New resting-state fMRI related studies at PubMed

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A multicenter study of ketamine effects on functional connectivity: Large scale network relationships, hubs and symptom mechanisms.

Fri, 12/27/2019 - 15:20
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A multicenter study of ketamine effects on functional connectivity: Large scale network relationships, hubs and symptom mechanisms.

Neuroimage Clin. 2019;22:101739

Authors: Fleming LM, Javitt DC, Carter CS, Kantrowitz JT, Girgis RR, Kegeles LS, Ragland JD, Maddock RJ, Lesh TA, Tanase C, Robinson J, Potter WZ, Carlson M, Wall MM, Choo TH, Grinband J, Lieberman J, Krystal JH, Corlett PR

Abstract
Ketamine is an uncompetitive N-methyl-d-aspartate (NMDA) glutamate receptor antagonist. It induces effects in healthy individuals that mimic symptoms associated with schizophrenia. We sought to root these experiences in altered brain function, specifically aberrant resting state functional connectivity (rsfMRI). In the present study, we acquired rsfMRI data under ketamine and placebo in a between-subjects design and analyzed seed-based measures of rsfMRI using large-scale networks, dorsolateral prefrontal cortex (DLPFC) and sub-nuclei of the thalamus. We found ketamine-induced alterations in rsfMRI connectivity similar to those seen in patients with schizophrenia, some changes that may be more comparable to early stages of schizophrenia, and other connectivity signatures seen in patients that ketamine did not recreate. We do not find any circuits from our regions of interest that correlates with positive symptoms of schizophrenia in our sample, although we find that DLPFC connectivity with ACC does correlate with a mood measure. These results provide support for ketamine's use as a model of certain biomarkers of schizophrenia, particularly for early or at-risk patients.

PMID: 30852397 [PubMed - indexed for MEDLINE]

Altered default mode network connectivity in adolescents with post-traumatic stress disorder.

Fri, 12/27/2019 - 15:20
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Altered default mode network connectivity in adolescents with post-traumatic stress disorder.

Neuroimage Clin. 2019;22:101731

Authors: Viard A, Mutlu J, Chanraud S, Guenolé F, Egler PJ, Gérardin P, Baleyte JM, Dayan J, Eustache F, Guillery-Girard B

Abstract
Post-traumatic stress disorder (PTSD) is characterized by intrusions, re-experiencing, avoidance and hyperarousal. These symptoms might be linked to dysfunction in core neurocognitive networks subserving self-referential mental processing (default mode network, DMN), detection of salient stimuli (salience network, SN) and cognitive dysfunction (central executive network, CEN). Resting state studies in adolescent PTSD are scarce and findings are inconsistent, probably due to differences in patient symptom severity. Resting state brain activity was measured in 14 adolescents with severe PTSD and 24 age-matched controls. Seed-based connectivity analyses were used to examine connectivity between the DMN and the whole brain, including regions from other networks (SN and CEN). The relationships of network properties with symptom dimensions (severity, anxiety and depression) and episodic memory were also examined. Analyses revealed decreased within-DMN connectivity (between PCC and occipital cortex) in patients compared to controls. Furthermore, within-DMN connectivity (between PCC and hippocampus) correlated negatively with symptom dimensions (severity and anxiety), while increased connectivity (DMN-SN and DMN-CEN) correlated positively with episodic memory measures. These abnormal network properties found in adolescent PTSD corroborate those previously reported in adult PTSD. Decreased within-DMN connectivity and disrupted DMN-SN and DMN-CEN coupling could form the basis for intrusive trauma recollection and impaired episodic autobiographical recall in PTSD.

PMID: 30831461 [PubMed - indexed for MEDLINE]

Low-rank network signatures in the triple network separate schizophrenia and major depressive disorder.

Fri, 12/27/2019 - 15:20
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Low-rank network signatures in the triple network separate schizophrenia and major depressive disorder.

Neuroimage Clin. 2019;22:101725

Authors: Han W, Sorg C, Zheng C, Yang Q, Zhang X, Ternblom A, Mawuli CB, Gao L, Luo C, Yao D, Li T, Liang S, Shao J

Abstract
Brain imaging studies have revealed that functional and structural brain connectivity in the so-called triple network (i.e., default mode network (DMN), salience network (SN) and central executive network (CEN)) are consistently altered in schizophrenia. However, similar changes have also been found in patients with major depressive disorder, prompting the question of specific triple network signatures for the two disorders. In this study, we proposed Supervised Convex Nonnegative Matrix Factorization (SCNMF) to extract distributed multi-modal brain patterns. These patterns distinguish schizophrenia and major depressive disorder in a latent low-dimensional space of the triple brain network. Specifically, 21 patients of schizophrenia and 25 patients of major depressive disorder were assessed by T1-weighted, diffusion-weighted, and resting-state functional MRIs. Individual structural and functional connectivity networks, based on pre-defined regions of the triple network were constructed, respectively. Afterwards, SCNMF was employed to extract the discriminative patterns. Experiments indicate that SCNMF allows extracting the low-rank discriminative patterns between the two disorders, achieving a classification accuracy of 82.6% based on the extracted functional and structural abnormalities with support vector machine. Experimental results show the specific brain patterns for schizophrenia and major depressive disorder that are multi-modal, complex, and distributed in the triple network. Parts of the prefrontal cortex including superior frontal gyri showed variation between patients with schizophrenia and major depression due to structural properties. In terms of functional properties, the middle cingulate cortex, inferior parietal lobule, and cingulate cortex were the most discriminative regions.

