Photosensitive epilepsy is associated with reduced inhibition of alpha rhythm generating networks.
Brain. 2017 Feb 20;:
Authors: Elisabetta Vaudano A, Ruggieri A, Avanzini P, Gessaroli G, Cantalupo G, Coppola A, Sisodiya SM, Meletti S
Photosensitivity is a condition in which lights induce epileptiform activities. This abnormal electroencephalographic response has been associated with hyperexcitability of the visuo-motor system. Here, we evaluate if intrinsic dysfunction of this network is present in brain activity at rest, independently of any stimulus and of any paroxysmal electroencephalographic activity. To address this issue, we investigated the haemodynamic correlates of the spontaneous alpha rhythm, which is considered the hallmark of the brain resting state, in photosensitive patients and in people without photosensitivity. Second, we evaluated the whole-brain functional connectivity of the visual thalamic nuclei in the various populations of subjects under investigation. Forty-four patients with epilepsy and 16 healthy control subjects underwent an electroencephalography-correlated functional magnetic resonance imaging study, during an eyes-closed condition. The following patient groups were included: (i) genetic generalized epilepsy with photosensitivity, 16 subjects (mean age 25 ± 10 years); (ii) genetic generalized epilepsy without photosensitivity, 13 patients (mean age 25 ± 11 years); (iii) focal epilepsy, 15 patients (mean age 25 ± 9 years). For each subject, the posterior alpha power variations were convolved with the standard haemodynamic response function and used as a regressor. Within- and between-groups second level analyses were performed. Whole brain functional connectivity was evaluated for two thalamic regions of interest, based on the haemodynamic findings, which included the posterior thalamus (pulvinar) and the medio-dorsal thalamic nuclei. Genetic generalized epilepsy with photosensitivity demonstrated significantly greater mean alpha-power with respect to controls and other epilepsy groups. In photosensitive epilepsy, alpha-related blood oxygen level-dependent signal changes demonstrated lower decreases relative to all other groups in the occipital, sensory-motor, anterior cingulate and supplementary motor cortices. Coherently, the same brain regions demonstrated abnormal connectivity with the visual thalamus only in epilepsy patients with photosensitivity. As predicted, our findings indicate that the cortical-subcortical network generating the alpha oscillation at rest is different in people with epilepsy and visual sensitivity. This difference consists of a decreased alpha-related inhibition of the visual cortex and sensory-motor networks at rest. These findings represent the substrate of the clinical manifestations (i.e. myoclonus) of the photoparoxysmal response. Moreover, our results provide the first evidence of the existence of a functional link between the circuits that trigger the visual sensitivity phenomenon and those that generate the posterior alpha rhythm.
PMID: 28334965 [PubMed - as supplied by publisher]
Decreased integration and information capacity in stroke measured by whole brain models of resting state activity.
Brain. 2017 Feb 20;:
Authors: Adhikari MH, Hacker CD, Siegel JS, Griffa A, Hagmann P, Deco G, Corbetta M
While several studies have shown that focal lesions affect the communication between structurally normal regions of the brain, and that these changes may correlate with behavioural deficits, their impact on brain's information processing capacity is currently unknown. Here we test the hypothesis that focal lesions decrease the brain's information processing capacity, of which changes in functional connectivity may be a measurable correlate. To measure processing capacity, we turned to whole brain computational modelling to estimate the integration and segregation of information in brain networks. First, we measured functional connectivity between different brain areas with resting state functional magnetic resonance imaging in healthy subjects (n = 26), and subjects who had suffered a cortical stroke (n = 36). We then used a whole-brain network model that coupled average excitatory activities of local regions via anatomical connectivity. Model parameters were optimized in each healthy or stroke participant to maximize correlation between model and empirical functional connectivity, so that the model's effective connectivity was a veridical representation of healthy or lesioned brain networks. Subsequently, we calculated two model-based measures: 'integration', a graph theoretical measure obtained from functional connectivity, which measures the connectedness of brain networks, and 'information capacity', an information theoretical measure that cannot be obtained empirically, representative of the segregative ability of brain networks to encode distinct stimuli. We found that both measures were decreased in stroke patients, as compared to healthy controls, particularly at the level of resting-state networks. Furthermore, we found that these measures, especially information capacity, correlate with measures of behavioural impairment and the segregation of resting-state networks empirically measured. This study shows that focal lesions affect the brain's ability to represent stimuli and task states, and that information capacity measured through whole brain models is a theory-driven measure of processing capacity that could be used as a biomarker of injury for outcome prediction or target for rehabilitation intervention.
