Neural Substrates of Motor and Non-Motor Symptoms in Parkinson's Disease: A Resting fMRI Study.
PLoS One. 2015;10(4):e0125455
Authors: Yoo K, Chung SJ, Kim HS, Choung OH, Lee YB, Kim MJ, You S, Jeong Y
BACKGROUND: Recently, non-motor symptoms of Parkinson's disease (PD) have been considered crucial factors in determining a patient's quality of life and have been proposed as the predominant features of the premotor phase. Researchers have investigated the relationship between non-motor symptoms and the motor laterality; however, this relationship remains disputed. This study investigated the neural connectivity correlates of non-motor and motor symptoms of PD with respect to motor laterality.
METHODS: Eight-seven patients with PD were recruited and classified into left-more-affected PD (n = 44) and right-more affected PD (n = 37) based on their MDS-UPDRS (Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale) motor examination scores. The patients underwent MRI scanning, which included resting fMRI. Brain regions were labeled as ipsilateral and contralateral to the more-affected body side. Correlation analysis between the functional connectivity across brain regions and the scores of various symptoms was performed to identify the neural connectivity correlates of each symptom.
RESULTS: The resting functional connectivity centered on the ipsilateral inferior orbito-frontal area was negatively correlated with the severity of non-motor symptoms, and the connectivity of the contralateral inferior parietal area was positively correlated with the severity of motor symptoms (p < 0.001, |r| > 0.3).
CONCLUSIONS: These results suggest that the inferior orbito-frontal area may play a crucial role in non-motor dysfunctions, and that the connectivity information may be utilized as a neuroimaging biomarker for the early diagnosis of PD.
PMID: 25909812 [PubMed - as supplied by publisher]
Identifying patients with Alzheimer's disease using resting-state fMRI and graph theory.
Clin Neurophysiol. 2015 Apr 1;
Authors: Khazaee A, Ebrahimzadeh A, Babajani-Feremi A
OBJECTIVE: Study of brain network on the basis of resting-state functional magnetic resonance imaging (fMRI) has provided promising results to investigate changes in connectivity among different brain regions because of diseases. Graph theory can efficiently characterize different aspects of the brain network by calculating measures of integration and segregation.
METHOD: In this study, we combine graph theoretical approaches with advanced machine learning methods to study functional brain network alteration in patients with Alzheimer's disease (AD). Support vector machine (SVM) was used to explore the ability of graph measures in diagnosis of AD. We applied our method on the resting-state fMRI data of twenty patients with AD and twenty age and gender matched healthy subjects. The data were preprocessed and each subject's graph was constructed by parcellation of the whole brain into 90 distinct regions using the automated anatomical labeling (AAL) atlas. The graph measures were then calculated and used as the discriminating features. Extracted network-based features were fed to different feature selection algorithms to choose most significant features. In addition to the machine learning approach, statistical analysis was performed on connectivity matrices to find altered connectivity patterns in patients with AD.
RESULTS: Using the selected features, we were able to accurately classify patients with AD from healthy subjects with accuracy of 100%.
CONCLUSION: Results of this study show that pattern recognition and graph of brain network, on the basis of the resting state fMRI data, can efficiently assist in the diagnosis of AD.
SIGNIFICANCE: Classification based on the resting-state fMRI can be used as a non-invasive and automatic tool to diagnosis of Alzheimer's disease.
PMID: 25907414 [PubMed - as supplied by publisher]
Temporal dynamics in fMRI resting-state activity.
Proc Natl Acad Sci U S A. 2015 Apr 20;
Authors: Yuste R, Fairhall AL
PMID: 25902550 [PubMed - as supplied by publisher]
Injury alters intrinsic functional connectivity within the primate spinal cord.
