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The Cerebral Cost of Breathing: An fMRI Case-Study in Congenital Central Hypoventilation Syndrome.

Thu, 10/02/2014 - 13:30

The Cerebral Cost of Breathing: An fMRI Case-Study in Congenital Central Hypoventilation Syndrome.

PLoS One. 2014;9(9):e107850

Authors: Sharman M, Gallea C, Lehongre K, Galanaud D, Nicolas N, Similowski T, Cohen L, Straus C, Naccache L

Abstract
Certain motor activities - like walking or breathing - present the interesting property of proceeding either automatically or under voluntary control. In the case of breathing, brainstem structures located in the medulla are in charge of the automatic mode, whereas cortico-subcortical brain networks - including various frontal lobe areas - subtend the voluntary mode. We speculated that the involvement of cortical activity during voluntary breathing could impact both on the "resting state" pattern of cortical-subcortical connectivity, and on the recruitment of executive functions mediated by the frontal lobe. In order to test this prediction we explored a patient suffering from central congenital hypoventilation syndrome (CCHS), a very rare developmental condition secondary to brainstem dysfunction. Typically, CCHS patients demonstrate efficient cortically-controlled breathing while awake, but require mechanically-assisted ventilation during sleep to overcome the inability of brainstem structures to mediate automatic breathing. We used simultaneous EEG-fMRI recordings to compare patterns of brain activity between these two types of ventilation during wakefulness. As compared with spontaneous breathing (SB), mechanical ventilation (MV) restored the default mode network (DMN) associated with self-consciousness, mind-wandering, creativity and introspection in healthy subjects. SB on the other hand resulted in a specific increase of functional connectivity between brainstem and frontal lobe. Behaviorally, the patient was more efficient in cognitive tasks requiring executive control during MV than during SB, in agreement with her subjective reports in everyday life. Taken together our results provide insight into the cognitive and neural costs of spontaneous breathing in one CCHS patient, and suggest that MV during waking periods may free up frontal lobe resources, and make them available for cognitive recruitment. More generally, this study reveals how the active maintenance of cortical control over a continuous motor activity impacts on brain functioning and cognition.

PMID: 25268234 [PubMed - as supplied by publisher]

Brain Scale-free Properties in Awake Rest and NREM Sleep: A Simultaneous EEG/fMRI Study.

Thu, 10/02/2014 - 13:30

Brain Scale-free Properties in Awake Rest and NREM Sleep: A Simultaneous EEG/fMRI Study.

Brain Topogr. 2014 Sep 30;

Authors: Lei X, Wang Y, Yuan H, Chen A

Abstract
Electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) studies revealed that spontaneous activity in the brain has scale-invariant properties, as indicated by a frequency spectrum that follows a power-law distribution. However, current knowledge about the exact relationship between scaling properties in EEG and fMRI signals is very limited. To address this question, we collected simultaneous EEG-fMRI data in healthy individuals during resting wakefulness and non-rapid eye movement (NREM) sleep. For either of these conditions, we found that both EEG and fMRI power spectra followed a power-law distribution. Furthermore, the EEG and fMRI scaling exponents were highly variable across subjects, and sensitive to the choice of reference and nuisance variables in EEG and fMRI data, respectively. Interestingly, the EEG exponent of the whole brain selectively corresponded to the fMRI exponent of the thalamus during NREM sleep. Together, our findings suggest that scale-free brain activity is characterized by robust temporal structures and behavioral significance. This motivates future studies to unravel its physiological mechanisms, as well as its relevance to behavior.

PMID: 25266046 [PubMed - as supplied by publisher]

Does resting-state connectivity reflect depressive rumination? A tale of two analyses.

Wed, 10/01/2014 - 12:30

Does resting-state connectivity reflect depressive rumination? A tale of two analyses.

