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Updated: 15 min 33 sec ago

Combined cognitive-psychological-physical intervention induces reorganization of intrinsic functional brain architecture in older adults.

15 min 33 sec ago

Combined cognitive-psychological-physical intervention induces reorganization of intrinsic functional brain architecture in older adults.

Neural Plast. 2015;2015:713104

Authors: Zheng Z, Zhu X, Yin S, Wang B, Niu Y, Huang X, Li R, Li J

Abstract
Mounting evidence suggests that enriched mental, physical, and socially stimulating activities are beneficial for counteracting age-related decreases in brain function and cognition in older adults. Here, we used functional magnetic resonance imaging (fMRI) to demonstrate the functional plasticity of brain activity in response to a combined cognitive-psychological-physical intervention and investigated the contribution of the intervention-related brain changes to individual performance in healthy older adults. The intervention was composed of a 6-week program of combined activities including cognitive training, Tai Chi exercise, and group counseling. The results showed improved cognitive performance and reorganized regional homogeneity of spontaneous fluctuations in the blood oxygen level-dependent (BOLD) signals in the superior and middle temporal gyri, and the posterior lobe of the cerebellum, in the participants who attended the intervention. Intriguingly, the intervention-induced changes in the coherence of local spontaneous activity correlated with the improvements in individual cognitive performance. Taken together with our previous findings of enhanced resting-state functional connectivity between the medial prefrontal cortex and medial temporal lobe regions following a combined intervention program in older adults, we conclude that the functional plasticity of the aging brain is a rather complex process, and an effective cognitive-psychological-physical intervention is helpful for maintaining a healthy brain and comprehensive cognition during old age.

PMID: 25810927 [PubMed - in process]

Effects of rTMS of Pre-Supplementary Motor Area on Fronto Basal Ganglia Network Activity during Stop-Signal Task.

15 min 33 sec ago

Effects of rTMS of Pre-Supplementary Motor Area on Fronto Basal Ganglia Network Activity during Stop-Signal Task.

J Neurosci. 2015 Mar 25;35(12):4813-23

Authors: Watanabe T, Hanajima R, Shirota Y, Tsutsumi R, Shimizu T, Hayashi T, Terao Y, Ugawa Y, Katsura M, Kunimatsu A, Ohtomo K, Hirose S, Miyashita Y, Konishi S

Abstract
Stop-signal task (SST) has been a key paradigm for probing human brain mechanisms underlying response inhibition, and the inhibition observed in SST is now considered to largely depend on a fronto basal ganglia network consisting mainly of right inferior frontal cortex, pre-supplementary motor area (pre-SMA), and basal ganglia, including subthalamic nucleus, striatum (STR), and globus pallidus pars interna (GPi). However, causal relationships between these frontal regions and basal ganglia are not fully understood in humans. Here, we partly examined these causal links by measuring human fMRI activity during SST before and after excitatory/inhibitory repetitive transcranial magnetic stimulation (rTMS) of pre-SMA. We first confirmed that the behavioral performance of SST was improved by excitatory rTMS and impaired by inhibitory rTMS. Afterward, we found that these behavioral changes were well predicted by rTMS-induced modulation of brain activity in pre-SMA, STR, and GPi during SST. Moreover, by examining the effects of the rTMS on resting-state functional connectivity between these three regions, we showed that the magnetic stimulation of pre-SMA significantly affected intrinsic connectivity between pre-SMA and STR, and between STR and GPi. Furthermore, the magnitudes of changes in resting-state connectivity were also correlated with the behavioral changes seen in SST. These results suggest a causal relationship between pre-SMA and GPi via STR during response inhibition, and add direct evidence that the fronto basal ganglia network for response inhibition consists of multiple top-down regulation pathways in humans.

PMID: 25810512 [PubMed - in process]

Age-Related Changes in Intrinsic Function of the Superior Temporal Sulcus in Autism Spectrum Disorders.

15 min 33 sec ago

Age-Related Changes in Intrinsic Function of the Superior Temporal Sulcus in Autism Spectrum Disorders.