Proc Natl Acad Sci U S A. 2015 Apr 22;
Authors: Chen LM, Mishra A, Yang PF, Wang F, Gore JC
Recent demonstrations of correlated low-frequency MRI signal variations between subregions of the spinal cord at rest in humans, similar to those found in the brain, suggest that such resting-state functional connectivity constitutes a common feature of the intrinsic organization of the entire central nervous system. We report our detection of functional connectivity within the spinal cords of anesthetized squirrel monkeys at rest and show that the strength of connectivity within these networks is altered by the effects of injuries. By quantifying the low-frequency MRI signal correlations between different horns within spinal cord gray matter, we found distinct functional connectivity relationships between the different sensory and motor horns, a pattern that was similar to activation patterns evoked by nociceptive heat or tactile stimulation of digits. All horns within a single spinal segment were functionally connected, with the strongest connectivity occurring between ipsilateral dorsal and ventral horns. Each horn was strongly connected to the same horn on neighboring segments, but this connectivity reduced drastically along the spinal cord. Unilateral injury to the spinal cord significantly weakened the strength of the intrasegment horn-to-horn connectivity only on the injury side and in slices below the lesion. These findings suggest resting-state functional connectivity may be a useful biomarker of functional integrity in injured and recovering spinal cords.
PMID: 25902510 [PubMed - as supplied by publisher]
White Matter Connectivity of the Thalamus Delineates the Functional Architecture of Competing Thalamocortical Systems.
Cereb Cortex. 2015 Apr 21;
Authors: O'Muircheartaigh J, Keller SS, Barker GJ, Richardson MP
There is an increasing awareness of the involvement of thalamic connectivity on higher level cortical functioning in the human brain. This is reflected by the influence of thalamic stimulation on cortical activity and behavior as well as apparently cortical lesion syndromes occurring as a function of small thalamic insults. Here, we attempt to noninvasively test the correspondence of structural and functional connectivity of the human thalamus using diffusion-weighted and resting-state functional MRI. Using a large sample of 102 adults, we apply tensor independent component analysis to diffusion MRI tractography data to blindly parcellate bilateral thalamus according to diffusion tractography-defined structural connectivity. Using resting-state functional MRI collected in the same subjects, we show that the resulting structurally defined thalamic regions map to spatially distinct, and anatomically predictable, whole-brain functional networks in the same subjects. Although there was significant variability in the functional connectivity patterns, the resulting 51 structural and functional patterns could broadly be reduced to a subset of 7 similar core network types. These networks were distinct from typical cortical resting-state networks. Importantly, these networks were distributed across the brain and, in a subset, map extremely well to known thalamocortico-basal-ganglial loops.
PMID: 25899706 [PubMed - as supplied by publisher]
Altered resting-state functional connectivity of the insula in young adults with Internet gaming disorder.
Addict Biol. 2015 Apr 20;
Authors: Zhang JT, Yao YW, Li CS, Zang YF, Shen ZJ, Liu L, Wang LJ, Liu B, Fang XY
The insula has been implicated in salience processing, craving, and interoception, all of which are critical to the clinical manifestations of drug and behavioral addiction. In this functional magnetic resonance imaging (fMRI) study, we examined resting-state functional connectivity (rsFC) of the insula and its association with Internet gaming characteristics in 74 young adults with Internet gaming disorder (IGD) and 41 age- and gender-matched healthy control subjects (HCs). In comparison with HCs, IGD subjects (IGDs) exhibited enhanced rsFC between the anterior insula and a network of regions including anterior cingulate cortex (ACC), putamen, angular gyrus, and precuneous, which are involved in salience, craving, self-monitoring, and attention. IGDs also demonstrated significantly stronger rsFC between the posterior insula and postcentral gyrus, precentral gyrus, supplemental motor area, and superior temporal gyrus (STG), which are involved in interoception, movement control, and auditory processing. Furthermore, IGD severity was positively associated with connectivity between the anterior insula and angular gyrus, and STG, and with connectivity between the posterior insula and STG. Duration of Internet gaming was positively associated with connectivity between the anterior insula and ACC. These findings highlight a key role of the insula in manifestation of the core symptoms of IGD and the importance to examine functional abnormalities of the anterior and posterior insula separately in IGDs.
PMID: 25899520 [PubMed - as supplied by publisher]
Comparison of functional thalamic segmentation from seed-based analysis and ICA.
