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Resting-State fMRI Reveals Functional Connectivity Between Face-selective Perirhinal Cortex and the Fusiform Face Area Related to Face Inversion.

Wed, 02/19/2014 - 15:00

Resting-State fMRI Reveals Functional Connectivity Between Face-selective Perirhinal Cortex and the Fusiform Face Area Related to Face Inversion.

Neuroimage. 2014 Feb 12;

Authors: O'Neil EB, Hutchison RM, McLean DA, Köhler S

Abstract
Studies examining the neural correlates of face perception and recognition in humans have revealed multiple brain regions that appear to play a specialized role in face processing. These include an anterior portion of perirhinal cortex (PrC) that appears to be homologous to the face-selective 'anterior face patch' recently reported in non-human primates. Electrical stimulation studies in the macaque indicate that the anterior face patch is highly integrated with other face-selective patches of cortex, even in the absence of face stimuli. The intrinsic functional connectivity of face-selective PrC and other regions of the face-processing network in humans is currently less well understood. Here, we examined resting-state fMRI connectivity across five face-selective regions in the right hemisphere that were identified with separate functional localizer scans: the PrC, amygdala (Amg), superior temporal sulcus, fusiform face area (FFA), and occipital face area. A partial correlation technique, controlling for fluctuations in occipitotemporal cortex that were not face specific, revealed connectivity between PrC, the FFA, as well as the Amg. When examining the 'unique' connectivity of PrC within this face processing network, we found that the connectivity between PrC and the FFA, as well as that between PrC and the Amg persisted even after controlling for potential mediating effects of other face-selective regions. Lastly, we examined the behavioral relevance of PrC connectivity by examining inter-individual differences in resting-state fluctuations in relation to differences in behavioral performance for a forced-choice recognition memory task that involved judgments on upright and inverted faces. This analysis revealed a significant correlation between the increased accuracy for upright faces (i.e., the face inversion effect) and the strength of connectivity between PrC and the FFA. Together, these findings point to a high degree of functional integration of face-selective aspects of PrC in the face processing network with notable behavioural relevance.

PMID: 24531049 [PubMed - as supplied by publisher]

MRI Measurement of Oxygen Extraction Fraction, Mean Vessel Size and Cerebral Blood Volume Using Serial Hyperoxia and Hypercapnia.

Wed, 02/19/2014 - 15:00

MRI Measurement of Oxygen Extraction Fraction, Mean Vessel Size and Cerebral Blood Volume Using Serial Hyperoxia and Hypercapnia.

Neuroimage. 2014 Feb 12;

Authors: Germuska M, Bulte DP

Abstract
Functional magnetic resonance imaging measures signal increases arising from a variety of interrelated effects and physiological sources. Recently there has been some success in disentangling this signal in order to quantify baseline physiological parameters, including the resting oxygen extraction fraction (OEF), cerebral blood volume (CBV) and mean vessel size. However, due to the complicated nature of the signal, each of these methods relies on certain physiological assumptions to derive a solution. In this work we present a framework for the simultaneous, voxelwise measurement of these three parameters. The proposed method removes the assumption of a fixed vessel size from the quantification of OEF and CBV, while simultaneously removing the need for an assumed OEF in the calculation of vessel size. The new framework is explored through simulations and validated with a pilot study in healthy volunteers. The MRI protocol uses a combined hyperoxia and hypercapnia paradigm with a modified spin labelling sequence collecting multi-slice gradient echo and spin echo data.

PMID: 24531048 [PubMed - as supplied by publisher]

Parkinson's disease-related modulation of functional connectivity associated with the striatum in the resting state in a nonhuman primate model.

Wed, 02/19/2014 - 15:00

Parkinson's disease-related modulation of functional connectivity associated with the striatum in the resting state in a nonhuman primate model.

