Most recent paper

Subscribe to Most recent paper feed Most recent paper
NCBI: db=pubmed; Term="resting"[All Fields] AND "fMRI"[All Fields]
Updated: 4 hours 17 min ago

Impaired frontostriatal functional connectivity among chronic opioid using pain patients is associated with dysregulated affect.

Fri, 04/05/2019 - 20:45
Related Articles

Impaired frontostriatal functional connectivity among chronic opioid using pain patients is associated with dysregulated affect.

Addict Biol. 2019 Apr 04;:

Authors: McConnell PA, Garland EL, Zubieta JK, Newman-Norlund R, Powers S, Froeliger B

Abstract
Preclinical studies have shown effects of chronic exposure to addictive drugs on glutamatergic-mediated neuroplasticity in frontostriatal circuitry. These initial findings have been paralleled by human functional magnetic resonance imaging (fMRI) research demonstrating weaker frontostriatal resting-state functional connectivity (rsFC) among individuals with psychostimulant use disorders. However, there is a dearth of human imaging literature describing associations between long-term prescription opioid use, frontostriatal rsFC, and brain morphology among chronic pain patients. We hypothesized that prescription opioid users with chronic pain, as compared with healthy control subjects, would evidence weaker frontostriatal rsFC coupled with less frontostriatal gray matter volume (GMV). Further, those opioid use-related deficits in frontostriatal circuitry would be associated with negative affect and drug misuse. Prescription opioid users with chronic pain (n = 31) and drug-free healthy controls (n = 30) underwent a high-resolution anatomical and an eyes-closed resting-state functional scan. The opioid group, relative to controls, exhibited weaker frontostriatal rsFC, and less frontostriatal GMV in both L.NAc and L.vmPFC. Frontostriatal rsFC partially mediated group differences in negative affect. Within opioid users, L.NAc GMV predicted opioid misuse severity. The current study revealed that prescription opioid use in the context of chronic pain is associated with functional and structural abnormalities in frontostriatal circuitry. These results suggest that opioid use-related abnormalities in frontostriatal circuitry may undergird disturbances in affect that may contribute to the ongoing maintenance of opioid use and misuse. These findings warrant further examination of interventions to treat opioid pathophysiology in frontostriatal circuitry over the course of treatment.

PMID: 30945801 [PubMed - as supplied by publisher]

Individualized Connectome-Targeted Transcranial Magnetic Stimulation for Neuropsychiatric Sequelae of Repetitive Traumatic Brain Injury in a Retired NFL Player.

Fri, 04/05/2019 - 20:45
Related Articles

Individualized Connectome-Targeted Transcranial Magnetic Stimulation for Neuropsychiatric Sequelae of Repetitive Traumatic Brain Injury in a Retired NFL Player.

J Neuropsychiatry Clin Neurosci. 2019 Apr 03;:appineuropsych18100230

Authors: Siddiqi SH, Trapp NT, Shahim P, Hacker CD, Laumann TO, Kandala S, Carter AR, Brody DL

Abstract
OBJECTIVE:: The recent advent of individualized resting-state network mapping (RSNM) has revealed substantial interindividual variability in anatomical localization of brain networks identified by using resting-state functional MRI (rsfMRI). RSNM enables personalized targeting of focal neuromodulation techniques such as repetitive transcranial magnetic stimulation (rTMS). rTMS is believed to exert antidepressant efficacy by modulating connectivity between the stimulation site, the default mode network (DMN), and the subgenual anterior cingulate cortex (sgACC). Personalized rTMS may be particularly useful after repetitive traumatic brain injury (TBI), which is associated with neurodegenerative tauopathy in medial temporal limbic structures. These degenerative changes are believed to be related to treatment-resistant neurobehavioral disturbances observed in many retired athletes.
METHODS:: The authors describe a case in which RSNM was successfully used to target rTMS to treat these neuropsychiatric disturbances in a retired NFL defensive lineman whose symptoms were not responsive to conventional treatments. RSNM was used to identify left-right dorsolateral prefrontal rTMS targets with maximal difference between dorsal attention network and DMN correlations. These targets were spatially distinct from those identified by prior methods. Twenty sessions of left-sided excitatory and right-sided inhibitory rTMS were administered at these targets.
RESULTS:: Treatment led to improvement in Montgomery-Åsberg Depression Rating Scale (72%), cognitive testing, and headache scales scores. Compared with healthy individuals and subjects with TBI-associated depression, baseline rsfMRI revealed substantially elevated DMN connectivity with the medial temporal lobe (MTL). Serial rsfMRI scans revealed gradual improvement in MTL-DMN connectivity and stimulation site connectivity with sgACC.
CONCLUSIONS:: These results highlight the possibility of individualized neuromodulation and biomarker-based monitoring for neuropsychiatric sequelae of repetitive TBI.