Soc Cogn Affect Neurosci. 2015 Mar 25;

Authors: Alaerts K, Nayar K, Kelly C, Raithel J, Milham MP, Di Martino A

Abstract
Currently, the developmental trajectories of neural circuits implicated in autism spectrum disorders (ASD) are largely unknown. Here, we specifically focused on age-related changes in the functional circuitry of the posterior superior temporal sulcus (pSTS), a key hub underlying social-cognitive processes known to be impaired in ASD. Using a cross-sectional approach, we analyzed resting-state fMRI data collected from children, adolescents, and adults available through the Autism Brain Imaging Data Exchange repository (n=106 with ASD and n=109 typical controls [TC], ages 7-30 years). The observed age-related changes of pSTS intrinsic functional connectivity (iFC) suggest that no single developmental pattern characterizes ASD. Instead, pSTS circuitry displayed a complex developmental picture, with some functional circuits showing patterns consistent with atypical development in ASD relative to TC (pSTS-iFC with fusiform gyrus and angular gyrus) and others showing delayed maturation (pSTS-iFC with regions of the action perception network). Distinct developmental trajectories in different functional circuits in ASD likely reflect differential age-related changes in the socio-cognitive processes they underlie. Increasing insight on these mechanisms is a critical step in the development of age-specific interventions in ASD.

PMID: 25809403 [PubMed - as supplied by publisher]

Experimentally induced thyrotoxicosis leads to increased connectivity in temporal lobe structures: A resting state fMRI study.

15 min 33 sec ago

Experimentally induced thyrotoxicosis leads to increased connectivity in temporal lobe structures: A resting state fMRI study.

Psychoneuroendocrinology. 2015 Mar 12;56:100-109

Authors: Göttlich M, Heldmann M, Göbel A, Dirk AL, Brabant G, Münte TF

Abstract
Adult onset hyperthyroidism may impact on different cognitive domains, including attention and concentration, memory, perceptual function, language and executive function. Previous PET studies implicated changed functionality of limbic regions, the temporal and frontal lobes in hyperthyroidism, whereas it is unknown whether cognitive effects of hyperthyroidism may be due to changed brain connectivity. This study aimed to investigate the effect of experimentally induced short-term hyperthyroidism thyrotoxicosis on resting-state functional connectivity using functional magnetic resonance imaging. Twenty-nine healthy male right-handed subjects were examined twice, once prior and once after 8 weeks of oral administration of 250μg levothyroxine per day. Resting-state fMRI was subjected to graph-theory based analysis methods to investigate whole-brain intrinsic functional connectivity. Despite a lack of subjective changes noticed by the subjects significant thyrotoxicosis was confirmed in all subjects. This induced a significant increase in resting-state functional connectivity specifically in the rostral temporal lobes (0.05 FDR corrected at the cluster level), which is caused by an increased connectivity to the cognitive control network. The increased connectivity between temporal poles and the cognitive control network shown here under experimental conditions supports an important function of thyroid hormones in the regulation of paralimbic structures.

PMID: 25808701 [PubMed - as supplied by publisher]

Investigation of Multiple Frequency Ranges using Discrete Wavelet Decomposition of Resting State Functional Connectivity in Mild Traumatic Brain Injury Patients.

15 min 33 sec ago

Investigation of Multiple Frequency Ranges using Discrete Wavelet Decomposition of Resting State Functional Connectivity in Mild Traumatic Brain Injury Patients.

Brain Connect. 2015 Mar 26;

Authors: Sours C, Chen H, Roys S, Zhuo J, Varshney A, Gullapalli RP

Abstract
The aim of this study was to investigate if discrete wavelet decomposition provides additional insight into resting state processes through the analysis of functional connectivity within specific frequency ranges within the default mode network (DMN) that may be affected by mild traumatic brain injury (mTBI). Participants included 32 mTBI patients [15 with post concussive syndrome (PCS+) and 17 without (PCS-)]. mTBI patients received rs-fMRI (resting state functional magnetic resonance imaging) at acute (within 10 days of injury) and chronic (6 months post injury) time points and were compared to 31 controls (HC). The wavelet decomposition divides the time series into multiple frequency ranges based on 4 scaling factors (SF1: 0.125-0.250 Hz, SF2: 0.060-0.125 Hz, SF3: 0.030-0.060 Hz, SF4: 0.015-0.030 Hz). Within each SF, wavelet connectivity matrices for nodes of the DMN were created for each group (HC, PCS+, PCS-), and bivariate measures of strength and diversity were calculated. The results demonstrate reduced strength of connectivity in PCS+ patients compared to PCS- patients within SF1 during both the acute and chronic stages of injury, as well as recovery of connectivity within SF1 across the two time points. Furthermore, the PCS- group demonstrated greater network strength compared to controls at both time points suggesting a potential compensatory or protective mechanism in these patients. These findings stress the importance of investigating resting state connectivity within multiple frequency ranges: however, many of our findings are within SF1, which may overlap with frequencies associated with cardiac and respiratory activity.