Neuroimage. 2014 Sep 26;

Authors: Berman MG, Misic B, Buschkuehl M, Kross E, Deldin PJ, Peltier S, Churchill NW, Jaeggi SM, Vakorin V, McIntosh AR, Jonides J

Abstract
Major Depressive Disorder (MDD) is characterized by rumination. Prior research suggests that resting-state brain activation reflects rumination when depressed individuals are not task engaged. However, no study has directly tested this. Here we investigated whether resting-state epochs differ from induced ruminative states for healthy and depressed individuals. Most previous research on resting-state networks comes from seed-based analyses with the posterior cingulate cortex (PCC). By contrast, we examined resting state connectivity by using the complete multivariate connectivity profile (i.e., connections across all brain nodes) and by comparing these results to seeded analyses. We find that unconstrained resting-state intervals differ from active rumination states in strength of connectivity and that overall connectivity was higher for healthy vs. depressed individuals. Relationships between connectivity and subjective mood (i.e., behavior) were strongly observed during induced rumination epochs. Furthermore, connectivity patterns that related to subjective mood were strikingly different for MDD and healthy control (HC) groups suggesting different mood regulation mechanisms.

PMID: 25264228 [PubMed - as supplied by publisher]

[Resting-state functional magnetic resonance imaging of first-onset major depressive disorder: analysis of 18 cases.]

Wed, 10/01/2014 - 12:30

[Resting-state functional magnetic resonance imaging of first-onset major depressive disorder: analysis of 18 cases.]

Nan Fang Yi Ke Da Xue Xue Bao. 2014 Sep 20;34(9):1277-1281

Authors: Guo MY, Zhang SX, Xu MZ, Hu XY, Yang CJ, Chen WB

Abstract
OBJECTIVE: To investigate the changes in brain regional homogeneity in first-onset major depressive disorders (MDDs) using resting-state functional magnetic resonance imaging (fMRI).
METHODS: Eighteen patients with first-onset MDDs and twenty gender- and age-matched healthy controls underwent resting-state fMRI scans to compare the regional homogeneities of the brain regions.
RESULTS: Compared with the normal controls, the patients with MDDs showed significantly decreased regional homogeneity in the left posterior cingulated gyrus, bilateral inferior temporal gyrus, bilateral superior temporal gyrus, left inferior frontal gyrus, left hippocampa gyrus, left posterior central gyrus, left angular gyrus, right amygdala, right orbital frontal gyrus, right supplementary motor area, and right cerebellar lobe.
CONCLUSION: Patients with first-onset MDDs have dysfunctions in the brain regions closed related with cognition and emotional control.

PMID: 25263358 [PubMed - as supplied by publisher]

Decreased functional connectivity between the mediodorsal thalamus and default mode network in patients with disorders of consciousness.

Wed, 10/01/2014 - 12:30

Decreased functional connectivity between the mediodorsal thalamus and default mode network in patients with disorders of consciousness.

Acta Neurol Scand. 2014 Sep 28;

Authors: He JH, Cui Y, Song M, Yang Y, Dang YY, Jiang TZ, Xu RX

Abstract
BACKGROUND: Interactions between the thalamus and the cortex play an important role in consciousness. The thalamus as a homogenous structure is less strongly connected with the default mode network (DMN) in patients with disorders of consciousness (DOC), but the roles of specific thalamic nuclei are not clear. The purpose of this study was to investigate the functional connectivity between individual thalamic nuclei and the DMN in DOC patients.
METHODS: Nine DOC patients and nine age-matched healthy controls were scanned with functional magnetic resonance imaging (fMRI) at resting state. Data-driven independent component analysis and hypothesis-driven region of interest-based correlation analysis were performed.
RESULTS: In comparison with healthy controls, DOC patients had significantly decreased functional connectivity between the mediodorsal thalamus and brain areas within the DMN, including the medial prefrontal cortex and posterior cingulate cortex/precuneus. Patients and controls did not show significant differences in functional connectivity in other thalamic nuclei.
CONCLUSION: Our results suggest that functional connections between the mediodorsal thalamus and the DMN may play important roles in the pathogenesis of DOC.

PMID: 25263131 [PubMed - as supplied by publisher]

Alterations in Amygdala Functional Connectivity Reflect Early Temperament.