PMID: 30798168 [PubMed - indexed for MEDLINE]

An Effect of Chronic Stress on Prospective Memory via Alteration of Resting-State Hippocampal Subregion Functional Connectivity.

Wed, 12/25/2019 - 13:00
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An Effect of Chronic Stress on Prospective Memory via Alteration of Resting-State Hippocampal Subregion Functional Connectivity.

Sci Rep. 2019 Dec 23;9(1):19698

Authors: Chen J, Wei Z, Han H, Jin L, Xu C, Dong D, Lu J, Wan G, Peng Z

Abstract
The alteration of hippocampal function by chronic stress impairs higher order cognitive functions such as prospective memory (PM). However, how chronic stress affects hippocampal subregions related to PM remains largely unknown. In this study, the altered functional network of hippocampal subregions related to PM in chronic stress was explored. College students (N = 21) completed PM tasks and resting-state functional magnetic resonance imaging scans one month prior to (baseline) and during the final examination week (chronic stress). Hippocampal subregions' seed-based functional connectivity (FC) and PM were compared between baseline and chronic stress. PM performance declined in chronic stress. The FC of the cornu ammonis 2, 3 and dentate gyrus (CA23DG) with the bilateral caudate and precuneus was increased in chronic stress, while the FC of the subicular complex (SUBC) with the left middle frontal gyrus, the left inferior parietal gyrus and the right supramarginal gyrus was decreased. There was a negative correlation between PM performance and the FC of hippocampal subregions. We found chronic stress impairs PM by decreasing the FC of SUBC and increasing the FC of CA23DG. These findings suggest functional changes in hippocampal subregion networks as a mechanism underlying the impairment of PM in chronic stress.

PMID: 31873134 [PubMed - in process]

Methodology for tDCS integration with fMRI.

Wed, 12/25/2019 - 13:00
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Methodology for tDCS integration with fMRI.

Hum Brain Mapp. 2019 Dec 24;:

Authors: Esmaeilpour Z, Shereen AD, Ghobadi-Azbari P, Datta A, Woods AJ, Ironside M, O'Shea J, Kirk U, Bikson M, Ekhtiari H

Abstract
Understanding and reducing variability of response to transcranial direct current stimulation (tDCS) requires measuring what factors predetermine sensitivity to tDCS and tracking individual response to tDCS. Human trials, animal models, and computational models suggest structural traits and functional states of neural systems are the major sources of this variance. There are 118 published tDCS studies (up to October 1, 2018) that used fMRI as a proxy measure of neural activation to answer mechanistic, predictive, and localization questions about how brain activity is modulated by tDCS. FMRI can potentially contribute as: a measure of cognitive state-level variance in baseline brain activation before tDCS; inform the design of stimulation montages that aim to target functional networks during specific tasks; and act as an outcome measure of functional response to tDCS. In this systematic review, we explore methodological parameter space of tDCS integration with fMRI spanning: (a) fMRI timing relative to tDCS (pre, post, concurrent); (b) study design (parallel, crossover); (c) control condition (sham, active control); (d) number of tDCS sessions; (e) number of follow up scans; (f) stimulation dose and combination with task; (g) functional imaging sequence (BOLD, ASL, resting); and (h) additional behavioral (cognitive, clinical) or quantitative (neurophysiological, biomarker) measurements. Existing tDCS-fMRI literature shows little replication across these permutations; few studies used comparable study designs. Here, we use a representative sample study with both task and resting state fMRI before and after tDCS in a crossover design to discuss methodological confounds. We further outline how computational models of current flow should be combined with imaging data to understand sources of variability. Through the representative sample study, we demonstrate how modeling and imaging methodology can be integrated for individualized analysis. Finally, we discuss the importance of conducting tDCS-fMRI with stimulation equipment certified as safe to use inside the MR scanner, and of correcting for image artifacts caused by tDCS. tDCS-fMRI can address important questions on the functional mechanisms of tDCS action (e.g., target engagement) and has the potential to support enhancement of behavioral interventions, provided studies are designed rationally.