Brain Res. 2014 Feb 12;

Authors: Li J, Luo C, Chen Y, Chen Q, Huang R, Sun J, Gong Q, Wu X, Qi Z, Liang Z, Li L, Li H, Li P, Wang W, Shang HF

Abstract
The goal of this study was to describe Parkinson's disease (PD)-related modulation of functional connectivity (FC) associated with the striatum in the resting state in a nonhuman primate model of early-stage PD. Weekly intravenous injections of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) (0.5mg/kg body weight) were performed until parkinsonian motor symptoms developed in four macaques. After 13 weeks of MPTP treatment, all monkeys displayed parkinsonian symptoms. During the course of the experiment, each animal underwent four magnetic resonance imaging scans and four positron emission tomography (PET) scans with the vesicular monoamine transporter 2 (VMAT2)-selective ligand 9-[(18)F] fluoropropyl-(+)-dihydrotetrabenazine, performed prior to the beginning of MPTP administration as well as after 4, 9, and 13 MPTP injections. The FC profile of the striatum was evaluated using a seed voxel correlation approach and post hoc region of interest analysis on resting-state functional magnetic resonance imaging data. The PET images were subjected to region of interest analysis to examine brain regional reductions in VMAT2 density in the PD model. Significant reductions in the connectivity pattern of the striatal regions were observed: limbic striatum and left hippocampus; caudate nucleus/associative and brain regions, including the right pre-supplementary motor area and bilateral dorsolateral prefrontal cortex; putamen/associative region and left inferior temporal gyrus or right orbital and medial prefrontal cortex; and putamen/motor and cortical structures, including the right superior temporal gyrus and bilateral postcentral gyrus. Subsequent PET studies showed the progressive loss of striatal VMAT2 in the striatum with the presentation of parkinsonism. Significant differences between the specific uptake ratio reductions in each striatal subdivision were not found. By using a long-term, low-dose MPTP-lesioned nonhuman primate model, this study demonstrated PD-related decreased corticostriatal FC in a resting state; moreover, altered sensorimotor integration was also found in early-stage PD.

PMID: 24530271 [PubMed - as supplied by publisher]

Oscillatory spatial profile of alcohol's effects on the resting state: Anatomically-constrained MEG.

Wed, 02/19/2014 - 15:00

Oscillatory spatial profile of alcohol's effects on the resting state: Anatomically-constrained MEG.

Alcohol. 2014 Jan 18;

Authors: Rosen BQ, O'Hara R, Kovacevic S, Schulman A, Padovan N, Marinkovic K

Abstract
It has been firmly established that opening and closing the eyes strongly modulate the electro- and magnetoencephalography (EEG and MEG) signals acquired during wakeful rest. Certain features of the resting EEG are altered in chronic alcoholics and their offspring, and have been proposed as biomarkers for alcoholism. Spontaneous brain oscillations are also affected by pharmacological manipulations, but the spectral and spatial characteristics of these changes are not clear. This study examined effects of the eyes-open (EO) and eyes-closed (EC) resting paradigm and alcohol challenge on the spatial profile of spontaneous MEG and EEG oscillations. Whole-head MEG and scalp EEG signals were acquired simultaneously from healthy social drinkers (n = 17) who participated in both alcohol (0.6 g/kg ethanol for men, 0.55 g/kg for women) and placebo conditions in a counterbalanced design. Power of the signal was calculated with Fast Fourier Transform and was decomposed into its constituent theta (4-7 Hz), alpha (8-12 Hz), and beta (15-20 Hz) frequency bands. High-resolution structural MRI images were additionally obtained from all participants and used to constrain distributed minimum norm inverse source power estimates. The spatial estimates of the main generator nodes were in agreement with studies using a combined fMRI-EEG approach. Alpha band oscillations dominated the spectral profile and their source was estimated to the medial parieto-occipital area. Power in theta and beta bands was weaker overall and their sources were estimated to a more focal medial prefrontal area. EO and EC manipulation most strongly modulated power in the alpha band, but a wide-band power increase was observed during the EC condition. Alcohol intoxication increased alpha power, particularly during the EC condition. Application of this methodology to cohorts of chronic alcoholics or individuals at risk could potentially provide insight into the neural basis of oscillatory differences that may be predictive of the vulnerability to alcoholism.

PMID: 24530007 [PubMed - as supplied by publisher]

Trait impulsivity is related to ventral ACC and amygdala activity during primary reward anticipation.

Tue, 02/18/2014 - 13:30

Trait impulsivity is related to ventral ACC and amygdala activity during primary reward anticipation.

