Reduced resting-state functional connectivity of the somatosensory cortex predicts psychopathological symptoms in women with bulimia nervosa.
Front Behav Neurosci. 2014;8:270
Authors: Lavagnino L, Amianto F, D'Agata F, Huang Z, Mortara P, Abbate-Daga G, Marzola E, Spalatro A, Fassino S, Northoff G
BACKGROUND: Alterations in the resting-state functional connectivity (rs-FC) of several brain networks have been demonstrated in eating disorders. However, very few studies are currently available on brain network dysfunctions in bulimia nervosa (BN). The somatosensory network is central in processing body-related stimuli and it may be altered in BN. The present study therefore aimed to investigate rs-FC in the somatosensory network in bulimic women.
METHODS: Sixteen medication-free women with BN (age = 23 ± 5 years) and 18 matched controls (age = 23 ± 3 years) underwent a functional magnetic resonance resting-state scan and assessment of eating disorder symptoms. Within-network and seed-based functional connectivity analyses were conducted to assess rs-FC within the somatosensory network and to other areas of the brain.
RESULTS: Bulimia nervosa patients showed a decreased rs-FC both within the somatosensory network (t = 9.0, df = 1, P = 0.005) and with posterior cingulate cortex and two visual areas (the right middle occipital gyrus and the right cuneus) (P = 0.05 corrected for multiple comparison). The rs-FC of the left paracentral lobule with the right middle occipital gyrus correlated with psychopathology measures like bulimia (r = -0.4; P = 0.02) and interoceptive awareness (r = -0.4; P = 0.01). Analyses were conducted using age, BMI (body mass index), and depressive symptoms as covariates.
CONCLUSION: Our findings show a specific alteration of the rs-FC of the somatosensory cortex in BN patients, which correlates with eating disorder symptoms. The region in the right middle occipital gyrus is implicated in body processing and is known as extrastriate body area (EBA). The connectivity between the somatosensory cortex and the EBA might be related to dysfunctions in body image processing. The results should be considered preliminary due to the small sample size.
PMID: 25136302 [PubMed]
Resting state functional connectivity of the anterior cingulate cortex in veterans with and without post-traumatic stress disorder.
Hum Brain Mapp. 2014 Aug 19;
Authors: Kennis M, Rademaker AR, van Rooij SJ, Kahn RS, Geuze E
Post-traumatic stress disorder (PTSD) is an anxiety disorder that is associated with structural and functional alterations in several brain areas, including the anterior cingulate cortex (ACC). Here, we examine resting state functional connectivity of ACC subdivisions in PTSD, using a seed-based approach. Resting state magnetic resonance images were obtained from male veterans with (n = 31) and without (n = 25) PTSD, and healthy male civilian controls (n = 25). Veterans with and without PTSD (combat controls) had reduced functional connectivity compared to healthy controls between the caudal ACC and the precentral gyrus, and between the perigenual ACC and the superior medial gyrus and middle temporal gyrus. Combat controls had increased connectivity between the rostral ACC and precentral/middle frontal gyrus compared to PTSD patients and healthy civilian controls. The resting state functional connectivity differences in the perigenual ACC network reported here indicate that veterans differ from healthy controls, potentially due to military training, deployment, and/or trauma exposure. In addition, specific alterations in the combat controls may potentially be related to resilience. These results underline the importance of distinguishing trauma-exposed (combat) controls from healthy civilian controls when studying PTSD. Hum Brain Mapp, 2014. © 2014 Wiley Periodicals, Inc.
PMID: 25137414 [PubMed - as supplied by publisher]
Evidence that neurovascular coupling underlying the BOLD effect increases with age during childhood.
Hum Brain Mapp. 2014 Aug 19;
Authors: Schmithorst VJ, Vannest J, Lee G, Hernandez-Garcia L, Plante E, Rajagopal A, Holland SK, The CMIND Authorship Consortium
Functional MRI using blood-oxygen-level-dependent (BOLD) imaging has provided unprecedented insights into the maturation of the human brain. Task-based fMRI studies have shown BOLD signal increases with age during development (ages 5-18) for many cognitive domains such as language and executive function, while functional connectivity (resting-state) fMRI studies investigating regionally synchronous BOLD fluctuations have revealed a developing functional organization of the brain from a local into a more distributed architecture. However, interpretation of these results is confounded by the fact that the BOLD signal is directly related to blood oxygenation driven by changes in blood flow and only indirectly related to neuronal activity, and may thus be affected by changing neuronal-vascular coupling. BOLD signal and cerebral blood flow (CBF) were measured simultaneously in a cohort of 113 typically developing awake participants ages 3-18 performing a narrative comprehension task. Using a novel voxelwise wild bootstrap analysis technique, an increased ratio of BOLD signal to relative CBF signal change with age (indicative of increased neuronal-vascular coupling) was seen in the middle temporal gyri and the left inferior frontal gyrus. Additionally, evidence of decreased relative oxygen metabolism (indicative of decreased neuronal activity) with age was found in the same regions. These findings raise concern that results of developmental BOLD studies cannot be unambiguously attributed to neuronal activity. Astrocytes and astrocytic processes may significantly affect the maturing functional architecture of the brain, consistent with recent research demonstrating a key role for astrocytes in mediating increased CBF following neuronal activity and for astrocyte processes in modulating synaptic connectivity. Hum Brain Mapp, 2014. © 2014 Wiley Periodicals, Inc.