PMID: 31872943 [PubMed - as supplied by publisher]

Hippocampal diaschisis contributes to anosognosia for hemiplegia: Evidence from lesion network-symptom-mapping.

Wed, 12/25/2019 - 13:00
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Hippocampal diaschisis contributes to anosognosia for hemiplegia: Evidence from lesion network-symptom-mapping.

Neuroimage. 2019 Dec 20;:116485

Authors: Klingbeil J, Wawrzyniak M, Stockert A, Karnath HO, Saur D

Abstract
Anosognosia for hemiplegia (AHP) is known to be associated with lesions to the motor system combined with varying lesions to the right insula, premotor cortex, parietal lobe or hippocampus. Due to this widespread cortical lesion distribution, AHP can be understood best as a network disorder. We used lesion maps and behavioral data (n = 49) from two previous studies on AHP and performed a lesion network-symptom-mapping (LNSM) analysis. This new approach permits the identification of relationships between behavior and regions connected to the lesion site based on normative functional connectome data. In a first step, using ordinary voxel-based lesion-symptom mapping, we found an association of AHP with lesions in the right posterior insula. This is in accordance with previous studies. Applying LNSM, we were able to additionally identify a region in the right posterior hippocampus where AHP was associated with significantly higher normative lesion connectivity. Notably, this region was spared by infarction in all patients. We therefore argue that remote neuronal dysfunction caused by disrupted functional connections between the lesion site and the hippocampus (i.e. diaschisis) contributed to the phenotype of AHP. An indirect affection of the hippocampus may lead to memory deficits which, in turn, impair the stable encoding of updated beliefs on the bodily state thus contributing to the multifactorial phenomenon of AHP.

PMID: 31870945 [PubMed - as supplied by publisher]

Functional connectivity among brain regions affected in Alzheimer's disease is associated with CSF TNF-α in APOE4 carriers.

Wed, 12/25/2019 - 13:00
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Functional connectivity among brain regions affected in Alzheimer's disease is associated with CSF TNF-α in APOE4 carriers.

Neurobiol Aging. 2019 Nov 05;:

Authors: Contreras JA, Aslanyan V, Sweeney MD, Sanders LMJ, Sagare AP, Zlokovic BV, Toga AW, Han SD, Morris JC, Fagan A, Massoumzadeh P, Benzinger TL, Pa J

Abstract
It is now recognized that understanding how neuroinflammation affects brain function may provide new insights into Alzheimer's pathophysiology. Tumor necrosis factor (TNF)-α, an inflammatory cytokine marker, has been implicated in Alzheimer's disease (AD), as it can impair neuronal function through suppression of long-term potentiation. Our study investigated the relationship between cerebrospinal fluid TNF-α and functional connectivity (FC) in a cohort of 64 older adults (μ age = 69.76 years; 30 cognitively normal, 34 mild AD). Higher cerebrospinal fluid TNF-α levels were associated with lower FC among brain regions important for high-level decision-making, inhibitory control, and memory. This effect was moderated by apolipoprotein E-ε4 (APOE4) status. Graph theory metrics revealed there were significant differences between APOE4 carriers at the node level, and by diagnosis at the network level suggesting global brain network dysfunction in participants with AD. These findings suggest proinflammatory mechanisms may contribute to reduced FC in regions important for high-level cognition. Future studies are needed to understand the role of inflammation on brain function and clinical progression, especially in APOE4 carriers.

PMID: 31870643 [PubMed - as supplied by publisher]

Circuits, Networks, and Neuropsychiatric Disease: Transitioning From Anatomy to Imaging.

Wed, 12/25/2019 - 13:00
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Circuits, Networks, and Neuropsychiatric Disease: Transitioning From Anatomy to Imaging.

Biol Psychiatry. 2019 Nov 06;:

Authors: Haber SN, Tang W, Choi EY, Yendiki A, Liu H, Jbabdi S, Versace A, Phillips M

Abstract
Since the development of cellular and myelin stains, anatomy has formed the foundation for understanding circuitry in the human brain. However, recent functional and structural studies using magnetic resonance imaging have taken the lead in this endeavor. These innovative and noninvasive approaches have the advantage of studying connectivity patterns under different conditions directly in the human brain. They demonstrate dynamic and structural changes within and across networks linked to normal function and to a wide range of psychiatric illnesses. However, these indirect methods are unable to link networks to the hardwiring that underlies them. In contrast, anatomic invasive experimental studies can. Following a brief review of prefrontal cortical, anterior cingulate, and striatal connections and the different methodologies used, this article discusses how data from anatomic studies can help inform how hardwired connections are linked to the functional and structural networks identified in imaging studies.

PMID: 31870495 [PubMed - as supplied by publisher]

Functional connectivity markers of depression in advanced Parkinson's disease.

Tue, 12/24/2019 - 11:40

Functional connectivity markers of depression in advanced Parkinson's disease.