PMID: 28334882 [PubMed - as supplied by publisher]
Testosterone Effects on the Brain in Transgender Men.
Cereb Cortex. 2017 Mar 10;:1-15
Authors: Burke SM, Manzouri AH, Dhejne C, Bergström K, Arver S, Feusner JD, Savic-Berglund I
Transgender individuals experience incongruence between their gender identity and birth-assigned sex. The resulting gender dysphoria (GD), which some gender-incongruent individuals experience, is theorized to be a consequence of atypical cerebral sexual differentiation, but support for this assertion is inconsistent. We recently found that GD is associated with disconnected networks involved in self-referential thinking and own body perception. Here, we investigate how these networks in trans men (assigned female at birth with male gender identity) are affected by testosterone. In 22 trans men, we obtained T1-weighted, diffusion-weighted, and resting-state functional magnetic resonance imaging scans before and after testosterone treatment, measuring cortical thickness (Cth), subcortical volumes, fractional anisotropy (FA), and functional connectivity. Nineteen cisgender controls (male and female) were also scanned twice. The medial prefrontal cortex (mPFC) was thicker in trans men than controls pretreatment, and remained unchanged posttreatment. Testosterone treatment resulted in increased Cth in the insular cortex, changes in cortico-cortical thickness covariation between mPFC and occipital cortex, increased FA in the fronto-occipital tract connecting these regions, and increased functional connectivity between mPFC and temporo-parietal junction, compared with controls. Concluding, in trans men testosterone treatment resulted in functional and structural changes in self-referential and own body perception areas.
PMID: 28334217 [PubMed - as supplied by publisher]
PCA leverage: outlier detection for high-dimensional functional magnetic resonance imaging data.
Biostatistics. 2017 Feb 27;:
Authors: Mejia AF, Nebel MB, Eloyan A, Caffo B, Lindquist MA
Outlier detection for high-dimensional (HD) data is a popular topic in modern statistical research. However, one source of HD data that has received relatively little attention is functional magnetic resonance images (fMRI), which consists of hundreds of thousands of measurements sampled at hundreds of time points. At a time when the availability of fMRI data is rapidly growing-primarily through large, publicly available grassroots datasets-automated quality control and outlier detection methods are greatly needed. We propose principal components analysis (PCA) leverage and demonstrate how it can be used to identify outlying time points in an fMRI run. Furthermore, PCA leverage is a measure of the influence of each observation on the estimation of principal components, which are often of interest in fMRI data. We also propose an alternative measure, PCA robust distance, which is less sensitive to outliers and has controllable statistical properties. The proposed methods are validated through simulation studies and are shown to be highly accurate. We also conduct a reliability study using resting-state fMRI data from the Autism Brain Imaging Data Exchange and find that removal of outliers using the proposed methods results in more reliable estimation of subject-level resting-state networks using independent components analysis.
PMID: 28334131 [PubMed - as supplied by publisher]
Structural and functional connectional fingerprints in mild cognitive impairment and Alzheimer's disease patients.
PLoS One. 2017;12(3):e0173426
Authors: Son SJ, Kim J, Park H
Regional volume atrophy and functional degeneration are key imaging hallmarks of Alzheimer's disease (AD) in structural and functional magnetic resonance imaging (MRI), respectively. We jointly explored regional volume atrophy and functional connectivity to better characterize neuroimaging data of AD and mild cognitive impairment (MCI). All data were obtained from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database. We compared regional volume atrophy and functional connectivity in 10 subcortical regions using structural MRI and resting-state functional MRI (rs-fMRI). Neuroimaging data of normal controls (NC) (n = 35), MCI (n = 40), and AD (n = 30) were compared. Significant differences of regional volumes and functional connectivity measures between groups were assessed using permutation tests in 10 regions. The regional volume atrophy and functional connectivity of identified regions were used as features for the random forest classifier to distinguish among three groups. The features of the identified regions were also regarded as connectional fingerprints that could distinctively separate a given group from the others. We identified a few regions with distinctive regional atrophy and functional connectivity patterns for NC, MCI, and AD groups. A three label classifier using the information of regional volume atrophy and functional connectivity of identified regions achieved classification accuracy of 53.33% to distinguish among NC, MCI, and AD. We identified distinctive regional atrophy and functional connectivity patterns that could be regarded as a connectional fingerprint.