PMID: 25137219 [PubMed - as supplied by publisher]
CHILDHOOD MALTREATMENT AND COMBAT POSTTRAUMATIC STRESS DIFFERENTIALLY PREDICT FEAR-RELATED FRONTO-SUBCORTICAL CONNECTIVITY.
Depress Anxiety. 2014 Aug 8;
Authors: Birn RM, Patriat R, Phillips ML, Germain A, Herringa RJ
BACKGROUND: Adult posttraumatic stress disorder (PTSD) has been characterized by altered fear-network connectivity. Childhood trauma is a major risk factor for adult PTSD, yet its contribution to fear-network connectivity in PTSD remains unexplored. We examined, within a single model, the contribution of childhood maltreatment, combat exposure, and combat-related posttraumatic stress symptoms (PTSS) to resting-state connectivity (rs-FC) of the amygdala and hippocampus in military veterans.
METHODS: Medication-free male veterans (n = 27, average 26.6 years) with a range of PTSS completed resting-state fMRI. Measures including the Clinician-Administered PTSD Scale (CAPS), Childhood Trauma Questionnaire (CTQ), and Combat Exposure Scale (CES) were used to predict rs-FC using multilinear regression. Fear-network seeds included the amygdala and hippocampus.
RESULTS: Amygdala: CTQ predicted lower connectivity to ventromedial prefrontal cortex (vmPFC), but greater anticorrelation with dorsal/lateral PFC. CAPS positively predicted connectivity to insula, and loss of anticorrelation with dorsomedial/dorsolateral (dm/dl)PFC. Hippocampus: CTQ predicted lower connectivity to vmPFC, but greater anticorrelation with dm/dlPFC. CES predicted greater anticorrelation, whereas CAPS predicted less anticorrelation with dmPFC.
CONCLUSIONS: Childhood trauma, combat exposure, and PTSS differentially predict fear-network rs-FC. Childhood maltreatment may weaken ventral prefrontal-subcortical circuitry important in automatic fear regulation, but, in a compensatory manner, may also strengthen dorsal prefrontal-subcortical pathways involved in more effortful emotion regulation. PTSD symptoms, in turn, appear to emerge with the loss of connectivity in the latter pathway. These findings suggest potential mechanisms by which developmental trauma exposure leads to adult PTSD, and which brain mechanisms are associated with the emergence of PTSD symptoms.
PMID: 25132653 [PubMed - as supplied by publisher]
Hyper-coupling between working memory task-evoked activations and amplitude of spontaneous fluctuations in first-episode schizophrenia.
Schizophr Res. 2014 Aug 14;
Authors: Zhou Y, Wang Z, Zuo XN, Zhang H, Wang Y, Jiang T, Liu Z
Working memory (WM) deficit is an important component of impaired cognition in schizophrenia. However, between-studies inconsistencies as to the specific functional substrate imply that inter-individual variability (IIV) in the WM performance is associated with IIV in brain activity in schizophrenia. To examine the neural substrate of this WM IIV, we studied whether the neural mechanisms that underlie individual differences in WM capacity are the same in schizophrenia patients and healthy people. We correlated the IIV of the task-evoked brain activity and task performance during an n-back WM task with the IIV of the moment-to-moment variability in intrinsic resting-state activity, as measured by the amplitude of low-frequency fluctuations (ALFFs) and further compared this relationship between 17 patients with first-episode schizophrenia (FES) and 18 healthy controls. Between-group comparisons of the correlation patterns indicated aberrant ALFF-WM activation correlations and ALFF-WM performance correlations in the FES patients, but no significant changes were detected in any single measurement of these three characteristics. Specifically, we found increased positive ALFF-WM activation correlations in the bilateral lateral prefrontal cortices, posterior parietal cortices and fusiform gyri in the FES patients. We also observed significant increases in positive ALFF-WM performance correlations in the bilateral ventromedial prefrontal cortices in the FES patients. This hyper-coupling between the ALFF and fMRI measures during a WM task may indicate that it was difficult for the patients to detach themselves from one state to transition to another and suggests that the inefficient cortical function in schizophrenia stems from the intrinsic functional architecture of the brain.
