Associations between interhemispheric functional connectivity and the Automated Neuropsychological Assessment Metrics (ANAM) in civilian mild TBI.
Brain Imaging Behav. 2014 Feb 21;
Authors: Sours C, Rosenberg J, Kane R, Roys S, Zhuo J, Shanmuganathan K, Gullapalli RP
This study investigates cognitive deficits and alterations in resting state functional connectivity in civilian mild traumatic brain injury (mTBI) participants with high and low symptoms. Forty-one mTBI participants completed a resting state fMRI scan and the Automated Neuropsychological Assessment Metrics (ANAM) during initial testing (<10 days of injury) and a 1 month follow up. Data were compared to 30 healthy control subjects. Results from the ANAM demonstrate that mTBI participants performed significantly worse than controls on the code substitution delayed subtest (p = 0.032) and weighted throughput score (p = 0.001). Among the mTBI patients, high symptom mTBI participants performed worse than those with low symptoms on the code substitution delayed (p = 0.017), code substitution (p = 0.012), repeated simple reaction time (p = 0.031), and weighted throughput score (p = 0.009). Imaging results reveal that during the initial visit, low symptom mTBI participants had reduced interhemispheric functional connectivity (IH-FC) within the lateral parietal lobe (p = 0.020); however, during follow up, high symptom mTBI participants showed reduced IH-FC compared to the control group within the dorsolateral prefrontal cortex (DLPFC) (p = 0.013). Reduced IH-FC within the DLPFC during the follow-up was associated with reduced cognitive performance. Together, these findings suggest that reduced rs-FC may contribute to the subtle cognitive deficits noted in high symptom mTBI participants compared to control subjects and low symptom mTBI participants.
PMID: 24557591 [PubMed - as supplied by publisher]
Functional connectivity alternation of the thalamus in restless legs syndrome patients during the asymptomatic period: a resting-state connectivity study using functional magnetic resonance imaging.
Sleep Med. 2014 Jan 30;
Authors: Ku J, Cho YW, Lee YS, Moon HJ, Chang H, Earley CJ, Allen RP
BACKGROUND: Restless legs syndrome (RLS) is a primary sensory disorder with a secondary motor component (e.g., urge to move), and the thalamus is known to play a central role in RLS. The purpose of our study was to explore the intrinsic changes in the thalamocortical circuit in RLS patients using a resting-state functional magnetic resonance imaging (fMRI) paradigm.
METHODS: Resting-state fMRIs were obtained in the morning from 25 idiopathic RLS patients who were not using RLS medications and 25 controls. Resting-state connectivity was analyzed by a seed-based method using Analysis of Functional NeuroImages (AFNI) software with the bilateral thalami (ventroposterolateral nucleus [VPLN]). The connectivity characteristics of RLS patients were compared to those of the controls.
RESULTS: We found that RLS patients showed reduced thalamic connectivity with the right parahippocampal gyrus, right precuneus, right precentral gyrus, and bilateral lingual gyri; however, the right superior temporal gyrus, bilateral middle temporal gyrus, and right medial frontal gyrus showed enhanced connectivity with the thalamus. RLS severity was negatively correlated with connectivity between the thalamus and right parahippocampal gyrus (r=-0.414; P=.040).
CONCLUSIONS: Our results suggest that the characteristics of the connectivity changes may reflect the pathways involved in producing RLS symptoms and indicate that RLS patients may have deficits in controlling and managing sensory information, which supports the act of viewing RLS as a disorder disrupting somatosensory processing.
PMID: 24555993 [PubMed - as supplied by publisher]
Neurofunctional correlates of attention rehabilitation in Parkinson's disease: an explorative study.
