Gender Specific Re-organization of Resting-State Networks in Older Age.
Front Aging Neurosci. 2016;8:285
Authors: Goldstone A, Mayhew SD, Przezdzik I, Wilson RS, Hale JR, Bagshaw AP
Advancing age is commonly associated with changes in both brain structure and function. Recently, the suggestion that alterations in brain connectivity may drive disruption in cognitive abilities with age has been investigated. However, the interaction between the effects of age and gender on the re-organization of resting-state networks is not fully understood. This study sought to investigate the effect of both age and gender on intra- and inter-network functional connectivity (FC) and the extent to which resting-state network (RSN) node definition may alter with older age. We obtained resting-state functional magnetic resonance images from younger (n = 20) and older (n = 20) adults and assessed the FC of three main cortical networks: default mode (DMN), dorsal attention (DAN), and saliency (SN). Older adults exhibited reduced DMN intra-network FC and increased inter-network FC between the anterior cingulate cortex (ACC) and nodes of the DAN, in comparison to younger participants. Furthermore, this increase in ACC-DAN inter-network FC with age was driven largely by male participants. However, further analyses suggested that the spatial location of ACC, bilateral anterior insula and orbitofrontal cortex RSN nodes changed with older age and that age-related gender differences in FC may reflect spatial re-organization rather than increases or decreases in FC strength alone. These differences in both the FC and spatial distribution of RSNs between younger and older adults provide evidence of re-organization of fundamental brain networks with age, which is modulated by gender. These results highlight the need to further investigate changes in both intra- and inter-network FC with age, whilst also exploring the modifying effect of gender. They also emphasize the difficulties in directly comparing the FC of RSN nodes between groups and suggest that caution should be taken when using the same RSN node definitions for different age or patient groups to investigate FC.
PMID: 27932978 [PubMed - in process]
Functional cortical changes in relapsing-remitting multiple sclerosis at amplitude configuration: a resting-state fMRI study.
Neuropsychiatr Dis Treat. 2016;12:3031-3039
Authors: Liu H, Chen H, Wu B, Zhang T, Wang J, Huang K, Song G, Zhan J
OBJECTIVE: The aim of this study was to explore the amplitude of spontaneous brain activity fluctuations in patients with relapsing-remitting multiple sclerosis (RRMS) using the amplitude of low-frequency fluctuation (ALFF) method.
METHODS: ALFF and SPM8 were utilized to assess alterations in regional spontaneous brain activities in patients with RRMS in comparison with healthy controls (HCs). The beta values of altered brain regions between patients with RRMS and HCs were extracted, and a receiver operating characteristic (ROC) curve was generated to calculate the sensitivities and specificities of these different brain areas for distinguishing patients with RRMS from HCs. Pearson correlation analyses were applied to assess the relationships between the beta values of altered brain regions and disease duration and Expanded Disability Status Scale (EDSS) score.
PATIENTS AND PARTICIPANTS: A total of 18 patients with RRMS (13 females; five males) and 18 sex-, age-, and education-matched HCs (14 females; four males) were recruited for this study.
MEASUREMENTS AND RESULTS: Compared with HCs, patients with RRMS showed higher ALFF responses in the right fusiform gyrus (Brodmann area [BA] 37) and lower ALFF responses in the bilateral anterior cingulate cortices (BA 24 and 32), bilateral heads of the caudate nuclei, and bilateral brainstem. The ROC analysis revealed that the beta values of these abnormal brain areas showed high degrees of sensitivity and specificity for distinguishing patients with RRMS from HCs. The EDSS score showed a significant negative Pearson correlation with the beta value of the caudate head (r=-0.474, P=0.047).
CONCLUSION: RRMS is associated with disturbances in spontaneous regional brain activity in specific areas, and these specific abnormalities may provide important information about the neural mechanisms underlying behavioral impairment in RRMS.
PMID: 27932883 [PubMed - in process]
Structural and Functional Integrity of the Intraparietal Sulcus in Moderate and Severe Traumatic Brain Injury.
