and also their impacts on the measured neural activity. We demonstrate that merely informing participants that fMRI has the potential to observe (thought-related) brain activity is sufficient to trigger changes in functional connectivity within and between relevant brain networks that have been previously associated selectively with executive and attentional control as well as self-relevant processing, social cognition, and theory of mind. These results demonstrate that an implied social presence, mediated here by recording brain activity with fMRI, can alter brain functional connectivity. These data provide a new manipulation of social attention, as well as shining light on a methodological hazard for researchers using equipment to monitor brain activity.

PMID: 31389302 [PubMed - as supplied by publisher]

High resolution resting state functional connectivity of the extended amygdala.

Thu, 08/08/2019 - 21:58
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High resolution resting state functional connectivity of the extended amygdala.

Brain Connect. 2019 Aug 07;:

Authors: Weis C, Huggins AA, Bennett KP, Parisi EA, Larson CL

Abstract
The extended amygdala has been implicated as a critical region in the neurocircuitry underlying anxiety. The circuitry of the extended amygdala, including the central (CeA) and basolateral (BLA) nuclei of the amygdala and the bed nucleus of the stria terminalis (BNST), has been well-defined in non-human animals; however, much less is known about the roles and interactions of these structures in humans given their small size. Therefore, the current study used high-resolution 7-Tesla MRI to define, compare, and contrast functional connectivity (FC) of these structures in 57 neurologically healthy young adults. In addition, FC was investigated in relation to self-reported measures of anxiety and intolerance of uncertainty, a key feature of anxiety. Results of the FC analysis of each of the nuclei largely replicated previous work. Conjunction analyses showed nuclei of the extended amygdala shared FC with hippocampal, cingulate, medial prefrontal, and subgenual cortices. Comparison of seed-to-voxel time series correlation maps demonstrated that compared to the BNST, the CeA and BLA were more strongly coupled with parahippocampal, temporal, fusiform, and occipital gyri. Relative to the CeA and BLA, the BNST was more strongly coupled with the anterior caudate and anterior cingulate cortex. Finally, greater trait anxiety and intolerance of uncertainty were related to greater FC of the extended amygdala and posterior cingulate and temporal cortices and decreased FC with the parahippocampal and insular cortices. Results of this study extend previous work to provide more clarity of the nuances of extended amygdala FC and its relationship with anxiety.

PMID: 31389253 [PubMed - as supplied by publisher]

Differentiation of Early Alzheimer's Disease, Mild Cognitive Impairment and Cognitively Healthy Elderly Samples using Multimodal Neuroimaging Indices.

Thu, 08/08/2019 - 21:58
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Differentiation of Early Alzheimer's Disease, Mild Cognitive Impairment and Cognitively Healthy Elderly Samples using Multimodal Neuroimaging Indices.

Brain Connect. 2019 Aug 07;:

Authors: Joshi H, Bharath S, Balachandar R, Sadanand S, Vishwakarma H, Aiyappan S, Saini J, Kumar KJ, John JP, Varghese M

Abstract
Brain resting state functional connectivity, white matter integrity and cortical morphometry as well as neuropsychological performance have seldom been studied together to differentiate Alzheimer's disease (AD), mild cognitive impairment (MCI) and elderly cognitively healthy comparison (eCHC) samples in the context of the same study. We examined brain resting state functional connectivity (rsFC) in samples of patients with mild AD (n=50) and MCI (n=49) in comparison to eCHC samples (n=48) and then explored whether rsFC abnormalities can be linked to underlying gray matter volumetric and/or white matter microstructural abnormalities. The mild AD sample showed significantly increased rsFC in Executive control network (ECN) and Dorsal attention network (DAN) compared to eCHC sample, and increased rsFC in ECN compared to MCI. Brain regions corresponding to both these resting state networks (RSNs) showed significant reduction in fractional anisotropy in mild AD in comparison to eCHC. Significant gray matter volumetric reductions were observed in brain regions corresponding to both RSNs in the mild AD sample compared to MCI as well as eCHC samples. The association of Default mode network (DMN)-DAN anticorrelation with cognitive performances differentiated mild AD and MCI from eCHC sample. These findings highlight the association between brain structural and functional abnormalities as well as cognitive impairment that enables differentiation between early AD, MCI and eCHC samples.

