Aerobic exercise increases hippocampal volume and improves memory in multiple sclerosis: Preliminary findings.
Neurocase. 2013 Oct 4;
Authors: Leavitt VM, Cirnigliaro C, Cohen A, Farag A, Brooks M, Wecht JM, Wylie GR, Chiaravalloti ND, Deluca J, Sumowski JF
Multiple sclerosis leads to prominent hippocampal atrophy, which is linked to memory deficits. Indeed, 50% of multiple sclerosis patients suffer memory impairment, with negative consequences for quality of life. There are currently no effective memory treatments for multiple sclerosis either pharmacological or behavioral. Aerobic exercise improves memory and promotes hippocampal neurogenesis in nonhuman animals. Here, we investigate the benefits of aerobic exercise in memory-impaired multiple sclerosis patients. Pilot data were collected from two ambulatory, memory-impaired multiple sclerosis participants randomized to non-aerobic (stretching) and aerobic (stationary cycling) conditions. The following baseline/follow-up measurements were taken: high-resolution MRI (neuroanatomical volumes), fMRI (functional connectivity), and memory assessment. Intervention was 30-minute sessions 3 times per week for 3 months. Aerobic exercise resulted in 16.5% increase in hippocampal volume and 53.7% increase in memory, as well as increased hippocampal resting-state functional connectivity. Improvements were specific, with no comparable changes in overall cerebral gray matter (+2.4%), non-hippocampal deep gray matter structures (thalamus, caudate: -4.0%), or in non-memory cognitive functioning (executive functions, processing speed, working memory: changes ranged from -11% to +4%). Non-aerobic exercise resulted in relatively no change in hippocampal volume (2.8%) or memory (0.0%), and no changes in hippocampal functional connectivity. This is the first evidence for aerobic exercise to increase hippocampal volume and connectivity and improve memory in multiple sclerosis. Aerobic exercise represents a cost-effective, widely available, natural, and self-administered treatment with no adverse side effects that may be the first effective memory treatment for multiple sclerosis patients.
PMID: 24090098 [PubMed - as supplied by publisher]
FMRI and fcMRI phenotypes map the genomic effect of chromosome 13 in Brown Norway and Dahl salt-sensitive rats.
Neuroimage. 2013 Sep 28;
Authors: Li Z, Ward BD, Dwinell MR, Lombard JH, Pawela CP
Genes have been implicated as major contributors to many biological traits and susceptibility to specific diseases. However, the mechanisms of genotype action on central nervous system function have been elusive. It has been previously observed that inbred Brown Norway (BN) rats exhibit a number of quantitative complex traits markedly different from those of inbred Dahl salt-sensitive (SS) rats. These strains have become so important to cardiovascular research that a novel chromosome substitution approach was used to create SS and BN strains that have a single chromosome replaced by the homologous chromosome of the other strain. The present study was conducted in an effort to evaluate whether fMRI neuroimaging measures could be employed as a phenotype of genetic influence on neural biology in SS, BN, and consomic SSBN13 rat strains. Electrical forepaw stimulation evoked robust differential BOLD-fMRI activation along the thalamocortical pathway among the three strains across different stimulus frequencies. Moreover, using the fMRI-guided seeds in thalamus and somatosensory cortex for the analysis of fcMRI, we were able to characterize the strain-specific difference in secondary somatosensory cortex, temporal association cortex, and the CA3 region. We were also able to define the genetic influences of Chr-13 on the projection and integration of sensory information in consomic SS-13(BN) strain. We provided objective imaging evidence supporting the hypothesis that rat strain-specific fMRI and fcMRI combined with consomic strategy can be a useful tool in identifying the complex genetic divergence that is related to neural circuits. These findings prove the concept of neuroimaging-based phenotypes as a novel approach to visualize and fine-map the genetic effects onto brain biology at a systems level.
PMID: 24084065 [PubMed - as supplied by publisher]
Abnormal synchrony of resting state networks in premanifest and symptomatic Huntington disease: the IMAGE-HD study.