Soc Cogn Affect Neurosci. 2014 Feb 12;

Authors: Kerr KL, Avery JA, Barcalow JC, Moseman S, Bodurka J, Bellgowan PS, Simmons WK

Abstract
Trait impulsivity is characterized by behavioral disinhibition and rash decision-making that contribute to many maladaptive behaviors. Previous research demonstrates that trait impulsivity is related to the activity of brain regions underlying reward sensitivity and emotion regulation, but little is known about this relationship in the context of immediately available primary reward. This is unfortunate, as impulsivity in these contexts can lead to unhealthy behaviors, including poor food choices, dangerous drug use, and risky sexual practices. In addition, little is known about the relationship between integration of reward and affective neurocircuitry, as measured by resting-state functional connectivity, and trait impulsivity in everyday life, as measured with a commonly used personality inventory. We therefore asked healthy adults to undergo a fMRI task in which they saw cues indicating the imminent oral administration of rewarding taste, as well as a resting-state scan. Trait impulsivity was associated with increased activation during anticipation of primary reward in the anterior cingulate cortex (ACC) and amygdala. Additionally, resting-state functional connectivity between the ACC and the right amygdala was negatively correlated with trait impulsivity. These findings demonstrate that trait impulsivity is related not only to ACC-amygdala activation, but also how tightly coupled these regions are to one another.

PMID: 24526181 [PubMed - as supplied by publisher]

The Role of Neuroimaging in Predicting Neurodevelopmental Outcomes of Preterm Neonates.

Tue, 02/18/2014 - 13:30

The Role of Neuroimaging in Predicting Neurodevelopmental Outcomes of Preterm Neonates.

Clin Perinatol. 2014 Mar;41(1):257-283

Authors: Kwon SH, Vasung L, Ment LR, Huppi PS

Abstract
Magnetic resonance imaging (MRI) is a safe and high-resolution neuroimaging modality that is increasingly used in the neonatal population to assess brain injury and its consequences on brain development. It is superior to cranial ultrasound for the definition of patterns of both white and gray matter maturation and injury and therefore has the potential to provide prognostic information on the neurodevelopmental outcomes of the preterm population. Furthermore, the development of sophisticated MRI strategies, including diffusion tensor imaging, resting state functional connectivity, and magnetic resonance spectroscopy, may increase the prognostic value, helping to guide parental counseling and allocate early intervention services.

PMID: 24524459 [PubMed - as supplied by publisher]

Analyzing the resting state functional connectivity in the human language system using near infrared spectroscopy.

Sat, 02/15/2014 - 14:00

Analyzing the resting state functional connectivity in the human language system using near infrared spectroscopy.

Front Hum Neurosci. 2013;7:921

Authors: Molavi B, May L, Gervain J, Carreiras M, Werker JF, Dumont GA

Abstract
We have evaluated the use of phase synchronization to identify resting state functional connectivity (RSFC) in the language system in infants using functional near infrared spectroscopy (fNIRS). We used joint probability distribution of phase between fNIRS channels with a seed channel in the language area to estimate phase relations and to identify the language system network. Our results indicate the feasibility of this method in identifying the language system. The connectivity maps are consistent with anatomical cortical connections and are also comparable to those obtained from functional magnetic resonance imaging (fMRI) functional connectivity studies. The results also indicate left hemisphere lateralization of the language network.

PMID: 24523685 [PubMed]

Structure of plasticity in human sensory and motor networks due to perceptual learning.

Sat, 02/15/2014 - 14:00

Structure of plasticity in human sensory and motor networks due to perceptual learning.

J Neurosci. 2014 Feb 12;34(7):2451-63

Authors: Vahdat S, Darainy M, Ostry DJ

Abstract
As we begin to acquire a new motor skill, we face the dual challenge of determining and refining the somatosensory goals of our movements and establishing the best motor commands to achieve our ends. The two typically proceed in parallel, and accordingly it is unclear how much of skill acquisition is a reflection of changes in sensory systems and how much reflects changes in the brain's motor areas. Here we have intentionally separated perceptual and motor learning in time so that we can assess functional changes to human sensory and motor networks as a result of perceptual learning. Our subjects underwent fMRI scans of the resting brain before and after a somatosensory discrimination task. We identified changes in functional connectivity that were due to the effects of perceptual learning on movement. For this purpose, we used a neural model of the transmission of sensory signals from perceptual decision making through to motor action. We used this model in combination with a partial correlation technique to parcel out those changes in connectivity observed in motor systems that could be attributed to activity in sensory brain regions. We found that, after removing effects that are linearly correlated with somatosensory activity, perceptual learning results in changes to frontal motor areas that are related to the effects of this training on motor behavior and learning. This suggests that perceptual learning produces changes to frontal motor areas of the brain and may thus contribute directly to motor learning.