Tue, 09/30/2014 - 17:00

Alterations in Amygdala Functional Connectivity Reflect Early Temperament.

Biol Psychol. 2014 Sep 24;

Authors: Roy AK, Benson BE, Degnan KA, Perez-Edgar K, Pine DS, Fox NA, Ernst M

Abstract
Behavioral inhibition (BI) is a temperament identified early in life that is associated with increased risk for anxiety disorders. Amygdala hyperresponsivity, found both in behaviorally inhibited and anxious individuals, suggests that amygdala dysfunction may represent a marker of anxiety risk. However, broader amygdala networks have not been examined in individuals with a history of childhood BI. This study uses resting state fMRI to assess amygdala intrinsic functional connectivity (iFC) in 38 healthy young adults (19 with a history of BI, 19 with no history of BI) selected from a longitudinal study. Centromedial, basolateral, and superficial amygdala iFCs were compared between groups and examined in relation to self-report measures of anxiety. Group differences were observed in amygdala iFC with prefrontal cortex, striatum, anterior insula, and cerebellum. Adults characterized with BI in childhood endorsed greater state anxiety prior to entering the scanner, which was associated with several of the group differences. Findings support enduring effects of BI on amygdala circuitry, even in the absence of current psychopathology.

PMID: 25261727 [PubMed - as supplied by publisher]

Reduced resting-state brain activity in the default mode network in children with (central) auditory processing disorders.

Tue, 09/30/2014 - 17:00

Reduced resting-state brain activity in the default mode network in children with (central) auditory processing disorders.

Behav Brain Funct. 2014 Sep 26;10(1):33

Authors: Pluta A, Wolak T, Czajka N, Lewandowska M, Cie la K, Rusiniak M, Grudzie D, Skar Y Ski H

Abstract
BACKGROUND: In recent years, there has been a growing interest in Central Auditory Processing Disorder (C)APD. However, the neural correlates of (C)APD are poorly understood. Previous neuroimaging experiments have shown changes in the intrinsic activity of the brain in various cognitive deficits and brain disorders. The present study investigated the spontaneous brain activity in (C)APD subjects with resting-state fMRI (rs-fMRI).
METHODS: Thirteen children diagnosed with (C)APD and fifteen age and gender-matched controls participated in a rs-fMRI study during which they were asked to relax keeping their eyes open. Two different techniques of the rs-fMRI data analysis were used: Regional Homogeneity (ReHo) and Independent Component Analysis (ICA), which approach is rare.
RESULTS: Both methods of data analysis showed comparable results in the pattern of DMN activity within groups. Additionally, ReHo analysis revealed increased co-activation of the superior frontal gyrus, the posterior cingulate cortex/the precuneus in controls, compared to the (C)APD group. ICA yielded inconsistent results across groups.
CONCLUSIONS: Our ReHo results suggest that (C)APD children seem to present reduced regional homogeneity in brain regions considered a part of the default mode network (DMN). These findings might contribute to a better understanding of neural mechanisms of (C)APD.

PMID: 25261349 [PubMed - as supplied by publisher]

Acupuncture modulates cortical thickness and functional connectivity in knee osteoarthritis patients.

Sun, 09/28/2014 - 14:30

Acupuncture modulates cortical thickness and functional connectivity in knee osteoarthritis patients.

Sci Rep. 2014;4:6482

Authors: Chen X, Spaeth RB, Retzepi K, Ott D, Kong J

Abstract
In this study, we investigated cortical thickness and functional connectivity across longitudinal acupuncture treatments in patients with knee osteoarthritis (OA). Over a period of four weeks (six treatments), we collected resting state functional magnetic resonance imaging (fMRI) scans from 30 patients before their first, third and sixth treatments. Clinical outcome showed a significantly greater Knee Injury and Osteoarthritis Outcome Score (KOOS) pain score (improvement) with verum acupuncture compared to the sham acupuncture. Longitudinal cortical thickness analysis showed that the cortical thickness at left posterior medial prefrontal cortex (pMPFC) decreased significantly in the sham group across treatment sessions as compared with verum group. Resting state functional connectivity (rsFC) analysis using the left pMPFC as a seed showed that after longitudinal treatments, the rsFC between the left pMPFC and the rostral anterior cingulate cortex (rACC), medial frontal pole (mFP) and periaquiduct grey (PAG) are significantly greater in the verum acupuncture group as compared with the sham group. Our results suggest that acupuncture may achieve its therapeutic effect on knee OA pain by preventing cortical thinning and decreases in functional connectivity in major pain related areas, therefore modulating pain in the descending pain modulatory pathway.