PMID: 25132644 [PubMed - as supplied by publisher]
Heritability of head motion during resting state functional MRI in 462 healthy twins.
Neuroimage. 2014 Aug 12;
Authors: Couvy-Duchesne B, Blokland GA, Hickie IB, Thompson PM, Martin NG, de Zubicaray GI, McMahon KL, Wright MJ
Head motion (HM) is a critical confounding factor in functional MRI. Here we investigate whether HM during resting state functional MRI (RS-fMRI) is influenced by genetic factors in a sample of 462 twins (65% female; 101 MZ (monozygotic) and 130 DZ (dizygotic) twin pairs; mean age: 21 (SD=3.16), range 16-29). Heritability estimates for three HM components-mean translation (MT), maximum translation (MAXT) and mean rotation (MR)-ranged from 37 to 51%. We detected a significant common genetic influence on HM variability, with about two-thirds (genetic correlations range 0.76-1.00) of the variance shared between MR, MT and MAXT. A composite metric (HM-PC1), which aggregated these three, was also moderately heritable (h(2)=42%). Using a sub-sample (N=35) of the twins we confirmed that mean and maximum translational and rotational motions were consistent "traits" over repeated scans (r=0.53-0.59); reliability was even higher for the composite metric (r=0.66). In addition, phenotypic and cross-trait cross-twin correlations between HM and resting state functional connectivities (RS-FCs) with Brodmann areas (BA) 44 and 45, in which RS-FCs were found to be moderately heritable (BA44: h(2)̅=0.23 (sd=0.041), BA45: h(2)̅=0.26 (sd=0.061) ), indicated that HM might not represent a major bias in genetic studies using FCs. Even so, the HM effect on FC was not completely eliminated after regression. HM may be a valuable endophenotype whose relationship with brain disorders remains to be elucidated.
PMID: 25132021 [PubMed - as supplied by publisher]
Synchronous multi-scale neuroimaging environment for critically sampled physiological analysis of brain function- Hepta-scan concept.
Brain Connect. 2014 Aug 16;
Authors: Korhonen VO, Hiltunen TK, Myllylä TS, Wang S, Kantola J, Nikkinen J, Zang YF, Levan P, Kiviniemi V
Functional connectivity of the resting state networks (RSNs) of the brain is thought to be mediated by very low frequency fluctuations (VLFFs < 0.1 Hz) in neuronal activity. However, vasomotor waves and cardiorespiratory pulsations influence indirect measures of brain function, such as the functional MRI (fMRI) blood oxygen level-dependent (BOLD) signal. How strongly physiological oscillations correlate with spontaneous BOLD signals is not known, partially due to differences in the data sampling rates of different methods. Recent ultrafast inverse imaging sequences, including magnetic resonance encephalography (MREG), enable critical sampling of these signals. In this study, we describe a multimodal concept, referred to as Hepta-scan, which incorporates synchronous MREG with scalp electroencephalography (EEG), near-infrared spectroscopy (NIRS), non-invasive blood pressure (NIBP) and anesthesia monitoring. Our preliminary results support the idea that, in the absence of aliased cardiorespiratory signals, very low frequency fluctuations in the BOLD signal are affected by vasomotor and electrophysiological sources. Furthermore, MREG signals showed a high correlation coefficient between the ventromedial default mode network (DMNvmpf) and electrophysiological signals, especially in the VLF range. Also oxy- and deoxyhemoglobin and vasomotor waves were found to correlate with DMNvmpf. Intriguingly, using shorter time windows in these correlation measurements produced significantly (p<0.05) higher positive and negative correlation coefficients, suggesting temporal non-stationary behavior between the measurements. Focusing on the VLF range strongly increased correlation strength.
PMID: 25131996 [PubMed - as supplied by publisher]
Resting-state functional connectivity of the human hypothalamus.