PMID: 25808612 [PubMed - as supplied by publisher]

To see bruxism: a functional magnetic resonance imaging study.

Fri, 03/27/2015 - 17:00

To see bruxism: a functional magnetic resonance imaging study.

Dentomaxillofac Radiol. 2015 Mar 25;:20150019

Authors: Yılmaz S

Abstract
OBJECTIVE: Since the pathophysiology of bruxism is not clearly understood; there exists no possible treatment. The aim of this study is to investigate the cerebral activation differences between healthy subjects and bruxism patients on behalf of possible etiologic factors.
METHODS: 12 healthy and 12 bruxism patients, a total of 24 right handed female subjects (aged 20-27) were examined using functional magnetic resonance imaging (fMRI) during tooth clenching and resting tasks. Imaging was performed with 3.0 Tesla MRI scanner with 32 channel head coil. Differences in regional brain activity between bruxism patients and healthy subjects (control group) were observed with BrainVoyager QX 2.8 (Brain Innovation, Maastricht, Netherlands) statistical data analysis program. Activation maps were created using the General Linear Model: single study and General Linear Model: multi study multi subject for statistical group analysis. This protocol was approved by the ethics committee of medical faculty of K…. University, T… (02/04), based on the guidelines set forth in the Declaration of Helsinki.
RESULTS: The group analysis relieved statistically significant increase in blood oxygenation level dependent (BOLD) signal of 3 clusters in control group (p<0,005) which may indicate brain regions related with somatognosis, repetitive passive motion, proprioception and tactile perception. These areas coincide with Brodmann areas (BA) 7, 31, 39 and 40. It is conceivable that there are differences between healthy subjects and bruxism patients.
CONCLUSIONS: Our findings indicate that there was a decrease of cortical activation pattern in bruxism patients in clenching tasks. This indicates decreased blood flow and activation in regional neuronal activity. Bruxism, as an oral motor disorder concerns dentistry, neurology and psychiatry. These results might improve the understanding and physiological handling of sleep bruxism.

PMID: 25806864 [PubMed - as supplied by publisher]

Across the consciousness continuum-from unresponsive wakefulness to sleep.

Fri, 03/27/2015 - 17:00

Across the consciousness continuum-from unresponsive wakefulness to sleep.

Front Hum Neurosci. 2015;9:105

Authors: Blume C, Del Giudice R, Wislowska M, Lechinger J, Schabus M

Abstract
Advances in the development of new paradigms as well as in neuroimaging techniques nowadays enable us to make inferences about the level of consciousness patients with disorders of consciousness (DOC) retain. They, moreover, allow to predict their probable development. Today, we know that certain brain responses (e.g., event-related potentials or oscillatory changes) to stimulation, circadian rhythmicity, the presence or absence of sleep patterns as well as measures of resting state brain activity can serve the diagnostic and prognostic evaluation process. Still, the paradigms we are using nowadays do not allow to disentangle VS/UWS and minimally conscious state (MCS) patients with the desired reliability and validity. Furthermore, even rather well-established methods have, unfortunately, not found their way into clinical routine yet. We here review current literature as well as recent findings from our group and discuss how neuroimaging methods (fMRI, PET) and particularly electroencephalography (EEG) can be used to investigate cognition in DOC or even to assess the degree of residual awareness. We, moreover, propose that circadian rhythmicity and sleep in brain-injured patients are promising fields of research in this context.

PMID: 25805982 [PubMed]

Differentiating the Functional Contributions of Resting Connectivity Networks to Memory Decision-making: fMRI Support for Multistage Control Processes.

Thu, 03/26/2015 - 16:00

Differentiating the Functional Contributions of Resting Connectivity Networks to Memory Decision-making: fMRI Support for Multistage Control Processes.

J Cogn Neurosci. 2015 Mar 24;:1-16

Authors: Mill RD, Cavin I, O'Connor AR

Abstract
Neural substrates of memory control are engaged when participants encounter unexpected mnemonic stimuli (e.g., a new word when told to expect an old word). The present fMRI study (n = 18) employed the likelihood cueing recognition task to elucidate the role of functional connectivity (fcMRI) networks in supporting memory control processes engaged by these unexpected events. Conventional task-evoked BOLD analyses recovered a memory control network similar to that previously reported, comprising medial prefrontal, lateral prefrontal, and inferior parietal regions. These were split by their differential affiliation to distinct fcMRI networks ("conflict detection" and "confirmatory retrieval" networks). Subsequent ROI analyses clarified the functional significance of this connectivity differentiation, with "conflict" network-affiliated regions specifically sensitive to cue strength, but not to response confidence, and "retrieval" network-affiliated regions showing the opposite pattern. BOLD time course analyses corroborated the segregation of memory control regions into "early" conflict detection and "late" retrieval analysis, with both processes underlying the allocation of memory control. Response specificity and time course findings were generalized beyond task-recruited ROIs to clusters within the large-scale fcMRI networks, suggesting that this connectivity architecture could underlie efficient processing of distinct processes within cognitive tasks. The findings raise important parallels between prevailing theories of memory and cognitive control.