J Neurotrauma. 2016 Dec 08;
Authors: Sours C, Raghavan P, Medina de Jesus A, Roys SR, Jiang L, Zhuo J, Gullapalli RP
Severe and Moderate TBI (sTBI) often results in long-term cognitive deficits such as reduced processing speed and attention. The intraparietal sulcus (IPS) is a neocortical structure that plays a crucial role in the deeply interrelated processes of multisensory processing and top down attention. Therefore, we hypothesized that disruptions in the functional and structural connections of the IPS may play a role in the development of such deficits. To examine these connections we used resting state fMRI (rsfMRI) and diffusion kurtosis imaging (DKI) in a cohort of 27 sTBI patients (29.3±8.9yrs) and 27 control participants (29.8±10.3yrs). Participants were prospectively recruited and received rsfMRI and neuropsychological assessments including the Automated Neuropsychological Assessment Metrics (ANAM) at greater than 6 months post injury. A subset of participants received a DKI scan. Results suggest that sTBI patients performed worse than controls on multiple subtests of the ANAM suggesting reduced cognitive performance. Reduced resting state functional between the IPS and cortical regions associated with multisensory processing and the dorsal attention network was observed in the sTBI patients. The patients also showed reduced structural integrity of the Superior Longitudinal Fasciculus (SLF), a key white matter tract connecting the IPS to anterior frontal areas, as measured by reduced mean kurtosis (MK) and fractional anisotropy (FA) and increased mean diffusivity (MD). Furthermore, this reduced structural integrity of the SLF was associated with a reduction in overall cognitive performance. These findings suggest that disruptions in the structural and functional connectivity of the IPS may contribute to chronic cognitive deficits experienced by these patients.
PMID: 27931179 [PubMed - as supplied by publisher]
Changed crossmodal functional connectivity in older adults with hearing loss.
Cortex. 2016 Oct 31;86:109-122
Authors: Puschmann S, Thiel CM
Previous work compellingly demonstrates a crossmodal plastic reorganization of auditory cortex in deaf individuals, leading to increased neural responses to non-auditory sensory input. Recent data indicate that crossmodal adaptive plasticity is not restricted to severe hearing impairments, but may also occur as a result of high-frequency hearing loss in older adults and affect audiovisual processing in these subjects. We here used functional magnetic resonance imaging (fMRI) to study the effect of hearing loss in older adults on auditory cortex response patterns as well as on functional connectivity between auditory and visual cortex during audiovisual processing. Older participants with a varying degree of high frequency hearing loss performed an auditory stimulus categorization task, in which they had to categorize frequency-modulated (FM) tones presented alone or in the context of matching or non-matching visual motion. A motion only condition served as control for a visual take-over of auditory cortex. While the individual hearing status did not affect auditory cortex responses to auditory, visual, or audiovisual stimuli, we observed a significant hearing loss-related increase in functional connectivity between auditory cortex and the right motion-sensitive visual area MT+ when processing matching audiovisual input. Hearing loss also modulated resting state connectivity between right area MT+ and parts of the left auditory cortex, suggesting the existence of permanent, task-independent changes in coupling between visual and auditory sensory areas with an increasing degree of hearing loss. Our data thus indicate that hearing loss impacts on functional connectivity between sensory cortices in older adults.
PMID: 27930898 [PubMed - as supplied by publisher]
Long-range projections coordinate distributed brain-wide neural activity with a specific spatiotemporal profile.