Hum Brain Mapp. 2014 Aug 14;
Authors: Kullmann S, Heni M, Linder K, Zipfel S, Häring HU, Veit R, Fritsche A, Preissl H
The hypothalamus is of enormous importance for multiple bodily functions such as energy homeostasis. Especially, rodent studies have greatly contributed to our understanding how specific hypothalamic subregions integrate peripheral and central signals into the brain to control food intake. In humans, however, the neural circuitry of the hypothalamus, with its different subregions, has not been delineated. Hence, the aim of this study was to map the hypothalamus network using resting-state functional connectivity (FC) analyses from the medial hypothalamus (MH) and lateral hypothalamus (LH) in healthy normal-weight adults (n = 49). Furthermore, in a separate sample, we examined differences within the LH and MH networks between healthy normal-weight (n = 25) versus overweight/obese adults (n = 23). FC patterns from the LH and MH revealed significant connections to the striatum, thalamus, brainstem, orbitofrontal cortex, middle and posterior cingulum and temporal brain regions. However, our analysis revealed subtler distinctions within hypothalamic subregions. The LH was functionally stronger connected to the dorsal striatum, anterior cingulum, and frontal operculum, while the MH showed stronger functional connections to the nucleus accumbens and medial orbitofrontal cortex. Furthermore, overweight/obese participants revealed heightened FC in the orbitofrontal cortex and nucleus accumbens within the MH network. Our results indicate that the MH and LH network are tapped into different parts of the dopaminergic circuitry of the brain, potentially modulating food reward based on the functional connections to the ventral and dorsal striatum, respectively. In obese adults, FC changes were observed in the MH network. Hum Brain Mapp, 2014. © 2014 Wiley Periodicals, Inc.
PMID: 25131690 [PubMed - as supplied by publisher]
Homotopic connectivity in drug-naïve, first-episode, early-onset schizophrenia.
J Child Psychol Psychiatry. 2014 Aug 18;
Authors: Li HJ, Xu Y, Zhang KR, Hoptman MJ, Zuo XN
BACKGROUND: The disconnection hypothesis of schizophrenia has been extensively tested in adults. Recent studies have reported the presence of brain disconnection in younger patients, adding evidence to support the neurodevelopmental hypothesis of schizophrenia. Because of drug confounds in chronic and medicated patients, it has been extremely challenging for researchers to directly investigate abnormalities in the development of connectivity and their role in the pathophysiology of schizophrenia. The present study aimed to examine functional homotopy - a measure of interhemispheric connection - and its relevance to clinical symptoms in first-episode drug-naïve early-onset schizophrenia (EOS) patients.
METHODS: Resting-state functional magnetic resonance imaging was performed in 26 first-episode drug-naïve EOS patients (age: 14.5 ± 1.94, 13 males) and 25 matched typically developing controls (TDCs) (age: 14.4 ± 2.97, 13 males). We were mainly concerned with the functional connectivity between any pair of symmetric interhemispheric voxels (i.e., functional homotopy) measured by voxel-mirrored homotopic connectivity (VMHC).
RESULTS: Early-onset schizophrenia patients exhibited both global and regional VMHC reductions in comparison with TDCs. Reduced VMHC values were observed within the superior temporal cortex and postcentral gyrus. These interhemispheric synchronization deficits were negatively correlated with negative symptom of the Positive and Negative Syndrome Scale. Moreover, regions of interest analyses based on left and right clusters of temporal cortex and postcentral gyrus revealed abnormal heterotopic connectivity in EOS patients.
CONCLUSIONS: Our findings provide novel neurodevelopmental evidence for the disconnection hypothesis of schizophrenia and suggest that these alterations occur early in the course of the disease and are independent of medication status.
PMID: 25130214 [PubMed - as supplied by publisher]
The neural correlates of tic inhibition in Gilles de la Tourette syndrome.
Neuropsychologia. 2014 Aug 13;
Authors: Ganos C, Kahl U, Brandt V, Schunke O, Bäumer T, Thomalla G, Roessner V, Haggard P, Münchau A, Kühn S
BACKGROUND: Tics in Gilles de la Tourette syndrome (GTS) resemble fragments of normal motor behaviour but appear in an intrusive, repetitive and context-inappropriate manner. Although tics can be voluntarily inhibited on demand, the neural correlates of this process remain unclear.
METHODS: 14 GTS adults without relevant comorbidities participated in this study. First, tic severity and voluntary tic inhibitory capacity were evaluated outside the scanner. Second, patients were examined with resting state functional magnetic resonance imaging (RS-fMRI) in two states, free ticcing and voluntary tic inhibition. Local synchronization of spontaneous fMRI-signal was analyzed with regional homogeneity (ReHo) and differences between both states (free ticcing<tic inhibition) were contrasted. Clinical correlations of the resulting differential ReHo parameters between both states and clinical measures of tic frequency, voluntary tic inhibition and premonitory urges were also performed.