PMID: 30945588 [PubMed - as supplied by publisher]

A 204-subject multimodal neuroimaging dataset to study language processing.

Fri, 04/05/2019 - 20:45
Related Articles

A 204-subject multimodal neuroimaging dataset to study language processing.

Sci Data. 2019 Apr 03;6(1):17

Authors: Schoffelen JM, Oostenveld R, Lam NHL, Uddén J, Hultén A, Hagoort P

Abstract
This dataset, colloquially known as the Mother Of Unification Studies (MOUS) dataset, contains multimodal neuroimaging data that has been acquired from 204 healthy human subjects. The neuroimaging protocol consisted of magnetic resonance imaging (MRI) to derive information at high spatial resolution about brain anatomy and structural connections, and functional data during task, and at rest. In addition, magnetoencephalography (MEG) was used to obtain high temporal resolution electrophysiological measurements during task, and at rest. All subjects performed a language task, during which they processed linguistic utterances that either consisted of normal or scrambled sentences. Half of the subjects were reading the stimuli, the other half listened to the stimuli. The resting state measurements consisted of 5 minutes eyes-open for the MEG and 7 minutes eyes-closed for fMRI. The neuroimaging data, as well as the information about the experimental events are shared according to the Brain Imaging Data Structure (BIDS) format. This unprecedented neuroimaging language data collection allows for the investigation of various aspects of the neurobiological correlates of language.

PMID: 30944338 [PubMed - in process]

Brain Functional Networks in Type 2 Diabetes Mellitus Patients: A Resting-State Functional MRI Study.

Thu, 04/04/2019 - 20:44
Related Articles

Brain Functional Networks in Type 2 Diabetes Mellitus Patients: A Resting-State Functional MRI Study.

Front Neurosci. 2019;13:239

Authors: Xu J, Chen F, Liu T, Wang T, Zhang J, Yuan H, Wang M

Abstract
Background: Previous diabetes mellitus studies of cognitive impairments in the early stages have focused on changes in brain structure and function, and more recently the focus has shifted to the relationships between encephalic regions and diversification of network topology. However, studies examining network topology in diabetic brain function are still limited.
Methods: The study included 102 subjects; 55 type 2 diabetes mellitus (T2DM) patients plus 47 healthy controls. All subjects were examined by resting-state functional magnetic resonance imaging (rs-fMRI) scan. According to Automated Anatomical Labeling, the brain was divided into 90 anatomical regions, and every region corresponds to a brain network analysis node. The whole brain functional network was constructed by thresholding the correlation matrices of the 90 brain regions, and the topological properties of the network were computed based on graph theory. Then, the topological properties of the network were compared between different groups by using a non-parametric test. Finally, the associations between differences in topological properties and the clinical indicators were analyzed.
Results: The brain functional networks of both T2DM patients and healthy controls were found to possess small-world characteristics, i.e., normalized clustering coefficient (γ) > 1, and normalized characteristic path length (λ) close to 1. No significant differences were found in the small-world characteristics (σ). Second, the T2DM patient group displayed significant differences in node properties in certain brain regions. Correlative analytic results showed that the node degree of the right inferior temporal gyrus (ITG) and the node efficiencies of the right ITG and superior temporal gyrus of T2DM patients were positively correlated with body mass index.
Conclusion: The brain network of T2DM patients has the same small-world characteristics as normal people, but the normalized clustering coefficient is higher and the normalized characteristic path length is lower than that of the normal control group, indicating that the brain function network of the T2DM patients has changed. The changes of node properties were mostly concentrated in frontal lobe, temporal lobe and posterior cingulate gyrus. The abnormal changes in these indices in T2DM patients might be explained as a compensatory behavior to reduce cognitive impairments, which is achieved by mobilizing additional neural resources, such as the excessive activation of the network and the efficient networking of multiple brain regions.

PMID: 30941007 [PubMed]

Interhemispheric functional connectivity in the zebra finch brain, absent the corpus callosum in normal ontogeny.

Thu, 04/04/2019 - 20:44
Related Articles

Interhemispheric functional connectivity in the zebra finch brain, absent the corpus callosum in normal ontogeny.

Neuroimage. 2019 Mar 30;:

Authors: Layden EA, Schertz KE, London SE, Berman MG

Abstract
Bilaterally symmetric intrinsic brain activity (homotopic functional connectivity; FC) is a fundamental feature of the mammalian brain's functional architecture. In mammals, homotopic FC is primarily mediated by the corpus callosum (CC), a large interhemispheric white matter tract thought to balance the bilateral coordination and hemispheric specialization critical for many complex brain functions, including human language. The CC first emerged with the Eutherian (placental) mammals ∼160 MYA and is not found among other vertebrates. Despite this, other vertebrates also exhibit complex brain functions requiring hemispheric specialization and coordination. For example, the zebra finch (Taeniopygia guttata) songbird learns to sing from tutors much as humans acquire speech and must balance hemispheric specialization and coordination to successfully learn and produce song. We therefore tested whether the zebra finch also exhibits homotopic FC, despite lacking the CC. Resting-state fMRI analyses demonstrated widespread homotopic FC throughout the zebra finch brain across development, including within a network required for learned song that lacks direct interhemispheric structural connectivity. The presence of homotopic FC in a non-Eutherian suggests that ancestral pathways, potentially including indirect connectivity via the anterior commissure, are sufficient for maintaining a homotopic functional architecture, an insight with broad implications for understanding interhemispheric coordination across phylogeny.