Proc Natl Acad Sci U S A. 2016 Dec 05;:
Authors: Leong AT, Chan RW, Gao PP, Chan YS, Tsia KK, Yung WH, Wu EX
One challenge in contemporary neuroscience is to achieve an integrated understanding of the large-scale brain-wide interactions, particularly the spatiotemporal patterns of neural activity that give rise to functions and behavior. At present, little is known about the spatiotemporal properties of long-range neuronal networks. We examined brain-wide neural activity patterns elicited by stimulating ventral posteromedial (VPM) thalamo-cortical excitatory neurons through combined optogenetic stimulation and functional MRI (fMRI). We detected robust optogenetically evoked fMRI activation bilaterally in primary visual, somatosensory, and auditory cortices at low (1 Hz) but not high frequencies (5-40 Hz). Subsequent electrophysiological recordings indicated interactions over long temporal windows across thalamo-cortical, cortico-cortical, and interhemispheric callosal projections at low frequencies. We further observed enhanced visually evoked fMRI activation during and after VPM stimulation in the superior colliculus, indicating that visual processing was subcortically modulated by low-frequency activity originating from VPM. Stimulating posteromedial complex thalamo-cortical excitatory neurons also evoked brain-wide blood-oxygenation-level-dependent activation, although with a distinct spatiotemporal profile. Our results directly demonstrate that low-frequency activity governs large-scale, brain-wide connectivity and interactions through long-range excitatory projections to coordinate the functional integration of remote brain regions. This low-frequency phenomenon contributes to the neural basis of long-range functional connectivity as measured by resting-state fMRI.
PMID: 27930323 [PubMed - as supplied by publisher]
Functional connectivity changes resemble patterns of pTDP-43 pathology in amyotrophic lateral sclerosis.
Sci Rep. 2016 Dec 08;6:38391
Authors: Schulthess I, Gorges M, Müller HP, Lulé D, Del Tredici K, Ludolph AC, Kassubek J
'Resting-state' fMRI allows investigation of alterations in functional brain organization that are associated with an underlying pathological process. We determine whether abnormal connectivity in amyotrophic lateral sclerosis (ALS) in a priori-defined intrinsic functional connectivity networks, according to a neuropathological staging scheme and its DTI-based tract correlates, permits recognition of a sequential involvement of functional networks. 'Resting-state' fMRI data from 135 ALS patients and 56 matched healthy controls were investigated for the motor network (corresponding to neuropathological stage 1), brainstem (stage 2), ventral attention (stage 3), default mode/hippocampal network (stage 4), and primary visual network (as the control network) in a cross-sectional analysis and longitudinally in a subgroup of 27 patients after 6 months. Group comparison from cross-sectional and longitudinal data revealed significantly increased functional connectivity (p < 0.05, corrected) in all four investigated networks (but not in the control network), presenting as a network expansion that was correlated with physical disability. Increased connectivity of functional networks, as investigated in a hypothesis-driven approach, is characterized by network expansions and resembled the pattern of pTDP-43 pathology in ALS. However, our data did not allow for the recognition of a sequential involvement of functional connectivity networks at the individual level.
PMID: 27929102 [PubMed - in process]
Cognitive Functioning in Temporal Lobe Epilepsy: A BOLD-fMRI Study.
Mol Neurobiol. 2016 Dec 06;
Authors: Guo L, Bai G, Zhang H, Lu D, Zheng J, Xu G
We aimed to analyze the association between resting-state functional magnetic resonance imaging (re-fMRI) and cognitive function (including language, executive, and memory functions) in temporal lobe epilepsy (TLE) patients, which will help to explore the mechanism of brain function in patients. 15 TLE patients and 15 non-TLE patients were recruited. All subjects underwent neuropsychological testing and memory functional evaluation. Changes in verbal intelligence quotient (VIQ), performance intelligence quotient (PIQ), full intelligence quotient (FIQ), and memory quotient (MQ) were compared between two groups. Re-fMRI data were also collected from two groups to evaluate these changes. Each individual score of neuropsychological testing and memory functional evaluation were higher in control group, which was statistically different (all P < 0.01) while the VIQ, PIQ, FIQ, and MQ showed the same trend (all P < 0.01). The data showed the positive activation differences in brain regions between experimental and control group, namely right frontal lobe, the left middle temporal gyrus back, right superior temporal gyrus, left cerebellum, left angular gyrus, left wedge anterior lobe, and left central back; while the negatively activated brain regions were left prefrontal, right cerebellum, right corner back, and right anterior cingulate gyrus. During the language task, the activated brain regions of the TLE patients were right prefrontal lobe, the lateral temporal gyri, the left cerebellum, left cornu laterale gyrus, left precuneus, and the left postcentral gyrus, whereas the negatively activated brain areas were the left prefrontal cortex, the right cerebellum, right cornu laterale gyrus, and the right anterior cingulate gyrus. During the executive task, epilepsy patients showed activation difference in right prefrontal and right frontal lobe and right brain, left superior temporal gyrus, and right cerebellum anterior lobe compared with the control group; no negatively activated differences in brain areas. During the memory task, the difference lay in bilateral anterior cingulate gyrus and bilateral wedge anterior lobe while the negatively activated brain areas were the left inferior frontal gyrus and postcentral gyrus. The cognitive functioning is related to the functional connectivity within the cortex. There is a significant difference in the activation of brain areas during different tasks between the TLE patients and the non-TLE patients.