PMID: 25258037 [PubMed - as supplied by publisher]

Impaired functional integration in multiple sclerosis: a graph theory study.

Sun, 09/28/2014 - 14:30

Impaired functional integration in multiple sclerosis: a graph theory study.

Brain Struct Funct. 2014 Sep 26;

Authors: Rocca MA, Valsasina P, Meani A, Falini A, Comi G, Filippi M

Abstract
Aim of this study was to explore the topological organization of functional brain network connectivity in a large cohort of multiple sclerosis (MS) patients and to assess whether its disruption contributes to disease clinical manifestations. Graph theoretical analysis was applied to resting state fMRI data from 246 MS patients and 55 matched healthy controls (HC). Functional connectivity between 116 cortical and subcortical brain regions was estimated using a bivariate correlation analysis. Global network properties (network degree, global efficiency, hierarchy, path length and assortativity) were abnormal in MS patients vs HC, and contributed to distinguish cognitively impaired MS patients (34 %) from HC, but not the main MS clinical phenotypes. Compared to HC, MS patients also showed: (1) a loss of hubs in the superior frontal gyrus, precuneus and anterior cingulum in the left hemisphere; (2) a different lateralization of basal ganglia hubs (mostly located in the left hemisphere in HC, and in the right hemisphere in MS patients); and (3) a formation of hubs, not seen in HC, in the left temporal pole and cerebellum. MS patients also experienced a decreased nodal degree in the bilateral caudate nucleus and right cerebellum. Such a modification of regional network properties contributed to cognitive impairment and phenotypic variability of MS. An impairment of global integration (likely to reflect a reduced competence in information exchange between distant brain areas) occurs in MS and is associated with cognitive deficits. A regional redistribution of network properties contributes to cognitive status and phenotypic variability of these patients.

PMID: 25257603 [PubMed - as supplied by publisher]

A Sticky Weighted Regression Model for Time-Varying Resting State Brain Connectivity Estimation.

Sat, 09/27/2014 - 12:30

A Sticky Weighted Regression Model for Time-Varying Resting State Brain Connectivity Estimation.

IEEE Trans Biomed Eng. 2014 Sep 19;

Authors: Liu A, Chen X, McKeown MJ, Wang ZJ

Abstract
Despite recent progress on brain connectivity modeling using neuroimaging data such as fMRI, most current approaches assume that brain connectivity networks have time-invariant topology/coefficients. This is clearly problematic as the brain is inherently non-stationary. Here we present a time-varying model to investigate the temporal dynamics of brain connectivity networks. The proposed method allows for abrupt changes in network structure via a fused LASSO scheme, as well as recovery of time-varying networks with smoothly changing coefficients via a weighted regression technique. Simulations demonstrate that the proposed method yields improved accuracy on estimating time-dependent connectivity patterns when compared to a static sparse regression model or a weighted time-varying regression model. When applied to real resting state fMRI data sets from Parkinson's disease (PD) and control subjects, significantly different temporal and spatial patterns were found to be associated with PD. Specifically, PD subjects demonstrated reduced network variability over time, which may be related to impaired cognitive flexibility previously reported in PD. The temporal dynamic properties of brain connectivity in PD subjects may provide insights into brain dynamics associated with PD and may serve as a potential biomarker in future studies.

PMID: 25252272 [PubMed - as supplied by publisher]

Stability of low-frequency fluctuation amplitudes in prolonged resting-state fMRI.

Sat, 09/27/2014 - 12:30

Stability of low-frequency fluctuation amplitudes in prolonged resting-state fMRI.