PMID: 30940612 [PubMed - as supplied by publisher]

The motor engram as a dynamic change of the cortical network during early sequence learning: an fMRI study.

Thu, 04/04/2019 - 20:44
Related Articles

The motor engram as a dynamic change of the cortical network during early sequence learning: an fMRI study.

Neurosci Res. 2019 Mar 30;:

Authors: Hamano YH, Sugawara SK, Yoshimoto T, Sadato N

Abstract
Neural substrates of motor engrams in the human brain are hard to identify because their dormant states are difficult to discriminate. We utilized eigenvector centrality (EC) to measure the network information that accumulates as an engram during learning. To discriminate engrams formed by emphasis on speed or accuracy, we conducted functional MRI on 58 normal volunteers as they performed a sequential finger-tapping task with the non-dominant left hand. Participants alternated between performing a tapping sequence as quickly as possible (maximum mode) or at a constant speed of 2 Hz, paced by a sequence-specifying visual cue (constant mode). We depicted the formation of the motor engram by characterizing the dormant state as the increase in EC of the resting epoch throughout the training course, and the ecphory, or activated state, as the increment in EC during the task epoch relative to the alternated resting epoch. We found that a network covering the left anterior intraparietal sulcus and inferior parietal lobule represented the engram for the speed of execution, whereas bilateral premotor cortex and right primary motor cortex represented the sequential order of movements. This constitutes the first demonstration of learning-mode specific motor engrams formed by only 30 min of training.

PMID: 30940459 [PubMed - as supplied by publisher]

High-level Integrative Networks: A Resting-state fMRI Investigation of Reading and Spelling.

Wed, 04/03/2019 - 20:43
Related Articles

High-level Integrative Networks: A Resting-state fMRI Investigation of Reading and Spelling.

J Cogn Neurosci. 2019 Apr 02;:1-17

Authors: Ellenblum G, Purcell JJ, Song X, Rapp B

Abstract
Orthographic processing skills (reading and spelling) are evolutionarily recent and mastered late in development, providing an opportunity to investigate how the properties of the neural networks supporting skills of this type compare to those supporting evolutionarily older, well-established "reference" networks. Although there has been extensive research using task-based fMRI to study the neural substrates of reading, there has been very little using resting-state fMRI to examine the properties of orthographic networks. In this investigation using resting-state fMRI, we compare the within-network and across-network coherence properties of reading and spelling networks directly to these properties of reference networks, and we also compare the network properties of the key node of the orthographic networks-the visual word form area-to those of the other nodes of the orthographic and reference networks. Consistent with previous results, we find that orthographic processing networks do not exhibit certain basic network coherence properties displayed by other networks. However, we identify novel distinctive properties of the orthographic processing networks and establish that the visual word form area has unusually high levels of connectivity with a broad range of brain areas. These characteristics form the basis of our proposal that orthographic networks represent a class of "high-level integrative networks" with distinctive properties that allow them to recruit and integrate multiple, lower level processes.

PMID: 30938593 [PubMed - as supplied by publisher]

Dysfunctional white-matter networks in medicated and unmedicated benign epilepsy with centrotemporal spikes.

Wed, 04/03/2019 - 20:43
Related Articles

Dysfunctional white-matter networks in medicated and unmedicated benign epilepsy with centrotemporal spikes.

Hum Brain Mapp. 2019 Apr 01;:

Authors: Jiang Y, Song L, Li X, Zhang Y, Chen Y, Jiang S, Hou C, Yao D, Wang X, Luo C