PMID: 24523536 [PubMed - in process]

Prognostic value of changes in resting-state functional connectivity patterns in cognitive recovery after stroke: A 3T fMRI pilot study.

Sat, 02/15/2014 - 14:00

Prognostic value of changes in resting-state functional connectivity patterns in cognitive recovery after stroke: A 3T fMRI pilot study.

Hum Brain Mapp. 2014 Feb 12;

Authors: Dacosta-Aguayo R, Graña M, Savio A, Fernández-Andújar M, Millán M, López-Cancio E, Cáceres C, Bargalló N, Garrido C, Barrios M, Clemente IC, Hernández M, Munuera J, Dávalos A, Auer T, Mataró M

Abstract
Resting-state studies conducted with stroke patients are scarce. First objective was to explore whether patients with good cognitive recovery showed differences in resting-state functional patterns of brain activity when compared to patients with poor cognitive recovery. Second objective was to determine whether such patterns were correlated with cognitive performance. Third objective was to assess the existence of prognostic factors for cognitive recovery. Eighteen right-handed stroke patients and eighteen healthy controls were included in the study. Stroke patients were divided into two groups according to their cognitive improvement observed at three months after stroke. Probabilistic independent component analysis was used to identify resting-state brain activity patterns. The analysis identified six networks: frontal, fronto-temporal, default mode network, secondary visual, parietal, and basal ganglia. Stroke patients showed significant decrease in brain activity in parietal and basal ganglia networks and a widespread increase in brain activity in the remaining ones when compared with healthy controls. When analyzed separately, patients with poor cognitive recovery (n = 10) showed the same pattern as the whole stroke patient group, while patients with good cognitive recovery (n = 8) showed increased activity only in the default mode network and fronto-temporal network, and decreased activity in the basal ganglia. We observe negative correlations between basal ganglia network activity and performance in Semantic Fluency test and Part A of the Trail Making Test for patients with poor cognitive recovery. A reverse pattern was observed between frontal network activity and the abovementioned tests for the same group. Hum Brain Mapp, 2014. © 2014 Wiley Periodicals, Inc.

PMID: 24523262 [PubMed - as supplied by publisher]

Regional homogeneity changes in hemodialysis patients with end stage renal disease: in vivo resting-state functional MRI study.

Fri, 02/14/2014 - 18:30

Regional homogeneity changes in hemodialysis patients with end stage renal disease: in vivo resting-state functional MRI study.

PLoS One. 2014;9(2):e87114

Authors: Li C, Su HH, Qiu YW, Lv XF, Shen S, Zhan WF, Tian JZ, Jiang GH

Abstract
OBJECTIVE: To prospectively investigate and detect early cerebral regional homogeneity (ReHo) changes in neurologically asymptomatic patients with end stage renal disease (ESRD) using in vivo resting-state functional MR imaging (Rs-fMRI).
METHODS: We enrolled 20 patients (15 men, 5 women; meanage, 37.1 years; range, 19-49 years) with ESRD and 20 healthy controls (15 men, 5 women; mean age, 38.3 years; range, 28-49 years). The mean duration of hemodialysis for the patient group was 10.7±6.4 monthes. There was no significant sex or age difference between the ESRD and control groups. Rs-fMRI was performed using a gradient-echo echo-planar imaging sequence. ReHo was calculated using software (DPARSF). Voxel-based analysis of the ReHo maps between ESRD and control groups was performed with a two-samples t test. Statistical maps were set at P value less than 0.05 and were corrected for multiple comparisons. The Mini-Mental State Examination (MMSE) was administered to all participants at imaging.
RESULTS: ReHo values were increased in the bilateral superior temporal gyrus and left medial frontal gyrus in the ERSD group compared with controls, but a significantly decreased ReHo value was found in the right middle temporal gyrus. There was no significant correlation between ReHo values and the duration of hemodialysis in the ESRD group. Both the patients and control subjects had normal MMSE scores (≥28).
CONCLUSIONS: Our finding revealed that abnormal brain activity was distributed mainly in the memory and cognition related cotices in patients with ESRD. The abnormal spontaneous neuronal activity in those areas provide information on the neural mechanisms underlying cognitive impairment in patients with ESRD, and demonstrate that Rs-fMRI with ReHo analysis is a useful non-invasive imaging tool for the detection of early cerebral ReHo changes in hemodialysis patients with ESRD.