J Psychiatry Neurosci. 2013 Oct 1;38(5):120226
Authors: Poudel GR, Egan GF, Churchyard A, Chua P, Stout JC, Georgiou-Karistianis N
BACKGROUND: Functional neural impairments have been documented in people with symptomatic Huntington disease (symp-HD) and in premanifest gene carriers (pre-HD). This study aimed to characterize synchrony in resting state cerebral networks in both pre-HD and symp-HD populations and to determine its association with disease burden and neurocognitive functions.
METHODS: We acquired functional magnetic resonance imaging (fMRI) data from pre-HD, symp-HD and healthy control participants. The fMRI data were analyzed using multisubject independent component analysis and dual regression. We compared networks of interest among the groups using a nonparametric permutation method and correcting for multiple comparisons.
RESULTS: Our study included 25 people in the pre-HD, 23 in the symp-HD and 18 in the healthy control groups. Compared with the control group, the pre-HD group showed decreased synchrony in the sensorimotor and dorsal attention networks; decreased level of synchrony in the sensorimotor network was associated with poorer motor performance. Compared with the control group, the symp-HD group showed widespread reduction in synchrony in the dorsal attention network, which was associated with poorer cognitive performance. The posterior putamen and superior parietal cortex were functionally disconnected from the frontal executive network in the symp-HD compared with control and pre-HD groups. Furthermore, the left frontoparietal network showed areas of increased synchrony in the symp-HD compared with the pre-HD group.
Limitations: We could not directly correct for influence of autonomic changes (e.g., heart rate) and respiration on resting state synchronization.
Conclusion: Our findings suggest that aberrant synchrony in the sensorimotor and dorsal attention networks may serve as an early signature of neural change in pre-HD individuals. The altered synchrony in dorsal attention, frontoparietal and corticostriatal networks may contribute to the development of clinical symptoms in people with Huntington disease.
PMID: 24083458 [PubMed - as supplied by publisher]
Distributed BOLD and CBV-weighted resting-state networks in the mouse brain.
Neuroimage. 2013 Sep 27;
Authors: Sforazzini F, Schwarz AJ, Galbusera A, Bifone A, Gozzi A
Laboratory mouse models represent a powerful tool to elucidate the biological foundations of disease, but translation to and from human studies rely upon valid cross-species measures. Resting-state functional connectivity (rsFC) represents a promising translational probe of brain function; however, no convincing demonstration of the presence of distributed, bilateral rsFC networks in the mouse brain has yet been reported. Here we used blood oxygen level dependent (BOLD) and cerebral blood volume (CBV) weighted fMRI to demonstrate the presence of robust and reproducible resting-state networks in the mouse brain. Independent-component analysis (ICA) revealed inter-hemispheric homotopic rsFC networks encompassing several established neuro-anatomical systems of the mouse brain, including limbic, motor and parietal cortex, striatum, thalamus and hippocampus. BOLD and CBV contrast produced consistent networks, with the latter exhibiting a superior anatomical preservation of brain regions close to air-tissue interfaces (e.g. ventral hippocampus). Seed-based analysis confirmed the inter-hemispheric specificity of the correlations observed with ICA and highlighted the presence of distributed anterior-posterior networks anatomically homologous to the human salience network (SN) and default-mode network (DMN). Consistent with rsFC investigations in humans, BOLD and CBV-weighted fMRI signals in the DMN-like network exhibited spontaneous anti-correlation with neighbouring fronto-parietal areas. These findings demonstrate the presence of robust distributed intrinsic functional connectivity networks in the mouse brain, and pave the way for the application of rsFC readouts in transgenic models to investigate the biological underpinnings of spontaneous BOLD fMRI fluctuations and their derangement in pathological states.
PMID: 24080504 [PubMed - as supplied by publisher]
The neural pathway underlying a numerical working memory task in abacus-trained children and associated functional connectivity in the resting brain.