Neuroimage. 2015 Apr 17;
Authors: Hale JR, Mayhew SD, Mullinger KJ, Wilson RS, Arvanitis TN, Francis ST, Bagshaw AP
Information flow between the thalamus and cerebral cortex is a crucial component of adaptive brain function, but the details of thalamocortical interactions in human subjects remain unclear. The principal aim of this study was to evaluate the agreement between functional thalamic network patterns, derived using seed-based connectivity analysis and independent component analysis (ICA) applied separately to resting state functional MRI (fMRI) data from 21 healthy participants. For the seed-based analysis, functional thalamic parcellation was achieved by computing functional connectivity (FC) between thalamic voxels and a set of pre-defined cortical regions. Thalamus-constrained ICA provided an alternative parcellation. Both FC analyses demonstrated plausible and comparable group-level thalamic subdivisions, in agreement with previous work. Quantitative assessment of the spatial overlap between FC thalamic segmentations, and comparison of each to a histological "gold-standard" thalamic atlas and a structurally-defined thalamic atlas, highlighted variations between them and, most notably, differences with both histological and structural results. Whilst deeper understanding of thalamocortical connectivity rests upon identification of features common to multiple non-invasive neuroimaging techniques (e.g. FC, structural connectivity and anatomical localisation of individual-specific nuclei), this work sheds further light on the functional organisation of the thalamus and the varying sensitivities of complementary analyses to resolve it.
PMID: 25896929 [PubMed - as supplied by publisher]
Regional amplitude of the low-frequency fluctuations at rest predicts word reading skill.
Neuroscience. 2015 Apr 17;
Authors: Xu M, Beuckelaer A, Wang X, Liu L, Song Y, Liu J
Individuals' reading skills are critical for their educational development, but variation in reading skill is known to be large. The present study used functional magnetic resonance imaging (fMRI) to examine the role of spontaneous brain activity at rest in individual differences in reading skill in a large sample of participants (N = 263). Specifically, we correlated individuals' word reading skill with their fractional amplitude of low-frequency fluctuation (fALFF) of the whole brain at rest and found that the fALFF of both the bilateral precentral gyrus (PCG) and superior temporal plane (STP) were positively associated with reading skill. The fALFF-reading association observed in these two regions remained after controlling for general cognitive abilities and in-scanner head motion. A cross-validation confirmed that the individual differences in word reading skill were reliably correlated with the fALFF values of the bilateral PCG and STP. A follow-up task-based fMRI experiment revealed that the reading-related regions overlapped with regions showing a higher response to sentences than to pseudo-sentences (strings of pseudo-words), suggesting the resting-state brain activity partly capture the characteristics of task-based brain activity. In short, our study provides one of the first pieces of evidence that links spontaneous brain activity to reading behavior and offers an easy-to-access neural marker for evaluating reading skill.
PMID: 25896801 [PubMed - as supplied by publisher]
Ketamine-induced modulation of the thalamo-cortical network in healthy volunteers as a model for schizophrenia.
Int J Neuropsychopharmacol. 2015 Apr 19;
Authors: Höflich A, Hahn A, Küblböck M, Kranz GS, Vanicek T, Windischberger C, Saria A, Kasper S, Winkler D, Lanzenberger R
BACKGROUND: Schizophrenia has been associated with disturbances of thalamic functioning. In the light of recent evidence suggesting a significant impact of the glutamatergic system on key symptoms of schizophrenia, we assessed whether the modulation of the glutamatergic system via blockage of the NMDA-receptor might lead to changes of thalamic functional connectivity.
METHODS: Based on the "ketamine-model" of psychosis we investigated changes in cortico-thalamic functional connectivity by intravenous ketamine challenge during a 55 minutes resting-state scan. 30 healthy volunteers were measured with pharmacological functional magnetic resonance imaging (fMRI) using a double-blind, randomized, placebo-controlled, crossover design.
RESULTS: Functional connectivity analysis revealed significant ketamine-specific changes within the "thalamus hub network", more precisely an increase of cortico-thalamic connectivity of the somatosensory and temporal cortex.
CONCLUSIONS: Our results indicate that changes of thalamic functioning as described for schizophrenia can be partly mimicked by NMDA-receptor blockage. This adds substantial knowledge about the neurobiological mechanisms underlying the profound changes of perception and behaviour during the application of NMDA-receptor antagonists.
PMID: 25896256 [PubMed - as supplied by publisher]
SCALABLE FUSED LASSO SVM FOR CONNECTOME-BASED DISEASE PREDICTION.
