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]
A Bayesian Double Fusion Model for Resting State Brain Connectivity Using Joint Functional and Structural Data.
Brain Connect. 2017 Mar 19;:
Authors: Kang H, Ombao H, Fonnesbeck C, Ding Z, Morgan VL
Current approaches separately analyze concurrently acquired diffusion tensor imaging (DTI) and functional magnetic resonance imaging (fMRI) data. The primary limitation of these approaches is that they do not take advantage of the information from DTI that could potentially enhance estimation of resting state functional connectivity (FC) between brain regions. To overcome this limitation, we develop a Bayesian hierarchical spatio-temporal model that incorporates structural connectivity into estimating FC. In our proposed approach, structural connectivity (SC) based on DTI data is used to construct an informative prior for functional connectivity based on resting state fMRI data via the Cholesky decomposition. Simulation studies showed that incorporating the two data produced significantly reduced mean squared errors compared to the standard approach of separately analyzing the two data from different modalities. We applied our model to analyze the resting state DTI and fMRI data collected to estimate FC between the brain regions that were hypothetically important in the origination and spread of temporal lobe epilepsy seizures. Our analysis concludes that the proposed model achieves smaller false positive rates and is much robust to data decimation compared to the conventional approach.
PMID: 28316255 [PubMed - as supplied by publisher]
Assessing the Impact of Post Traumatic Stress Symptoms on Resting State Function Networks in a Military Chronic Mild Traumatic Brain Injury Sample.
Brain Connect. 2017 Mar 19;:
Authors: Nathan DE, Bellgowan JF, French LM, Wolf JP, Oakes T, Mielke JB, Sham EB, Liu W, Riedy G
The relationship between post traumatic stress disorder (PTSD) and chronic symptoms of mild traumatic brain injury (mTBI) is difficult to discern and poorly understood. An accurate differential diagnosis, assessment and treatment of mTBI and PTSD is challenging due to significant symptom overlap and the absence of clearly established biomarkers. The objective of this work is to examine how post traumatic stress influences task-free brain networks in chronic mTBI subjects. Control subjects (N=44) were compared with chronic mTBI subjects with low (N=58, PCLC total<30), medium (N=124, PCLC total = 31-49) and high (N=105, PCLC total ≥ 60) post traumatic stress symptoms (PTSS). The results indicate significant differences in Brodmann area 10 for all mTBI subject groups, indicating potential mTBI related disruptions with regulation of emotions and decision-making. The effects of PTSS were observed in the anterior cingulate, and parahippocampus suggesting possible disruptions pertaining to memory regulation, encoding and retrieval. The overall results indicate the presence of aberrant connectivity patterns between controls and chronic mTBI subjects with low, medium and high PTSS. Furthermore, the findings suggest a disruption in attention relating to a network of brain regions involved with emotional regulation and memory coding, rather than a fear related response. Taken together, the results suggest these regions form a network that could be a target for future research pertaining to PTSD and chronic mTBI. Furthermore, the use of clinical measures, task based imaging studies or multimodal imaging could help further elucidate specific neural correlates of PTSS and mTBI.
PMID: 28316248 [PubMed - as supplied by publisher]
Single or Multi-Frequency Generators in on-going brain activity: a mechanistic whole-brain model of empirical MEG data.
Neuroimage. 2017 Mar 14;:
Authors: Deco G, Cabral J, Woolrich MW, Stevner AB, van Hartevelt TJ, Kringelbach ML
During rest, envelopes of band-limited on-going MEG signals co-vary across the brain in consistent patterns, which have been related to resting-state networks measured with fMRI. To investigate the genesis of such envelope correlations, we consider a whole-brain network model assuming two distinct fundamental scenarios: one where each brain area generates oscillations in a single frequency, and a novel one where each brain area can generate oscillations in multiple frequency bands. The models share, as a common generator of damped oscillations, the normal form of a supercritical Hopf bifurcation operating at the critical border between the steady state and the oscillatory regime. The envelopes of the simulated signals are compared with empirical MEG data using new methods to analyse the envelope dynamics in terms of their phase coherence and stability across the spectrum of carrier frequencies. Considering the whole-brain model with a single frequency generator in each brain area, we obtain the best fit with the empirical MEG data when the fundamental frequency is tuned at 12Hz. However, when multiple frequency generators are placed at each local brain area, we obtain an improved fit of the spatio-temporal structure of on-going MEG data across all frequency bands. Our results indicate that the brain is likely to operate on multiple frequency channels during rest, introducing a novel dimension for future models of large-scale brain activity.
PMID: 28315461 [PubMed - as supplied by publisher]
Dynamic reorganization of intrinsic functional networks in the mouse brain.