Brain Res. 2013 Sep 27;
Authors: Li Y, Hu Y, Zhao M, Wang Y, Huang J, Chen F
Training can induce significant changes in brain functioning and behavioral performance. One consequence of training is changing the pattern of brain activation. Abacus training is of interest because abacus experts gain the ability to handle digits with unusual speed and accuracy. However, the neural correlates of numerical memory in abacus-trained children remain unknown. In the current study, we aimed to detect a training effect of abacus-based mental calculations on numerical working memory in children. We measured brain functional magnetic resonance imaging (fMRI) activation patterns in 17 abacus-trained children and 17 control children as they performed two numerical working memory tasks (digits and beads). Functional MRI results revealed higher activation in abacus-trained children than in the controls in the right posterior superior parietal lobule/superior occipital gyrus (PSPL/SOG) and the right supplementary motor area (SMA) in both tasks. When these regions were used as seeds in a functional connectivity analysis of the resting brain, the abacus-trained children showed significantly enhanced integration between the right SMA and the right inferior frontal gyrus (IFG). The IFG is considered to be the key region for the control of attention. These findings demonstrate that extensive engagement of the fronto-parietal network occurs during numerical memory tasks in the abacus-trained group. Furthermore, abacus training may increase the functional integration of visuospatial-attention circuitry, which and thus enhances high-level cognitive process.
PMID: 24080400 [PubMed - as supplied by publisher]
Underconnectivity of the Superior Temporal Sulcus predicts Emotion recognition deficits in Autism.
Soc Cogn Affect Neurosci. 2013 Sep 26;
Authors: Alaerts K, Woolley DG, Steyaert J, Di Martino A, Swinnen SP, Wenderoth N
Neurodevelopmental disconnections have been assumed to cause behavioral alterations in autism spectrum disorders (ASD). Here, we combined measurements of intrinsic functional connectivity (iFC) from resting-state fMRI with task-based fMRI to explore whether altered activity and/or iFC of the right posterior superior temporal sulcus (pSTS) mediates deficits in emotion recognition in ASD. Fifteen adults with ASD and fifteen matched-controls underwent resting-state and task-based fMRI, during which participants discriminated emotional states from point light displays (PLDs). Intrinsic FC of the right pSTS was further examined using 584 (278 ASD/306 controls) resting-state data of the Autism Brain Imaging Data Exchange (ABIDE).Participants with ASD were less accurate than controls in recognizing emotional states from PLDs. Analyses revealed pronounced ASD-related reductions both in task-based activity and resting-state iFC of the right pSTS with fronto-parietal areas typically encompassing the action observation network. Notably, pSTS-hypo-activity was related to pSTS-hypo-connectivity and both measures were predictive of emotion recognition performance with each measure explaining a unique part of the variance. Analyses with the large independent ABIDE-dataset replicated reductions in pSTS-iFC to fronto-parietal regions.These findings provide novel evidence that pSTS hypo-activity and hypo-connectivity with the fronto-parietal action observation network are linked to the social deficits characteristic of ASD.
PMID: 24078018 [PubMed - as supplied by publisher]
Food can lift mood by affecting mood-regulating neurocircuits via a serotonergic mechanism.
Neuroimage. 2013 Sep 24;
Authors: Kroes MC, van Wingen GA, Wittwer J, Mohajeri MH, Kloek J, Fernández G
It is commonly assumed that food can affect mood. One prevalent notion is that food containing tryptophan increases serotonin levels in the brain and alters neural processing in mood-regulating neurocircuits. However, tryptophan competes with other long-neutral-amino-acids (LNAA) for transport across the blood-brain-barrier, a limitation that can be mitigated by increasing the tryptophan/LNAA ratio. We therefore tested in a double-blind, placebo-controlled crossover study (N=32) whether a drink with a favourable tryptophan/LNAA ratio improves mood and modulates specific brain processes as assessed by functional magnetic resonance imaging (fMRI). We show that one serving of this drink increases the tryptophan/LNAA ratio in blood plasma, lifts mood in healthy young women and alters task-specific and resting-state processing in brain regions implicated in mood regulation. Specifically, Test-drink consumption reduced neural responses of the dorsal caudate nucleus during reward anticipation, increased neural responses in the dorsal cingulate cortex during fear processing, and increased ventromedial prefrontal-lateral prefrontal connectivity under resting-state conditions. Our results suggest that increasing tryptophan/LNAA ratios can lift mood by affecting mood-regulating neurocircuits.
PMID: 24076224 [PubMed - as supplied by publisher]
Decreased resting-state interhemispheric coordination in first-episode, drug-naive paranoid schizophrenia.