PMID: 31389245 [PubMed - as supplied by publisher]

Genetic and environmental influences on functional connectivity within and between canonical cortical resting-state networks throughout adolescent development in boys and girls.

Wed, 08/07/2019 - 18:57

Genetic and environmental influences on functional connectivity within and between canonical cortical resting-state networks throughout adolescent development in boys and girls.

Neuroimage. 2019 Aug 03;:116073

Authors: Teeuw J, Brouwer RM, Guimarães JPOFT, Brandner P, Koenis MMG, Swagerman SC, Verwoert M, Boomsma DI, Hulshoff Pol HE

Abstract
The human brain is active during rest and hierarchically organized into intrinsic functional networks. These functional networks are largely established early in development, with reports of a shift from a local to more distributed organization during childhood and adolescence. It remains unknown to what extent genetic and environmental influences on functional connectivity change throughout adolescent development. We measured functional connectivity within and between eight cortical networks in a longitudinal resting-state fMRI study of adolescent twins and their older siblings on two occasions (mean ages 13 and 18 years). We modelled the reliability for these inherently noisy and head-motion sensitive measurements by analyzing data from split-half sessions. Functional connectivity between resting-state networks decreased with age whereas functional connectivity within resting-state networks generally increased with age, independent of general cognitive functioning. Sex effects were sparse, with stronger functional connectivity in the default mode network for girls compared to boys, and stronger functional connectivity in the salience network for boys compared to girls. Heritability explained up to 53% of the variation in functional connectivity within and between resting-state networks, and common environment explained up to 33%. Genetic influences on functional connectivity remained stable during adolescent development. In conclusion, longitudinal age-related changes in functional connectivity within and between cortical resting-state networks are subtle but wide-spread throughout adolescence. Genes play a considerable role in explaining individual variation in functional connectivity with mostly stable influences throughout adolescence.

PMID: 31386921 [PubMed - as supplied by publisher]

Acute Exercise Effects Predict Training Change in Cognition and Connectivity.

Wed, 08/07/2019 - 18:57

Acute Exercise Effects Predict Training Change in Cognition and Connectivity.

Med Sci Sports Exerc. 2019 Aug 02;:

Authors: Voss MW, Weng TB, Narayana-Kumanan K, Cole RC, Wharff C, Reist L, DuBose L, Sigurdsson G, Mills JA, Long JD, Magnotta VA, Pierce GL

Abstract
PURPOSE: Previous studies report memory and functional connectivity of memory systems improve acutely after a single aerobic exercise session or with training, suggesting the acute effects of aerobic exercise may reflect initial changes that adapt over time. In this trial, for the first time, we test the proof-of-concept of whether the acute and training effects of aerobic exercise on working memory and brain network connectivity are related in the same participants.
METHODS: Cognitively normal older participants (N=34) were enrolled in a randomized clinical trial (NCT02453178). Participants completed fMRI resting state and a face working memory N-back task acutely after light and moderate intensity exercise and after a 12-week aerobic training intervention.
RESULTS: Functional connectivity did not change more after moderate compared with light intensity training. However, both training groups showed similar changes in cardiorespiratory fitness (maximal exercise oxygen uptake, VO2peak), limiting group-level comparisons. Acute effects of moderate intensity aerobic exercise on hippocampal-cortical connections in the default network predicted training enhancements in the same connections. Working memory also improved acutely, especially following moderate intensity, and greater acute improvements predicted greater working memory improvement with training. Exercise effects on functional connectivity of right lateralized fronto-parietal connections were related to both acute and training gains in working memory.
CONCLUSION: Our data support the concept of acute aerobic exercise effects on functional brain systems and performance as an activity-evoked biomarker for exercise training benefits in the same outcomes. These findings may lead to new insights and methods for improving memory outcomes with aerobic exercise training.