PMID: 28333946 [PubMed - in process]
Altered functional brain connectivity in patients with visually induced dizziness.
Neuroimage Clin. 2017;14:538-545
Authors: Van Ombergen A, Heine L, Jillings S, Roberts RE, Jeurissen B, Van Rompaey V, Mucci V, Vanhecke S, Sijbers J, Vanhevel F, Sunaert S, Bahri MA, Parizel PM, Van de Heyning PH, Laureys S, Wuyts FL
BACKGROUND: Vestibular patients occasionally report aggravation or triggering of their symptoms by visual stimuli, which is called visually induced dizziness (VID). These patients therefore experience dizziness, discomfort, disorientation and postural unsteadiness. The underlying pathophysiology of VID is still poorly understood.
OBJECTIVE: The aim of the current explorative study was to gain a first insight in the underlying neural aspects of VID.
METHODS: We included 10 VID patients and 10 healthy matched controls, all of which underwent a resting state fMRI scan session. Changes in functional connectivity were explored by means of the intrinsic connectivity contrast (ICC). Seed-based analysis was subsequently performed in visual and vestibular seeds.
RESULTS: We found a decreased functional connectivity in the right central operculum (superior temporal gyrus), as well as increased functional connectivity in the occipital pole in VID patients as compared to controls in a hypothesis-free analysis. A weaker functional connectivity between the thalamus and most of the right putamen was measured in VID patients in comparison to controls in a seed-based analysis. Furthermore, also by means of a seed-based analysis, a decreased functional connectivity between the visual associative area and the left parahippocampal gyrus was found in VID patients. Additionally, we found increased functional connectivity between thalamus and occipital and cerebellar areas in the VID patients, as well as between the associative visual cortex and both middle frontal gyrus and precuneus.
CONCLUSIONS: We found alterations in the visual and vestibular cortical network in VID patients that could underlie the typical VID symptoms such as a worsening of their vestibular symptoms when being exposed to challenging visual stimuli. These preliminary findings provide the first insights into the underlying functional brain connectivity in VID patients. Future studies should extend these findings by employing larger sample sizes, by investigating specific task-based paradigms in these patients and by exploring the implications for treatment.
PMID: 28331800 [PubMed - in process]
Multimodal MR-imaging reveals large-scale structural and functional connectivity changes in profound early blindness.
PLoS One. 2017;12(3):e0173064
Authors: Bauer CM, Hirsch GV, Zajac L, Koo BB, Collignon O, Merabet LB
In the setting of profound ocular blindness, numerous lines of evidence demonstrate the existence of dramatic anatomical and functional changes within the brain. However, previous studies based on a variety of distinct measures have often provided inconsistent findings. To help reconcile this issue, we used a multimodal magnetic resonance (MR)-based imaging approach to provide complementary structural and functional information regarding this neuroplastic reorganization. This included gray matter structural morphometry, high angular resolution diffusion imaging (HARDI) of white matter connectivity and integrity, and resting state functional connectivity MRI (rsfcMRI) analysis. When comparing the brains of early blind individuals to sighted controls, we found evidence of co-occurring decreases in cortical volume and cortical thickness within visual processing areas of the occipital and temporal cortices respectively. Increases in cortical volume in the early blind were evident within regions of parietal cortex. Investigating white matter connections using HARDI revealed patterns of increased and decreased connectivity when comparing both groups. In the blind, increased white matter connectivity (indexed by increased fiber number) was predominantly left-lateralized, including between frontal and temporal areas implicated with language processing. Decreases in structural connectivity were evident involving frontal and somatosensory regions as well as between occipital and cingulate cortices. Differences in white matter integrity (as indexed by quantitative anisotropy, or QA) were also in general agreement with observed pattern changes in the number of white matter fibers. Analysis of resting state sequences showed evidence of both increased and decreased functional connectivity in the blind compared to sighted controls. Specifically, increased connectivity was evident between temporal and inferior frontal areas. Decreases in functional connectivity were observed between occipital and frontal and somatosensory-motor areas and between temporal (mainly fusiform and parahippocampus) and parietal, frontal, and other temporal areas. Correlations in white matter connectivity and functional connectivity observed between early blind and sighted controls showed an overall high degree of association. However, comparing the relative changes in white matter and functional connectivity between early blind and sighted controls did not show a significant correlation. In summary, these findings provide complimentary evidence, as well as highlight potential contradictions, regarding the nature of regional and large scale neuroplastic reorganization resulting from early onset blindness.