Abstract
Benign epilepsy with centrotemporal spikes (BECT) is the most common childhood idiopathic focal epilepsy syndrome, which characterized with white-matter abnormalities in the rolandic cortex. Although diffusion tensor imaging research could characterize white-matter structural architecture, it cannot detect neural activity or white-matter functions. Recent studies demonstrated the functional organization of white-matter by using functional magnetic resonance imaging (fMRI), suggesting that it is feasible to investigate white-matter dysfunctions in BECT. Resting-state fMRI data were collected from 24 new-onset drug-naive (unmedicated [NMED]), 21 medicated (MED) BECT patients, and 27 healthy controls (HC). Several white-matter functional networks were obtained using a clustering analysis on voxel-by-voxel correlation profiles. Subsequently, conventional functional connectivity (FC) was calculated in four frequency sub-bands (Slow-5:0.01-0.027, Slow-4:0.027-0.073, Slow-3:0.073-0.198, and Slow-2:0.198-0.25 Hz). We also employed a functional covariance connectivity (FCC) to estimate the covariant relationship between two white-matter networks based on their correlations with multiple gray-matter regions. Compared with HC, the NMED showed increased FC and/or FCC in rolandic network (RN) and precentral/postcentral network, and decreased FC and/or FCC in dorsal frontal network, while these alterations were not observed in the MED group. Moreover, the changes exhibited frequency-specific properties. Specifically, only two alterations were shared in at least two frequency bands. Most of these alterations were observed in the frequency bands of Slow-3 and Slow-4. This study provided further support on the existence of white-matter functional networks which exhibited frequency-specific properties, and extended abnormalities of rolandic area from the perspective of white-matter dysfunction in BECT.

PMID: 30937973 [PubMed - as supplied by publisher]

Increased Functional Connectivity of the Angular Gyrus During Imagined Music Performance.

Wed, 04/03/2019 - 20:43
Related Articles

Increased Functional Connectivity of the Angular Gyrus During Imagined Music Performance.

Front Hum Neurosci. 2019;13:92

Authors: Tanaka S, Kirino E

Abstract
The angular gyrus (AG) is a hub of several networks that are involved in various functions, including attention, self-processing, semantic information processing, emotion regulation, and mentalizing. Since these functions are required in music performance, it is likely that the AG plays a role in music performance. Considering that these functions emerge as network properties, this study analyzed the functional connectivity of the AG during the imagined music performance task and the resting condition. Our hypothesis was that the functional connectivity of the AG is modulated by imagined music performance. In the resting condition, the AG had connections with the medial prefrontal cortex (mPFC), posterior cingulate cortex (PCC), and precuneus as well as the superior and inferior frontal gyri and with the temporal cortex. Compared with the resting condition, imagined music performance increased the functional connectivity of the AG with the superior frontal gyrus (SFG), mPFC, precuneus, PCC, hippocampal/parahippocampal gyrus (H/PHG), and amygdala. The anterior cingulate cortex (ACC) and superior temporal gyrus (STG) were newly engaged or added to the AG network during the task. In contrast, the supplementary motor area (SMA), sensorimotor areas, and occipital regions, which were anti-correlated with the AG in the resting condition, were disengaged during the task. These results lead to the conclusion that the functional connectivity of the AG is modulated by imagined music performance, which suggests that the AG plays a role in imagined music performance.

PMID: 30936827 [PubMed]

Phase fMRI Reveals More Sparseness and Balance of Rest Brain Functional Connectivity Than Magnitude fMRI.

Wed, 04/03/2019 - 20:43
Related Articles

Phase fMRI Reveals More Sparseness and Balance of Rest Brain Functional Connectivity Than Magnitude fMRI.

Front Neurosci. 2019;13:204

Authors: Chen Z, Fu Z, Calhoun V

Abstract
Conventionally, brain function is inferred from the magnitude data of the complex-valued fMRI output. Since the fMRI phase image (unwrapped) provides a representation of brain internal magnetic fieldmap (by a constant scale difference), it can also be used to study brain function while providing a more direct representation of the brain's magnetic state. In this study, we collected a cohort of resting-state fMRI magnitude and phase data pairs from 600 subjects (age from 10 to 76, 346 males), decomposed the phase data by group independent component analysis (pICA), calculated the functional network connectivity (pFNC). In comparison with the magnitude-based brain function analysis (mICA and mFNC), we find that the pFNC matrix contains fewer significant functional connections (with p-value thresholding) than the mFNC matrix, which are sparsely distributed across the whole brain with near/far interconnections and positive/negative correlations in rough balance. We also find a few of brain rest sub-networks within the phase data, primarily in subcortical, cerebellar, and visual regions. Overall, our findings offer new insights into brain function connectivity in the context of a focus on the brain's internal magnetic state.

PMID: 30936819 [PubMed]

Modulations in resting state networks of subcortical structures linked to creativity.

Wed, 04/03/2019 - 20:43
Related Articles

Modulations in resting state networks of subcortical structures linked to creativity.

Neuroimage. 2019 Mar 29;:

Authors: Schuler AL, Tik M, Sladky R, Luft CDB, Hoffmann A, Woletz M, Zioga I, Bhattacharya J, Windischberger C

Abstract
Creativity is a sine qua non ability for almost all aspects of everyday life. Although very profound behavioural models were provided by 21st century psychologists, the neural correlates of these personality features associated with creativity are largely unknown. Recent models suggest strong relationships between dopamine release and various creative skills. Herein, we employed functional connectivity analyses of resting-state functional magnetic imaging data in order to shed light on these neural underpinnings of creative aspects. For improved sensitivity, we performed the study at ultra-high magnetic field (7 T). Seed regions were defined based on subcortical (ventral tegmental area/substantia nigra, nucleus caudatus) activation foci of a remote associates task (RAT). In addition, bilateral PCC was used as seed region to examine the default-mode network. Network strength across subjects was regressed against a battery of psychological variables related to creativity. Dopaminergic network variations turned out to be indicative for individual differences in creative traits. In this regard, the caudate network showed stronger connectivity in individuals with higher extraversion measures, while connectivity with the midbrain network was found increased with higher ideational behaviour and emotional stability.