PMID: 31385912 [PubMed - as supplied by publisher]

The State of Resting State Networks.

Wed, 08/07/2019 - 18:57

The State of Resting State Networks.

Top Magn Reson Imaging. 2019 Aug;28(4):189-196

Authors: Seitzman BA, Snyder AZ, Leuthardt EC, Shimony JS

Abstract
Functional MRI (fMRI) is currently used for pre-surgical planning, but is often limited to information on the motor and language systems. Resting state fMRI can provide more information on multiple other networks to the neurosurgeon and neuroradiologist; however, currently, these networks are not well known among clinicians. The purpose of this manuscript is to provide an introduction to these networks for the clinician and to discuss how they could be used in the future for precise and individualized surgical planning. We provide a short introduction to resting state fMRI and discuss multiple currently accepted resting state networks with a review of the literature. We review the characteristics and function of multiple somatosensory, association, and other networks. We discuss the concept of critical nodes in the brain and how the neurosurgeon can use this information to individually customize patient care. Although further research is necessary, future application of pre-surgical planning will require consideration of networks other than just motor and language in order to minimize post-surgical morbidity and customize patient care.

PMID: 31385898 [PubMed - in process]

Cingulo-opercular adaptive control for younger and older adults during a challenging gap detection task.

Wed, 08/07/2019 - 18:57
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Cingulo-opercular adaptive control for younger and older adults during a challenging gap detection task.

J Neurosci Res. 2019 Aug 05;:

Authors: Vaden KI, Eckert MA, Dubno JR, Harris KC

Abstract
Cingulo-opercular activity is hypothesized to reflect an adaptive control function that optimizes task performance through adjustments in attention and behavior, and outcome monitoring. While auditory perceptual task performance appears to benefit from elevated activity in cingulo-opercular regions of frontal cortex before stimuli are presented, this association appears reduced for older adults compared to younger adults. However, adaptive control function may be limited by difficult task conditions for older adults. An fMRI study was used to characterize adaptive control differences while 15 younger (average age = 24 years) and 15 older adults (average age = 68 years) performed a gap detection in noise task designed to limit age-related differences. During the fMRI study, participants listened to a noise recording and indicated with a button-press whether it contained a gap. Stimuli were presented between sparse fMRI scans (TR = 8.6 s) and BOLD measurements were collected during separate listening and behavioral response intervals. Age-related performance differences were limited by presenting gaps in noise with durations calibrated at or above each participant's detection threshold. Cingulo-opercular BOLD increased significantly throughout listening and behavioral response intervals, relative to a resting baseline. Correct behavioral responses were significantly more likely on trials with elevated pre-stimulus cingulo-opercular BOLD, consistent with an adaptive control framework. Cingulo-opercular adaptive control estimates appeared higher for participants with better gap sensitivity and lower response bias, irrespective of age, which suggests that this mechanism can benefit performance across the lifespan under conditions that limit age-related performance differences.

PMID: 31385349 [PubMed - as supplied by publisher]

Evidence of altered brain network centrality in patients with diabetic nephropathy and retinopathy: an fMRI study using a voxel-wise degree centrality approach.

Wed, 08/07/2019 - 18:57
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Evidence of altered brain network centrality in patients with diabetic nephropathy and retinopathy: an fMRI study using a voxel-wise degree centrality approach.