RESULTS: ReHo of the left inferior frontal gyrus (IFG) was increased during voluntary tic inhibition compared to free ticcing. ReHo increases were positively correlated with participants' ability to inhibit their tics during scanning sessions but also outside the scanner. There was no correlation with ratings of premonitory urges.
CONCLUSION: Voluntary tic inhibition is associated with increased ReHo of the left IFG. Premonitory urges are unrelated to this process.
PMID: 25128587 [PubMed - as supplied by publisher]
Brain Networks during Free Viewing of Complex Erotic Movie: New Insights on Psychogenic Erectile Dysfunction.
PLoS One. 2014;9(8):e105336
Authors: Cera N, Di Pierro ED, Ferretti A, Tartaro A, Romani GL, Perrucci MG
Psychogenic erectile dysfunction (ED) is defined as a male sexual dysfunction characterized by a persistent or recurrent inability to attain adequate penile erection due predominantly or exclusively to psychological or interpersonal factors. Previous fMRI studies were based on the common occurrence in the male sexual behaviour represented by the sexual arousal and penile erection related to viewing of erotic movies. However, there is no experimental evidence of altered brain networks in psychogenic ED patients (EDp). Some studies showed that fMRI activity collected during non sexual movie viewing can be analyzed in a reliable manner with independent component analysis (ICA) and that the resulting brain networks are consistent with previous resting state neuroimaging studies. In the present study, we investigated the modification of the brain networks in EDp compared to healthy controls (HC), using whole-brain fMRI during free viewing of an erotic video clip. Sixteen EDp and nineteen HC were recruited after RigiScan evaluation, psychiatric, and general medical evaluations. The performed ICA showed that visual network (VN), default-mode network (DMN), fronto-parietal network (FPN) and salience network (SN) were spatially consistent across EDp and HC. However, between-group differences in functional connectivity were observed in the DMN and in the SN. In the DMN, EDp showed decreased connectivity values in the inferior parietal lobes, posterior cingulate cortex and medial prefrontal cortex, whereas in the SN decreased and increased connectivity was observed in the right insula and in the anterior cingulate cortex respectively. The decreased levels of intrinsic functional connectivity principally involved the subsystem of DMN relevant for the self relevant mental simulation that concerns remembering of past experiences, thinking to the future and conceiving the viewpoint of the other's actions. Moreover, the between group differences in the SN nodes suggested a decreased recognition of autonomical and sexual arousal changes in EDp.
PMID: 25126947 [PubMed - as supplied by publisher]
A comprehensive assessment of resting state networks: bidirectional modification of functional integrity in cerebro-cerebellar networks in dementia.
Front Neurosci. 2014;8:223
Authors: Castellazzi G, Palesi F, Casali S, Vitali P, Sinforiani E, Wheeler-Kingshott CA, D'Angelo E
In resting state fMRI (rs-fMRI), only functional connectivity (FC) reductions in the default mode network (DMN) are normally reported as a biomarker for Alzheimer's disease (AD). In this investigation we have developed a comprehensive strategy to characterize the FC changes occurring in multiple networks and applied it in a pilot study of subjects with AD and Mild Cognitive Impairment (MCI), compared to healthy controls (HC). Resting state networks (RSNs) were studied in 14 AD (70 ± 6 years), 12 MCI (74 ± 6 years), and 16 HC (69 ± 5 years). RSN alterations were present in almost all the 15 recognized RSNs; overall, 474 voxels presented a reduced FC in MCI and 1244 in AD while 1627 voxels showed an increased FC in MCI and 1711 in AD. The RSNs were then ranked according to the magnitude and extension of FC changes (gFC), putting in evidence 6 RSNs with prominent changes: DMN, frontal cortical network (FCN), lateral visual network (LVN), basal ganglia network (BGN), cerebellar network (CBLN), and the anterior insula network (AIN). Nodes, or hubs, showing alterations common to more than one RSN were mostly localized within the prefrontal cortex and the mesial-temporal cortex. The cerebellum showed a unique behavior where voxels of decreased gFC were only found in AD while a significant gFC increase was only found in MCI. The gFC alterations showed strong correlations (p < 0.001) with psychological scores, in particular Mini-Mental State Examination (MMSE) and attention/memory tasks. In conclusion, this analysis revealed that the DMN was affected by remarkable FC increases, that FC alterations extended over several RSNs, that derangement of functional relationships between multiple areas occurred already in the early stages of dementia. These results warrant future work to verify whether these represent compensatory mechanisms that exploit a pre-existing neural reserve through plasticity, which evolve in a state of lack of connectivity between different networks with the worsening of the pathology.