Prog Neuropsychopharmacol Biol Psychiatry. 2013 Sep 26;
Authors: Guo W, Xiao C, Liu G, Wooderson SC, Zhang Z, Zhang J, Yu L, Liu J
BACKGROUND: Dysconnectivity hypothesis posits that schizophrenia relates to abnormalities in neuronal connectivity. However, little is known about the alterations of the interhemispheric resting-state functional connectivity (FC) in patients with paranoid schizophrenia. In the present study, we used a newly developed voxel-mirrored homotopic connectivity (VMHC) method to investigate the interhemispheric FC of the whole brain in patients with paranoid schizophrenia at rest.
METHODS: Forty-nine first-episode, drug-naive patients with paranoid schizophrenia and 50 age-, gender-, and education-matched healthy subjects underwent a resting-state functional magnetic resonance imaging (fMRI) scans. An automated VMHC approach was used to analyze the data.
RESULTS: Patients exhibited lower VMHC than healthy subjects in the precuneus (PCu), the precentral gyrus, the superior temporal gyrus (STG), the middle occipital gyrus (MOG), and the fusiform gyrus/cerebellum lobule VI. No region showed greater VMHC in the patient group than in the control group. Significantly negative correlation was observed between VMHC in the precentral gyrus and the PANSS positive/total scores, and between VMHC in the STG and the PANSS positive/negative/total scores.
CONCLUSIONS: Our results suggest that interhemispheric resting-state FC of VMHC is reduced in paranoid schizophrenia with clinical implications for psychiatric symptomatology thus further contribute to the dysconnectivity hypothesis of schizophrenia.
PMID: 24075897 [PubMed - as supplied by publisher]
Reduced functional connectivity in early-stage drug-naive Parkinson's disease: a resting-state fMRI study.
Neurobiol Aging. 2013 Sep 25;
Authors: Luo C, Song W, Chen Q, Zheng Z, Chen K, Cao B, Yang J, Li J, Huang X, Gong Q, Shang HF
Although cardinal motor symptoms in Parkinson's disease (PD) are attributed to dysfunction of corticostriatal loops, early clinical nonmotor features are more likely to be associated with other pathologic mechanisms. We enrolled 52 early-stage drug-naive PD patients and 52 age- and sex-matched healthy controls and used resting-state functional connectivity magnetic resonance imaging to evaluate alteration of the functional brain network in PD, focusing in particular on the functional connectivity of the striatum subregions. Relative to healthy controls, the PD patient group showed reduced functional connectivity in mesolimbic-striatal and corticostriatal loops. Although the deceased functional connectivity within cortical sensorimotor areas was only evident in the most affected putamen subregion, reduced functional connectivity with mesolimbic regions was prevalent throughout the striatum. No increased functional connectivity was found in this cohort. By studying a cohort of early-stage drug-naive PD patients, we ruled out the potential confounding effect of prolonged antiparkinson medication use on the functional integration of neural networks. We demonstrate decreased functional integration across neural networks involving striatum, mesolimbic cortex, and sensorimotor regions in these patients and postulate that the prevalent disconnection in mesolimbic-striatal loops is associated with some early clinical nonmotor features in PD. This study offers additional insight into the early functional integration of neural networks in PD.
PMID: 24074808 [PubMed - as supplied by publisher]
Impaired and facilitated functional networks in temporal lobe epilepsy.