Proc IEEE Int Conf Acoust Speech Signal Process. 2014 May;2014:5989-5993
Authors: Watanabe T, Scott CD, Kessler D, Angstadt M, Sripada CS
There is substantial interest in developing machine-based methods that reliably distinguish patients from healthy controls using high dimensional correlation maps known as functional connectomes (FC's) generated from resting state fMRI. To address the dimensionality of FC's, the current body of work relies on feature selection techniques that are blind to the spatial structure of the data. In this paper, we propose to use the fused Lasso regularized support vector machine to explicitly account for the 6-D structure of the FC (defined by pairs of points in 3-D brain space). In order to solve the resulting nonsmooth and large-scale optimization problem, we introduce a novel and scalable algorithm based on the alternating direction method. Experiments on real resting state scans show that our approach can recover results that are more neuroscientifically informative than previous methods.
PMID: 25892971 [PubMed - as supplied by publisher]
Long-term effects of marijuana use on the brain.
Proc Natl Acad Sci U S A. 2014 Nov 25;111(47):16913-8
Authors: Filbey FM, Aslan S, Calhoun VD, Spence JS, Damaraju E, Caprihan A, Segall J
Questions surrounding the effects of chronic marijuana use on brain structure continue to increase. To date, however, findings remain inconclusive. In this comprehensive study that aimed to characterize brain alterations associated with chronic marijuana use, we measured gray matter (GM) volume via structural MRI across the whole brain by using voxel-based morphology, synchrony among abnormal GM regions during resting state via functional connectivity MRI, and white matter integrity (i.e., structural connectivity) between the abnormal GM regions via diffusion tensor imaging in 48 marijuana users and 62 age- and sex-matched nonusing controls. The results showed that compared with controls, marijuana users had significantly less bilateral orbitofrontal gyri volume, higher functional connectivity in the orbitofrontal cortex (OFC) network, and higher structural connectivity in tracts that innervate the OFC (forceps minor) as measured by fractional anisotropy (FA). Increased OFC functional connectivity in marijuana users was associated with earlier age of onset. Lastly, a quadratic trend was observed suggesting that the FA of the forceps minor tract initially increased following regular marijuana use but decreased with protracted regular use. This pattern may indicate differential effects of initial and chronic marijuana use that may reflect complex neuroadaptive processes in response to marijuana use. Despite the observed age of onset effects, longitudinal studies are needed to determine causality of these effects.
PMID: 25385625 [PubMed - indexed for MEDLINE]
Developmental sex differences in resting state functional connectivity of amygdala sub-regions.
Neuroimage. 2015 Apr 14;
Authors: Alarcón G, Cservenka A, Rudolph MD, Fair DA, Nagel BJ
During adolescence, considerable social and biological changes occur that interact with functional brain maturation, some of which are sex-specific. The amygdala is one brain area that has displayed sexual dimorphism, specifically in socio-affective (superficial amygdala [SFA]), stress (centromedial amygdala [CMA]), and learning and memory (basolateral amygdala [BLA]) processing. The amygdala has also been implicated in mood and anxiety disorders which also display sex-specific features, most prominently observed during adolescence. Using functional magnetic resonance imaging (fMRI), the present study examined the interaction of age and sex on resting state functional connectivity (RSFC) of amygdala sub-regions, BLA and SFA, in a sample of healthy adolescents between the ages 10-16 years (n=122, 71 boys). Whole-brain, voxel-wise partial correlation analyses were conducted to determine RSFC of bilateral BLA and SFA seed regions, created using the Eickhoff-Zilles maximum probability maps based on cytoarchitectonic mapping and FMRIB's Integrated Registration and Segmentation Tool (FIRST). Monte Carlo simulation was implemented to correct for multiple comparisons (threshold of 53 contiguous voxels with a z-value ≥ 2.25). Results indicated that with increasing age, there was a corresponding decrease in RSFC between both amygdala sub-regions and parieto-occipital cortices, with a concurrent increase in RSFC with medial prefrontal cortex (mPFC). Specifically, boys and girls demonstrated increased coupling of mPFC and left and right SFA with age, respectively; however, neither sex showed increased connectivity between mPFC and BLA, which could indicate relative immaturity of fronto-limbic networks that is similar across sex. A dissociation in connectivity between BLA- and SFA- parieto-occipital RSFC emerged, in which girls had weaker negative RSFC between SFA and parieto-occipital regions and boys had weaker negative RSFC of BLA and parieto-occipital regions with increased age, both standing in contrast to adult patterns of amygdala sub-regional RSFC. The present findings suggest relative immaturity of amygdala sub-regional RSFC with parieto-occipital cortices during adolescence, with unique patterns in both sexes that may support memory and socio-affective processing in boys and girls, respectively. Understanding the underlying normative functional architecture of brain networks associated with the amygdala during adolescence may better inform future research of the neural features associated with increased risk for internalizing psychopathology.