PMID: 25126054 [PubMed]
Altered Resting-State fMRI Signals in Acute Stroke Patients with Ischemic Penumbra.
PLoS One. 2014;9(8):e105117
Authors: Tsai YH, Yuan R, Huang YC, Weng HH, Yeh MY, Lin CP, Biswal BB
BACKGROUND: Identifying the ischemic penumbra in acute stroke subjects is important for the clinical decision making process. The aim of this study was to use resting-state functional magnetic resonance singal (fMRI) to investigate the change in the amplitude of low-frequency fluctuations (ALFF) of these subjects in three different subsections of acute stroke regions: the infarct core tissue, the penumbra tissue, and the normal brain tissue. Another aim of this study was to test the feasilbility of consistently detecting the penumbra region of the brain through ALFF analysis.
METHODS: Sixteen subjects with first-ever acute ischemic stroke were scanned within 27 hours of the onset of stroke using magnetic resonance imaging. The core of infarct regions and penumbra regions were determined by diffusion and perfusion-weighted imaging respectively. The ALFF were measured from resting-state blood oxygen level dependent (BOLD) fMRI scans. The averaged relative ALFF value of each regions were correlated with the time after the onset of stroke.
RESULTS: Relative ALFF values were significantly different in the infarct core tissue, penumbra tissue and normal brain tissue. The locations of lesions in the ALFF maps did not match perfectly with diffusion and perfusion-weighted imagings; however, these maps provide a contrast that can be used to differentiate between penumbra brain tissue and normal brain tissue. Significant correlations between time after stroke onset and the relative ALFF values were present in the penumbra tissue but not in the infarct core and normal brain tissue.
CONCLUSION: Preliminary results from this study suggest that the ALFF reflects the underlying neurovascular activity and has a great potential to estimate the brain tissue viability after ischemia. Results also show that the ALFF may contribute to acute stroke imaging for thrombolytic or neuroprotective therapies.
PMID: 25121486 [PubMed - as supplied by publisher]
On the generalizability of resting-state fMRI machine learning classifiers.
Front Hum Neurosci. 2014;8:502
Authors: Huf W, Kalcher K, Boubela RN, Rath G, Vecsei A, Filzmoser P, Moser E
Machine learning classifiers have become increasingly popular tools to generate single-subject inferences from fMRI data. With this transition from the traditional group level difference investigations to single-subject inference, the application of machine learning methods can be seen as a considerable step forward. Existing studies, however, have given scarce or no information on the generalizability to other subject samples, limiting the use of such published classifiers in other research projects. We conducted a simulation study using publicly available resting-state fMRI data from the 1000 Functional Connectomes and COBRE projects to examine the generalizability of classifiers based on regional homogeneity of resting-state time series. While classification accuracies of up to 0.8 (using sex as the target variable) could be achieved on test datasets drawn from the same study as the training dataset, the generalizability of classifiers to different study samples proved to be limited albeit above chance. This shows that on the one hand a certain amount of generalizability can robustly be expected, but on the other hand this generalizability should not be overestimated. Indeed, this study substantiates the need to include data from several sites in a study investigating machine learning classifiers with the aim of generalizability.
PMID: 25120443 [PubMed]
Anatomic Connectivity Assessed Using Pathway Radial Diffusivity is Related to Functional Connectivity in Monosynaptic Pathways.
Brain Connect. 2014 Aug 12;
Authors: Lowe MJ, Koenig K, Beall EB, Sakaie KE, Stone L, Bermel R, Phillips MD
This work presents a pathway-dependent anatomic and functional connectivity analysis in 19 patients with relapse-remitting multiple sclerosis (MS) and 16 age-, education-, and gender-matched controls. An MS population is used in this study as a model for anatomic connectivity, permitting us to observe relationships between anatomic and functional connectivity more easily. A combined resting state fMRI and whole brain HARDI analysis is performed in three independent, monosynaptic pathways. The pathways chosen were: transcallosal pathway connecting the bilateral primary sensorimotor regions, right and left posterior portion of the Papez circuit, connecting the posterior cingulate cortex and hippocampus. The Papez circuit is known to be involved in memory function, one of the most frequently impacted cognitive domains in patients with MS. . We show that anatomic connectivity, as measured with diffusion-weighted imaging, and functional connectivity, as measured with resting state fMRI, are significantly reduced in patients as compared to controls for at least some of the pathways considered. In addition when all pathway measures are combined, anatomic and functional connectivity are significantly correlated in patients with MS as well as healthy controls. We suggest that anatomic and functional connectivity are related for monosynaptic pathways and that radial diffusivity, as a diffusion-tensor based measure of white matter integrity, is a robust measure of anatomic connectivity in the general population.