PMID: 28328939 [PubMed - in process]
Resting-State Functional Connectivity Predicts Longitudinal Pain Symptom Change In Urologic Chronic Pelvic Pain Syndrome: A Mapp Network Study.
Pain. 2017 Mar 17;:
Authors: Kutch JJ, Labus JS, Harris RE, Martucci KT, Farmer MA, Fenske S, Fling C, Ichesco E, Peltier S, Petre B, Guo W, Hou X, Stephens AJ, Mullins C, Clauw DJ, Mackey SC, Apkarian AV, Landis JR, Mayer EA, MAPP Research Network
Chronic pain symptoms often change over time, even in individuals who have had symptoms for years. Studying biological factors that predict trends in symptom change in chronic pain may uncover novel pathophysiological mechanisms and potential therapeutic targets. In this study, we investigated whether brain functional connectivity measures obtained from resting-state functional MRI (rs-fMRI) at baseline can predict longitudinal symptom change (3, 6, and 12 months post-scan) in urologic chronic pelvic pain syndrome (UCPPS). We studied 52 individuals with UCPPS (34 female, 18 male) who had baseline neuroimaging followed by symptom tracking every 2 weeks for 1 year as part of the Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) Research Network study. We found that brain functional connectivity can make a significant prediction of short-term (3 month) pain reduction with 73.1% accuracy (69.2% sensitivity and 75.0% precision). Additionally, we found that the brain regions with greatest contribution to the classification were preferentially aligned with the left frontoparietal network (L-FPN). rs-fMRI measures appeared to be less informative about 6 or 12 month symptom change. Our study provides the first evidence that future trends in symptom change in patients in a state of chronic pain may be linked to functional connectivity within specific brain networks.
PMID: 28328579 [PubMed - as supplied by publisher]
Altered resting-state hippocampal functional networks associated with chemotherapy-induced prospective memory impairment in breast cancer survivors.
Sci Rep. 2017 Mar 22;7:45135
Authors: Cheng H, Li W, Gong L, Xuan H, Huang Z, Zhao H, Wang LS, Wang K
In this study, we aimed to investigate the intrinsic hippocampal functional connectivity (FC) network and its relationship with prospective memory in patients with breast cancer suffering from chemotherapy-induced cognitive impairment (CICI). Thirty-four breast cancer patients before and after adjuvant chemotherapy (CB and CC, respectively) and 31 age- and education-matched cognitively normal (CN) women were recruited and subjected to a prospective memory task and a resting-state functional magnetic resonance imaging scan. Seed-based functional connectivity analysis was used to compare the hippocampal FC networks between CC and CN groups. Partial correction analysis was used to examine the association between the hippocampal FC network and prospective memory in the CC group. The cancer group that underwent chemotherapy obtained significantly poorer scores than the CN group on mini-mental state examination, verbal fluency test, digit span, and prospective memory examination. Compared to the CN group, CC group showed increased hippocampal connectivity in the frontal and parietal cortex, precuneus, posterior cingulate cortex, and the cerebellum. In addition, the increasing hippocampal FC networks were negatively correlated with prospective memory performance in the CC group. These findings suggest maladaptive hippocampal functioning as a mechanism underlying the impairment of prospective memory in patients experiencing CICI.
PMID: 28327626 [PubMed - in process]
Differences on Brain Connectivity in Adulthood Are Present in Subjects with Iron Deficiency Anemia in Infancy.
Front Aging Neurosci. 2017;9:54
Authors: Algarin C, Karunakaran KD, Reyes S, Morales C, Lozoff B, Peirano P, Biswal B
Iron deficiency continues to be the most prevalent micronutrient deficit worldwide. Since iron is involved in several processes including myelination, dopamine neurotransmission and neuronal metabolism, the presence of iron deficiency anemia (IDA) in infancy relates to long-lasting neurofunctional effects. There is scarce data regarding whether these effects would extend to former iron deficient anemic human adults. Resting state functional magnetic resonance imaging (fMRI) is a novel technique to explore patterns of functional connectivity. Default Mode Network (DMN), one of the resting state networks, is deeply involved in memory, social cognition and self-referential processes. The four core regions consistently identified in the DMN are the medial prefrontal cortex, posterior cingulate/retrosplenial cortex and left and right inferior parietal cortex. Therefore to investigate the DMN in former iron deficient anemic adults is a particularly useful approach to elucidate de long term effects on functional brain. We conducted this research to explore the connection between IDA in infancy and altered patterns of resting state brain functional networks in young adults. Resting-state fMRI studies were performed to 31 participants that belong to a follow-up study since infancy. Of them, 14 participants were former iron deficient anemic in infancy and 17 were controls, with mean age of 21.5 years (±1.5) and 54.8% were males. Resting-state fMRI protocol was used and the data was analyzed using the seed based connectivity statistical analysis to assess the DMN. We found that compared to controls, former iron deficient anemic subjects showed posterior DMN decreased connectivity to the left posterior cingulate cortex (PCC), whereas they exhibited increased anterior DMN connectivity to the right PCC. Differences between groups were also apparent in the left medial frontal gyrus, with former iron deficient anemic participants having increased connectivity with areas included in DMN and dorsal attention networks. These preliminary results suggest different patterns of functional connectivity between former iron deficient anemic and control young adults. Indeed, IDA in infancy, a common nutritional problem among human infants, may turn out to be important for understanding the mechanisms of cognitive alterations, common in adulthood.