PMID: 25887261 [PubMed - as supplied by publisher]
Frequency-Dependent Changes in the Regional Amplitude and Synchronization of Resting-State Functional MRI in Stroke.
PLoS One. 2015;10(4):e0123850
Authors: Zhu J, Jin Y, Wang K, Zhou Y, Feng Y, Yu M, Jin X
Resting-state functional magnetic resonance imaging (R-fMRI) has been intensively used to assess alterations of inter-regional functional connectivity in patients with stroke, but the regional properties of brain activity in stroke have not yet been fully investigated. Additionally, no study has examined a frequency effect on such regional properties in stroke patients, although this effect has been shown to play important roles in both normal brain functioning and functional abnormalities. Here we utilized R-fMRI to measure the amplitude of low-frequency fluctuations (ALFF) and regional homogeneity (ReHo), two major methods for characterizing the regional properties of R-fMRI, in three different frequency bands (slow-5: 0.01-0.027 Hz; slow-4: 0.027-0.73 Hz; and typical band: 0.01-0.1 Hz) in 19 stroke patients and 15 healthy controls. Both the ALFF and ReHo analyses revealed changes in brain activity in a number of brain regions, particularly the parietal cortex, in stroke patients compared with healthy controls. Remarkably, the regions with changed activity as detected by the slow-5 band data were more extensive, and this finding was true for both the ALFF and ReHo analyses. These results not only confirm previous studies showing abnormality in the parietal cortex in patients with stroke, but also suggest that R-fMRI studies of stroke should take frequency effects into account when measuring intrinsic brain activity.
PMID: 25885897 [PubMed - as supplied by publisher]
Dual Logic and Cerebral Coordinates for Reciprocal Interaction in Eye Contact.
PLoS One. 2015;10(4):e0121791
Authors: Lee RF
In order to scientifically study the human brain's response to face-to-face social interaction, the scientific method itself needs to be reconsidered so that both quantitative observation and symbolic reasoning can be adapted to the situation where the observer is also observed. In light of the recent development of dyadic fMRI which can directly observe dyadic brain interacting in one MRI scanner, this paper aims to establish a new form of logic, dual logic, which provides a theoretical platform for deductive reasoning in a complementary dual system with emergence mechanism. Applying the dual logic in the dfMRI experimental design and data analysis, the exogenous and endogenous dual systems in the BOLD responses can be identified; the non-reciprocal responses in the dual system can be suppressed; a cerebral coordinate for reciprocal interaction can be generated. Elucidated by dual logic deductions, the cerebral coordinate for reciprocal interaction suggests: the exogenous and endogenous systems consist of the empathy network and the mentalization network respectively; the default-mode network emerges from the resting state to activation in the endogenous system during reciprocal interaction; the cingulate plays an essential role in the emergence from the exogenous system to the endogenous system. Overall, the dual logic deductions are supported by the dfMRI experimental results and are consistent with current literature. Both the theoretical framework and experimental method set the stage to formally apply the scientific method in studying complex social interaction.
PMID: 25885446 [PubMed - as supplied by publisher]
Impairment of preoperative language mapping by lesion location: a functional magnetic resonance imaging, navigated transcranial magnetic stimulation, and direct cortical stimulation study.