PMID: 24516545 [PubMed - in process]

Early Evaluation of Nerve Regeneration After Nerve Injury and Repair Using Functional Connectivity MRI.

Fri, 02/14/2014 - 18:30

Early Evaluation of Nerve Regeneration After Nerve Injury and Repair Using Functional Connectivity MRI.

Neurorehabil Neural Repair. 2014 Feb 10;

Authors: Li R, Hettinger PC, Liu X, Machol J, Yan JG, Matloub HS, Hyde JS

Abstract
Resting state functional connectivity magnetic resonance imaging studies in rat brain show brain reorganization caused by nerve injury and repair. In this study, distinguishable differences were found in healthy, nerve transection without repair (R-) and nerve transection with repair (R+) groups in the subacute stage (2 weeks after initial injury). Only forepaw on the healthy side was used to determine seed voxel regions in this study. Disturbance of neuronal network in the primary sensory region of cortex occurs within two hours after initial injury, and the network pattern was restored in R+ group in subacute stage, while the disturbed pattern remained in R- group. These are the central findings of the study. This technique provides a novel way of detecting and monitoring the effectiveness of peripheral nerve injury treatment in the early stage and potentially offers a tool for clinicians to avoid poor clinical outcomes.

PMID: 24515926 [PubMed - as supplied by publisher]

Altered Regional Homogeneity and Efficient Response Inhibition in Restrained Eaters.

Fri, 02/14/2014 - 18:30

Altered Regional Homogeneity and Efficient Response Inhibition in Restrained Eaters.

Neuroscience. 2014 Feb 7;

Authors: Dong D, Lei X, Jackson T, Wang Y, Su Y, Chen H

Abstract
Restrained eaters (REs) characterized by less efficient response inhibition are at risk for future onset of binge eating and bulimic pathology. Previous imaging studies investigating REs have been based on task-related functional Magnetic Resonance Imaging (fMRI) and little is known about resting state neural activity underlying restrained eating. To illuminate this issue, we investigated resting state fMRI differences between REs (n=22) and unrestrained eaters (UREs) (n=30) using regional homogeneity (ReHo) analysis, which measures the temporal synchronization of spontaneous fluctuations. Samples were equated on body mass index (BMI) and caloric deprivation levels (i.e., 14 ± 2.1 hours since last evening meal) before undergoing fMRI. Correlation analyses were performed between the ReHo index of identified regions and response inhibition based on stop signal reaction time (SSRT) within each sample. Compared with UREs, REs showed more ReHo in brain regions associated with food reward (i.e., orbitofrontal cortex (OFC), dorsal-lateral prefrontal cortex (dlPFC)), attention (i.e., lingual gyrus, cuneus, inferior parietal lobule) and somatosensory functioning (i.e., paracentral lobule, anterior insula). In addition, ReHo values for the left dlPFC and left anterior insula, respectively, were negatively and positively correlated with SSRT among REs but not UREs. In concert with previous studies, these results suggest altered local synchronization may help to explain why dieting to maintain or lose weight often fails or increases risk for binge eating among REs.

PMID: 24513387 [PubMed - as supplied by publisher]

The effects of caffeine ingestion on cortical areas: Functional imaging study.

Fri, 02/14/2014 - 18:30

The effects of caffeine ingestion on cortical areas: Functional imaging study.