PMID: 28326037 [PubMed - in process]
Impact of Resveratrol on Glucose Control, Hippocampal Structure and Connectivity, and Memory Performance in Patients with Mild Cognitive Impairment.
Front Neurosci. 2017;11:105
Authors: Köbe T, Witte AV, Schnelle A, Tesky VA, Pantel J, Schuchardt JP, Hahn A, Bohlken J, Grittner U, Flöel A
In healthy older adults, resveratrol supplementation has been shown to improve long-term glucose control, resting-state functional connectivity (RSFC) of the hippocampus, and memory function. Here, we aimed to investigate if these beneficial effects extend to individuals at high-risk for dementia, i.e., patients with mild cognitive impairment (MCI). In a randomized, double-blind interventional study, 40 well-characterized patients with MCI (21 females; 50-80 years) completed 26 weeks of resveratrol (200 mg/d; n = 18) or placebo (1,015 mg/d olive oil; n = 22) intake. Serum levels of glucose, glycated hemoglobin A1c and insulin were determined before and after intervention. Moreover, cerebral magnetic resonance imaging (MRI) (3T) (n = 14 vs. 16) was conducted to analyze hippocampus volume, microstructure and RSFC, and neuropsychological testing was conducted to assess learning and memory (primary endpoint) at both time points. In comparison to the control group, resveratrol supplementation resulted in lower glycated hemoglobin A1c concentration with a moderate effect size (ANOVARMp = 0.059, Cohen's d = 0.66), higher RSFC between right anterior hippocampus and right angular cortex (p < 0.001), and led to a moderate preservation of left anterior hippocampus volume (ANOVARMp = 0.061, Cohen's d = 0.68). No significant differences in memory performance emerged between groups. This proof-of-concept study indicates for the first-time that resveratrol intake may reduce glycated hemoglobin A1c, preserves hippocampus volume, and improves hippocampus RSFC in at-risk patients for dementia. Larger trials with longer intervention time should now determine if these benefits can be validated and extended to cognitive function.
PMID: 28326010 [PubMed - in process]
Brain network characteristics separating individuals at clinical high risk for psychosis into normality or psychosis.
Schizophr Res. 2017 Mar 18;:
Authors: Choi SH, Kyeong S, Cho KI, Yun JY, Lee TY, Park HY, Kim SN, Kwon JS
We aimed to separate individuals at clinical high risk for psychosis (CHR) state into subgroups according to neurobiological characteristics using structural and functional network constructs and examine their clinical characteristics. Structural diffusion tensor imaging and resting-state functional magnetic resonance imaging were performed in 61 healthy controls (HC), 57 individuals at CHR and 29 patients with schizophrenia (SZ). The main outcome was a likelihood ratio calculated from measures of structural and functional network efficiencies, coupling strength of structural and functional networks, and a disease-specific data analysis, resulting in the most probable classification of CHR into HC or SZ. The likelihood ratios revealed that 33 individuals at CHR were likely similar to HC (CHR-HC), and the remaining 24 CHR individuals were similar to SZ (CHR-SZ). The CHR subgroups were comparable to each other in demographic characteristics and clinical symptoms. However, the verbal and executive functions of CHR-HC were similar to those of HC, and those of CHR-SZ similar to SZ. Additionally, CHR-SZ was more responsive to treatment than CHR-HC during the follow-up period. By combining structural and functional data, we could detect the vulnerable population and provide an active intervention in the early phase of the CHR state.