Ther Adv Endocrinol Metab. 2019;10:2042018819865723

Authors: Wang Y, Jiang L, Wang XY, Chen W, Shao Y, Chen QK, Lv JL

Abstract
Background: Over recent years, some researchers believe that diabetic nephropathy (DN) and diabetic retinopathy (DR) both independently increase the incidence of brain diseases, such as stroke, cerebral infarction, and cerebral hemorrhage. In the present study, we used the voxel-wise degree centrality (DC) method to investigate potential changes of functional network brain activity in patients with DN and retinopathy (DNR).
Methods: Twenty DNR patients (9 men, 11 women) and 20 healthy controls (HCs; 9 men, 11 women) were recruited; the controls were matched for age, sex, and educational background. All subjects underwent resting-state functional magnetic resonance imaging. Ophthalmoscopy, renal biopsy and single-photon emission computed tomography were used to evaluate microvascular lesions in the eye and kidney. Data were categorized using receiver operating characteristic curves, and correlation analysis was performed using Pearson's correlation analysis.
Results: Compared with HCs, DNR patients showed reduced mean DC values in the right inferior temporal gyrus (RITG) and left subcallosal gyrus regions (LSG) and increased mean DC values in the bilateral precuneus (BP). Moreover, mean DC in the BP was correlated with renal estimated glomerular filtration rate (eGFR; r = 0.762). The area under the curve (AUC) value was 0.829 for BP and 0.839 for RITG and LSG.
Conclusion: DNR patients showed dysfunction in three different brain regions. The linear correlation between eGFR and mean brain DC values indicates the presence of common diabetic microangiopathy in the brain and kidney, which may provide new ideas for multiorgan microvascular lesions of diabetics.

PMID: 31384421 [PubMed]

RIGHT STRUCTURAL AND FUNCTIONAL REORGANIZATION IN 4-YEAR-OLD CHILDREN WITH PERINATAL ARTERIAL ISCHEMIC STROKE PREDICT LANGUAGE PRODUCTION.

Wed, 08/07/2019 - 18:57
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RIGHT STRUCTURAL AND FUNCTIONAL REORGANIZATION IN 4-YEAR-OLD CHILDREN WITH PERINATAL ARTERIAL ISCHEMIC STROKE PREDICT LANGUAGE PRODUCTION.

eNeuro. 2019 Aug 05;:

Authors: François C, Ripollés P, Ferreri L, Muchart J, Sierpowska J, Fons C, Solé J, Rebollo M, Zatorre RJ, Garcia-Alix A, Bosch L, Rodriguez-Fornells A

Abstract
Brain imaging methods have contributed to shed light on the mechanisms of recovery after early brain insult. The assumption that the unaffected right hemisphere can take over language functions after left perinatal stroke is still under debate. Here, we report how patterns of brain structural and functional reorganization were associated with language outcomes in a group of 4-year-old children with left perinatal arterial ischemic stroke. Specifically, we gathered specific fine-grained developmental measures of receptive and productive aspects of language as well as standardized measures of cognitive development. We also collected structural neuroimaging data as well as functional activations during a passive listening story-telling fMRI task and a resting state session (rs-fMRI). Children with a left perinatal stroke showed larger lateralization indices of both structural and functional connectivity of the dorsal language pathway towards the right hemisphere that, in turn, were associated with better language outcomes. Importantly, the pattern of structural asymmetry was significantly more right-lateralized in children with a left perinatal brain insult than in a group of matched healthy controls. These results strongly suggest that early lesions of the left dorsal pathway and the associated perisylvian regions can induce the inter-hemispheric transfer of language functions to right homolog regions. This study provides combined evidence of structural and functional brain reorganization of language networks after early stroke with strong implications for neurobiological models of language development.Significance statement The prevalent theories explaining the functional recovery of language functions after perinatal ischemic stroke strikingly differ on the role of perilesional functionally spared regions as opposed to the homologous non-affected contralesional brain areas. Here, we assessed how patterns of brain functional and structural reorganization were associated with language outcomes in a group of 4-year-old children with left perinatal arterial ischemic stroke. Larger lateralization indices of both functional and structural connectivity towards the right hemisphere were associated with higher levels of language development. Thus, inter-hemispheric plasticity through structural and functional hyper-connectivity mechanisms might be crucial in early damage, probably through the degeneration of neurons projecting from temporal to frontal areas together with contralateral axonal sprouting over the right hemisphere.

PMID: 31383726 [PubMed - as supplied by publisher]

Aberrant Brain Activity at Early Delay Stage Post-radiotherapy as a Biomarker for Predicting Neurocognitive Dysfunction Late-Delayed in Patients With Nasopharyngeal Carcinoma.