PMID: 25117651 [PubMed - as supplied by publisher]
A Potential Biomarker in Sports-Related Concussion: Brain Functional Connectivity Alteration of the Default-Mode Network Measured with Longitudinal Resting-State fMRI over 30 Days.
J Neurotrauma. 2014 Aug 12;
Authors: Zhu DC, Covassin T, Nogle S, Doyle S, Russell D, Pearson RL, Monroe J, Liszewski CM, DeMarco JK, Kaufman DI
Current diagnosis and monitoring of sports-related concussion rely on clinical signs and symptoms, and balance, vestibular and neuropsychological examinations. Conventional brain imaging often does not reveal abnormalities. We sought to assess if the longitudinal change of functional and structural connectivity of the default-mode network (DMN) can serve as a potential biomarker. Eight concussed Division 1 collegiate football student-athletes in season (one participated twice) and 11 control subjects participated in this study. ImPACT (Immediate Post-Concussion Assessment and Cognitive Testing) was administered over the course of recovery. High-resolution 3D T1-weighted, T2*-weighted, diffusion-tensor and resting-state fMRI (rs-fMRI) images were collected from each subject within 24 hours, 7 ± 1 and 30 ± 1 days after concussion. Both network-based and whole-brain based functional correlation analyses on DMN were performed. ImPACT findings demonstrated significant cognitive impairment across multiple categories and a significant increase of symptom severity on Day 1 following a concussion, but fully recovered by 6 ± 2.4 days. While the structural connectivity within DMN and gross anatomy appeared unchanged, a significantly reduced functional connectivity within DMN from Day 1 to 7 was found in the concussed group in this small pilot study. This reduction was seen in eight of our nine concussion cases. Compared to the control group, there appears a general trend of increased DMN functional connectivity on Day 1, a significant drop on Day 7, and partial recovery on Day 30. The results from this pilot study suggest that the functional connectivity of DMN measured with longitudinal rs-fMRI can serve as a potential biomarker to monitor the dynamically changing brain function after sports-related concussion, even in patients who have clinically improved.
PMID: 25116397 [PubMed - as supplied by publisher]
Increased Low-Frequency Oscillation Amplitude of Sensorimotor Cortex Associated with the Severity of Structural Impairment in Cervical Myelopathy.
PLoS One. 2014;9(8):e104442
Authors: Zhou F, Gong H, Liu X, Wu L, Luk KD, Hu Y
Decreases in metabolites and increased motor-related, but decreased sensory-related activation of the sensorimotor cortex (SMC) have been observed in patients with cervical myelopathy (CM) using advanced MRI techniques. However, the nature of intrinsic neuronal activity in the SMC, and the relationship between cerebral function and structural damage of the spinal cord in patients with CM are not fully understood. The purpose of this study was to assess intrinsic neuronal activity by calculating the regional amplitude of low frequency fluctuations (ALFF) using resting-state functional MRI (rs-fMRI), and correlations with clinical and imaging indices. Nineteen patients and 19 age- and sex-matched healthy subjects underwent rs-fMRI scans. ALFF measurements were performed in the SMC, a key brain network likely to impaired or reorganized patients with CM. Compared with healthy subjects, increased amplitude of cortical low-frequency oscillations (LFO) was observed in the right precentral gyrus, right postcentral gyrus, and left supplementary motor area. Furthermore, increased z-ALFF values in the right precentral gyrus and right postcentral gyrus correlated with decreased fractional anisotropy values at the C2 level, which indicated increased intrinsic neuronal activity in the SMC corresponding to the structural impairment in the spinal cord of patients with CM. These findings suggest a complex and diverging relationship of cortical functional reorganization and distal spinal anatomical compression in patients with CM and, thus, add important information in understanding how spinal cord integrity may be a factor in the intrinsic covariance of spontaneous low-frequency fluctuations of BOLD signals involved in cortical plasticity.
PMID: 25111566 [PubMed - as supplied by publisher]
Characteristics of the default mode functional connectivity in normal ageing and Alzheimer's disease using resting state fMRI with a combined approach of entropy-based and graph theoretical measurements.