PMID: 27924527 [PubMed - as supplied by publisher]
Regional homogeneity associated with overgeneral autobiographical memory of first-episode treatment-naive patients with major depressive disorder in the orbitofrontal cortex: A resting-state fMRI study.
J Affect Disord. 2016 Nov 30;209:163-168
Authors: Liu Y, Zhao X, Cheng Z, Zhang F, Chang J, Wang H, Xie R, Wang Z, Cao L, Wang G
BACKGROUND: Overgeneral autobiographical memory (OGM) is involved in the onset and maintenance of depression. Recent studies have shown correlations between OGM and alterations of some brain regions by using task-state functional magnetic resonance imaging (fMRI). However, the correlation between OGM and spontaneous brain activity in depression remains unclear. The purpose of this study was to determine whether patients with major depressive disorder (MDD) show abnormal regional homogeneity (ReHo) and, if so, whether the brain areas with abnormal ReHo are associated with OGM.
METHODS: Twenty five patients with MDD and 25 age-matched, sex-matched, and education-matched healthy controls underwent resting-state fMRI. All participants were also assessed by 17-item Hamilton Depression Rating Scale and autobiographical memory test. The ReHo method was used to analyze regional synchronization of spontaneous neuronal activity.
RESULTS: Patients with MDD, compared to healthy controls, exhibited extensive ReHo abnormalities in some brain regions, including the frontal, temporal, and occipital cortex. Moreover, ReHo value of the orbitofrontal cortex was negatively correlated with OGM scores in patients with MDD.
LIMITATIONS: The sample size of this study was relatively small, and the influence of physiological noise was not completely excluded.
CONCLUSIONS: These results suggest that abnormal ReHo of spontaneous brain activity in the orbitofrontal cortex may be involved in the pathophysiology of OGM in patients with MDD.
PMID: 27923192 [PubMed - as supplied by publisher]
Brain network reorganization differs in response to stress in rats genetically predisposed to depression and stress-resilient rats.
Transl Psychiatry. 2016 Dec 06;6(12):e970
Authors: Gass N, Becker R, Schwarz AJ, Weber-Fahr W, Clemm von Hohenberg C, Vollmayr B, Sartorius A
Treatment-resistant depression (TRD) remains a pressing clinical problem. Optimizing treatment requires better definition of the specificity of the involved brain circuits. The rat strain bred for negative cognitive state (NC) represents a genetic animal model of TRD with high face, construct and predictive validity. Vice versa, the positive cognitive state (PC) strain represents a stress-resilient phenotype. Although NC rats show depressive-like behavior, some symptoms such as anhedonia require an external trigger, i.e. a stressful event, which is similar to humans when stressful event induces a depressive episode in genetically predisposed individuals (gene-environment interaction). We aimed to distinguish neurobiological predisposition from the depressogenic pathology at the level of brain-network reorganization. For this purpose, resting-state functional magnetic resonance imaging time series were acquired at 9.4 Tesla scanner in NC (N=11) and PC (N=7) rats before and after stressful event. We used a graph theory analytical approach to calculate the brain-network global and local properties. There was no difference in the global characteristics between the strains. At the local level, the response in the risk strain was characterized with an increased internodal role and reduced local clustering and efficiency of the anterior cingulate cortex (ACC) and prelimbic cortex compared to the stress-resilient strain. We suggest that the increased internodal role of these prefrontal regions could be due to the enhancement of some of their long-range connections, given their connectivity with the amygdala and other default-mode-like network hubs, which could create a bias to attend to negative information characteristic for depression.