Neuroimage (Amst). 2013;2:862-72
Authors: Maccotta L, He BJ, Snyder AZ, Eisenman LN, Benzinger TL, Ances BM, Corbetta M, Hogan RE
How epilepsy affects brain functional networks remains poorly understood. Here we investigated resting state functional connectivity of the temporal region in temporal lobe epilepsy. Thirty-two patients with unilateral temporal lobe epilepsy underwent resting state blood-oxygenation level dependent functional magnetic resonance imaging. We defined regions of interest a priori focusing on structures involved, either structurally or metabolically, in temporal lobe epilepsy. These structures were identified in each patient based on their individual anatomy. Our principal findings are decreased local and inter-hemispheric functional connectivity and increased intra-hemispheric functional connectivity ipsilateral to the seizure focus compared to normal controls. Specifically, several regions in the affected temporal lobe showed increased functional coupling with the ipsilateral insula and immediately neighboring subcortical regions. Additionally there was significantly decreased functional connectivity between regions in the affected temporal lobe and their contralateral homologous counterparts. Intriguingly, decreased local and inter-hemispheric connectivity was not limited or even maximal for the hippocampus or medial temporal region, which is the typical seizure onset region. Rather it also involved several regions in temporal neo-cortex, while also retaining specificity, with neighboring regions such as the amygdala remaining unaffected. These findings support a view of temporal lobe epilepsy as a disease of a complex functional network, with alterations that extend well beyond the seizure onset area, and the specificity of the observed connectivity changes suggests the possibility of a functional imaging biomarker for temporal lobe epilepsy.
PMID: 24073391 [PubMed]
Sleep and Cortisol Interact to Support Memory Consolidation.
Cereb Cortex. 2013 Sep 26;
Authors: Bennion KA, Mickley Steinmetz KR, Kensinger EA, Payne JD
Separate lines of research have demonstrated that rises in cortisol can benefit memory consolidation, as can the occurrence of sleep soon after encoding. For the first time, we demonstrate that pre-learning cortisol interacts with sleep to benefit memory consolidation, particularly for negative arousing items. Resting cortisol levels during encoding were positively correlated with subsequent memory, but only following a period of sleep. There was no such relation following a period of wakefulness. Using eye tracking, we further reveal that for negative stimuli, this facilitative effect may arise because cortisol strengthens the relationship between looking time at encoding and subsequent memory. We suggest that elevated cortisol may "tag" attended information as important to remember at the time of encoding, thus enabling sleep-based processes to optimally consolidate salient information in a selective manner. Neuroimaging data suggest that this optimized consolidation leads to a refinement of the neural processes recruited for successful retrieval of negative stimuli, with the retrieval of items attended in the presence of elevated cortisol and consolidated over a night of sleep associated with activity in the amygdala and vmPFC.
PMID: 24072888 [PubMed - as supplied by publisher]
Changes of brain resting state functional connectivity predict the persistence of cognitive rehabilitation effects in patients with multiple sclerosis.
Mult Scler. 2013 Sep 26;
Authors: Parisi L, Rocca MA, Mattioli F, Copetti M, Capra R, Valsasina P, Stampatori C, Filippi M
OBJECTIVE: We investigated whether the efficacy of 12-week cognitive rehabilitation in MS patients persists six months after treatment termination and, together with resting state (RS) functional connectivity (FC), changes on neuropsychological performance at follow-up.
METHODS: Eighteen MS patients with cognitive deficits, assigned randomly either to undergo treatment (n=9) or not (n=9), underwent neuropsychological evaluation at baseline (t0), after 12 weeks of rehabilitation (t1) and at six-month follow-up (t2). RS fMRI was obtained at t0 and t1. Changes in neuropsychological performance and their correlations with RS FC modifications were assessed using longitudinal linear models.
RESULTS: At t2 vs. t0, compared with the control group, treated group patients improved in tests of attention, executive function, depression and quality of life (QoL). Neuropsychological scores in these tests at t2 were significantly correlated with RS FC changes in cognitive-related networks and RS FC of the anterior cingulum. RS FC changes in the default mode network predicted cognitive performance and less severe depression, whereas RS FC changes of the executive network predicted better QoL.
DISCUSSION: Changes in RS FC of cognitive-related networks helps to explain the persistence of the effects of cognitive rehabilitation after several months in relapsing-remitting multiple sclerosis patients and their improvement on depression and QoL scales.
PMID: 24072724 [PubMed - as supplied by publisher]
Quasi-periodic patterns (QPP): Large-scale dynamics in resting state fMRI that correlate with local infraslow electrical activity.