Neuroimage. 2014 Aug 8;
Authors: Toussaint PJ, Maiz S, Coynel D, Doyon J, Messé A, de Souza LC, Sarazin M, Perlbarg V, Habert MO, Benali H
Cognitive decline in normal ageing and Alzheimer's disease (AD) emerges from functional disruption in the coordination of large-scale brain systems sustaining cognition. Integrity of these systems can be examined by correlation methods based on analysis of resting state functional magnetic resonance imaging (fMRI). Here we investigate functional connectivity within the default mode network (DMN) in normal ageing and AD using resting state fMRI. Images from young and elderly controls, and patients with AD were processed using spatial independent component analysis to identify the DMN. Functional connectivity was quantified using integration and indices derived from graph theory. Four DMN sub-systems were identified: Frontal (medial and superior), Parietal (precuneus-posterior cingulate, lateral parietal), Temporal (medial temporal), and Hippocampal (bilateral). There was a decrease in antero-posterior interactions (lower global efficiency), but increased interactions within the Frontal and Parietal sub-systems (higher local clustering) in elderly compared to young controls. This decreased antero-posterior integration was more pronounced in AD patients compared to elderly controls, particularly in the precuneus-posterior cingulate region. Conjoint knowledge of integration measures and graph indices in the same data helps in the interpretation of functional connectivity results, as comprehension of one measure improves with understanding of the other. The approach allows for complete characterisation of connectivity changes and could be applied to other resting state networks and different pathologies.
PMID: 25111470 [PubMed - as supplied by publisher]
Synchronous activation within the default mode network correlates with perceived social support.
Neuropsychologia. 2014 Aug 8;
Authors: Che X, Zhao J, Wei D, Li B, Guo Y, Qiu J, Zhang Q, Liu Y
Perceived social support emphasizes subjective feeling of provisions offered by family, friends and significant others. In consideration of the great significance of perceived social support to health outcomes, attempt to reveal the neural substrates of perceived social support will facilitate its application in a series of mental disorders. Perceived social support potentially relies on healthy interpersonal relationships calling for cognitive processes like perspective taking, empathy and theory of mind. Interestingly, functional activations and connectivity within the default mode network (DMN) are extensively involved in these interpersonal skills. As a result, it is proposed that synchronous activities among brain regions within the DMN will correlate with self-report of perceived social support. In the present study, we tried to investigate the associations between coherence among the DMN regions and perceived social support at resting state. A total of 333 (145 men) participants were directed to fulfill the Multidimensional Scale of Perceived Social Support (MSPSS) after a 484-seconds functional magnetic resonance imaging (fMRI) scanning without any task. As a result, seed-based functional connectivity and power spectrum analyses revealed that heightened synchronicity among the DMN regions was associated with better performance on perceived social support. Moreover, results in the present study were independent of different methods, structural changes, and general cognitive performance.
PMID: 25111033 [PubMed - as supplied by publisher]
Spontaneous neural activity alterations in temporomandibular disorders: a cross-sectional and longitudinal resting-state fMRI study.
Neuroscience. 2014 Aug 8;
Authors: He S, Li F, Song F, Wu S, Chen J, He N, Zou S, Huang X, Lui S, Gong Q, Chen S
The involvement of central nervous system in the pathophysiology of temporomandibular disorders (TMD) has been noticed. TMD patients have been shown dysfunction of motor performance and reduced cognitive ability in neuropsychological tests. The aim of this study is to explore the spontaneous neural activity in TMD patients with centric relation (CR)-maximum intercuspation (MI) discrepancy before and after stabilization splint treatment. Twenty-three patients and twenty controls underwent clinical evaluations, including CR-MI discrepancy, Helkimo indices and chronic pain, and resting state functional magnetic resonance imaging scans at baseline. Eleven patients repeated the evaluations and scanning after the initial wearing (T1) and three months of wearing (T2) of the stabilization splint. The fractional amplitude of low-frequency fluctuation (fALFF) was calculated to compare the neural functions. At baseline, the patients showed decreased fALFF in the left precentral gyrus, supplementary motor area, middle frontal gyrus and right orbitofrontal cortex compared with the controls (P<0.05, AlphaSim corrected). Negative correlations were found between the fALFF in the left precentral gyrus and vertical CR-MI discrepancy of bilateral temporomandibular joints of patients (P<0.05, two-tailed). At T2, the symptoms and signs of the patients were improved, and a stable condylar position on the centric relation was recovered, with increased fALFF in the left precentral gyrus and left posterior insula compared with pretreatment. The fALFF decrease in the patients before treatment was no longer evident at T2 compared with the controls. The results suggested that TMD patients with CR-MI discrepancy showed significantly decreased brain activity in their frontal cortexes. The stabilization splint elicited functional recovery in these cortical areas. These findings provided insight into the cortical neuroplastic processes underlying TMD with CR-MI discrepancy and the therapeutic mechanisms of stabilization splint.
PMID: 25110816 [PubMed - as supplied by publisher]