Neurol Sci. 2014 Feb 20;
Authors: Cerasa A, Gioia MC, Salsone M, Donzuso G, Chiriaco C, Realmuto S, Nicoletti A, Bellavia G, Banco A, D'amelio M, Zappia M, Quattrone A
The effectiveness of cognitive rehabilitation (CR) in Parkinson's disease (PD) is in its relative infancy, and nowadays there is insufficient information to support evidence-based clinical protocols. This study is aimed at testing a validated therapeutic strategy characterized by intensive computer-based attention-training program tailored to attention deficits. We further investigated the presence of synaptic plasticity by means of functional magnetic resonance imaging (fMRI). Using a randomized controlled study, we enrolled eight PD patients who underwent a CR program (Experimental group) and seven clinically/demographically-matched PD patients who underwent a placebo intervention (Control group). Brain activity was assessed using an 8-min resting state (RS) fMRI acquisition. Independent component analysis and statistical parametric mapping were used to assess the effect of CR on brain function. Significant effects were detected both at a phenotypic and at an intermediate phenotypic level. After CR, the Experimental group, in comparison with the Control group, showed a specific enhanced performance in cognitive performance as assessed by the SDMT and digit span forward. RS fMRI analysis for all networks revealed two significant groups (Experimental vs Control) × time (T0 vs T1) interaction effects on the analysis of the attention (superior parietal cortex) and central executive neural networks (dorsolateral prefrontal cortex). We demonstrated that intensive CR tailored for the impaired abilities impacts neural plasticity and improves some aspects of cognitive deficits of PD patients. The reported neurophysiological and behavioural effects corroborate the benefits of our therapeutic approach, which might have a reliable application in clinical management of cognitive deficits.
PMID: 24554416 [PubMed - as supplied by publisher]
Aberrant interhemispheric functional coordination in patients with HBV-related cirrhosis and minimal hepatic encephalopathy.
Metab Brain Dis. 2014 Feb 20;
Authors: Chen HJ, Wang Y, Yang M, Zhu XQ, Teng GJ
Aberrant brain functional connectivity has been considered as the important mechanism underlying minimal hepatic encephalopathy (MHE); however, little is known about the change in interhemispheric connection in MHE patients. Twenty patients with HBV-related cirrhosis and MHE and 15 healthy controls were included in this study and underwent the resting-state fMRI scanning and diffusion tensor imaging. The functional connectivity between symmetric interhemispheric voxels was computed by a technique called voxel-mirrored homotopic connectivity (VMHC), in which the time series for each voxel in one hemisphere was correlated with that of its homotopic voxel. Diffusion tensor imaging was conducted to measure the mean diffusivity (MD) and fractional anisotropy (FA) values in corpus callosum (CC). Compared with controls, MHE patients showed decreased regional VMHC in medial frontal gyrus, superior frontal gryus, anterior cingulate gyrus, inferior parietal lobule, postcentral gyrus, lingual gyrus, and middle occipital gyrus. MHE patients had significant decreased FA value in CC genu and CC splenium and increased MD value in CC genu. Pearson correlation analyses showed that the VMHC in anterior cingulate gyrus/medial frontal gyrus was correlated with FA/MD values of CC genu. These findings may suggest aberrant interhemispheric coordination in MHE and may provide new insight into the disease-related mechanisms.
PMID: 24553880 [PubMed - as supplied by publisher]
SINGULAR SPECTRUM ANALYSIS AND ADAPTIVE FILTERING ENHANCE THE FUNCTIONAL CONNECTIVITY ANALYSIS OF RESTING STATE fMRI DATA.
Int J Neural Syst. 2014 May;24(3):1450010
Authors: Piaggi P, Menicucci D, Gentili C, Handjaras G, Gemignani A, Landi A
Sources of noise in resting-state fMRI experiments include instrumental and physiological noises, which need to be filtered before a functional connectivity analysis of brain regions is performed. These noisy components show autocorrelated and nonstationary properties that limit the efficacy of standard techniques (i.e. time filtering and general linear model). Herein we describe a novel approach based on the combination of singular spectrum analysis and adaptive filtering, which allows a greater noise reduction and yields better connectivity estimates between regions at rest, providing a new feasible procedure to analyze fMRI data.
PMID: 24552511 [PubMed - as supplied by publisher]
Assessment of unconstrained cerebrovascular reactivity marker for large age-range FMRI studies.