Neuroimage. 2013 Sep 23;
Authors: Thompson GJ, Pan WJ, Magnuson ME, Jaeger D, Keilholz SD
Functional connectivity measurements from resting state blood-oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) are proving a powerful tool to probe both normal brain function and neuropsychiatric disorders. However, the neural mechanisms that coordinate these large networks are poorly understood, particularly in the context of the growing interest in network dynamics. Recent work in anesthetized rats has shown that the spontaneous BOLD fluctuations are tightly linked to infraslow local field potentials (LFPs) that are seldom recorded but comparable in frequency to the slow BOLD fluctuations. These findings support the hypothesis that long-range coordination involves low frequency neural oscillations and establishes infraslow LFPs as an excellent candidate for probing the neural underpinnings of the BOLD spatiotemporal patterns observed in both rats and humans. To further examine the link between large-scale network dynamics and infraslow LFPs, simultaneous fMRI and microelectrode recording were performed in anesthetized rats. Using an optimized filter to isolate shared components of the signals, we found that time-lagged correlation between infraslow LFPs and BOLD is comparable in spatial extent and timing to a quasi-periodic pattern (QPP) found from BOLD alone, suggesting that fMRI-measured QPPs and the infraslow LFPs share a common mechanism. As fMRI allows spatial resolution and whole brain coverage not available with electroencephalography, QPPs can be used to better understand the role of infraslow oscillations in normal brain function and neurological or psychiatric disorders.
PMID: 24071524 [PubMed - as supplied by publisher]
Abnormalities of frontal-parietal resting-state functional connectivity are related to disease activity in patients with systemic lupus erythematosus.
PLoS One. 2013;8(9):e74530
Authors: Hou J, Lin Y, Zhang W, Song L, Wu W, Wang J, Zhou D, Zou Q, Fang Y, He M, Li H
Cerebral involvement is common in patients with systemic Lupus erythematosus (SLE) and is characterized by multiple clinical presentations, including cognitive disorders, headaches, and syncope. Several neuroimaging studies have demonstrated cerebral dysfunction during different tasks among SLE patients; however, there have been few studies designed to characterize network alterations or to identify clinical markers capable of reflecting the cerebral involvement in SLE patients. This study was designed to characterize the profile of the cerebral activation area and the functional connectivity of cognitive function in SLE patients by using a task-based and a resting state functional magnetic resonance imaging (fMRI) technique, and to determine whether or not any clinical biomarkers could serve as an indicator of cerebral involvement in this disease. The well-established cognitive function test (Paced Visual Serial Adding Test [PVSAT]) was used. Thirty SLE patients without neuropsychiatric symptoms and 25 age- and gender-matched healthy controls were examined using PVSAT task-based and resting state fMRI. Outside the scanner, the performance of patients and the healthy controls was similar. In the PVSAT task-based fMRI, patients presented significantly expanded areas of activation, and the activated areas exhibited significantly higher functional connectivity strength in patients in the resting state. A positive correlation existed between individual connectivity strength and disease activity scoring. No correlation with cerebral involvement existed for serum markers, such as C3, C4, and anti-dsDNA. Thus, our findings may shed new light on the pathologic mechanism underlying neuropsychiatric SLE, and suggests that disease activity may be a potential effective biomarker reflecting cerebral involvement in SLE.
PMID: 24069318 [PubMed - in process]
Mapping the voxel-wise effective connectome in resting state FMRI.
PLoS One. 2013;8(9):e73670
Authors: Wu GR, Stramaglia S, Chen H, Liao W, Marinazzo D
A network approach to brain and dynamics opens new perspectives towards understanding of its function. The functional connectivity from functional MRI recordings in humans is widely explored at large scale, and recently also at the voxel level. The networks of dynamical directed connections are far less investigated, in particular at the voxel level. To reconstruct full brain effective connectivity network and study its topological organization, we present a novel approach to multivariate Granger causality which integrates information theory and the architecture of the dynamical network to efficiently select a limited number of variables. The proposed method aggregates conditional information sets according to community organization, allowing to perform Granger causality analysis avoiding redundancy and overfitting even for high-dimensional and short datasets, such as time series from individual voxels in fMRI. We for the first time depicted the voxel-wise hubs of incoming and outgoing information, called Granger causality density (GCD), as a complement to previous repertoire of functional and anatomical connectomes. Analogies with these networks have been presented in most part of default mode network; while differences suggested differences in the specific measure of centrality. Our findings could open the way to a new description of global organization and information influence of brain function. With this approach is thus feasible to study the architecture of directed networks at the voxel level and individuating hubs by investigation of degree, betweenness and clustering coefficient.