PMID: 28325573 [PubMed - as supplied by publisher]
Comparing resting state fMRI de-noising approaches using multi- and single-echo acquisitions.
PLoS One. 2017;12(3):e0173289
Authors: Dipasquale O, Sethi A, Laganà MM, Baglio F, Baselli G, Kundu P, Harrison NA, Cercignani M
Artifact removal in resting state fMRI (rfMRI) data remains a serious challenge, with even subtle head motion undermining reliability and reproducibility. Here we compared some of the most popular single-echo de-noising methods-regression of Motion parameters, White matter and Cerebrospinal fluid signals (MWC method), FMRIB's ICA-based X-noiseifier (FIX) and ICA-based Automatic Removal Of Motion Artifacts (ICA-AROMA)-with a multi-echo approach (ME-ICA) that exploits the linear dependency of BOLD on the echo time. Data were acquired using a clinical scanner and included 30 young, healthy participants (minimal head motion) and 30 Attention Deficit Hyperactivity Disorder patients (greater head motion). De-noising effectiveness was assessed in terms of data quality after each cleanup procedure, ability to uncouple BOLD signal and motion and preservation of default mode network (DMN) functional connectivity. Most cleaning methods showed a positive impact on data quality. However, based on the investigated metrics, ME-ICA was the most robust. It minimized the impact of motion on FC even for high motion participants and preserved DMN functional connectivity structure. The high-quality results obtained using ME-ICA suggest that using a multi-echo EPI sequence, reliable rfMRI data can be obtained in a clinical setting.
PMID: 28323821 [PubMed - in process]
Mindfulness Meditation Training and Executive Control Network Resting State Functional Connectivity: A Randomized Controlled Trial.
Psychosom Med. 2017 Mar 20;:
Authors: Taren AA, Gianaros PJ, Greco CM, Lindsay EK, Fairgrieve A, Brown KW, Rosen RK, Ferris JL, Julson E, Marsland AL, Creswell JD
OBJECTIVE: Mindfulness meditation training has been previously shown to enhance behavioral measures of executive control (e.g. attention, working memory, cognitive control), but the neural mechanisms underlying these improvements are largely unknown. Here, we test whether mindfulness training interventions foster executive control by strengthening functional connections between dorsolateral prefrontal cortex (dlPFC) - a hub of the executive control network - and frontoparietal regions that coordinate executive function.
METHODS: Thirty-five adults with elevated levels of psychological distress participated in a 3 day RCT of intensive mindfulness meditation or relaxation training. Participants completed a resting state fMRI scan before and after the intervention. We tested whether mindfulness meditation training increased resting state functional connectivity (rsFC) between dlPFC and frontoparietal control network regions.
RESULTS: Left dlPFC showed increased connectivity to the right inferior frontal gyrus (T = 3.74), right middle frontal gyrus (T = 3.98), right supplementary eye field (T = 4.29), right parietal cortex (T = 4.44), and left middle temporal gyrus (T = 3.97; all p<0.05) following mindfulness training relative to the relaxation control. Right dlPFC showed increased connectivity to right middle frontal gyrus (T = 4.97, p < 0.05).
CONCLUSIONS: We report that mindfulness training increases rsFC between dlPFC and dorsal network (superior parietal lobule, supplementary eye field, MFG) and ventral network (right IFG, middle temporal/angular gyrus) regions. These findings extend previous work showing increased functional connectivity amongst brain regions associated with executive function during active meditation by identifying specific neural circuits in which rsFC is enhanced by a mindfulness intervention in individuals with high levels of psychological distress.
TRIAL REGISTRATION: Clinicaltrials.gov (#NCT01628809).
PMID: 28323668 [PubMed - as supplied by publisher]
Disrupted functional connectivity of periaqueductal gray subregions in episodic migraine.
J Headache Pain. 2017 Dec;18(1):36
Authors: Chen Z, Chen X, Liu M, Liu S, Ma L, Yu S
BACKGROUND: The periaqueductal gray (PAG) dysfunction was recognized in migraine, and the altered dysfunction of PAG subregions were not totally detected up to now. The aim of this study is to investigate the altered functional connectivity of PAG subregions in EM patients.
METHODS: The brain structural images and resting state functional MR imaging (rs-fMRI) data were obtained from 18 normal controls (NC) and 18 EM patients on 3.0 T MR system. Seven subregions of PAG were classified as bilateral ventrolateral PAG (vlPAG), lateral PAG (lPAG), dorsolateral PAG (dlPAG) and dorsomedial PAG (dmPAG). The functional connectivity maps of each PAG subregion were calculated, and Two sample t-test was applied with age and sex as covariables.