PLoS One. 2014;9(2):e88751
Authors: Kannurpatti SS, Motes MA, Biswal BB, Rypma B
Breath hold (BH), a commonly used task to measure cerebrovascular reactivity (CVR) in fMRI studies varies in outcome among individuals due to subject-physiology and/or BH-inspiration/expiration differences (i.e., performance). In prior age-related fMRI studies, smaller task-related BOLD response variability is observed among younger than older individuals. Also, a linear CVR versus task relationship exists in younger individuals which maybe useful to test the accuracy of CVR responses in older groups. Hence we hypothesized that subject-related physiological and/or BH differences, if present, may compromise CVR versus task linearity in older individuals. To test the hypothesis, empirical BH versus task relationships from motor and cognitive areas were obtained in younger (mean age = 26 years) and older (mean age = 58 years) human subjects. BH versus task linearity was observed only in the younger group, confirming our hypothesis. Further analysis indicated BH responses and its variability to be similar in both younger and older groups, suggesting that BH may not accurately represent CVR in a large age range. Using the resting state fluctuation of amplitude (RSFA) as an unconstrained alternative to BH, subject-wise correspondence between BH and RSFA was tested. Correlation between BH versus RSFA was significant within the motor but was not significant in the cognitive areas in the younger and was completely disrupted in both areas in the older subjects indicating that BH responses are constrained by subject-related physiology and/or performance-related differences. Contrasting BH to task, RSFA-task relationships were independent of age accompanied by age-related increases in CVR variability as measured by RSFA, not observed with BH. Together the results obtained indicate that RSFA accurately represents CVR in any age range avoiding multiple and yet unknown physiologic and task-related pitfalls of BH.
PMID: 24551151 [PubMed - in process]
The effect of mild-to-moderate hearing loss on auditory and emotion processing networks.
Front Syst Neurosci. 2014;8:10
Authors: Husain FT, Carpenter-Thompson JR, Schmidt SA
We investigated the impact of hearing loss (HL) on emotional processing using task- and rest-based functional magnetic resonance imaging. Two age-matched groups of middle-aged participants were recruited: one with bilateral high-frequency HL and a control group with normal hearing (NH). During the task-based portion of the experiment, participants were instructed to rate affective stimuli from the International Affective Digital Sounds (IADS) database as pleasant, unpleasant, or neutral. In the resting state experiment, participants were told to fixate on a "+" sign on a screen for 5 min. The results of both the task-based and resting state studies suggest that NH and HL patients differ in their emotional response. Specifically, in the task-based study, we found slower response to affective but not neutral sounds by the HL group compared to the NH group. This was reflected in the brain activation patterns, with the NH group employing the expected limbic and auditory regions including the left amygdala, left parahippocampus, right middle temporal gyrus and left superior temporal gyrus to a greater extent in processing affective stimuli when compared to the HL group. In the resting state study, we observed no significant differences in connectivity of the auditory network between the groups. In the dorsal attention network (DAN), HL patients exhibited decreased connectivity between seed regions and left insula and left postcentral gyrus compared to controls. The default mode network (DMN) was also altered, showing increased connectivity between seeds and left middle frontal gyrus in the HL group. Further targeted analysis revealed increased intrinsic connectivity between the right middle temporal gyrus and the right precentral gyrus. The results from both studies suggest neuronal reorganization as a consequence of HL, most notably in networks responding to emotional sounds.
PMID: 24550791 [PubMed]
Decomposition of spontaneous brain activity into distinct fMRI co-activation patterns.
Front Syst Neurosci. 2013;7:101
Authors: Liu X, Chang C, Duyn JH
Recent fMRI studies have shown that analysis of the human brain's spontaneous activity may provide a powerful approach to reveal its functional organization. Dedicated methods have been proposed to investigate co-variation of signals from different brain regions, with the goal of revealing neuronal networks (NNs) that may serve specialized functions. However, these analysis methods generally do not take into account a potential non-stationary (variable) interaction between brain regions, and as a result have limited effectiveness. To address this, we propose a novel analysis method that uses clustering analysis to sort and selectively average fMRI activity time frames to produce a set of co-activation patterns. Compared to the established networks extracted with conventional analysis methods, these co-activation patterns demonstrate novel network features with apparent relevance to the brain's functional organization.
PMID: 24550788 [PubMed]
[Study of resting state functional connectivity of the red nucleus and substantia nigra were in normal adult].
Zhonghua Yi Xue Za Zhi. 2013 Dec 17;93(47):3758-61
Authors: Wang N, Wu JT, Chen WX, Xu Y, Ye J, Yin YL, Zhang HY
OBJECTIVE: To detect the functional networks of the red nucleus and substantia nigra duing the resting state in normal subjects with functional magnetic resonance imaging (fMRI).
METHODS: Sixteen normal subjects were performed resting state fMRI scanning and susceptibility weighted imaging. The function connectivity networks base on seed regions of the red nucleus and substantia nigra were extracted from low frequency fluctuation signal in fMRI data by using a temporal correlation method. Individual functional maps were entered two-tailed one-sample t test to determine brain regions with significant positive correlation to the seeds. The statistic threshold was set at P < 0.001, cluster size>42 (336 mm(3)), cluster connectivity criterion 5 rmm with Alphasim correction.