J Neurosurg. 2015 Apr 17;:1-11
Authors: Ille S, Sollmann N, Hauck T, Maurer S, Tanigawa N, Obermueller T, Negwer C, Droese D, Boeckh-Behrens T, Meyer B, Ringel F, Krieg SM
OBJECT Language mapping by repetitive navigated transcranial magnetic stimulation (rTMS) is increasingly used and has already replaced functional MRI (fMRI) in some institutions for preoperative mapping of neurosurgical patients. Yet some factors affect the concordance of both methods with direct cortical stimulation (DCS), most likely by lesions affecting cortical oxygenation levels. Therefore, the impairment of the accuracy of rTMS and fMRI was analyzed and compared with DCS during awake surgery in patients with intraparenchymal lesions. METHODS Language mapping was performed by DCS, rTMS, and fMRI using an object-naming task in 27 patients with left-sided perisylvian lesions, and the induced language errors of each method were assigned to the cortical parcellation system. Subsequently, the receiver operating characteristics were calculated for rTMS and fMRI and compared with DCS as ground truth for regions with (w/) and without (w/o) the lesion in the mapped regions. RESULTS The w/ subgroup revealed a sensitivity of 100% (w/o 100%), a specificity of 8% (w/o 5%), a positive predictive value of 34% (w/o: 53%), and a negative predictive value (NPV) of 100% (w/o: 100%) for the comparison of rTMS versus DCS. Findings for the comparison of fMRI versus DCS within the w/ subgroup revealed a sensitivity of 32% (w/o: 62%), a specificity of 88% (w/o: 60%), a positive predictive value of 56% (w/o: 62%), and a NPV of 73% (w/o: 60%). CONCLUSIONS Although strengths and weaknesses exist for both rTMS and fMRI, the results show that rTMS is less affected by a brain lesion than fMRI, especially when performing mapping of language-negative cortical regions based on sensitivity and NPV.
PMID: 25884257 [PubMed - as supplied by publisher]
Cognitive rehabilitation in multiple sclerosis: the role of plasticity.
Front Neurol. 2015;6:67
Authors: Chiaravalloti ND, Genova HM, DeLuca J
Cognitive deficits are common in multiple sclerosis (MS), documented at many stages of the disease. Both structural and functional neuroimaging have demonstrated a relationship with cognitive abilities in MS. Significant neuroplasticity of cognitive functions in individuals with MS is evident. Homologous region adaptation, local activation expansion, and extra-region recruitment all occur in an effort to maintain cognitive functioning. While much of this neuroplasticity is adaptive, it may also be maladaptive, particularly in individuals that are demonstrating significant cognitive impairment and/or with disease progression. This maladaptive neuroplasticity may come at the cost of other cognitive functions. Studies of cognitive rehabilitation efficacy have also recently applied neuroimaging techniques to establish outcome. Researchers have successfully applied various neuroimaging techniques to study the effects of cognitive rehabilitation in MS including task-based fMRI and resting state functional connectivity across multiple realms of cognition including episodic memory, executive functioning, attention, and processing speed. These studies have demonstrated neuroplasticity in the brains of persons with MS through the documentation of changes at the level of the cerebral substrate from before to after non-invasive, non-pharmacological, behavioral treatment for deficits in cognition. Future research should seek to identify adaptive versus maladaptive neuroplasticity associated with specific cognitive rehabilitation programs within all MS phenotypes to foster the validation of the most effective cognitive rehabilitation interventions for persons with MS.
PMID: 25883585 [PubMed]
cTBS delivered to the left somatosensory cortex changes its functional connectivity during rest.
Neuroimage. 2015 Apr 13;
Authors: Valchev N, Ćurčić-Blake B, Renken RJ, Avenanti A, Keysers C, Gazzola V, Maurits NM
The primary somatosensory cortex (SI) plays a critical role in somatosensation as well as in action performance and social cognition. Although SI has been a major target of experimental and clinical research using non-invasive transcranial magnetic stimulation (TMS), to date information on the effect of TMS over SI on its resting-state functional connectivity is very scant. Here, we explored whether continuous theta burst stimulation (cTBS), a repetitive TMS protocol, administered over SI can change the functional connectivity of the brain at rest, as measured using resting-state functional magnetic resonance imaging (rs-fMRI). In a randomized order on two different days we administered active TMS or sham TMS over the left SI. TMS was delivered off-line before scanning by means of cTBS. The target area was selected previously and individually for each subject as the part of SI activated both when the participant executes and observes actions. Three analytical approaches, both theory driven (partial correlations and seed based whole brain regression) and more data driven (Independent Component Analysis), indicated a reduction in functional connectivity between the stimulated part of SI and several brain regions functionally associated with SI including the dorsal premotor cortex, the cerebellum, basal ganglia, and anterior cingulate cortex. These findings highlight the impact of cTBS delivered over SI on its functional connectivity at rest. Our data may have implications for experimental and therapeutic applications of cTBS over SI.