Neuroimage. 2017 Mar 14;:
Authors: Grandjean J, Giulia Preti M, Bolton TA, Buerge M, Seifritz E, Pryce CR, Van De Ville D, Rudin M
Functional connectivity (FC) derived from resting-state functional magnetic resonance imaging (rs-fMRI) allows for the integrative study of neuronal processes at a macroscopic level. The majority of studies to date have assumed stationary interactions between brain regions, without considering the dynamic aspects of network organization. Only recently has the latter received increased attention, predominantly in human studies. Applying dynamic FC (dFC) analysis to mice is attractive given the relative simplicity of the mouse brain and the possibility to explore mechanisms underlying network dynamics using pharmacological, environmental or genetic interventions. Therefore, we have evaluated the feasibility and research potential of mouse dFC using the interventions of social stress or anesthesia duration as two case-study examples. By combining a sliding-window correlation approach with dictionary learning, several dynamic functional states (dFS) with a complex organization were identified, exhibiting highly dynamic inter- and intra-modular interactions. Each dFS displayed a high degree of reproducibility upon changes in analytical parameters and across datasets. They fluctuated at different degrees as a function of anesthetic depth, and were sensitive indicators of pathology as shown for the chronic psychosocial stress mouse model of depression. Dynamic functional states are proposed to make a major contribution to information integration and processing in the healthy and diseased brain.
PMID: 28315459 [PubMed - as supplied by publisher]
7,8-dihydroxyflavone facilitates the action exercise to restore plasticity and functionality: Implications for early brain trauma recovery.
Biochim Biophys Acta. 2017 Mar 14;:
Authors: Krishna G, Agrawal R, Zhuang Y, Ying Z, Paydar A, Harris NG, Royes LF, Gomez-Pinilla F
Metabolic dysfunction accompanying traumatic brain injury (TBI) severely impairs the ability of injured neurons to comply with functional demands. This limits the success of rehabilitative strategies by compromising brain plasticity and function, and highlights the need for early interventions to promote energy homeostasis. We sought to examine whether the TrkB agonist, 7,8-dihydroxyflavone (7,8-DHF) normalizes brain energy deficits and restablishes more normal patterns of functional connectivity, while enhancing the effects of exercise during post-TBI period. Moderate fluid percussion injury (FPI) was performed and 7,8-DHF (5mg/kg, i.p.) was administered in animals subjected to FPI that either had access to voluntary wheel running for 7days after injury or were sedentary. Compared to sham-injured controls, TBI resulted in reduced hippocampal activation of the BDNF receptor TrkB and associated CREB, reduced levels of plasticity markers GAP-43 and Syn I, as well as impaired memory as indicated by the Barnes maze task. While 7,8-DHF treatment and exercise individually mitigated TBI-induced effects, administration of 7,8-DHF concurrently with exercise facilitated memory performance and augmented levels of markers of cell energy metabolism viz., PGC-1α, COII and AMPK. In parallel to these findings, resting-state functional MRI (fMRI) acquired at 2weeks after injury showed that 7,8-DHF with exercise enhanced hippocampal functional connectivity, and suggests 7,8-DHF and exercise to promote increases in functional connectivity. Together, these findings indicate that post-injury 7,8-DHF treatment promotes enhanced levels of cell metabolism, synaptic plasticity in combination with exercise increases in brain circuit function that facilitates greater physical rehabilitation after TBI.
PMID: 28315455 [PubMed - as supplied by publisher]
Amygdala functional connectivity is associated with locus of control in the context of cognitive aging.
Neuropsychologia. 2017 Mar 14;:
Authors: Ren P, Anthony M, Chapman BP, Heffner K, Lin F
Locus of control (LOC) measures the extent to which individuals perceive control over their lives. Those with a more "internal" LOC feel self-sufficient and able to determine important aspects of their own future, while those with a more "external" LOC feel that their lives are governed by events beyond their control. Reduced internal LOC and increased external LOC have been found in cognitive disorders, but the neural substrates of these control perceptions are yet unknown. In the present study, we explored the relationship between amygdala functional connectivity and LOC in 18 amnestic mild cognitive impairment (MCI) and age-, sex-, and education-matched, 22 cognitively healthy controls (HC). Participants completed cognitive challenge tasks (Stroop Word Color task and Dual 1-back) for 20minutes, and underwent resting-state functional magnetic resonance imaging immediately before and after the tasks. We found significantly lower internal LOC and higher external LOC in the MCI group than the HC group. Compared to HC, MCI group showed significantly stronger positive associations between internal LOC and baseline right amygdala connections (including right middle frontal gyrus and anterior cingulate cortex), and stronger negative associations between internal LOC and change of these right amygdala connections. Across all participants, external LOC explained the relationships between associations of another set of right amygdala connections (including middle cingulate cortex and right superior frontal gyrus), both at baseline and for change, and performance in the cognitive challenge tasks. Our findings indicate that the right amygdala networks might be critical in understanding the neural mechanisms underlying LOC's role in cognitive aging.
PMID: 28315366 [PubMed - as supplied by publisher]