RESULTS: Bilateral vlPAG and left dlPAG presented decreased functional connectivity, and the other subregions (bilateral lPAGs, right dlPAG and dmPAG) showed no significant altered functional connectivity in EM compared with NC. The brain regions with decreased functional connectivity mainly located in bilateral prefrontal cortex(PFC), middle temporal gyrus, primary motor area (PMA) and supplementary motor area (SMA) and right ventrolateral PFC (vlPFC) in EM patients in this study. Disease duration was positively related to the functional connectivity of bilateral vlPAG on the bilateral thalamus and putamen, left pallidum and right medial orbitofrontal gyrus in EM patients.
CONCLUSION: The present study suggested that the dysfunction of bilateral vlPAG and left dlPAG presented in EM, and functional evaluation of PAG subregions may be help for the diagnosis and understanding of EM pathogenesis.
PMID: 28321594 [PubMed - in process]
Lumbar spondylolysis in the adolescent athlete.
Phys Ther Sport. 2016 Jul;20:56-60
Authors: Lawrence KJ, Elser T, Stromberg R
INTRODUCTION: Spondylolysis is a common occurrence for adolescent athletes who have low back pain. The injury involves a defect in the pars interarticularis, occurring as a result of repeated hyperextension and rotation.
CLINICAL PRESENTATION: Clinical findings might include tightness of the hip flexors and hamstrings, weakness of the abdominals and gluteals, and an excessive lordotic posture. The validity of several clinical tests were compared alongside magnetic resonance imaging, but were not able to distinguish spondylolysis from other causes of low back pain. Medical referral should be arranged so that medical imaging and diagnostic testing can be completed to insure a proper diagnosis.
INTERVENTIONS: Initial intervention includes rest from sport, which may vary from 2 weeks to 6 months. Bracing is also used to help minimize lumbar lordosis and lumbar extension. Exercises that focus on stabilization and spine neutral position should be incorporated in physical therapy intervention. Avoiding end ranges is important while performing exercises to minimize the translational and rotational stresses on the spine. Surgical interventions have also been recommended for athletes who have had persistent low back pain for more than six months with no relief from rest and bracing.
PMID: 27234265 [PubMed - indexed for MEDLINE]
Convergent and divergent effects of apolipoprotein E ε4 and ε2 alleles on amygdala functional networks in nondemented older adults.
Neurobiol Aging. 2017 Feb 24;54:31-39
Authors: Gong L, Shu H, He C, Ye Q, Bai F, Xie C, Zhang Z
Traditionally, in the context of Alzheimer's disease, the apolipoprotein E ε2 (APOEε2) allele is a protective factor and the APOEε4 allele is a destructive factor. However, this inverse relationship has recently been challenged, and the neural mechanisms underlying the effects of APOE genotype on Alzheimer's disease remain unclear. A resting-state functional magnetic resonance imaging study was conducted to investigate the effects of APOE genotype and age on amygdala functional connectivity (AFC) networks in 84 patients with amnestic mild cognitive impairment and 124 cognitively normal order adults. The results indicated that the APOEε2 and APOEε4 alleles produced convergent effects in the right AFC network but divergent effects in the left AFC network. As age increased, APOEε2 carriers showed stable AFC, whereas APOEε4 carriers exhibited decreased AFC in all participants. Furthermore, mediation analysis revealed that connectivity strength regulates the effects of APOE genotype and age on cognitive function in amnestic mild cognitive impairment patients. Our findings suggest that the APOEε2 and APOEε4 alleles produce both convergent and divergent topological effects on brain function.
PMID: 28319835 [PubMed - as supplied by publisher]
Repetitive transcranial magnetic stimulation (rTMS) of the dorsolateral prefrontal cortex reduces resting-state insula activity and modulates functional connectivity of the orbitofrontal cortex in cigarette smokers.
Drug Alcohol Depend. 2017 Feb 28;174:98-105
Authors: Li X, Du L, Sahlem GL, Badran BW, Henderson S, George MS
BACKGROUND: Previous studies reported that repetitive transcranial magnetic stimulation (rTMS) can reduce cue-elicited craving and decrease cigarette consumption in smokers. The mechanism of this effect however, remains unclear. We used resting-state functional magnetic resonance imaging (rsfMRI) to test the effect of rTMS in non-treatment seeking smokers.