Neuroimage. 2014 Sep 20;

Authors: Küblböck M, Woletz M, Höflich A, Sladky R, Kranz GS, Hoffmann A, Lanzenberger R, Windischberger C

Abstract
The (fractional) amplitudes of low-frequency fluctuations (f)ALFF are popular measures for the magnitude of low-frequency oscillations in resting-state fMRI (R-fMRI) data. Both measures can be directly derived from the spectral power of R-fMRI time courses. Numerous studies suggest that ALFF and fALFF might be used as biomarkers for a variety of diseases including schizophrenia, major depressive disorder, and obsessive-compulsive disorder. However, the temporal stability of (f)ALFF values, which is of great importance for the application of (f)ALFF both as a biomarker and scaling parameter, have not been studied in detail yet. Here, we quantify the temporal stability, robustness and reproducibility of both ALFF and fALFF maps obtained from R-fMRI data by performing statistical analyses over 55-minute resting-state scans which included a period of NaCl infusion. We also examine the differences of using either raw or standardised (f)ALFF maps. Our analyses show that no significant changes of (f)ALFF values over the 55minute period occur for both raw and standardised (f)ALFF maps. In addition, we demonstrate that raw (f)ALFF maps across subject are correlated with head motion as quantified via frame-wise displacement, whereas no such correlation is present in standardised (f)ALFF maps. In conclusion, the results of our study show that both ALFF and fALFF qualify as potential biomarkers due to their high temporal stability.

PMID: 25251869 [PubMed - as supplied by publisher]

Intranasal Insulin Enhanced Resting-State Functional Connectivity of Hippocampal Regions in Type 2 Diabetes.

Sat, 09/27/2014 - 12:30

Intranasal Insulin Enhanced Resting-State Functional Connectivity of Hippocampal Regions in Type 2 Diabetes.

Diabetes. 2014 Sep 23;

Authors: Zhang H, Hao Y, Manor B, Novak P, Milberg W, Zhang J, Fang J, Novak V

Abstract
Type 2 diabetes mellitus alters brain function and manifests as brain atrophy. Intranasal insulin has emerged as a promising intervention for treatment of cognitive impairment. We evaluated the acute effects of intranasal insulin on resting-state brain functional connectivity in older adults with type 2 diabetes.This proof-of-concept, randomized, double-blind, placebo-controlled study evaluated the effects of a single 40IU dose of insulin or saline in 14 diabetic and 14 control subjects. Resting-state functional connectivity between the hippocampal region and default mode network (DMN) was quantified using functional MRI (fMRI) at 3Tesla.Following insulin administration, diabetic patients demonstrated increased resting-state connectivity between the hippocampal regions and the medio-frontal cortex (MFC) as compared to placebo (cluster size right, p=0.03), and other DMN regions. On placebo, the diabetes group had lower connectivity between the hippocampal region and the MFC as compared to controls (cluster size: right, p=0.02), but on insulin MFC connectivity was similar to controls. Resting state connectivity correlated with cognitive performance. A single dose of intranasal insulin increases resting-state functional connectivity between the hippocampal regions and multiple DMN regions in older adults with type 2 diabetes. Intranasal insulin administration may modify functional connectivity among brain regions regulating memory and complex cognitive behaviors.

PMID: 25249577 [PubMed - as supplied by publisher]

Effects of far-infrared radiation on heart rate variability and central manifestations in healthy subjects: a resting-fMRI study.

Sat, 09/27/2014 - 12:30

Effects of far-infrared radiation on heart rate variability and central manifestations in healthy subjects: a resting-fMRI study.