PMID: 30935909 [PubMed - as supplied by publisher]

Evaluating the evidence for biotypes of depression: Methodological replication and extension of.

Wed, 04/03/2019 - 20:43
Related Articles

Evaluating the evidence for biotypes of depression: Methodological replication and extension of.

Neuroimage Clin. 2019 Mar 27;:101796

Authors: Dinga R, Schmaal L, Penninx BWJH, van Tol MJ, Veltman DJ, van Velzen L, Mennes M, van der Wee NJA, Marquand AF

Abstract
BACKGROUND: Psychiatric disorders are highly heterogeneous, defined based on symptoms with little connection to potential underlying biological mechanisms. A possible approach to dissect biological heterogeneity is to look for biologically meaningful subtypes. A recent study Drysdale et al. (2017) showed promising results along this line by simultaneously using resting state fMRI and clinical data and identified four distinct subtypes of depression with different clinical profiles and abnormal resting state fMRI connectivity. These subtypes were predictive of treatment response to transcranial magnetic stimulation therapy.
OBJECTIVE: Here, we attempted to replicate the procedure followed in the Drysdale et al. study and their findings in a different clinical population and a more heterogeneous sample of 187 participants with depression and anxiety. We aimed to answer the following questions: 1) Using the same procedure, can we find a statistically significant and reliable relationship between brain connectivity and clinical symptoms? 2) Is the observed relationship similar to the one found in the original study? 3) Can we identify distinct and reliable subtypes? 4) Do they have similar clinical profiles as the subtypes identified in the original study?
METHODS: We followed the original procedure as closely as possible, including a canonical correlation analysis to find a low dimensional representation of clinically relevant resting state fMRI features, followed by hierarchical clustering to identify subtypes. We extended the original procedure using additional statistical tests, to test the statistical significance of the relationship between resting state fMRI and clinical data, and the existence of distinct subtypes. Furthermore, we examined the stability of the whole procedure using resampling.
RESULTS AND CONCLUSION: As in the original study, we found extremely high canonical correlations between functional connectivity and clinical symptoms, and an optimal three-cluster solution. However, neither canonical correlations nor clusters were statistically significant. On the basis of our extensive evaluations of the analysis methodology used and within the limits of comparison of our sample relative to the sample used in Drysdale et al., we argue that the evidence for the existence of the distinct resting state connectivity-based subtypes of depression should be interpreted with caution.

PMID: 30935858 [PubMed - as supplied by publisher]

Symptoms of fatigue and depression is reflected in altered default mode network connectivity in multiple sclerosis.

Tue, 04/02/2019 - 21:36
Related Articles

Symptoms of fatigue and depression is reflected in altered default mode network connectivity in multiple sclerosis.

PLoS One. 2019;14(4):e0210375

Authors: Høgestøl EA, Nygaard GO, Alnæs D, Beyer MK, Westlye LT, Harbo HF

Abstract
BACKGROUND: Fatigue and depression are frequent and often co-occurring symptoms in multiple sclerosis (MS). Resting-state functional magnetic resonance imaging (rs-fMRI) represents a promising tool for disentangling differential associations between depression and fatigue and brain network function and connectivity. In this study we tested for associations between symptoms of fatigue and depression and DMN connectivity in patients with MS.
MATERIALS AND METHODS: Seventy-four MS patients were included on average 14 months after diagnosis. They underwent MRI scanning of the brain including rs-fMRI, and symptoms of fatigue and depression were assessed with Fatigue Severity Scale (FSS) and Beck Depression Inventory II (BDI). A principal component analysis (PCA) on FSS and BDI scores was performed, and the component scores were analysed using linear regression models to test for associations with default mode network (DMN) connectivity.
RESULTS: We observed higher DMN connectivity with higher scores on the primary principal component reflecting common symptom burden for fatigue and depression (Cohen's f2 = 0.075, t = 2.17, p = 0.03). The secondary principal component reflecting a pattern of low fatigue scores with high scores of depression was associated with lower DMN connectivity (Cohen's f2 = 0.067, t = -2.1, p = 0.04). Using continuous mean scores of FSS we also observed higher DMN connectivity with higher symptom burden (t = 3.1, p = 0.003), but no significant associations between continuous sum scores of BDI and DMN connectivity (t = 0.8, p = 0.4).
CONCLUSION: Multivariate decomposition of FSS and BDI data supported both overlapping and unique manifestation of fatigue and depression in MS patients. Rs-fMRI analyses showed that symptoms of fatigue and depression were reflected in altered DMN connectivity, and that higher DMN activity was seen in MS patients with fatigue even with low depression scores.