PMID: 25882754 [PubMed - as supplied by publisher]
Proneness to social anxiety modulates neural complexity in the absence of exposure: A resting state fMRI study using Hurst exponent.
Psychiatry Res. 2015 Mar 23;
Authors: Gentili C, Vanello N, Cristea I, David D, Ricciardi E, Pietrini P
To test the hypothesis that brain activity is modulated by trait social anxiety, we measured the Hurst Exponent (HE), an index of complexity in time series, in healthy individuals at rest in the absence of any social trigger. Functional magnetic resonance imaging (fMRI) time series were recorded in 36 subjects at rest. All volunteers were healthy without any psychiatric, medical or neurological disorder. Subjects completed the Liebowitz Social Anxiety Scale (LSAS) and the Brief Fear of Negative Evaluation (BFNE) to assess social anxiety and thoughts in social contexts. We also obtained the fractional Amplitude of Low Frequency Fluctuations (fALFF) of the BOLD signal as an independent control measure for HE data. BFNE scores correlated positively with HE in the posterior cingulate/precuneus, while LSAS scores correlated positively with HE in the precuneus, in the inferior parietal sulci and in the parahippocamus. Results from fALFF were highly consistent with those obtained using LSAS and BFNE to predict HE. Overall our data indicate that spontaneous brain activity is influenced by the degree of social anxiety, on a continuum and in the absence of social stimuli. These findings suggest that social anxiety is a trait characteristic that shapes brain activity and predisposes to different reactions in social contexts.
PMID: 25882042 [PubMed - as supplied by publisher]
Quantifying the predictive power of resting-state functional connectivity (rs-fc) fMRI for identifying patients with Alzheimer's disease (AD).
Clin Neurophysiol. 2015 Apr 2;
Authors: Dimitriadis SI
PMID: 25881782 [PubMed - as supplied by publisher]
Pathological uncoupling between amplitude and connectivity of brain fluctuations in epilepsy.
Hum Brain Mapp. 2015 Apr 16;
Authors: Zhang Z, Xu Q, Liao W, Wang Z, Li Q, Yang F, Zhang Z, Liu Y, Lu G
Amplitude and functional connectivity are two fundamental parameters for describing the spontaneous brain fluctuations. These two parameters present close coupling in physiological state, and present different alteration patterns in epilepsy revealed by functional MRI (fMRI). We hypothesized that the alteration of coupling between these two imaging parameters may be underpinned by specific pathological factors of epilepsy, and can be employed to improve the capability for epileptic focus detection. Forty-seven patients (26 left- and 21 right-sided) with mesial temporal lobe epilepsy (mTLE) and 32 healthy controls underwent resting-state fMRI scans. All patients were detected to have interictal epileptic discharges on simultaneous electroencephalograph (EEG) recordings. Amplitude-connectivity coupling was calculated by correlating amplitude and functional connectivity density of low-frequency brain fluctuations. We observed reduced amplitude-connectivity coupling associated with epileptic discharges in the mesial temporal regions in both groups of patients, and increased coupling associated with epilepsy durations in the posterior regions of the default-mode network in the right-sided patients. Moreover, we proposed a new index of amplitude subtracting connectivity, which elevated imaging contrast for differentiating the patients from the controls. The findings indicated that epileptic discharges and chronic damaging effect of epilepsy might both contribute to alterations of amplitude-connectivity coupling in different pivotal regions in mTLE. Investigation on imaging coupling provides synergistic approach for describing brain functional changing features in epilepsy. Hum Brain Mapp, 2015. © 2015 Wiley Periodicals, Inc.
PMID: 25879781 [PubMed - as supplied by publisher]