PMID: 27922640 [PubMed - in process]
Resting-state theta band connectivity and graph analysis in generalized social anxiety disorder.
Neuroimage Clin. 2017;13:24-32
Authors: Xing M, Tadayonnejad R, MacNamara A, Ajilore O, DiGangi J, Phan KL, Leow A, Klumpp H
BACKGROUND: Functional magnetic resonance imaging (fMRI) resting-state studies show generalized social anxiety disorder (gSAD) is associated with disturbances in networks involved in emotion regulation, emotion processing, and perceptual functions, suggesting a network framework is integral to elucidating the pathophysiology of gSAD. However, fMRI does not measure the fast dynamic interconnections of functional networks. Therefore, we examined whole-brain functional connectomics with electroencephalogram (EEG) during resting-state.
METHODS: Resting-state EEG data was recorded for 32 patients with gSAD and 32 demographically-matched healthy controls (HC). Sensor-level connectivity analysis was applied on EEG data by using Weighted Phase Lag Index (WPLI) and graph analysis based on WPLI was used to determine clustering coefficient and characteristic path length to estimate local integration and global segregation of networks.
RESULTS: WPLI results showed increased oscillatory midline coherence in the theta frequency band indicating higher connectivity in the gSAD relative to HC group during rest. Additionally, WPLI values positively correlated with state anxiety levels within the gSAD group but not the HC group. Our graph theory based connectomics analysis demonstrated increased clustering coefficient and decreased characteristic path length in theta-based whole brain functional organization in subjects with gSAD compared to HC.
CONCLUSIONS: Theta-dependent interconnectivity was associated with state anxiety in gSAD and an increase in information processing efficiency in gSAD (compared to controls). Results may represent enhanced baseline self-focused attention, which is consistent with cognitive models of gSAD and fMRI studies implicating emotion dysregulation and disturbances in task negative networks (e.g., default mode network) in gSAD.
PMID: 27920976 [PubMed - in process]
Donepezil Enhances Frontal Functional Connectivity in Alzheimer's Disease: A Pilot Study.
Dement Geriatr Cogn Dis Extra. 2016 Sep-Dec;6(3):518-528
Authors: Griffanti L, Wilcock GK, Voets N, Bonifacio G, Mackay CE, Jenkinson M, Zamboni G
BACKGROUND: We have previously shown that increased resting-state functional magnetic resonance imaging (fMRI)-based functional connectivity (FC) within the frontal resting-state networks in Alzheimer's disease (AD) patients reflects residual, possibly compensatory, function. This suggests that symptomatic treatments should aim to enhance FC specifically in these networks.
METHODS: 18 patients with probable AD underwent brain MRI and neuropsychological assessment at baseline and after 12 weeks of treatment with donepezil. We tested if changes in cognitive performance after treatment correlated with changes in FC in resting-state networks known to be altered in AD.
RESULTS: We found increases in FC in the orbitofrontal network that correlated with cognitive improvement after treatment. The increased FC was greatest in patients who responded most to treatment.
CONCLUSION: This 'proof of concept' study suggests that changes in network-specific FC might be a biomarker of pharmacological intervention efficacy in AD.
PMID: 27920795 [PubMed - in process]
Less head motion during MRI under task than resting-state conditions.