RESULTS: Brain regions involved in the functional connectivity network of the red nucleus include: dorsal anterior cingutate, supramarginal gyrus, the ventrolateral and the ventromedial nucleus of the thalamus, globus pallidus, dorsal thalamus, hippocampus, substantia nigra, red nucleus, pons, dentate nucleus, vermis; Brain regions involved in the functional connectivity network of the substantia nigra include: anterior cingutate, supramarginal gyrus, globus pallidus, dorsal thalamus, hippocampus, lobus insularis, substantia nigra, red nucleus, pons, dentate nucleus. The distribution of thhe networks of the red nucleus and substantia nigra presented symmetrical. Although the functional networks of the red nucleus and substantia nigra overlaped largely with each other, the rubral network was slightly different with the nigral network, witch showed strong correlations with more wide-spread striatum and thalamus areas.
CONCLUSION: The functional networks of the red nucleus and substantia nigra reflected strong interplay within the extrapyramidal subcortical system, as well as correlations between some limited cerebral cortices; Functional magnetic resonance imaging is a potential powerful tool to explore the extrapyramidal system.
PMID: 24548392 [PubMed - in process]
Amygdala-cingulate intrinsic connectivity is associated with degree of social inhibition.
Biol Psychol. 2014 Feb 14;
Authors: Blackford JU, Clauss JA, Avery SN, Cowan RL, Benningfield MM, Vanderklok RM
The tendency to approach or avoid novel people is a fundamental human behavior and is a core dimension of social anxiety. Resting state fMRI was used to test for an association between social inhibition and intrinsic connectivity in 40 young adults ranging from low to high in social inhibition. Higher levels of social inhibition were associated with specific patterns of reduced amygdala-cingulate cortex connectivity. Connectivity was reduced between the superficial amygdala and the rostral cingulate cortex and between the centromedial amygdala and the dorsal anterior cingulate cortex. Social inhibition also modulated connectivity in several well-established intrinsic networks; higher social inhibition correlated with reduced connectivity with default mode and dorsal attention networks and enhanced connectivity in salience and executive control networks. These findings provide important preliminary evidence that social inhibition reflects differences in the underlying intrinsic connectivity of the brain in the absence of social stimuli or stressors.
PMID: 24534162 [PubMed - as supplied by publisher]
A Brain-Wide Study of Age-Related Changes in Functional Connectivity.
Cereb Cortex. 2014 Feb 13;
Authors: Geerligs L, Renken RJ, Saliasi E, Maurits NM, Lorist MM
Aging affects functional connectivity between brain areas, however, a complete picture of how aging affects integration of information within and between functional networks is missing. We used complex network measures, derived from a brain-wide graph, to provide a comprehensive overview of age-related changes in functional connectivity. Functional connectivity in young and older participants was assessed during resting-state fMRI. The results show that aging has a large impact, not only on connectivity within functional networks but also on connectivity between the different functional networks in the brain. Brain networks in the elderly showed decreased modularity (less distinct functional networks) and decreased local efficiency. Connectivity decreased with age within networks supporting higher level cognitive functions, that is, within the default mode, cingulo-opercular and fronto-parietal control networks. Conversely, no changes in connectivity within the somatomotor and visual networks, networks implicated in primary information processing, were observed. Connectivity between these networks even increased with age. A brain-wide analysis approach of functional connectivity in the aging brain thus seems fundamental in understanding how age affects integration of information.
PMID: 24532319 [PubMed - as supplied by publisher]
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
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.
Neuroimage. 2014 Feb 12;
Authors: Germuska M, Bulte DP
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.
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
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.
Alcohol. 2014 Jan 18;
Authors: Rosen BQ, O'Hara R, Kovacevic S, Schulman A, Padovan N, Marinkovic K
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.
Soc Cogn Affect Neurosci. 2014 Feb 12;
Authors: Kerr KL, Avery JA, Barcalow JC, Moseman S, Bodurka J, Bellgowan PS, Simmons WK
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.
Clin Perinatol. 2014 Mar;41(1):257-283
Authors: Kwon SH, Vasung L, Ment LR, Huppi PS
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.
Front Hum Neurosci. 2013;7:921
Authors: Molavi B, May L, Gervain J, Carreiras M, Werker JF, Dumont GA
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.
J Neurosci. 2014 Feb 12;34(7):2451-63
Authors: Vahdat S, Darainy M, Ostry DJ
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.
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
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]