Lasers Med Sci. 2014 Sep 24;

Authors: Lin YJ, Kung YY, Kuo WJ, Niddam DM, Cheng CM, Chou CC, Yeh TC, Hsieh JC, Chiu JH

Abstract
The aim of this study was to investigate the autonomic responses and central manifestations by peripheral FIR stimulation. Ten subjects (mean ± SD age 26.2 ± 3.52 years) received FIR stimulation at left median nerve territory for 40 min. Electrocardiograph was continuously recorded and heart rate variability (HRV) were analyzed. By using a 3 T-MRI scanner, three sessions of resting-state functional magnetic resonance images (fMRI) were acquired, namely, before (baseline-FIR), immediately after (IA-FIR) and 15 min after FIR was turned off (Post-FIR). The fractional amplitude of low-frequency (0.01-0.08 Hz) fluctuation (fALFF) of each session to evaluate the intensity of resting-brain activity in each session was analyzed. Our results showed that FIR stimulation induced significant HRV responses such as an increasing trend of nLF and LF/HF ratio, while FIR increased fALFF in right superior front gyrus, middle frontal gyrus and decreased the resting brain activity at fusiform gyrus, extrastriae cortex, inferior temporal gyrus and middle temporal gyrus, especially 15 min after FIR was turned off. We conclude that the central manifestation and the autonomic responses are prominent during and after FIR stimulation, which provide important mechanistic explanation on human disorder treated by such energy medicine.

PMID: 25249495 [PubMed - as supplied by publisher]

Functional Specialization and Flexibility in Human Association Cortex.

Sat, 09/27/2014 - 12:30

Functional Specialization and Flexibility in Human Association Cortex.

Cereb Cortex. 2014 Sep 23;

Authors: Yeo BT, Krienen FM, Eickhoff SB, Yaakub SN, Fox PT, Buckner RL, Asplund CL, Chee MW

Abstract
The association cortex supports cognitive functions enabling flexible behavior. Here, we explored the organization of human association cortex by mathematically formalizing the notion that a behavioral task engages multiple cognitive components, which are in turn supported by multiple overlapping brain regions. Application of the model to a large data set of neuroimaging experiments (N = 10 449) identified complex zones of frontal and parietal regions that ranged from being highly specialized to highly flexible. The network organization of the specialized and flexible regions was explored with an independent resting-state fMRI data set (N = 1000). Cortical regions specialized for the same components were strongly coupled, suggesting that components function as partially isolated networks. Functionally flexible regions participated in multiple components to different degrees. This heterogeneous selectivity was predicted by the connectivity between flexible and specialized regions. Functionally flexible regions might support binding or integrating specialized brain networks that, in turn, contribute to the ability to execute multiple and varied tasks.

PMID: 25249407 [PubMed - as supplied by publisher]

Default Network Connectivity Is Linked to Memory Status in Multiple Sclerosis.

Wed, 09/24/2014 - 20:31

Default Network Connectivity Is Linked to Memory Status in Multiple Sclerosis.

J Int Neuropsychol Soc. 2014 Sep 23;:1-8

Authors: Leavitt VM, Paxton J, Sumowski JF

Abstract
Memory impairment affects 50% of multiple sclerosis (MS) patients. Altered resting-state functional connectivity (FC) has been observed in the default network (DN) of MS patients. No study to date has examined the association of DN FC to its behavioral concomitant, memory. The approach of the present study represents a methodological shift allowing straightforward interpretation of FC alterations in MS, as it presupposes specificity of a network to its paired cognitive function. We examined FC from fMRI collected during rest in the DN of 43 MS patients with and without memory-impairment. Memory-intact patients showed increased DN FC relative to memory-impaired patients. There were no regions of higher FC in memory-impaired patients. DN FC was positively correlated with memory function, such that higher FC was associated with better memory performance. Results were unchanged after controlling for cognitive efficiency, supporting specificity of the DN to memory and not cognitive status more generally. These findings support DN FC as a marker of memory function in MS patients that can be targeted by future treatment interventions. Pairing a functional network with its behavioral concomitant represents a straightforward method for interpreting FC alterations in patients with MS. (JINS, 2014, 20, 1-8).

PMID: 25248054 [PubMed - as supplied by publisher]

Altered regional homogeneity in rolandic epilepsy: a resting-state FMRI study.

Wed, 09/24/2014 - 20:31

Altered regional homogeneity in rolandic epilepsy: a resting-state FMRI study.