Tue, 08/06/2019 - 18:57

Aberrant Brain Activity at Early Delay Stage Post-radiotherapy as a Biomarker for Predicting Neurocognitive Dysfunction Late-Delayed in Patients With Nasopharyngeal Carcinoma.

Front Neurol. 2019;10:752

Authors: Yang Y, Lin X, Li J, Han L, Li Z, Liu S, Hou G, Xie C, Lv X, Qiu Y

Abstract
Background: Increasing evidence indicates that early radiation-induced subtle cerebral changes may be the precursors to permanent brain dysfunction at the late-delayed (LDS) post-radiotherapy (RT) stage. In this study, we aim to track the RT-related longitudinal brain activity in nasopharyngeal carcinoma (NPC) patients and to determine whether early abnormal brain activity can predict late neurocognitive dysfunction after RT. Methods: Thirty-three NPC patients were finally included and longitudinally followed up at the following time points: prior to treatment initiation, early-delayed stage (EDS, 1-3 months), and LDS (six months) after RT. Fifteen comparable healthy controls (HCs) were finally included and followed up in parallel. Montreal Cognitive Assessment (MoCA) was used to assess the general cognitive function. Brain activity was recorded via resting-state fMRI and regional homogeneity (ReHo). A whole-brain voxel-wise-based one-way repeated-measure analysis of variance (ANOVA) was conducted to evaluate the longitudinal ReHo changes among the three time points for NPC patients and HCs, respectively. Results were reported at the significant level of a threshold of two-tailed voxel-wise P < 0.01 and cluster level P < 0.05 with Gaussian Random Field (GRF) correction. Finally, the efficacies of the aberrant ReHo at EDS for predicting the cognitive impairment at LDS in NPC patients were evaluated. Results: Significant differences were detected in ReHo among the three time points in NPC patients but not in HCs. Aberrant ReHo was distributed in the bilateral cerebellum, the right temporal lobe, and the left insular areas, which showed different dynamic changes patterns over time. Logistic regression model combining the mean ReHo, age, and irradiation dose on the bilateral temporal lobe had the highest diagnostic efficiency according to the area under the curve (AUC) score (AUC = 0.752, P = 0.023). Conclusions: The post-RT brain activity revealed by ReHo in NPC patients was dynamic, complex, and multifactorial. Furthermore, the combination of the aberrant ReHo at EDS, age, and irradiation dose may serve as a potential biomarker of the RT-induced cognitive impairments at LDS.

PMID: 31379710 [PubMed]

Changes in Resting-State Functional Connectivity of the Hippocampus Following Cognitive Effort Predict Memory Decline at Older Age-A Longitudinal fMRI Study.

Tue, 08/06/2019 - 18:57

Changes in Resting-State Functional Connectivity of the Hippocampus Following Cognitive Effort Predict Memory Decline at Older Age-A Longitudinal fMRI Study.

Front Aging Neurosci. 2019;11:163

Authors: Oren N, Ash EL, Shapira-Lichter I, Elkana O, Reichman-Eisikovits O, Chomsky L, Lerner Y

Abstract
Memory decline is a feature of some, but not all, healthy older adults. The neural patterns of this variability are still largely unknown. We examined the resting-state functional connectivity (RSFC) of older and younger adults before and after cognitive effort as an underlying feature for subsequent memory changes, focusing on the RSFC between the left anterior hippocampus (laHC) and the posterior hippocampi (pHC). Results showed that for younger adults, post-effort increases in laHC-pHC RSFC were related to increases in RSFC between the laHC and the hubs of the default mode network (DMN). However, for older adults, post-effort increases in the RSFC of laHC-pHC were related to decreases in the RSFC of the laHC and right precentral gyrus. Thus, the correlation between intra-HC and inter-HC RSFC was altered with cognitive effort and aging. Importantly, older adults who had lower post-effort RSFC between the laHC and the pHC demonstrated a decline in episodic memory 2 years later. Hence, the change in intra-HC RSFC following cognitive effort was able to predict subsequent memory function with aging in our sample.

PMID: 31379554 [PubMed]

Motor-Cognitive Neural Network Communication Underlies Walking Speed in Community-Dwelling Older Adults.