PMID: 30933977 [PubMed - in process]

Atypical Functional Connectivity Associated with Autonomous Sensory Meridian Response (ASMR): An Examination of Five Resting-State Networks.

Tue, 04/02/2019 - 21:36
Related Articles

Atypical Functional Connectivity Associated with Autonomous Sensory Meridian Response (ASMR): An Examination of Five Resting-State Networks.

Brain Connect. 2019 Mar 30;:

Authors: Smith SD, Fredborg BK, Kornelsen J

Abstract
Autonomous Sensory Meridian Response (ASMR) is a perceptual phenomenon in which specific auditory and/or visual stimuli consistently elicit tingling sensations on the neck, scalp, and shoulders, as well as a positive and relaxed emotional state. The 'ASMR triggers' that initiate these responses generally consist of soft sounds (e.g., whispering), repetitive noises (e.g., tapping sounds), or videos of people performing socially intimate acts (e.g., watching someone brush her hair). Despite being a relatively common phenomenon, little is known about the neural substrates of ASMR. In the current research, resting-state functional MRI was used to examine whether ASMR was associated with atypical patterns of functional connectivity. Seventeen individuals with ASMR and 17 matched control participants underwent an anatomical MRI scan and a resting-state functional MRI scan. An independent components analysis was used to identify the default mode, salience, central executive, sensorimotor, and visual networks. An analysis of variance with group (ASMR vs. control) as a between-subjects variable was performed to contrast the functional connectivity of each of these networks. The results demonstrated that ASMR was associated with reduced functional connectivity in the salience and visual networks, and with atypical patterns of connectivity in the default mode, central executive, and sensorimotor networks.

PMID: 30931592 [PubMed - as supplied by publisher]

Technical note: can resting state functional MRI assist in routine clinical diagnosis?

Tue, 04/02/2019 - 21:36
Related Articles

Technical note: can resting state functional MRI assist in routine clinical diagnosis?

BJR Case Rep. 2018 Dec;4(4):20180030

Authors: Harman P, Law C, Pardhan S, Lin ZH, Johnson M, Walter S, Fassbender K, Aspinall R, Grunwald IQ

Abstract
Despite some differences in clinical presentation, it is often difficult to differentiate between dementia with Lewy bodies (DLB), clinical Alzheimer's dementia (AD) and Parkinson's disease dementia. However, differentiation can be crucial, especially as patients with DLB characteristically have a hypersensitivity to most antiemetic and neuroleptic drugs as they affect the cholinergic and dopaminergic system, potentially leading to life-threatening catatonia, loss of cognitive function and muscle rigidity. The aim of this study is to evaluate if resting state (RS) functional MRI (fMRI) can be used in routine practice on a 1.5 T scanner to differentiate between AD and DLB on an individual basis. We age- and gender-matched a known DLB patient with an AD patient and a human control (HC). Individual independent component analysis was carried out. Region of interest seeds were chosen from the midcingulate and insula regions. Functional connectivity from insula to midcingulate and within the midcingulate network (part of the Salience network) was lower in DLB than AD or HC. RS-fMRI on a 1.5 T scanner, in a routine clinical setting, detected abnormal functional connectivity patterns and allowed differentiation of DLB and AD in a routine clinical setting. This is the first evaluation of RS-fMRI in a routine clinical setting. It shows that incorporating RS-fMRI into the clinical scanning protocol can assist in early diagnosis and likely assist in monitoring the natural history of the disease or disease modifying treatments.

PMID: 30931142 [PubMed]

Prefrontal-Temporal Pathway Mediates the Cross-Modal and Cognitive Reorganization in Sensorineural Hearing Loss With or Without Tinnitus: A Multimodal MRI Study.

Tue, 04/02/2019 - 21:36
Related Articles

Prefrontal-Temporal Pathway Mediates the Cross-Modal and Cognitive Reorganization in Sensorineural Hearing Loss With or Without Tinnitus: A Multimodal MRI Study.