PMID: 25803597 [PubMed - as supplied by publisher]

Cerebral hyperperfusion and decreased cerebrovascular reactivity correlate with neurologic disease severity in MELAS.

Thu, 03/26/2015 - 16:00

Cerebral hyperperfusion and decreased cerebrovascular reactivity correlate with neurologic disease severity in MELAS.

Mitochondrion. 2015 Mar 20;

Authors: Rodan LH, Poublanc J, Fisher JA, Sobczyk O, Wong T, Hlasny E, Mikulis D, Tein I

Abstract
OBJECTIVE: To study the mechanisms underlying stroke-like episodes (SLEs) in MELAS syndrome.
METHODS: We performed a case control study in 3 siblings with MELAS syndrome (m.3243A>G tRNA(Leu(UUR))) with variable % mutant mtDNA in blood (35 to 59%) to evaluate regional cerebral blood flow (CBF) and arterial cerebrovascular reactivity (CVR) compared to age- and sex-matched healthy study controls and a healthy control population. Subjects were studied at 3T MRI using arterial spin labeling (ASL) to measure CBF; CVR was measured as a change in % Blood Oxygen Level Dependent signal (as a surrogate of CBF) to repeated 10 mmHg step increase in arterial partial pressure of CO2 (PaCO2).
RESULTS: MELAS siblings had decreased CVR (p<0.002) and increased CBF (p<0.0026) compared to controls; changes correlated with disease severity and % mutant mtDNA (inversely for CVR: r = - 0.82 frontal, r = - 0.91 occipital cortex; directly for CBF: r = +0.85 frontal, not for occipital infarct penumbra). Mean CVR was reduced more in frontal (p<0.001) versus occipital cortex (p=0.002); mean CBF was increased more in occipital (p=0.001) than frontal (p=0.0026) cortices compared to controls. CBF correlated inversely with CVR (r = -0.99 in frontal; not in occipital infarct penumbra) suggesting that increased frontal resting flows are at the expense of flow reserve.
INTERPRETATION: MELAS disease severity and mutation load were inversely correlated with Interictal CVR and directly correlated with frontal CBF. These metrics offer further insight into the cerebrovascular hemodynamics in MELAS syndrome and may serve as noninvasive prognostic markers to stratify risk for SLEs.
CLASSIFICATION OF EVIDENCE: Class III.

PMID: 25801712 [PubMed - as supplied by publisher]

Frequency-Dependent Changes of Local Resting Oscillations in Sleep-Deprived Brain.

Wed, 03/25/2015 - 14:30

Frequency-Dependent Changes of Local Resting Oscillations in Sleep-Deprived Brain.

PLoS One. 2015;10(3):e0120323

Authors: Gao L, Bai L, Zhang Y, Dai XJ, Netra R, Min Y, Zhou F, Niu C, Dun W, Gong H, Zhang M

Abstract
Sleep deprivation (SD) adversely affects brain function and is accompanied by frequency dependent changes in EEG. Recent studies have suggested that BOLD fluctuations pertain to a spatiotemporal organization with different frequencies. The present study aimed to investigate the frequency-dependent SD-related brain oscillatory activity by using the amplitude of low-frequency fluctuation (ALFF) analysis. The ALFF changes were measured across different frequencies (Slow-4: 0.027-0.073 Hz; Slow-5: 0.01-0.027 Hz; and Typical band: 0.01-0.08 Hz) in 24 h SD as compared to rested wakeful during resting-state fMRI. Sixteen volunteers underwent two fMRI sessions, once during rested wakefulness and once after 24 h of SD. SD showed prominently decreased ALFF in the right inferior parietal lobule (IPL), bilateral orbitofrontal cortex (OFC) and dorsolateral prefrontal cortex (DLPFC), while increased ALFF in the visual cortex, left sensorimotor cortex and fusiform gyrus. Across the Slow-4 and Slow-5, results differed significantly in the OFC, DLPFC, thalamus and caudate in comparison to typical frequency band; and Slow-4 showed greater differences. In addition, negative correlations of behavior performance and ALFF patterns were found mainly in the right IPL across the typical frequency band. These observations provided novel insights about the physiological responses of SD, identified how it disturbs the brain rhythms, and linked SD with frequency-dependent alterations in amplitude patterns.