Neuroimage Clin. 2019 Dec 13;25:102130

Authors: Lin H, Cai X, Zhang D, Liu J, Na P, Li W

Abstract
BACKGROUND: Depression is a common comorbid condition in Parkinson's disease and a major contributor to poor quality of life. Despite this, depression in PD is under-diagnosed due to overlapping symptoms and difficulties in the assessment of depression in cognitively impaired old patients.
OBJECTIVES: This study is to explore functional connectivity markers of depression in PD patients using resting-state fMRI and help diagnose whether patients have depression or not.
METHODS: We reviewed 156 advanced PD patients (duration > 5 years; 59 depressed ones) and 45 healthy control subjects who underwent a resting-state fMRI scanning. Functional connectivity analysis was employed to characterize intrinsic connectivity networks using group independent component analysis and extract connectivity features. Features were put into an all-relevant feature selection procedure within cross-validation loops, to identify features with significant discriminative power for classification. Random forest classifiers were built for depression diagnosis, on the basis of identified features.
RESULTS: 42 intrinsic connectivity networks were identified and arranged into subcortical, auditory, somatomotor, visual, cognitive control, default-mode and cerebellar networks. Six features were significantly relevant to classification. They were connectivity within posterior cingulate cortex, within insula, between posterior cingulate cortex and insula/hippocampus+amygdala, between insula and precuneus, and between superior parietal lobule and medial prefrontal cortex. The mean accuracy achieved with classifiers to discriminate depressed patients from the non-depressed was 82.4%.
CONCLUSIONS: Our findings provide preliminary evidence that resting-state functional connectivity can characterize depressed PD patients and help distinguish them from non-depressed ones.

PMID: 31869768 [PubMed - as supplied by publisher]

Functional connectivity of the orbitofrontal cortex, anterior cingulate cortex, and inferior frontal gyrus in humans.

Tue, 12/24/2019 - 11:40

Functional connectivity of the orbitofrontal cortex, anterior cingulate cortex, and inferior frontal gyrus in humans.

Cortex. 2019 Nov 16;123:185-199

Authors: Du J, Rolls ET, Cheng W, Li Y, Gong W, Qiu J, Feng J

Abstract
Parcellation of the orbitofrontal cortex, anterior cingulate cortex, and inferior frontal gyrus based on their functional connectivity with the whole brain in resting state fMRI with 654 participants was performed to investigate how these regions with different functions in reward, emotion and their disorders are functionally connected to each other and to the whole brain. The human medial and lateral orbitofrontal cortex, the ventromedial prefrontal cortex, the anterior cingulate cortex, and the right and left inferior frontal gyrus have different functional connectivity with other brain areas and with each other; and each of these regions has several parcels with different functional connectivity with other brain areas. In terms of functional connectivity, the lateral orbitofrontal cortex extends especially on the right into the orbital part of the inferior frontal gyrus and provides connectivity with premotor cortical areas. The orbitofrontal cortex, especially the lateral orbitofrontal cortex, has connectivity not only with language-related areas in the inferior frontal gyrus (Broca's area), but also with the angular and supramarginal gyri. In this context, whereas the connectivity of the orbitofrontal cortex, ventromedial prefrontal cortex, and anterior cingulate cortex is symmetrical, the connectivity of the inferior frontal gyrus triangular and opercular parts is asymmetrical for the right and the left hemispheres. These findings have implications for understanding the neural bases of human emotion and decision-making, and for their disorders including depression.

PMID: 31869573 [PubMed - as supplied by publisher]

A modality-specific dysfunction of pain processing in schizophrenia.

Tue, 12/24/2019 - 11:40

A modality-specific dysfunction of pain processing in schizophrenia.

Hum Brain Mapp. 2019 Dec 23;:

Authors: Zhou L, Bi Y, Liang M, Kong Y, Tu Y, Zhang X, Song Y, Du X, Tan S, Hu L

Abstract
Clinical observations showed that schizophrenia (SCZ) patients reported little or no pain under various conditions that are commonly associated with intense painful sensations, leading to a higher risk of morbidity and mortality. However, this phenomenon has received little attention and its underlying neural mechanisms remain unclear. Here, we conducted two experiments combining psychophysics, electroencephalography (EEG), and functional magnetic resonance imaging (fMRI) techniques to investigate neural mechanisms of pain insensitivity in SCZ patients. Specifically, we adopted a stimulus-response paradigm with brief stimuli of different sensory modalities (i.e., nociceptive, non-nociceptive somatosensory, and auditory) to test whether pain insensitivity in SCZ patients is supra-modal or modality-specific, and used EEG and fMRI techniques to clarify its neural mechanisms. We observed that perceived intensities to nociceptive stimuli were significantly smaller in SCZ patients than healthy controls, whereas perceived intensities to non-nociceptive somatosensory and auditory stimuli were not significantly different. The behavioral results were confirmed by stimulus-evoked brain responses sampled by EEG and fMRI techniques, thus verifying the modality-specific nature of the modulation of nociceptive information processing in SCZ patients. Additionally, significant group differences were observed in the spectral power of alpha oscillations in prestimulus EEG and the seed-based functional connectivity in resting-state fMRI (seeds: the thalamus and periaqueductal gray that are key nodes in ascending and descending pain pathways respectively), suggesting a possible contribution of cortical-subcortical dysfunction to the phenomenon. Overall, our study provides insight into the neural mechanisms of pain insensitivity in SCZ and highlights a need for systematic assessments of their pain-related diseases.