Neuroimage. 2016 Dec 02;:
Authors: Huijbers W, Van Dijk KR, Boenniger MM, Stirnberg R, Breteler MM
Head motion reduces data quality of neuroimaging data. In three functional magnetic resonance imaging (MRI) experiments we demonstrate that people make less head movements under task than resting-state conditions. In Experiment 1, we observed less head motion during a memory encoding task than during the resting-state condition. In Experiment 2, using publicly shared data from the UCLA Consortium for Neuropsychiatric Phenomics LA5c Study, we again found less head motion during several active task conditions than during a resting-state condition, although some task conditions also showed comparable motion. In the healthy controls, we found more head motion in men than in women and more motion with increasing age. When comparing clinical groups, we found that patients with a clinical diagnosis of bipolar disorder, or schizophrenia, move more compared to healthy controls or patients with ADHD. Both these experiments had a fixed acquisition order across participants, and we could not rule out that a first or last scan during a session might be particularly prone to more head motion. Therefore, we conducted Experiment 3, in which we collected several task and resting-state fMRI runs with an acquisition order counter-balanced. The results of Experiment 3 show again less head motion during several task conditions than during rest. Together these experiments demonstrate that small head motions occur during MRI even with careful instruction to remain still and fixation with foam pillows, but that head motion is lower when participants are engaged in a cognitive task. These finding may inform the choice of functional runs when studying difficult-to-scan populations, such as children or certain patient populations. Our findings also indicate that differences in head motion complicate direct comparisons of measures of functional neuronal networks between task and resting-state fMRI because of potential differences in data quality. In practice, a task to reduce head motion might be especially useful when acquiring structural MRI data such as T1/T2-weighted and diffusion MRI in research and clinical settings.
PMID: 27919751 [PubMed - as supplied by publisher]
Mapping the functional connectome in traumatic brain injury: What can graph metrics tell us?
Neuroimage. 2016 Dec 02;:
Authors: Caeyenberghs K, Verhelst H, Clemente A, Wilson PH
OBJECTIVE: Traumatic brain injury (TBI) is associated with cognitive and motor deficits, and poses a significant personal, societal, and economic burden. One mechanism by which TBI is thought to affect cognition and behaviour is through changes in functional connectivity. Graph theory is a powerful framework for quantifying topological features of neuroimaging-derived functional networks. The objective of this paper is to review studies examining functional connectivity in TBI with an emphasis on graph theoretical analysis that is proving to be valuable in uncovering network abnormalities in this condition.
METHODS: We review studies that have examined TBI-related alterations in different properties of the functional brain network, including global integration, segregation, centrality and resilience. We focus on functional data using task-related fMRI or resting state fMRI in patients with TBI of different severity and recovery phase, and consider how graph metrics may inform rehabilitation and enhance efficacy. Moreover, we outline some methodological challenges associated with the examination of functional connectivity in patients with brain injury, including the sample size, parcellation scheme used, node definition and subgroup analyses.
RESULTS: The findings suggest that TBI is associated with hyperconnectivity and a suboptimal global integration, characterized by increased connectivity degree and strength and reduced efficiency of functional networks. This altered functional connectivity, also evident in other clinical populations, is attributable to diffuse white matter pathology and reductions in gray and white matter volume. These functional alterations are implicated in post-concussional symptoms, posttraumatic stress and neurocognitive dysfunction after TBI. Finally, the effects of focal lesions have been found to depend critically on topological position and their role in the network.
CONCLUSION: Graph theory is a unique and powerful tool for exploring functional connectivity in brain-injured patients. One limitation is that its results do not provide specific measures about the biophysical mechanism underlying TBI. Continued work in this field will hopefully see graph metrics used as biomarkers to provide more accurate diagnosis and help guide treatment at the individual patient level.
PMID: 27919750 [PubMed - as supplied by publisher]
The role of anxiety in stuttering: evidence from functional connectivity.