PMID: 25798918 [PubMed - as supplied by publisher]

Asymmetric development of dorsal and ventral attention networks in the human brain.

Wed, 03/25/2015 - 14:30

Asymmetric development of dorsal and ventral attention networks in the human brain.

Dev Cogn Neurosci. 2015 Feb 12;12:165-174

Authors: Farrant K, Uddin LQ

Abstract
Two neural systems for goal-directed and stimulus-driven attention have been described in the adult human brain; the dorsal attention network (DAN) centered in the frontal eye fields (FEF) and intraparietal sulcus (IPS), and the ventral attention network (VAN) anchored in the temporoparietal junction (TPJ) and ventral frontal cortex (VFC). Little is known regarding the processes governing typical development of these attention networks in the brain. Here we use resting state functional MRI data collected from thirty 7 to 12 year-old children and thirty 18 to 31 year-old adults to examine two key regions of interest from the dorsal and ventral attention networks. We found that for the DAN nodes (IPS and FEF), children showed greater functional connectivity with regions within the network compared with adults, whereas adults showed greater functional connectivity between the FEF and extra-network regions including the posterior cingulate cortex. For the VAN nodes (TPJ and VFC), adults showed greater functional connectivity with regions within the network compared with children. Children showed greater functional connectivity between VFC and nodes of the salience network. This asymmetric pattern of development of attention networks may be a neural signature of the shift from over-representation of bottom-up attention mechanisms to greater top-down attentional capacities with development.

PMID: 25797238 [PubMed - as supplied by publisher]

Altered intrinsic brain activity in patients with familial cortical myoclonic tremor and epilepsy: An amplitude of low-frequency fluctuation study.

Tue, 03/24/2015 - 12:30

Altered intrinsic brain activity in patients with familial cortical myoclonic tremor and epilepsy: An amplitude of low-frequency fluctuation study.

J Neurol Sci. 2015 Mar 10;

Authors: Wang P, Luo C, Dong L, Bin Y, Ma S, Yao D, Guo F, Yang Z

Abstract
PURPOSE: To investigate localized cerebral function abnormalities in patients with familial cortical myoclonic tremor and epilepsy (FCMTE) using resting-state functional magnetic resonance imaging (fMRI).
METHODS: Seven patients with FCMTE from a Chinese family, seven patients with essential tremor (ET), and ten healthy controls were recruited. Amplitude of low-frequency fluctuation (ALFF) analysis was utilized to reveal the potential functional changes in patients with FCMTE.
RESULTS: Significant differences in the bilateral frontal lobe and fusiform gyrus among the three groups were revealed by one-way analysis of variance (ANOVA). The t-tests between groups were performed to compare ALFF in these ROIs. The FCMTE subjects exhibited decreased ALFF in the right fusiform gyrus and posterior cingulate cortex (PCC) with increased ALFF in the frontal lobe, compared with the ET and healthy control groups. Furthermore, the ALFF in the frontal lobe was positively correlated with the duration of tremor in patients with FCMTE and ET.
CONCLUSION: These findings suggest that frontal cortex and PCC impairment might be related to the epileptic activity and that the abnormality of the fusiform gyrus may be associated with impairment of visuospatial in FCMTE. Due to the positive correlation between the duration of tremor and ALFF in the frontal lobe, changes in the frontal lobe could be a potential indicator of a candidate causative gene for FCMTE.

PMID: 25796300 [PubMed - as supplied by publisher]

Agreement and repeatability of vascular reactivity estimates based on a breath-hold task and a resting state scan.

Mon, 03/23/2015 - 17:00

Agreement and repeatability of vascular reactivity estimates based on a breath-hold task and a resting state scan.