Magn Reson Imaging. 2014 Jan 6;

Authors: Park CA, Kang CK, Son YD, Choi EJ, Kim SH, Oh ST, Kim YB, Park CW, Cho ZH

Abstract
The effect of caffeine as a cognitive enhancer is well known; however, caffeine-induced changes in the cortical regions are still not very clear. Therefore, in this study, we conducted an investigation of the activation and deactivation with blood-oxygenation-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) and of metabolic activity change with positron emission tomography (PET) in the human brain. Fourteen healthy subjects performed a visuomotor task inducing attention with 3T MRI, and PET imaging was also carried out in seven subjects to determine the cerebral glucose metabolic changes of caffeine at rest. The result by fMRI showed increased BOLD activation in the left cerebellum, putamen, insula, thalamus and the right primary motor cortex, and decreased BOLD deactivation in the posterior medial and the left posterior lateral cortex. Also, the resting state PET data showed reduced metabolic activity in the putamen, caudate nucleus, insula, pallidum and posterior medial cortex. The common cortical regions between fMRI and PET, such as putamen, insula and posterior medial cortex, where significant changes occurred after caffeine ingestion, are well known to play an important role in cognitive function like attention. This result suggests that the effect of caffeine as a cognitive enhancer is derived by modulating the attentional areas.

PMID: 24512799 [PubMed - as supplied by publisher]

A study on small-world brain functional networks altered by postherpetic neuralgia.

Fri, 02/14/2014 - 18:30

A study on small-world brain functional networks altered by postherpetic neuralgia.

Magn Reson Imaging. 2013 Dec 30;

Authors: Zhang Y, Liu J, Li L, Du M, Fang W, Wang D, Jiang X, Hu X, Zhang J, Wang X, Fang J

Abstract
Understanding the effect of postherpetic neuralgia (PHN) pain on brain activity is important for clinical strategies. This is the first study, to our knowledge, to relate PHN pain to small-world properties of brain functional networks. Functional magnetic resonance imaging (fMRI) was used to construct functional brain networks of the subjects during the resting state. Sixteen patients with PHN pain and 16 (8 males, 8 females for both groups) age-matched controls were studied. The PHN patients exhibited decreased local efficiency along with non-significant changes of global efficiency in comparison with the healthy controls. Moreover, regional nodal efficiency was found to be significantly affected by PHN pain in the areas related to sense (postcentral gyrus, inferior parietal gyrus and thalamus), memory/affective processes (parahippocampal gyrus) and emotional activities (putamen). Significant correlation (p<0.05) was also found between the nodal efficiency of putamen and pain intensity in PHN patients. Our results suggest that PHN modulates the local efficiency, and the small-world properties of brain networks may have potentials to objectively evaluate pain information in clinic.

PMID: 24512793 [PubMed - as supplied by publisher]

Intranetwork and internetwork functional connectivity abnormalities in pediatric multiple sclerosis.

Wed, 02/12/2014 - 15:30

Intranetwork and internetwork functional connectivity abnormalities in pediatric multiple sclerosis.

Hum Brain Mapp. 2014 Feb 7;

Authors: Rocca MA, Valsasina P, Absinta M, Moiola L, Ghezzi A, Veggiotti P, Amato MP, Horsfield MA, Falini A, Comi G, Filippi M

Abstract
Active motor functional magnetic resonance imaging (fMRI) studies have shown that pediatric multiple sclerosis (MS) patients have a strictly lateralized pattern of activations and a preserved functional connectivity (FC) within the motor system when compared to age-matched healthy controls. However, it is still not clear whether a preserved FC in pediatric MS is present only in the motor system, or involves other relevant functional system. Resting-state (RS) fMRI is a valuable tool for an unbiased investigation of FC abnormalities of multiple networks. This study explored abnormalities of RS FC within and between large-scale neuronal networks from 44 pediatric MS patients and 27 controls and their correlation with clinical, neuropsychological, and conventional MRI measures. Compared to controls, pediatric MS patients had a decreased FC of several regions of the sensorimotor, secondary visual, default-mode (DMN), executive control, and bilateral working memory (WMN) networks. They also experienced an increased FC in the right medial frontal gyrus of the attention network, which was correlated with T2 lesion volume. Cognitively impaired patients had decreased RS FC of the right precuneus of the left WMN. An increased FC between the sensorimotor network and the DMN, and between the L WMN and the attention network as well as a decreased FC between L WMN and the DMN were also found. A distributed pattern of FC abnormalities within large-scale neuronal networks occurs in pediatric MS patients, contributes to their cognitive status, and is partially driven by focal white matter lesions. Internetwork connectivity is relatively preserved in these patients. Hum Brain Mapp, 2014. © 2014 Wiley Periodicals, Inc.