Neuroscience. 2016 Dec 02;:
Authors: Yang Y, Jia F, Ting Siok W, Hai Tan L
Persistent developmental stuttering is a neurologically based speech disorder associated with cognitive-linguistic, motor and emotional abnormalities. Previous studies investigating the relationship between anxiety and stuttering have yielded mixed results, but it has not yet been examined whether anxiety influences brain activity underlying stuttering. Here, by using functional magnetic resonance imaging (fMRI), we investigated the functional connectivity associated with state anxiety in a syllable repetition task, and trait anxiety during rest in adults who stutter (N=19) and fluent controls (N=19). During the speech task, people who stutter (PWS) showed increased functional connectivity of the right amygdala with the prefrontal gyrus (the left ventromedial frontal gyrus and right middle frontal gyrus) and the left insula compared to controls. During rest, PWS showed stronger functional connectivity between the right hippocampus and the left orbital frontal gyrus, and between the left hippocampus and left motor areas than controls. Taken together, our results suggest aberrant bottom-up and/or top-down interactions for anxiety regulation, which might be responsible for the higher level of state anxiety during speech and for the anxiety-prone trait in PWS. To our knowledge, this is the first study to examine the neural underpinnings of anxiety in PWS, thus yielding new insight in the causes of stuttering which might aid strategies for the diagnosis and treatment of stuttering.
PMID: 27919696 [PubMed - as supplied by publisher]
Resting-state connectivity biomarkers define neurophysiological subtypes of depression.
Nat Med. 2016 Dec 05;:
Authors: Drysdale AT, Grosenick L, Downar J, Dunlop K, Mansouri F, Meng Y, Fetcho RN, Zebley B, Oathes DJ, Etkin A, Schatzberg AF, Sudheimer K, Keller J, Mayberg HS, Gunning FM, Alexopoulos GS, Fox MD, Pascual-Leone A, Voss HU, Casey BJ, Dubin MJ, Liston C
Biomarkers have transformed modern medicine but remain largely elusive in psychiatry, partly because there is a weak correspondence between diagnostic labels and their neurobiological substrates. Like to other neuropsychiatric disorders, depression is not a unitary disease, but rather a heterogeneous syndrome that encompasses varied, co-occurring symptoms and divergent responses to treatment. By using functional magnetic resonance imaging (fMRI) in a large multisite sample (n = 1,188), we show here that patients with depression can be subdivided into four neurophysiological subtypes ('biotypes') defined by distinct patterns of dysfunctional connectivity in limbic and frontostriatal networks. Clustering patients on this basis enabled the development of diagnostic classifiers (biomarkers) with high (82-93%) sensitivity and specificity for depression subtypes in multisite validation (n = 711) and out-of-sample replication (n = 477) data sets. These biotypes cannot be differentiated solely on the basis of clinical features, but they are associated with differing clinical-symptom profiles. They also predict responsiveness to transcranial-magnetic-stimulation therapy (n = 154). Our results define novel subtypes of depression that transcend current diagnostic boundaries and may be useful for identifying the individuals who are most likely to benefit from targeted neurostimulation therapies.
PMID: 27918562 [PubMed - as supplied by publisher]
Distinct intrinsic functional brain network abnormalities in methamphetamine-dependent patients with and without a history of psychosis.
Addict Biol. 2016 Dec 05;:
Authors: Ipser JC, Uhlmann A, Taylor P, Harvey BH, Wilson D, Stein DJ
Chronic methamphetamine use is associated with executive functioning deficits that suggest dysfunctional cognitive control networks (CCNs) in the brain. Likewise, abnormal connectivity between intrinsic CCNs and default mode networks (DMNs) has also been associated with poor cognitive function in clinical populations. Accordingly, we tested the extent to which methamphetamine use predicts abnormal connectivity between these networks, and whether, as predicted, these abnormalities are compounded in patients with a history of methamphetamine-associated psychosis (MAP). Resting-state fMRI data were acquired from 46 methamphetamine-dependent patients [19 with MAP, 27 without (MD)], as well as 26 healthy controls (CTRL). Multivariate network modelling and whole-brain voxel-wise connectivity analyses were conducted to identify group differences in intrinsic connectivity across four cognitive control and three DMN networks identified using an independent components analysis approach (meta-ICA). The relationship of network connectivity and psychotic symptom severity, as well as antipsychotic treatment and methamphetamine use variables, was also investigated. Robust evidence of hyper-connectivity was observed between the right frontoparietal and anterior DMN networks in MAP patients, and 'normalized' with increased duration of treatment with antipsychotics. Attenuation of anticorrelated anterior DMN-dorsal attention network activity was also restricted to this group. Elevated coupling detected in MD participants between anterior and posterior DMN networks became less apparent with increasing duration of abstinence from methamphetamine. In summary, we observed both alterations of RSN connectivity between DMN networks with chronic methamphetamine exposure, as well as DMN-CCN coupling abnormalities consistent with possible MAP-specific frontoparietal deficits in the biasing of task-appropriate network activity.