PMID: 31868305 [PubMed - as supplied by publisher]

Characterizing impulsivity and resting-state functional connectivity in normal-weight binge eaters.

Tue, 12/24/2019 - 11:40

Characterizing impulsivity and resting-state functional connectivity in normal-weight binge eaters.

Int J Eat Disord. 2019 Dec 23;:

Authors: Oliva R, Morys F, Horstmann A, Castiello U, Begliomini C

Abstract
OBJECTIVE: Binge eating is characterized by episodes of uncontrolled eating, within discrete periods of time. Although it is usually described in obese individuals or as a symptom of Binge Eating Disorder (BED), this behavior can also occur in the normal-weight (NW) population. An interesting premise suggests that impulsivity might contribute to the onset of binge eating and the progression toward weight gain. Drawing upon this evidence, here we explored impulsivity in NW individuals reporting binge-eating episodes through a functional connectivity approach. We hypothesized that, even in the absence of an eating disorder, NW binge eaters would be characterized by connectivity pattern changes in corticostriatal regions implicated in impulsivity, similarly to the results described in BED individuals.
METHODS: A resting-state functional magnetic resonance imaging study tested 39 NW men and women, with and without binge eating (binge eaters, BE and non-BE). Brain functional connectivity was explored by means of graph theoretic centrality measures and traditional seed-based analysis; trait impulsivity was assessed with self-report questionnaires.
RESULTS: The BE group was characterized by a higher degree of trait impulsivity. Brain functional connectivity measures revealed lower degree centrality within the right middle frontal gyrus, left insula/putamen and left temporoparietal regions and a lower functional connectivity between the right middle frontal gyrus and right insula in the BE group.
DISCUSSION: The results support previous evidence on BED of altered functional connectivity and higher impulsivity at the roots of overeating behavior, but further extend this concept excluding any potential confounding effect exerted by the weight status.

PMID: 31868249 [PubMed - as supplied by publisher]

[Instant adjustive effect of auricular electroacupuncture on brain default model network of patients with primary insomnia].

Tue, 12/24/2019 - 11:40
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[Instant adjustive effect of auricular electroacupuncture on brain default model network of patients with primary insomnia].

Zhen Ci Yan Jiu. 2019 Dec 25;44(12):884-7

Authors: Zhao B, Li L, Zhang JL, Zhang L, Wang JY, Wang Y, Li SY, Hou LW, Fang JL, Rong PJ

Abstract
OBJECTIVE: To investigate the immediate brain effect of auricular electroacupuncture (EA) in the treatment of primary insomnia (PI).
METHODS: In this study, 15 subjects with PI who were diagnosed according to Pitsburgh Sleep Quality Index (PSQI), and other 15 age- and gender-matched subjects without insomnia were recruited in the present study. The PI patients received EA (4 Hz/20 Hz, a tolerable electrical current strength) of auricular concha for 30 min, and their resting state functional magnetic resonance imaging (fMRI) data before and after treatment were collected. The healthy subjects received no any treatment and their resting state fMRI data were collected. The diffe-rence of default mode network functional connectivity between the patients and healthy subjects, and changes of the patient's brain functional connectivity after EA treatment were estimated by using seed-point-based analysis (SPBA).
RESULTS: Analysis by taking the posterior cingulate gyrus as the seed-point showed that compared with the healthy participants before treatment, the patient's brain functional connectivity between the posterior cingulate gyrus and the right insula, or the inferior frontal gyrus of the right opercularis region, or the right rolandic operculum was increased. After 30 minutes' EA treatment, the functional connectivity between the posterior cingulate gyrus and the precuneus, the left angular gyrus, the left frontal superior gyrus, the left frontal middle cortex, the right temporalis inferior gyrus, the right temporalis middle gyrus or the left medial orbitofrontal cortex was decreased, while the functional connectivity between the posterior cingulate gyrus and the right lingual gyrus, or the cortex surrounding the right calcarine fissure was increased.
CONCLUSION: EA of auricular concha has an instant effect in modulating the brain default mode network in PI patients, which may be its brain mechanism underlying improvement of PI.