PMID: 24510680 [PubMed - as supplied by publisher]

Pupil diameter covaries with BOLD activity in human locus coeruleus.

Wed, 02/12/2014 - 15:30

Pupil diameter covaries with BOLD activity in human locus coeruleus.

Hum Brain Mapp. 2014 Feb 7;

Authors: Murphy PR, O'Connell RG, O'Sullivan M, Robertson IH, Balsters JH

Abstract
The locus coeruleus-noradrenergic (LC-NA) neuromodulatory system has been implicated in a broad array of cognitive processes, yet scope for investigating this system's function in humans is currently limited by an absence of reliable non-invasive measures of LC activity. Although pupil diameter has been employed as a proxy measure of LC activity in numerous studies, empirical evidence for a relationship between the two is lacking. In the present study, we sought to rigorously probe the relationship between pupil diameter and BOLD activity localized to the human LC. Simultaneous pupillometry and fMRI revealed a relationship between continuous pupil diameter and BOLD activity in a dorsal pontine cluster overlapping with the LC, as localized via neuromelanin-sensitive structural imaging and an LC atlas. This relationship was present both at rest and during performance of a two-stimulus oddball task, with and without spatial smoothing of the fMRI data, and survived retrospective image correction for physiological noise. Furthermore, the spatial extent of this pupil/LC relationship guided a volume-of-interest analysis in which we provide the first demonstration in humans of a fundamental characteristic of animal LC activity: phasic modulation by oddball stimulus relevance. Taken together, these findings highlight the potential for utilizing pupil diameter to achieve a more comprehensive understanding of the role of the LC-NA system in human cognition. Hum Brain Mapp, 2014. © 2014 Wiley Periodicals, Inc.

PMID: 24510607 [PubMed - as supplied by publisher]

Diagnostic Classification Based on Functional Connectivity in Chronic Pain: Model Optimization in Fibromyalgia and Rheumatoid Arthritis.

Wed, 02/12/2014 - 15:30

Diagnostic Classification Based on Functional Connectivity in Chronic Pain: Model Optimization in Fibromyalgia and Rheumatoid Arthritis.

Acad Radiol. 2014 Mar;21(3):369-77

Authors: Sundermann B, Burgmer M, Pogatzki-Zahn E, Gaubitz M, Stüber C, Wessolleck E, Heuft G, Pfleiderer B

Abstract
RATIONALE AND OBJECTIVES: The combination of functional magnetic resonance imaging (fMRI) of the brain with multivariate pattern analysis (MVPA) has been proposed as a possible diagnostic tool. Goal of this investigation was to identify potential functional connectivity (FC) differences in the salience network (SN) and default mode network (DMN) between fibromyalgia syndrome (FMS), rheumatoid arthritis (RA), and controls (HC) and to evaluate the diagnostic applicability of derived pattern classification approaches.
MATERIALS AND METHODS: The resting period during an fMRI examination was retrospectively analyzed in women with FMS (n = 17), RA (n = 16), and HC (n = 17). FC was calculated for SN and DMN subregions. Classification accuracies of discriminative MVPA models were evaluated with cross-validation: (1) inferential test of a single method, (2) explorative model optimization.
RESULTS: No inferentially tested model was able to classify subjects with statistically significant accuracy. However, the diagnostic ability for the differential diagnostic problem exhibited a trend to significance (accuracy: 69.7%, P = .086). Optimized models in the explorative analysis reached accuracies up to 73.5% (FMS vs. HC), 78.8% (RA vs. HC), and 78.8% (FMS vs. RA) whereas other models performed at or below chance level. Comparable support vector machine approaches performed above average for all three problems.
CONCLUSIONS: Observed accuracies are not sufficient to reliably differentiate between FMS and RA for diagnostic purposes. However, some indirect evidence in support of the feasibility of this approach is provided. This exploratory analysis constitutes a fundamental model optimization effort to be based on in further investigations.