PMID: 27917569 [PubMed - as supplied by publisher]
Aberrant regional homogeneity in Parkinson's disease: A voxel-wise meta-analysis of resting-state functional magnetic resonance imaging studies.
Neurosci Biobehav Rev. 2016 Dec 01;:
Authors: Pan P, Zhan H, Xia M, Zhang Y, Guan D, Xu Y
Studies of abnormal regional homogeneity (ReHo) in Parkinson's disease (PD) have reported inconsistent results. Therefore, we conducted a meta-analysis using the Seed-based d Mapping software package to identify the most consistent and replicable findings. A systematic literature search was performed to identify eligible whole-brain resting-state functional magnetic resonance imaging studies that had measured differences in ReHo between patients with PD and healthy controls between January 2000 and June 4, 2016. A total of ten studies reporting 11 comparisons (212 patients; 182 controls) were included. Increased ReHo was consistently identified in the bilateral inferior parietal lobules, bilateral medial prefrontal cortices, and left cerebellum of patients with PD when compared to healthy controls, while decreased ReHo was observed in the right putamen, right precentral gyrus, and left lingual gyrus. The results of the current meta-analysis demonstrate a consistent and coexistent pattern of impairment and compensation of intrinsic brain activity that predominantly involves the default mode and motor networks, which may advance our understanding of the pathophysiological mechanisms underlying PD.
PMID: 27916710 [PubMed - as supplied by publisher]
Directed functional connectivity of posterior cingulate cortex and whole brain in Alzheimer's disease and mild cognitive impairment.
Curr Alzheimer Res. 2016 Dec 01;
Authors: Yu E, Liao Z, Mao D, Zhang Q, Ji G, Li Y, Ding Z
BACKGROUND: Impaired functional connectivity in the default mode network (DMN) is supposedly involved in Alzheimer's disease (AD) progression. The posterior cingulate cortex (PCC) might be an imaging marker for monitoring AD progression.
OBJECTIVE: To investigate the alterations in the directed functional connectivity between the PCC and whole brain in patients with AD, patients with mild cognitive impairment (MCI), and healthy controls.
METHODS: A total of 116 enrolled participants were divided into three groups: AD (n=32), MCI (n=26), and controls (n=58). Using resting-state functional magnetic resonance imaging (rs-fMRI), the directed functional connectivity was studied using Granger causality analysis (GCA).
RESULTS: Almost all of the directed functional connections with significant differences were unidirectional. Compared with the NC group, the AD group showed enhanced directed connectivity from the whole brain to the PCC mainly for regions outside the DMN, and reduced connectivity from the PCC to the whole brain mainly for regions inside the DMN. Compared with the NC group, the MCI group showed enhanced directed connectivity from the PCC to the whole brain for the bilateral precuneus and postcentralgyrus, and reduced connectivity from the whole brain to the PCC for regions outside the DMN. Compared with the MCI group, the abnormal directed connectivity in the AD group was predominantly in the left hemisphere, possibly suggesting asymmetric characteristics.
CONCLUSION: In patients with AD, the PCC in the DMN shows disorders in receiving and transmitting information, and these abnormalities are directional.
PMID: 27915993 [PubMed - as supplied by publisher]