PMID: 31867907 [PubMed - in process]

[Correlation between blood oxygen level dependent fMRI signal and GABA content in anterior cingulate cortex after acupuncture of Hegu (LI4)].

Tue, 12/24/2019 - 11:40
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[Correlation between blood oxygen level dependent fMRI signal and GABA content in anterior cingulate cortex after acupuncture of Hegu (LI4)].

Zhen Ci Yan Jiu. 2019 Dec 25;44(12):878-83

Authors: Sun L, Chen YY, Fang JL, Hong Y, Wang Y, Xu K, Li XJ, Chen LM, Zhang GL, Zhao YP

Abstract
OBJECTIVE: To explore the correlation between blood oxygen level dependent functional magnetic resonance imaging (BOLD-fMRI) signal and neurotransmitter γ-aminobutyric acid (GABA) concentration in the prefrontal cortex area after acupuncture or Von Frey filament stimulation (epidermal stimulation) at the right Hegu (LI4).
METHODS: A total of 76 healthy volunteers (23 men and 53 women, 24.5±1.4 years in age) were recruited in the pre-sent study. Each volunteer received two sessions of fMRI magnetic resonance scanning (MRS) examinations, with an interval of one week between two sessions. The MRI scan sequences included pre-task MRS, resting state BOLD and task MRS, BOLD. A region of Interest (ROI) of 35 mm×30 mm×25 mm was located at the bilateral medial prefrontal cortex areas. In the two sessions of examinations, the right LI4 point was stimulated by manual acupuncture or Von Frey filament-pressing. The tasks were designed as the block design. Each block contained 3 intermittent acupoint stimulations, lasting 30 s in each stimulation and with two minutes' pause between two stimulations. The MRS data were processed by using Linear Combination (LC) Model software (for assessing GABA content), and the BOLD data of fMRI was analyzed by using SPM12 software (comparison within each group), REST1.8 (comparison between two groups), separately.
RESULTS: Extensive deactivations were induced by both stimulations, mainly involving the midline regions as the medial prefrontal lobe, and limbic lobe. The deactivation effect of manual acupuncture stimulation was more extensive and intensive than that of Von Frey filament stimulation, especially in the medial prefrontal lobe. Data from 66 volunteers (after exclusion of 10 participants due to bigger standard deviation of GABA/Glx) showed no marked correlation between the GABA concentration and BOLD activation in the anterior cingulate cortex area in both groups(manual acupuncture stimulation group: r=-0.07, -0.08, 0.04; P=0.57, 0.88, 0.74; Von Frey filament epidermal stimulation group: r=-0.10, -0.09, -0.01; P=0.43, 0.46, 0.96).
CONCLUSION: Acupuncture of LI4 elicits a stronger and broader negative activation effect in the limbic-paralimbic-neocortical network including the medial prefrontal cortex in comparison with Von Frey filament stimulation, but no apparent correlation was found between the GABA concentration and BOLD activation in the anterior cingulate cortex after manual acupuncture and Von Frey stimulation.

PMID: 31867906 [PubMed - in process]

Beyond the Epileptic Focus: Functional Epileptic Networks in Focal Epilepsy.

Tue, 12/24/2019 - 11:40
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Beyond the Epileptic Focus: Functional Epileptic Networks in Focal Epilepsy.

Cereb Cortex. 2019 Dec 21;:

Authors: Gil F, Padilla N, Soria-Pastor S, Setoain X, Boget T, Rumiá J, Roldán P, Reyes D, Bargalló N, Conde E, Pintor L, Vernet O, Manzanares I, Ådén U, Carreño M, Donaire A

Abstract
Focal epilepsy can be conceptualized as a network disorder, and the functional epileptic network can be described as a complex system of multiple brain areas that interact dynamically to generate epileptic activity. However, we still do not fully understand the functional architecture of epileptic networks. We studied a cohort of 21 patients with extratemporal focal epilepsy. We used independent component analysis of functional magnetic resonance imaging (fMRI) data. In order to identify the epilepsy-related components, we examined the general linear model-derived electroencephalography-fMRI (EEG-fMRI) time courses associated with interictal epileptic activity as intrinsic hemodynamic epileptic biomarkers. Independent component analysis revealed components related to the epileptic time courses in all 21 patients. Each epilepsy-related component described a network of spatially distributed brain areas that corresponded to the specific epileptic network in each patient. We also provided evidence for the interaction between the epileptic activity generated at the epileptic network and the physiological resting state networks. Our findings suggest that independent component analysis, guided by EEG-fMRI epileptic time courses, have the potential to define the functional architecture of the epileptic network in a noninvasive way. These data could be useful in planning invasive EEG electrode placement, guiding surgical resections, and more effective therapeutic interventions.

PMID: 31867595 [PubMed - as supplied by publisher]

Outdoor Air Pollution and Brain Structure and Function From Across Childhood to Young Adulthood: A Methodological Review of Brain MRI Studies.