Biomed Res Int. 2014;2014:960395

Authors: Tang YL, Ji GJ, Yu Y, Wang J, Wang ZJ, Zang YF, Liao W, Ding MP

Abstract
Children with rolandic epilepsy (RE) are often associated with cognitive deficits and behavioral problems. Findings from neurophysiological and neuroimaging studies in RE have now demonstrated dysfunction not only in rolandic focus, but also in distant neuronal circuits. Little is known, however, about whether there is distributed abnormal spontaneous brain activity in RE. Using resting-state functional magnetic resonance imaging (RS-fMRI), the present study aimed to determine whether children with RE show abnormal local synchronization during resting state and, if so, whether these changes could be associated with the behavioral/clinical characteristics of RE. Regional homogeneity (ReHo) in children with RE (n = 30) and healthy children (n = 20) was computed on resting-state functional MRI data. In comparison with healthy children, children with RE showed increased ReHo in the central, premotor, and prefrontal regions, while they showed decreased ReHo in bilateral orbitofrontal cortex and temporal pole. In addition, the ReHo value in the left orbitofrontal cortex negatively was corrected with performance intelligence quotient in the children with RE. The aberrant local synchronization, not strictly related to primary site of the typical rolandic focus, indicates the neuropathophysiological mechanism of RE. The study findings may shed new light on the understanding of neural correlation of neuropsychological deficiencies in the children with RE.

PMID: 25247197 [PubMed - in process]

Localizing hand motor area using resting-state fMRI: validated with direct cortical stimulation.

Wed, 09/24/2014 - 20:31

Localizing hand motor area using resting-state fMRI: validated with direct cortical stimulation.

Acta Neurochir (Wien). 2014 Sep 24;

Authors: Qiu TM, Yan CG, Tang WJ, Wu JS, Zhuang DX, Yao CJ, Lu JF, Zhu FP, Mao Y, Zhou LF

Abstract
BACKGROUND: Resting-state functional magnetic resonance imaging (R-fMRI) is a promising tool in clinical application, especially in presurgical mapping for neurosurgery. This study aimed to investigate the sensitivity and specificity of R-fMRI in the localization of hand motor area in patients with brain tumors validated by direct cortical stimulation (DCS). We also compared this technique to task-based blood oxygenation level-dependent (BOLD) fMRI (T-fMRI).
METHODS: R-fMRI and T-fMRI were acquired from 17 patients with brain tumors. The cortex sites of the hand motor area were recorded by DCS. Site-by-site comparisons between R-fMRI/T-fMRI and DCS were performed to calculate R-fMRI and T-fMRI sensitivity and specificity using DCS as a "gold standard". R-fMRI and T-fMRI performances were compared statistically RESULTS: A total of 609 cortex sites were tested with DCS and compared with R-fMRI findings in 17 patients. For hand motor area localization, R-fMRI sensitivity and specificity were 90.91 and 89.41 %, respectively. Given that two subjects could not comply with T-fMRI, 520 DCS sites were compared with T-fMRI findings in 15 patients. The sensitivity and specificity of T-fMRI were 78.57 and 84.76 %, respectively. In the 15 patients who successfully underwent both R-fMRI and T-fMRI, there was no statistical difference in sensitivity or specificity between the two methods (p = 0.3198 and p = 0.1431, respectively) CONCLUSIONS: R-fMRI sensitivity and specificity are high for localizing hand motor area and even equivalent or slightly higher compared with T-fMRI. Given its convenience for patients, R-fMRI is a promising substitute for T-fMRI for presurgical mapping.

PMID: 25246146 [PubMed - as supplied by publisher]

Creativity and the default network: A Functional Connectivity Analysis of the Creative Brain at Rest.

Wed, 09/24/2014 - 20:31

Creativity and the default network: A Functional Connectivity Analysis of the Creative Brain at Rest.