Neuroimage. 2015 Mar 17;

Authors: Lipp I, Murphy K, Caseras X, Wise RG

Abstract
FMRI BOLD responses to changes in neural activity are influenced by the reactivity of the vasculature. By complementing a task-related BOLD acquisition with a vascular reactivity measure obtained through breath-holding or hypercapnia, this unwanted variance can be statistically reduced in the BOLD responses of interest. Recently, it has been suggested that vascular reactivity can also be estimated using a resting state scan. This study aimed to compare three breath-hold based analysis approaches (block design, sine-cosine regressor and CO2 regressor) and a resting state approach (CO2 regressor) to measure vascular reactivity. We tested BOLD variance explained by the model and repeatability of the measures. Fifteen healthy participants underwent a breath-hold task and a resting state scan with end-tidal CO2 being recorded during both. Vascular reactivity was defined as CO2 - related BOLD percent signal change / mmHg change in CO2. Maps and regional vascular reactivity estimates showed high repeatability when the breath-hold task was used. Repeatability and variance explained by the CO2 trace regressor were lower for resting state data based approach, which resulted in highly variable measures of vascular reactivity. We conclude that breath-hold based vascular reactivity estimations are more repeatable than resting-based estimates, and that there are limitations with replacing breath-hold scans by resting state scans for vascular reactivity assessment.

PMID: 25795342 [PubMed - as supplied by publisher]

Altered temporal features of intrinsic connectivity networks in boys with combined type of attention deficit hyperactivity disorder.

Mon, 03/23/2015 - 17:00

Altered temporal features of intrinsic connectivity networks in boys with combined type of attention deficit hyperactivity disorder.

Eur J Radiol. 2015 Mar 9;

Authors: Wang XH, Li L

Abstract
PURPOSE: Investigating the altered temporal features within and between intrinsic connectivity networks (ICNs) for boys with attention-deficit/hyperactivity disorder (ADHD); and analyzing the relationships between altered temporal features within ICNs and behavior scores.
MATERIALS AND METHODS: A cohort of boys with combined type of ADHD and a cohort of age-matched healthy boys were recruited from ADHD-200 Consortium. All resting-state fMRI datasets were preprocessed and normalized into standard brain space. Using general linear regression, 20 ICNs were taken as spatial templates to analyze the time-courses of ICNs for each subject. Amplitude of low frequency fluctuations (ALFFs) were computed as univariate temporal features within ICNs. Pearson correlation coefficients and node strengths were computed as bivariate temporal features between ICNs. Additional correlation analysis was performed between temporal features of ICNs and behavior scores.
RESULTS: ADHD exhibited more activated network-wise ALFF than normal controls in attention and default mode-related network. Enhanced functional connectivities between ICNs were found in ADHD. The network-wise ALFF within ICNs might influence the functional connectivity between ICNs. The temporal pattern within posterior default mode network (pDMN) was positively correlated to inattentive scores. The subcortical network, fusiform-related DMN and attention-related networks were negatively correlated to Intelligence Quotient (IQ) scores.
CONCLUSION: The temporal low frequency oscillations of ICNs in boys with ADHD were more activated than normal controls during resting state; the temporal features within ICNs could provide additional information to investigate the altered network patterns of ADHD.

PMID: 25795197 [PubMed - as supplied by publisher]

White matter damage and brain network alterations in concussed patients: a review of recent diffusion tensor imaging and resting-state functional connectivity data.

Mon, 03/23/2015 - 17:00

White matter damage and brain network alterations in concussed patients: a review of recent diffusion tensor imaging and resting-state functional connectivity data.

Curr Pain Headache Rep. 2015 May;19(5):485

Authors: Chong CD, Schwedt TJ

Abstract
Over 2 million people are diagnosed with concussion each year in the USA, resulting in substantial individual and societal burdens. Although 'routine' clinical neuroimaging is useful for the diagnosis of more severe forms of traumatic brain injury, it is insensitive for detecting pathology associated with concussion. Diffusion tensor imaging (DTI) and blood-oxygenation-level-dependent (BOLD) resting-state functional connectivity magnetic resonance imaging (rs-fMRI) are techniques that allow for investigation of brain structural and functional connectivity patterns. DTI and rs-fMRI may be more sensitive than routine neuroimaging for detecting brain sequelae of concussion. This review summarizes recent DTI and rs-fMRI findings of altered structural and functional connectivity patterns in concussed patients.

PMID: 25795157 [PubMed - in process]

Relationship between simultaneously acquired resting-state regional cerebral glucose metabolism and functional MRI: A PET/MR hybrid scanner study.

Sun, 03/22/2015 - 15:30

Relationship between simultaneously acquired resting-state regional cerebral glucose metabolism and functional MRI: A PET/MR hybrid scanner study.