METHODS: We used a single blinded, sham-controlled, randomized counterbalanced crossover design where participants underwent two visits separated by at least 1 week. Participants received active rTMS over the left dorsolateral prefrontal cortex (DLPFC) during one of their visits, and sham rTMS during their other visit. They had two rsFMRI scans before and after each rTMS session. We used the same rTMS stimulation parameters as in a previous study (10Hz, 5s-on, 10s-off, 100% resting motor threshold, 3000 pulses).
RESULTS: Ten non-treatment-seeking, nicotine-dependent, cigarette smokers (6 women, an average age of 39.72 and an average cigarette per day of 17.30) finished the study. rsFMRI results demonstrate that as compared to a single session of sham rTMS, a single session of active rTMS inhibits brain activity in the right insula and thalamus in fractional amplitude of low frequency fluctuation (fALFF). For intrinsic brain connectivity comparisons, active TMS resulted in significantly decreased connectivity from the site of rTMS to the left orbitomedial prefrontal cortex.
CONCLUSIONS: This data suggests that one session of rTMS can reduce activity in the right insula and right thalamus as measured by fALFF. The data also demonstrates that rTMS can reduce rsFC between the left DLPFC and the medial orbitofrontal cortex.
PMID: 28319755 [PubMed - as supplied by publisher]
The impact of high grade glial neoplasms on human cortical electrophysiology.
PLoS One. 2017;12(3):e0173448
Authors: Bandt SK, Roland JL, Pahwa M, Hacker CD, Bundy DT, Breshears JD, Sharma M, Shimony JS, Leuthardt EC
OBJECTIVE: The brain's functional architecture of interconnected network-related oscillatory patterns in discrete cortical regions has been well established with functional magnetic resonance imaging (fMRI) studies or direct cortical electrophysiology from electrodes placed on the surface of the brain, or electrocorticography (ECoG). These resting state networks exhibit a robust functional architecture that persists through all stages of sleep and under anesthesia. While the stability of these networks provides a fundamental understanding of the organization of the brain, understanding how these regions can be perturbed is also critical in defining the brain's ability to adapt while learning and recovering from injury.
METHODS: Patients undergoing an awake craniotomy for resection of a tumor were studied as a unique model of an evolving injury to help define how the cortical physiology and the associated networks were altered by the presence of an invasive brain tumor.
RESULTS: This study demonstrates that there is a distinct pattern of alteration of cortical physiology in the setting of a malignant glioma. These changes lead to a physiologic sequestration and progressive synaptic homogeneity suggesting that a de-learning phenomenon occurs within the tumoral tissue compared to its surroundings.
SIGNIFICANCE: These findings provide insight into how the brain accommodates a region of "defunctionalized" cortex. Additionally, these findings may have important implications for emerging techniques in brain mapping using endogenous cortical physiology.
PMID: 28319187 [PubMed - in process]
Functional disconnection of thalamic and cerebellar dentate nucleus networks in progressive supranuclear palsy and corticobasal syndrome.
Parkinsonism Relat Disord. 2017 Mar 15;:
Authors: Upadhyay N, Suppa A, Piattella MC, Giannì C, Bologna M, Di Stasio F, Petsas N, Tona F, Fabbrini G, Berardelli A, Pantano P
AIM: To assess functional rearrangement following neurodegeneration in the thalamus and dentate nucleus in patients with progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS).
METHODS: We recruited 19 patients with PSP, 11 with CBS and 14 healthy subjects. All the subjects underwent resting-state (rs) fMRI using a 3T system. Whole brain functional connectivity of the thalamus and dentate nucleus were calculated by means of a seed-based approach with FEAT script in FSL toolbox. Thalamic volume was calculated by means of FIRST, and the dentate area by means of Jim software.
RESULTS: Both thalamic volume and dentate area were significantly smaller in PSP and CBS patients than in healthy subjects. No significant difference emerged in thalamic volume between PSP and CBS patients, whereas dentate area was significantly smaller in PSP than in CBS. Thalamic functional connectivity was significantly reduced in both patient groups in various cortical, subcortical and cerebellar areas. By contrast, changes in dentate nucleus functional connectivity differed in PSP and CBS: it decreased in subcortical and prefrontal cortical areas in PSP, but increased asymmetrically in the frontal cortex in CBS.
CONCLUSIONS: Evaluating the dentate nucleus size and its functional connectivity may help to differentiate patients with PSP from those with CBS.
PMID: 28318985 [PubMed - as supplied by publisher]