Front Neurosci. 2019;13:222

Authors: Luan Y, Wang C, Jiao Y, Tang T, Zhang J, Teng GJ

Abstract
Objective: Hearing loss, one main risk factor of tinnitus and hyperacusis, is believed to involve significant central functional abnormalities. The recruitment of the auditory cortex in non-auditory sensory and higher-order cognitive processing has been demonstrated in the hearing-deprived brain. The dorsolateral prefrontal cortex (dlPFC), which has dense anatomical connections with the auditory pathway, is known to play a crucial role in multi-sensory integration, auditory regulation, and cognitive processing. This study aimed to verify the role of the dlPFC in the cross-modal reorganization and cognitive participation of the auditory cortex in long-term sensorineural hearing loss (SNHL) by combining functional and structural measurements. Methods: Thirty five patients with long-term bilateral SNHL and 35 matched healthy controls underwent structural imaging, resting-state functional magnetic resonance imaging (rs-fMRI), diffusion tensor imaging (DTI), and neuropsychological assessments. Ten SNHL patients were with subjective tinnitus. Results: No differences in gray matter volume, spontaneous neural activity, or diffusion characteristics in the dlPFC were found between the SNHL and control groups. The functional connectivity (FC) between the dlPFC and the auditory cortex and visual areas, such as the cuneus, fusiform, lingual cortex, and calcarine sulcus was increased in patients with SNHL. ANOVA and post hoc tests revealed similar FC alterations in the SNHL patients with and without tinnitus when compared with the normal hearing controls, and SNHL patients with and without tinnitus showed no difference in the dlPFC FC. The FC in the auditory cortex was associated with the symbol digit modality test (SDMT) scores in the SNHL patients, which reflect attentional function, processing speed, and visual working memory. Hearing-related FC with the dlPFC was found in the lingual cortex. A tract-based spatial statistics (TBSS) analysis revealed decreased fractional anisotropy (FA) values, mainly in the temporal inferior fronto-occipital fasciculus (IFOF), which showed remarkable negative correlations with the mean hearing thresholds in SNHL. Conclusion: Higher functional coupling between the dlPFC and auditory and visual areas, accompanied by decreased FA along the IFOF connecting the frontal cortex and the occipito-temporal area, might mediate cross-modal plasticity via top-down regulation and facilitate the involvement of the auditory cortex in higher-order cognitive processing following long-term SNHL.

PMID: 30930739 [PubMed]

Brain Connectivity and Information-Flow Breakdown Revealed by a Minimum Spanning Tree-Based Analysis of MRI Data in Behavioral Variant Frontotemporal Dementia.

Tue, 04/02/2019 - 21:36
Related Articles

Brain Connectivity and Information-Flow Breakdown Revealed by a Minimum Spanning Tree-Based Analysis of MRI Data in Behavioral Variant Frontotemporal Dementia.

Front Neurosci. 2019;13:211

Authors: Saba V, Premi E, Cristillo V, Gazzina S, Palluzzi F, Zanetti O, Gasparotti R, Padovani A, Borroni B, Grassi M

Abstract
Brain functional disruption and cognitive shortfalls as consequences of neurodegeneration are among the most investigated aspects in current clinical research. Traditionally, specific anatomical and behavioral traits have been associated with neurodegeneration, thus directly translatable in clinical terms. However, these qualitative traits, do not account for the extensive information flow breakdown within the functional brain network that deeply affect cognitive skills. Behavioural variant Frontotemporal Dementia (bvFTD) is a neurodegenerative disorder characterized by behavioral and executive functions disturbances. Deviations from the physiological cognitive functioning can be accurately inferred and modeled from functional connectivity alterations. Although the need for unbiased metrics is still an open issue in imaging studies, the graph-theory approach applied to neuroimaging techniques is becoming popular in the study of brain dysfunction. In this work, we assessed the global connectivity and topological alterations among brain regions in bvFTD patients using a minimum spanning tree (MST) based analysis of resting state functional MRI (rs-fMRI) data. Whilst several graph theoretical methods require arbitrary criteria (including the choice of network construction thresholds and weight normalization methods), MST is an unambiguous modeling solution, ensuring accuracy, robustness, and reproducibility. MST networks of 116 regions of interest (ROIs) were built on wavelet correlation matrices, extracted from 41 bvFTD patients and 39 healthy controls (HC). We observed a global fragmentation of the functional network backbone with severe disruption of information-flow highways. Frontotemporal areas were less compact, more isolated, and concentrated in less integrated structures, respect to healthy subjects. Our results reflected such complex breakdown of the frontal and temporal areas at both intra-regional and long-range connections. Our findings highlighted that MST, in conjunction with rs-fMRI data, was an effective method for quantifying and detecting functional brain network impairments, leading to characteristic bvFTD cognitive, social, and executive functions disorders.

PMID: 30930736 [PubMed]

Anesthesia differentially modulates neuronal and vascular contributions to the BOLD signal.

Tue, 04/02/2019 - 21:36
Related Articles

Anesthesia differentially modulates neuronal and vascular contributions to the BOLD signal.