Neuroimage. 2015 Mar 16;

Authors: Aiello M, Salvatore E, Cachia A, Pappatà S, Cavaliere C, Prinster A, Nicolai E, Salvatore M, Baron JC, Quarantelli M

Abstract
Recently introduced hybrid PET/MR scanners provide the opportunity to measure simultaneously, and in direct spatial correspondence, both metabolic demand and functional activity of the brain, hence capturing complementary information on the brain's physiological state. Here we exploited PET/MR simultaneous imaging to explore the relationship between the metabolic information provided by resting-state fluorodeoxyglucose-PET (FDG-PET) and fMRI (rs-fMRI) in neurologically healthy subjects. Regional Homogeneity (ReHo), Fractional Amplitude of Low Frequency Fluctuations (fALFF), and Degree of Centrality (DC) maps were generated from the rs-fMRI data in 23 subjects, and voxel-wise comparison to glucose uptake distribution provided by simultaneously acquired FDG-PET was performed. The mutual relationships among each couple of these four metrics were explored in terms of similarity, both of spatial distribution across the brain and the whole group, and voxel-wise across subjects, taking into account partial volume effects by adjusting for gray matter (GM) volume. Although a significant correlation between the spatial distribution of glucose uptake and rs-fMRI derived metrics was present, only a limited percentage of GM voxels correlated with PET across subjects. Moreover, the correlation between the spatial distributions of PET and RS-fMRI-derived metrics is spatially heterogeneous across both anatomic regions and functional networks, with lowest correlation strength in the limbic network (Spearman rho around -0.11 for DC), and strongest correlation for the default-mode network (up to 0.89 for ReHo and 0.86 for fALFF). Overall, ReHo and fALFF provided significantly higher correlation coefficients with PET (p=10(-8) and 10(-7), respectively) as compared to DC, while no significant differences were present between ReHo and fALFF. Local GM volume variations introduced a limited overestimation of the rs-fMRI to FDG correlation between the modalities under investigation through partial volume effects. These novel results provide the basis for future studies of alterations of the coupling between brain metabolism and functional connectivity in pathologic conditions.

PMID: 25791784 [PubMed - as supplied by publisher]

Spatial and temporal characteristics of error-related activity in the human brain.

Sun, 03/22/2015 - 15:30
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Spatial and temporal characteristics of error-related activity in the human brain.

J Neurosci. 2015 Jan 7;35(1):253-66

Authors: Neta M, Miezin FM, Nelson SM, Dubis JW, Dosenbach NU, Schlaggar BL, Petersen SE

Abstract
A number of studies have focused on the role of specific brain regions, such as the dorsal anterior cingulate cortex during trials on which participants make errors, whereas others have implicated a host of more widely distributed regions in the human brain. Previous work has proposed that there are multiple cognitive control networks, raising the question of whether error-related activity can be found in each of these networks. Thus, to examine error-related activity broadly, we conducted a meta-analysis consisting of 12 tasks that included both error and correct trials. These tasks varied by stimulus input (visual, auditory), response output (button press, speech), stimulus category (words, pictures), and task type (e.g., recognition memory, mental rotation). We identified 41 brain regions that showed a differential fMRI BOLD response to error and correct trials across a majority of tasks. These regions displayed three unique response profiles: (1) fast, (2) prolonged, and (3) a delayed response to errors, as well as a more canonical response to correct trials. These regions were found mostly in several control networks, each network predominantly displaying one response profile. The one exception to this "one network, one response profile" observation is the frontoparietal network, which showed prolonged response profiles (all in the right hemisphere), and fast profiles (all but one in the left hemisphere). We suggest that, in the place of a single localized error mechanism, these findings point to a large-scale set of error-related regions across multiple systems that likely subserve different functions.

PMID: 25568119 [PubMed - indexed for MEDLINE]

Modality-spanning deficits in attention-deficit/hyperactivity disorder in functional networks, gray matter, and white matter.

Sun, 03/22/2015 - 15:30
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Modality-spanning deficits in attention-deficit/hyperactivity disorder in functional networks, gray matter, and white matter.