Tue, 12/24/2019 - 11:40
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Outdoor Air Pollution and Brain Structure and Function From Across Childhood to Young Adulthood: A Methodological Review of Brain MRI Studies.

Front Public Health. 2019;7:332

Authors: Herting MM, Younan D, Campbell CE, Chen JC

Abstract
Outdoor air pollution has been recognized as a novel environmental neurotoxin. Studies have begun to use brain Magnetic Resonance Imaging (MRI) to investigate how air pollution may adversely impact developing brains. A systematic review was conducted to evaluate and synthesize the reported evidence from MRI studies on how early-life exposure to outdoor air pollution affects neurodevelopment. Using PubMed and Web of Knowledge, we conducted a systematic search, followed by structural review of original articles with individual-level exposure data and that met other inclusion criteria. Six studies were identified, each sampled from 3 cohorts of children in Spain, The Netherlands, and the United States. All studies included a one-time assessment of brain MRI when children were 6-12 years old. Air pollutants from traffic and/or regional sources, including polycyclic aromatic hydrocarbons (PAHs), nitrogen dioxide, elemental carbon, particulate matter (<2.5 or <10 μm), and copper, were estimated prenatally (n = 1), during childhood (n = 3), or both (n = 2), using personal monitoring and urinary biomarkers (n = 1), air sampling at schools (n = 4), or a land-use regression (LUR) modeling based on residences (n = 2). Associations between exposure and brain were noted, including: smaller white matter surface area (n = 1) and microstructure (n = 1); region-specific patterns of cortical thinness (n = 1) and smaller volumes and/or less density within the caudate (n = 3); altered resting-state functional connectivity (n = 2) and brain activity to sensory stimuli (n = 1). Preliminary findings suggest that outdoor air pollutants may impact MRI brain structure and function, but limitations highlight that the design of future air pollution-neuroimaging studies needs to incorporate a developmental neurosciences perspective, considering the exposure timing, age of study population, and the most appropriate neurodevelopmental milestones.

PMID: 31867298 [PubMed]

Altered Directed Functional Connectivity of the Hippocampus in Mild Cognitive Impairment and Alzheimer's Disease: A Resting-State fMRI Study.

Tue, 12/24/2019 - 11:40
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Altered Directed Functional Connectivity of the Hippocampus in Mild Cognitive Impairment and Alzheimer's Disease: A Resting-State fMRI Study.

Front Aging Neurosci. 2019;11:326

Authors: Xue J, Guo H, Gao Y, Wang X, Cui H, Chen Z, Wang B, Xiang J

Abstract
The hippocampus is generally reported as one of the regions most impacted by Alzheimer's disease (AD) and is closely associated with memory function and orientation. Undirected functional connectivity (FC) alterations occur in patients with mild cognitive impairment (MCI) and AD, and these alterations have been the subject of many studies. However, abnormal patterns of directed FC remain poorly understood. In this study, to identify changes in directed FC between the hippocampus and other brain regions, Granger causality analysis (GCA) based on voxels was applied to resting-state functional magnetic resonance imaging (rs-fMRI) data from 29 AD, 65 MCI, and 30 normal control (NC) subjects. The results showed significant differences in the patterns of directed FC among the three groups. There were fewer brain regions showing changes in directed FC with the hippocampus in the MCI group than the NC group, and these regions were mainly located in the temporal lobe, frontal lobe, and cingulate cortex. However, regarding the abnormalities in directed FC in the AD group, the number of affected voxels was greater, the size of the clusters was larger, and the distribution was wider. Most of the abnormal connections were unidirectional and showed hemispheric asymmetry. In addition, we also investigated the correlations between the abnormal directional FCs and cognitive and clinical measurement scores in the three groups and found that some of them were significantly correlated. This study revealed abnormalities in the transmission and reception of information in the hippocampus of MCI and AD patients and offer insight into the neurophysiological mechanisms underlying MCI and AD.

PMID: 31866850 [PubMed]

Chronic Tinnitus Exhibits Bidirectional Functional Dysconnectivity in Frontostriatal Circuit.

Tue, 12/24/2019 - 11:40
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Chronic Tinnitus Exhibits Bidirectional Functional Dysconnectivity in Frontostriatal Circuit.