PMID: 24069220 [PubMed - in process]
Large-Scale Brain Networks of the Human Left Temporal Pole: A Functional Connectivity MRI Study.
Cereb Cortex. 2013 Sep 24;
Authors: Pascual B, Masdeu JC, Hollenbeck M, Makris N, Insausti R, Ding SL, Dickerson BC
The most rostral portion of the human temporal cortex, the temporal pole (TP), has been described as "enigmatic" because its functional neuroanatomy remains unclear. Comparative anatomy studies are only partially helpful, because the human TP is larger and cytoarchitectonically more complex than in nonhuman primates. Considered by Brodmann as a single area (BA 38), the human TP has been recently parceled into an array of cytoarchitectonic subfields. In order to clarify the functional connectivity of subregions of the TP, we undertook a study of 172 healthy adults using resting-state functional connectivity MRI. Remarkably, a hierarchical cluster analysis performed to group the seeds into distinct subsystems according to their large-scale functional connectivity grouped 87.5% of the seeds according to the recently described cytoarchitectonic subregions of the TP. Based on large-scale functional connectivity, there appear to be 4 major subregions of the TP: 1) dorsal, with predominant connectivity to auditory/somatosensory and language networks; 2) ventromedial, predominantly connected to visual networks; 3) medial, connected to paralimbic structures; and 4) anterolateral, connected to the default-semantic network. The functional connectivity of the human TP, far more complex than its known anatomic connectivity in monkey, is concordant with its hypothesized role as a cortical convergence zone.
PMID: 24068551 [PubMed - as supplied by publisher]
Quantitative Prediction of Individual Psychopathology in Trauma Survivors Using Resting-State fMRI.
Neuropsychopharmacology. 2013 Sep 25;
Authors: Gong Q, Li L, Du M, Pettersson-Yeo W, Crossley N, Yang X, Li J, Huang X, Mechelli A
Neuroimaging techniques hold the promise that they may one day aid the clinical assessment of individual psychiatric patients. However, the vast majority of studies published so far have been based on average differences between groups. This study employed a multivariate approach to examine the potential of resting-state functional Magnetic Resonance Imaging (MRI) data for making accurate predictions about psychopathology in survivors of the 2008 Sichuan earthquake at individual level. Resting-state functional MRI data was acquired for 121 survivors of the 2008 Sichuan earthquake each of whom was assessed for symptoms of posttraumatic stress disorder (PTSD) using the 17-item PTSD-Checklist (PCL). Using a multivariate analytical method known as relevance vector regression (RVR), we examined the relationship between resting-state functional MRI data and symptom scores. We found that the use of RVR allowed quantitative prediction of clinical scores with statistically significant accuracy (correlation=0.32, p=0.006; mean squared error=176.88, p=0.001). Accurate prediction was based on functional activation in a number of prefrontal, parietal and occipital regions. This is the first evidence that neuroimaging techniques may inform the clinical assessment of trauma-exposed individuals by providing an accurate and objective quantitative estimation of psychopathology. Furthermore, the significant contribution of parietal and occipital regions to such estimation challenges the traditional view of PTSD as a disorder specific to the fronto-limbic network.Neuropsychopharmacology accepted article preview online, 25 September 2013. doi:10.1038/npp.2013.251.
PMID: 24064470 [PubMed - as supplied by publisher]
Regional homogeneity abnormalities in patients with transient ischaemic attack: A resting-state fMRI study.
Clin Neurophysiol. 2013 Sep 21;
Authors: Guo J, Chen N, Li R, Wu Q, Chen H, Gong Q, He L
OBJECTIVE: To investigate regional activity abnormalities in the resting state in patients with transient ischaemic attack (TIA) using a regional homogeneity (ReHo) method combined with functional magnetic resonance imaging (fMRI) and to examine the relationship between regional activity abnormalities and clinical variables.
METHODS: Resting-state fMRI was conducted in 21 patients with right-sided TIA and in 21 healthy volunteers. The ReHo was calculated to assess the strength of the local signal synchrony and was compared between the two groups.