J Neurosci. 2014 Dec 10;34(50):16555-66

Authors: Kessler D, Angstadt M, Welsh RC, Sripada C

Abstract
Previous neuroimaging investigations in attention-deficit/hyperactivity disorder (ADHD) have separately identified distributed structural and functional deficits, but interconnections between these deficits have not been explored. To unite these modalities in a common model, we used joint independent component analysis, a multivariate, multimodal method that identifies cohesive components that span modalities. Based on recent network models of ADHD, we hypothesized that altered relationships between large-scale networks, in particular, default mode network (DMN) and task-positive networks (TPNs), would co-occur with structural abnormalities in cognitive regulation regions. For 756 human participants in the ADHD-200 sample, we produced gray and white matter volume maps with voxel-based morphometry, as well as whole-brain functional connectomes. Joint independent component analysis was performed, and the resulting transmodal components were tested for differential expression in ADHD versus healthy controls. Four components showed greater expression in ADHD. Consistent with our a priori hypothesis, we observed reduced DMN-TPN segregation co-occurring with structural abnormalities in dorsolateral prefrontal cortex and anterior cingulate cortex, two important cognitive control regions. We also observed altered intranetwork connectivity in DMN, dorsal attention network, and visual network, with co-occurring distributed structural deficits. There was strong evidence of spatial correspondence across modalities: For all four components, the impact of the respective component on gray matter at a region strongly predicted the impact on functional connectivity at that region. Overall, our results demonstrate that ADHD involves multiple, cohesive modality spanning deficits, each one of which exhibits strong spatial overlap in the pattern of structural and functional alterations.

PMID: 25505309 [PubMed - indexed for MEDLINE]

The Dissociative Subtype of Posttraumatic Stress Disorder: Unique Resting-State Functional Connectivity of Basolateral and Centromedial Amygdala Complexes.

Sat, 03/21/2015 - 14:30

The Dissociative Subtype of Posttraumatic Stress Disorder: Unique Resting-State Functional Connectivity of Basolateral and Centromedial Amygdala Complexes.

Neuropsychopharmacology. 2015 Mar 19;

Authors: Nicholson AA, Densmore M, Frewen PA, Théberge J, Neufeld RW, McKinnon MC, Lanius RA

Abstract
Previous studies point towards differential connectivity patterns among basolateral (BLA) and centromedial (CMA) amygdala regions in patients with posttraumatic stress disorder (PTSD) as compared to controls. Here, we describe the first study to compare directly connectivity patterns of the BLA and CMA complexes between PTSD patients with and without the dissociative subtype (PTSD+DS and PTSD-DS, respectively). Amygdala connectivity to regulatory prefrontal regions and parietal regions involved in consciousness and proprioception were expected to differ between these two groups based on differential limbic regulation and behavioural symptoms. PTSD patients (n=49), with (n=13) and without (n=36) the dissociative subtype, and age-matched healthy controls (n=40) underwent resting-state fMRI. Bilateral BLA and CMA connectivity patterns were compared using a seed-based approach via SPM Anatomy Toolbox. Among patients with PTSD, the PTSD+DS group exhibited greater amygdala functional connectivity to prefrontal regions involved in emotion regulation (bilateral BLA and left CMA to the middle frontal gyrus and bilateral CMA to the medial frontal gyrus) as compared to the PTSD-DS group. In addition, the PTSD+DS group showed greater amygdala connectivity to regions involved in consciousness, awareness, and proprioception -implicated in depersonalization and derealization (left BLA to superior parietal lobe and cerebellar culmen; left CMA to dorsal posterior cingulate and precuneus). Differences in amygdala complex connectivity to specific brain regions parallel the unique symptom profiles of the PTSD subgroups and point towards unique biological markers of the dissociative subtype of PTSD.Neuropsychopharmacology accepted article preview online, 19 March 2015. doi:10.1038/npp.2015.79.

PMID: 25790021 [PubMed - as supplied by publisher]

Default Mode Network, Motor Network, Dorsal and Ventral Basal Ganglia Networks in the Rat Brain: Comparison to Human Networks Using Resting State-fMRI.

Sat, 03/21/2015 - 14:30

Default Mode Network, Motor Network, Dorsal and Ventral Basal Ganglia Networks in the Rat Brain: Comparison to Human Networks Using Resting State-fMRI.

PLoS One. 2015;10(3):e0120345

Authors: Sierakowiak A, Monnot C, Aski SN, Uppman M, Li TQ, Damberg P, Brené S

Abstract
Rodent models are developed to enhance understanding of the underlying biology of different brain disorders. However, before interpreting findings from animal models in a translational aspect to understand human disease, a fundamental step is to first have knowledge of similarities and differences of the biological systems studied. In this study, we analyzed and verified four known networks termed: default mode network, motor network, dorsal basal ganglia network, and ventral basal ganglia network using resting state functional MRI (rsfMRI) in humans and rats. Our work supports the notion that humans and rats have common robust resting state brain networks and that rsfMRI can be used as a translational tool when validating animal models of brain disorders. In the future, rsfMRI may be used, in addition to short-term interventions, to characterize longitudinal effects on functional brain networks after long-term intervention in humans and rats.

PMID: 25789862 [PubMed - as supplied by publisher]