Front Neurosci. 2019;13:1299

Authors: Xu JJ, Cui J, Feng Y, Yong W, Chen H, Chen YC, Yin X, Wu Y

Abstract
Purpose: The phantom sound of tinnitus is considered to be associated with abnormal functional coupling between the nucleus accumbens (NAc) and the prefrontal cortex, which may form a frontostriatal top-down gating system to evaluate and modulate sensory signals. Resting-state functional magnetic resonance imaging (fMRI) was used to recognize the aberrant directional connectivity of the NAc in chronic tinnitus and to ascertain the relationship between this connectivity and tinnitus characteristics.
Methods: Participants included chronic tinnitus patients (n = 50) and healthy controls (n = 55), matched for age, sex, education, and hearing thresholds. The hearing status of both groups was comparable. On the basis of the NAc as a seed region, a Granger causality analysis (GCA) study was conducted to investigate the directional connectivity and the relationship with tinnitus duration or distress.
Results: Compared with healthy controls, tinnitus patients exhibited abnormal directional connectivity between the NAc and the prefrontal cortex, principally the middle frontal gyrus (MFG), orbitofrontal cortex (OFC), and inferior frontal gyrus (IFG). Additionally, positive correlations between tinnitus handicap questionnaire (THQ) scores and increased directional connectivity from the right NAc to the left MFG (r = 0.357, p = 0.015) and from the right MFG to the left NAc (r = 0.626, p < 0.001) were observed. Furthermore, the enhanced directional connectivity from the right NAc to the right OFC was positively associated with the duration of tinnitus (r = 0.599, p < 0.001).
Conclusion: In concurrence with expectations, tinnitus distress was correlated with enhanced directional connectivity between the NAc and the prefrontal cortex. The current study not only helps illuminate the neural basis of the frontostriatal gating control of tinnitus sensation but also contributes to deciphering the neuropathological features of tinnitus.

PMID: 31866810 [PubMed]

Neuroplasticity of the sensorimotor neural network associated with walking aid training in people with multiple sclerosis.

Tue, 12/24/2019 - 11:40
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Neuroplasticity of the sensorimotor neural network associated with walking aid training in people with multiple sclerosis.

Mult Scler Relat Disord. 2019 Jun;31:1-4

Authors: Fling BW, Martini DN, Zeeboer E, Hildebrand A, Cameron M

Abstract
The objective of this pilot study was to identify neural descriptors and correlates of participation in a multicomponent walking aid program, the Assistive Device Selection, Training and Education Program (ADSTEP), in people with multiple sclerosis, as reflected by resting state functional MRI. Fourteen people with multiple sclerosis who used a walking aid at baseline and reported falling at least once in the prior year were recruited from the multiple sclerosis clinic in a Veterans Affairs and the surrounding community to participate in a trial of ADSTEP, a multicomponent program of walking aid selection, fitting and six weekly progressive task-oriented walking aid training sessions and undergo resting state functional brain MRI. The functional MRI was performed at baseline and at program completion to assess for changes in neural connectivity of the sensorimotor neural network. Compared to baseline, following ADSTEP participation, functional connectivity between the supplementary motor areas and both the primary somatosensory cortices and the putamen was increased; whereas functional connectivity between the supplementary motor areas and the cerebellum was decreased. This study provides preliminary support for supraspinal sensorimotor neuroplasticity in response to rehabilitation interventions such as task-oriented walking aid training, suggests specific neural targets for future mobility interventions, and supports the need for full-scale randomized controlled trials in this area.

PMID: 30875527 [PubMed - indexed for MEDLINE]

Calcium channel blockade with nimodipine reverses MRI evidence of cerebral oedema following acute hypoxia.

Tue, 12/24/2019 - 11:40
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Calcium channel blockade with nimodipine reverses MRI evidence of cerebral oedema following acute hypoxia.

J Cereb Blood Flow Metab. 2019 02;39(2):285-301

Authors: Rowland MJ, Ezra M, Winkler A, Garry P, Lamb C, Kelly M, Okell TW, Westbrook J, Wise RG, Douaud G, Pattinson KT

Abstract
Acute cerebral hypoxia causes rapid calcium shifts leading to neuronal damage and death. Calcium channel antagonists improve outcomes in some clinical conditions, but mechanisms remain unclear. In 18 healthy participants we: (i) quantified with multiparametric MRI the effect of hypoxia on the thalamus, a region particularly sensitive to hypoxia, and on the whole brain in general; (ii) investigated how calcium channel antagonism with the drug nimodipine affects the brain response to hypoxia. Hypoxia resulted in a significant decrease in apparent diffusion coefficient (ADC), a measure particularly sensitive to cell swelling, in a widespread network of regions across the brain, and the thalamus in particular. In hypoxia, nimodipine significantly increased ADC in the same brain regions, normalizing ADC towards normoxia baseline. There was positive correlation between blood nimodipine levels and ADC change. In the thalamus, there was a significant decrease in the amplitude of low frequency fluctuations (ALFF) in resting state functional MRI and an apparent increase of grey matter volume in hypoxia, with the ALFF partially normalized towards normoxia baseline with nimodipine. This study provides further evidence that the brain response to acute hypoxia is mediated by calcium, and importantly that manipulation of intracellular calcium flux following hypoxia may reduce cerebral cytotoxic oedema.

PMID: 28857714 [PubMed - indexed for MEDLINE]

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