Neuroimage. 2019 Mar 28;:

Authors: van Alst TM, Wachsmuth L, Datunashvili M, Albers F, Just N, Budde T, Faber C

Abstract
Most studies involving BOLD fMRI in basic neuroscience research are conducted with anesthetized animals. This study investigates neural and hemodynamic activity through a combination of experiments comprising BOLD fMRI, optical calcium recordings and ASL in vivo. Patch clamp experiments of neurons were conducted to evaluate electrophysiological correlates of neural activity in vitro. Various anesthetic conditions embracing numerous anesthetic depths evoked by different concentrations of isoflurane (ISO) and different degrees of hypercapnia under a constant stimulus were investigated. We observed that different anesthetic conditions had major impact on the results obtained, particularly that anesthesia could cause a massive divergence of different experimental modalities. In ventilated animals, robust BOLD responses were detectable even with relatively deep anesthesia, while in non-ventilated animals, BOLD responses were not detectable under these conditions. This was most likely due to hypercapnia caused by respiratory depression, as in ventilated animals administered CO2 had the same effect. This observation agreed with measurements of perfusion, which showed that inhaled CO2 increased perfusion significantly, while ISO did not. In optical calcium measurements, higher concentrations of ISO decreased spontaneous neural activity, but not stimulus-evoked responses. This observation was explained by a generally lower excitability of neurons under ISO, which suppressed spontaneous activity, and consequently left more neurons available to fire synchronously in response to a stimulus. Interpreting this phenomenon as an integrated signal of independent single neurons was supported by patch clamp experiments as the number of action potentials (APs) per stimulus was decreased by addition of CO2. Addition of ISO on the other hand had no significant effect. Our results provide an explanation on the cellular level for anesthesia-dependent observations in previous studies of task-induced BOLD and resting state connectivity. They further inform selection of the adequate anesthetic regimen for a given combination of modalities.

PMID: 30930308 [PubMed - as supplied by publisher]

Differences in the intra-cerebellar connections and graph theoretical measures between Parkinson's disease and multiple system atrophy.

Mon, 04/01/2019 - 18:33

Differences in the intra-cerebellar connections and graph theoretical measures between Parkinson's disease and multiple system atrophy.

J Neurol Sci. 2019 Mar 25;400:129-134

Authors: Sako W, Abe T, Furukawa T, Oki R, Haji S, Murakami N, Izumi Y, Harada M, Kaji R

Abstract
BACKGROUND AND PURPOSE: Parkinson's disease (PD) does not present with motor symptoms until dopaminergic neuronal loss exceeds 50%. This might indicate that a network-level compensatory mechanism involving surviving regions in PD acts to reduce brain abnormalities. In contrast, there is no evidence of a compensatory mechanism in multiple system atrophy (MSA). We hypothesized that a comparison of these two diseases would help to identify compensatory effects in PD.
METHODS: We recruited 23 patients with PD, 11 patients with MSA, and 11 controls that showed an aging brain but no neurological deficits. All subjects underwent resting state functional magnetic resonance imaging (fMRI). Regions of interest were defined according to the motor network related to the basal ganglia and cerebellum. Network-level analyses were performed.
RESULTS: Network-based statistical analyses revealed that functional connectivity in PD brains was reduced between cerebellar lobules IX on both sides and vermis X, as compared with MSA brains. Transitivity was reduced in MSA as compared with controls.
CONCLUSION: We demonstrated that a part of the intra-cerebellar connectivity was reduced in PD, and that network segregation was reduced in MSA. However, there was no evidence of compensatory effects in PD.

PMID: 30928779 [PubMed - as supplied by publisher]

Altered relationship between prefrontal glutamate and activation during cognitive control in people with high trait anxiety.

Mon, 04/01/2019 - 18:33

Altered relationship between prefrontal glutamate and activation during cognitive control in people with high trait anxiety.

Cortex. 2019 Mar 07;117:53-63

Authors: Morgenroth E, Orlov N, Lythgoe DJ, Stone JM, Barker H, Munro J, Eysenck M, Allen P

Abstract
Trait anxiety can affect cognitive control resulting in ineffective and/or inefficient task performance. Moreover, previous functional Magnetic Resonance Imaging (fMRI) studies have reported altered dorsolateral prefrontal cortex (DLPFC) activity in anxious cohorts, particularly when executive control is required. Recently, it has been demonstrated that cortical glutamate levels can predict both functional activation during cognitive control, and anxiety levels. In the present study we sought to investigate the relationship between trait anxiety, prefrontal glutamate levels and functional activation in DLPFC during a cognitive control task. Thirty-nine participants assigned to either low trait anxiety (LTA) or high trait anxiety (HTA) groups underwent 1H-Magnetic Resonance Spectroscopy (1H-MRS) to measure levels of resting glutamate in the prefrontal cortex (PFC). Participants also completed fMRI during a Stroop task comprising congruent and incongruent colour word trials. The HTA group showed reduced task performance relative to the LTA group. In the LTA group, there was a positive association between PFC Glu levels and DLPFC activation during incongruent trials. This association was absent in the HTA group. Individual differences in trait anxiety affect the relationship between PFC glutamate levels and DLPFC activation, possibly contributing to ineffective task performance when cognitive control is required.

PMID: 30928721 [PubMed - as supplied by publisher]