RESULTS: Compared with the controls, the TIA patients exhibited a decreased ReHo in the right dorsolateral prefrontal cortex (dlPFC), the right inferior prefrontal cortex (iPFC), the right ventral anterior cingulate cortex (vACC) and the right dorsal posterior cingulate cortex (dPCC). In addition, the mean ReHo values in the right dlPFC and the right iPFC were significantly correlated with the Montreal Cognitive Assessment (MoCA) in TIA patients.
CONCLUSIONS: Neural activities in the resting state are changed in TIA patients even without visible ischaemic lesions on conventional MRI. The positive correlation between the ReHo of resting-state fMRI and cognition suggests that ReHo could be a promising tool to observe the neurobiological consequences of TIA.
SIGNIFICANCE: The present study revealed abnormal local synchronisation of spontaneous neural activities in patients with TIA.
PMID: 24064249 [PubMed - as supplied by publisher]
Development of deactivation of the default-mode network during episodic memory formation.
Neuroimage. 2013 Sep 21;
Authors: Chai XJ, Ofen N, Gabrieli JD, Whitfield-Gabrieli S
Task-induced deactivation of the default-mode network (DMN) has been associated in adults with successful episodic memory formation, possibly as a mechanism to focus allocation of mental resources for successful encoding of external stimuli. We investigated developmental changes of deactivation of the DMN (posterior cingulate, medial prefrontal, and bilateral lateral parietal cortices) during episodic memory formation in children, adolescents, and young adults (ages 8-24), who studied scenes during functional magnetic resonance imaging (fMRI). Recognition memory improved with age. We defined DMN regions of interest from a different sample of participants with the same age range, using resting-state fMRI. In adults, there was greater deactivation of the DMN for scenes that were later remembered than scenes that were later forgotten. In children, deactivation of the default-network did not differ reliably between scenes that were later remembered or forgotten. Adolescents exhibited a pattern of activation intermediate to that of children and adults. The hippocampal region, often considered part of the DMN, showed a functional dissociation with the rest of the DMN by exhibiting increased activation for later remembered than later forgotten scene that was similar across age groups. These findings suggest that development of memory ability from childhood through adulthood may involve increased deactivation of the neocortical DMN during learning.
PMID: 24064072 [PubMed - as supplied by publisher]
Resting State Networks and the Functional Connectome of the Human Brain in Agenesis of the Corpus Callosum.
Brain Connect. 2013 Sep 24;
Authors: Owen JP, Li YO, Yang FP, Bukshpun P, Vora S, Wakahiro M, Hinkley LB, Nagarajan S, Sherr EH, Mukherjee P
The corpus callosum is the largest white matter fiber bundle connecting the two cerebral hemispheres. In this work, we investigate the effect of callosal dysgenesis on fMRI resting state networks and the functional connectome. Since alternate commissural routes between the cerebral hemispheres exist, we hypothesize that bilateral cortical networks can still be maintained in partial or even complete agenesis of the corpus callosum (AgCC). However, since these commissural routes are frequently indirect, requiring polysynaptic pathways, we hypothesize that quantitative measurements of interhemispheric functional connectivity in bilateral networks will be reduced in AgCC compared to matched controls, especially in the most highly interconnected cortical regions that are the hubs of the connectome. Seventeen resting state networks were extracted from fMRI of 11 subjects with partial or complete AgCC and 11 matched controls. The results show that the qualitative organization of resting state networks is very similar between controls and AgCC. However, interhemispheric functional connectivity of precuneus, posterior cingulate cortex, and insular-opercular regions was significantly reduced in AgCC. The preserved network organization was confirmed with a connectomic analysis of the resting state fMRI data, showing 5 functional modules that are largely consistent across the control and AgCC groups. Hence, the reduction or even complete absence of callosal connectivity does not affect the qualitative organization of bilateral resting state networks or the modular organization of the functional connectome, although quantitatively reduced functional connectivity can be demonstrated by measurements within bilateral cortical hubs, supporting the hypothesis that indirect polysynaptic pathways are utilized to preserve interhemispheric temporal synchrony.
PMID: 24063289 [PubMed - as supplied by publisher]