Neuropsychologia. 2014 Sep 19;

Authors: Beaty RE, Benedek M, Wilkins RW, Jauk E, Fink A, Silvia PJ, Hodges DA, Koschutnig K, Neubauer AC

Abstract
The present research used resting-state functional magnetic resonance imaging (fMRI) to examine whether the ability to generate creative ideas corresponds to differences in the intrinsic organization of functional networks in the brain. We examined the functional connectivity between regions commonly implicated in neuroimaging studies of divergent thinking, including the inferior prefrontal cortex and the core hubs of the default network. Participants were prescreened on a battery of divergent thinking tests and assigned to high- and low-creative groups based on task performance. Seed-based functional connectivity analysis revealed greater functional coupling of the left inferior frontal gyrus (IFG) with the entire default mode network in the high-creative group. The right IFG also showed greater functional connectivity with bilateral inferior parietal cortex and the left dorsolateral prefrontal cortex in the high-creative group. The results suggest that the ability to generate creative ideas is characterized by increased functional connectivity between the inferior prefrontal cortex and the default network, pointing to a greater cooperation between brain regions associated with cognitive control and low-level imaginative processes.

PMID: 25245940 [PubMed - as supplied by publisher]

Resting state functional magnetic resonance imaging and neural network classified autism and control.

Wed, 09/24/2014 - 14:00

Resting state functional magnetic resonance imaging and neural network classified autism and control.

Cortex. 2014 Aug 28;63C:55-67

Authors: Iidaka T

Abstract
Although the neurodevelopmental and genetic underpinnings of autism spectrum disorder (ASD) have been investigated, the etiology of the disorder has remained elusive, and clinical diagnosis continues to rely on symptom-based criteria. In this study, to classify both control subjects and a large sample of patients with ASD, we used resting state functional magnetic resonance imaging (rs-fMRI) and a neural network. Imaging data from 312 subjects with ASD and 328 subjects with typical development was downloaded from the multi-center research project. Only subjects under 20 years of age were included in this analysis. Correlation matrices computed from rs-fMRI time-series data were entered into a probabilistic neural network (PNN) for classification. The PNN classified the two groups with approximately 90% accuracy (sensitivity = 92%, specificity = 87%). The accuracy of classification did not differ among the institutes, or with respect to experimental and imaging conditions, sex, handedness, or intellectual level. Medication status and degree of head movement did not affect accuracy values. The present study indicates that an intrinsic connectivity matrix produced from rs-fMRI data could yield a possible biomarker of ASD. These results support the view that altered network connectivity within the brain contributes to the neurobiology of ASD.

PMID: 25243989 [PubMed - as supplied by publisher]

Decreased default-mode network homogeneity in unaffected siblings of schizophrenia patients at rest.

Wed, 09/24/2014 - 14:00

Decreased default-mode network homogeneity in unaffected siblings of schizophrenia patients at rest.

Psychiatry Res. 2014 Sep 1;

Authors: Guo W, Liu F, Yao D, Jiang J, Su Q, Zhang Z, Zhang J, Yu L, Zhai J, Xiao C

Abstract
The dysconnectivity hypothesis proposes that abnormal resting state connectivity within the default-mode network (DMN) plays a key role in schizophrenia. Little is known, however, about alterations of the network homogeneity (NH) of the DMN in unaffected siblings of patients with schizophrenia. Unaffected siblings have unique advantages as subjects of neuroimaging studies independent of the clinical and treatment issues that complicate studies of the patients themselves. In the present study, we investigated NH of the DMN in unaffected siblings of schizophrenia. Participants comprised 46 unaffected siblings of schizophrenia patients and 50 age-, sex-, and education-matched healthy controls who underwent resting state functional magnetic resonance imaging (fMRI). Automated NH and group independent component analysis (ICA) approaches were used to analyze the data. Compared with healthy controls, the unaffected siblings of schizophrenia patients showed decreased DMN homogeneity in the left precuneus. No significantly increased DMN homogeneity was found in the sibling group relative to the control group. Our results suggest that there is decreased NH of the DMN in unaffected siblings of schizophrenia patients and indicate that the alternative perspective of examining the DMN NH in patients׳ siblings may improve understanding of the nature of schizophrenia.

PMID: 25242670 [PubMed - as supplied by publisher]