Tue, 08/06/2019 - 18:57

Motor-Cognitive Neural Network Communication Underlies Walking Speed in Community-Dwelling Older Adults.

Front Aging Neurosci. 2019;11:159

Authors: Poole VN, Lo OY, Wooten T, Iloputaife I, Lipsitz LA, Esterman M

Abstract
While walking was once thought to be a highly automated process, it requires higher-level cognition with older age. Like other cognitive tasks, it also becomes further challenged with increased cognitive load (e.g., the addition of an unrelated dual task) and often results in poorer performance (e.g., slower speed). It is not well known, however, how intrinsic neural network communication relates to walking speed, nor to this "cost" to gait performance; i.e., "dual-task cost (DTC)." The current study investigates the relationship between network connectivity, using resting-state functional MRI (rs-fMRI), and individual differences in older adult walking speed. Fifty participants (35 females; 84 ± 4.5 years) from the MOBILIZE Boston Study cohort underwent an MRI protocol and completed a gait assessment during two conditions: walking quietly at a preferred pace and while concurrently performing a serial subtraction task. Within and between neural network connectivity measures were calculated from rs-fMRI and were correlated with walking speeds and the DTC (i.e., the percent change in speed between conditions). Among the rs-fMRI correlates, faster walking was associated with increased connectivity between motor and cognitive networks and decreased connectivity between limbic and cognitive networks. Smaller DTC was associated with increased connectivity within the motor network and increased connectivity between the ventral attention and executive networks. These findings support the importance of both motor network integrity as well as inter-network connectivity amongst higher-level cognitive networks in older adults' ability to maintain mobility, particularly under dual-task (DT) conditions.

PMID: 31379552 [PubMed]

Emotion Regulation of Hippocampus Using Real-Time fMRI Neurofeedback in Healthy Human.

Tue, 08/06/2019 - 18:57

Emotion Regulation of Hippocampus Using Real-Time fMRI Neurofeedback in Healthy Human.

Front Hum Neurosci. 2019;13:242

Authors: Zhu Y, Gao H, Tong L, Li Z, Wang L, Zhang C, Yang Q, Yan B

Abstract
Real-time functional magnetic resonance imaging neurofeedback (rtfMRI-NF) is a prospective tool to enhance the emotion regulation capability of participants and to alleviate their emotional disorders. The hippocampus is a key brain region in the emotional brain network and plays a significant role in social cognition and emotion processing in the brain. However, few studies have focused on the emotion NF of the hippocampus. This study investigated the feasibility of NF training of healthy participants to self-regulate the activation of the hippocampus and assessed the effect of rtfMRI-NF on the hippocampus before and after training. Twenty-six right-handed healthy volunteers were randomly assigned to the experimental group receiving hippocampal rtfMRI-NF (n = 13) and the control group (CG) receiving rtfMRI-NF from the intraparietal sulcus rtfMRI-NF (n = 13) and completed a total of four NF runs. The hippocampus and the intraparietal sulcus were defined based on the Montreal Neurological Institute (MNI) standard template, and NF signal was measured as a percent signal change relative to the baseline obtained by averaging the fMRI signal for the preceding 20 s long rest block. NF signal (percent signal change) was updated every 2 s and was displayed on the screen. The amplitude of low-frequency fluctuation and regional homogeneity values was calculated to evaluate the effects of NF on spontaneous neural activity in resting-state fMRI. A standard general linear model (GLM) analysis was separately conducted for each fMRI NF run. Results showed that the activation of hippocampus increased after four NF training runs. The hippocampal activity of the experiment group participants was higher than that of the CG. They also showed elevated hippocampal activity and the greater amygdala-hippocampus connectivity. The anterior temporal lobe, parahippocampal gyrus, hippocampus, and amygdala of brain regions associated with emotional processing were activated during training. We presented a proof-of-concept study using rtfMRI-NF for hippocampus up-regulation in the recall of positive autobiographical memories. The current study may provide a new method to regulate our emotions and can potentially be applied to the clinical treatment of emotional disorders.