PMID: 24507423 [PubMed - in process]

Small-worldness and modularity of the resting-state functional brain network decrease with aging.

Wed, 02/12/2014 - 15:30
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Small-worldness and modularity of the resting-state functional brain network decrease with aging.

Neurosci Lett. 2013 Nov 27;556:104-8

Authors: Onoda K, Yamaguchi S

Abstract
The human brain is a complex network that is known to be affected by normal aging. Graph-based analysis has been used to estimate functional brain network efficiency and effects of normal aging on small-worldness have been reported. This relationship is further investigated here along with network modularity, a statistic reflecting how well a network is organized into modules of densely interconnected nodes. Modularity has previously been observed to vary as a function of working memory capacity, therefore we hypothesized that both small-worldness and modularity would show age-related declines. We found that both small-worldness and modularity were negatively correlated with increasing age but that this decline was relatively slow.

PMID: 24157850 [PubMed - indexed for MEDLINE]

Resting-state synchrony during early alcohol abstinence can predict subsequent relapse.

Wed, 02/12/2014 - 15:30
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Resting-state synchrony during early alcohol abstinence can predict subsequent relapse.

Cereb Cortex. 2013 Sep;23(9):2086-99

Authors: Camchong J, Stenger A, Fein G

Abstract
Short-term abstinent alcoholics have shown increased engagement of reward regions and reduced engagement of executive control regions. There is no report yet on whether these differences can predict relapse. This is the first study that investigates whether differences in resting-state networks can predict later relapse. Resting-state functional magnetic resonance imaging data were collected from 69 short-term abstinent alcoholics. Participants performed the affective go/no-go task outside of the scanner. At 6-month follow-up, participants were grouped as abstainers (N = 40; age: M = 46.70, standard deviation [SD] = 6.83) and relapsers (N = 29; age: M = 46.91, SD = 7.25). We examined baseline resting-state synchrony (RSS) using seed-based measures. Compared with abstainers, relapsers showed significantly decreased RSS within both the reward and executive control networks as well as within the visual network (P < 0.05). Lower RSS in relapsers could predict relapse (P < 0.05) and was significantly correlated with poor inhibitory control of emotional-laden stimuli (P < 0.017) and with alcohol use (P < 0.05). Results suggest that lower RSS during short-term abstinence may predict subsequent relapse. The association of lower RSS with poorer inhibitory control suggests that low RSS may constitute a faulty foundation for future responses to external cues, which can be manifested as the inability to inhibit behavior.

PMID: 22819968 [PubMed - indexed for MEDLINE]

Implications of inconsistencies between fMRI and dMRI on multimodal connectivity estimation.

Tue, 02/11/2014 - 14:00

Implications of inconsistencies between fMRI and dMRI on multimodal connectivity estimation.

Med Image Comput Comput Assist Interv. 2013;16(Pt 3):652-9

Authors: Ng B, Varoquaux G, Poline JB, Thirion B

Abstract
There is a recent trend towards integrating resting state functional magnetic resonance imaging (RS-fMRI) and diffusion MRI (dMRI) for brain connectivity estimation, as motivated by how estimates from these modalities are presumably two views reflecting the same underlying brain circuitry. In this paper, we show on a cohort of 60 subjects that conventional functional connectivity (FC) estimates based on Pearson's correlation and anatomical connectivity (AC) estimates based on fiber counts are actually not that highly correlated for typical RS-fMRI (approximately 7 min) and dMRI (approximately 32 gradient directions) data. The FC-AC correlation can be significantly increased by considering sparse partial correlation and modeling fiber endpoint uncertainty, but the resulting FC-AC correlation is still rather low in absolute terms. We further exemplify the inconsistencies between FC and AC estimates by integrating them as priors into activation detection and demonstrating significant differences in their detection sensitivity. Importantly, we illustrate that these inconsistencies can be useful in fMRI-dMRI integration for improving brain connectivity estimation.

PMID: 24505817 [PubMed - in process]