PMID: 31379539 [PubMed]

Bias Introduced by Multiple Head Coils in MRI Research: An 8 Channel and 32 Channel Coil Comparison.

Tue, 08/06/2019 - 18:57

Bias Introduced by Multiple Head Coils in MRI Research: An 8 Channel and 32 Channel Coil Comparison.

Front Neurosci. 2019;13:729

Authors: Panman JL, To YY, van der Ende EL, Poos JM, Jiskoot LC, Meeter LHH, Dopper EGP, Bouts MJRJ, van Osch MJP, Rombouts SARB, van Swieten JC, van der Grond J, Papma JM, Hafkemeijer A

Abstract
Neuroimaging MRI data in scientific research is increasingly pooled, but the reliability of such studies may be hampered by the use of different hardware elements. This might introduce bias, for example when cross-sectional studies pool data acquired with different head coils, or when longitudinal clinical studies change head coils halfway. In the present study, we aimed to estimate this possible bias introduced by using different head coils to create awareness and to avoid misinterpretation of results. We acquired, with both an 8 channel and 32 channel head coil, T1-weighted, diffusion tensor imaging and resting state fMRI images at 3T MRI (Philips Achieva) with stable acquisition parameters in a large group of cognitively healthy participants (n = 77). Standard analysis methods, i.e., voxel-based morphometry, tract-based spatial statistics and resting state functional network analyses, were used in a within-subject design to compare 8 and 32 channel head coil data. Signal-to-noise ratios (SNR) for both head coils showed similar ranges, although the 32 channel SNR profile was more homogeneous. Our data demonstrates specific patterns of gray and white matter volume differences between head coils (relative volume change of 6 to 9%), related to altered image contrast and therefore, altered tissue segmentation. White matter connectivity (fractional anisotropy and diffusivity measures) showed hemispherical dependent differences between head coils (relative connectivity change of 4 to 6%), and functional connectivity in resting state networks was higher using the 32 channel head coil in posterior cortical areas (relative change up to 27.5%). This study shows that, even when acquisition protocols are harmonized, the results of standardized analysis models can be severely affected by the use of different head coils. Researchers should be aware of this when combining multiple neuroimaging MRI datasets, to prevent coil-related bias and avoid misinterpretation of their findings.

PMID: 31379483 [PubMed]

Close yet independent: Dissociation of social from valence and abstract semantic dimensions in the left anterior temporal lobe.

Tue, 08/06/2019 - 18:57
Related Articles

Close yet independent: Dissociation of social from valence and abstract semantic dimensions in the left anterior temporal lobe.

Hum Brain Mapp. 2019 Aug 04;:

Authors: Wang X, Wang B, Bi Y

Abstract
The anterior temporal lobe (ATL) is engaged in various types of semantic dimensions. One consistently reported dimension is social information, with abstract words describing social behaviors inducing stronger activations in the ATL than nonsocial words. One potential factor that has been systematically confounded in this finding is emotional valence, given that abstract social words tend to be associated with emotional feelings. We investigated which factors drove the ATL sensitivity using a 2 (social/nonsocial) × 2 (valenced/neutral) factorial design in an fMRI study with relatively high spatial resolutions. We found that sociality and valence were processed in different ATL regions without significant interactions: The social effect was found in the left anterior superior temporal sulcus (aSTS), whereas the valence effect activated small clusters in the bilateral temporal poles (TP). In the left ATL, the social- and valence-related clusters were distinct from another superior ATL area that exhibited a general "abstractness" effect with little modulation of sociality or valence. These subregions exhibited distinct whole-brain functional connectivity patterns during the resting state, with the social cluster functionally connected to the default mode network, the valence cluster connected to the adjacent temporal regions and amygdala, and the abstractness cluster connected to a distributed network including a set of language-related regions. These results of activation profiles and connectivity patterns together indicate that the way in which the left ATL supports semantic processing is highly fine-grained, with the neural substrate for social semantic effects dissociated from those for emotional valence and abstractness.

PMID: 31379052 [PubMed - as supplied by publisher]