Resting‐state functional connectivity and motor imagery brain activation

Motor imagery (MI) relies on the mental simulation of an action without any overt motor execution (ME), and can facilitate motor learning and enhance the effect of rehabilitation in patients with neurological conditions. While functional magnetic resonance imaging (fMRI) during MI and ME reveals shared cortical representations, the role and functional relevance of the resting‐state functional connectivity (RSFC) of brain regions involved in MI is yet unknown. Here, we performed resting‐state fMRI followed by fMRI during ME and MI with the dominant hand. We used a behavioral chronometry test to measure ME and MI movement duration and compute an index of performance (IP). Then, we analyzed the voxel‐matched correlation between the individual MI parameter estimates and seed‐based RSFC maps in the MI network to measure the correspondence between RSFC and MI fMRI activation. We found that inter‐individual differences in intrinsic connectivity in the MI network predicted several clusters of activation. Taken together, present findings provide first evidence that RSFC within the MI network is predictive of the activation of MI brain regions, including those associated with behavioral performance, thus suggesting a role for RSFC in obtaining a deeper understanding of neural substrates of MI and of MI ability. Hum Brain Mapp 37:3847–3857, 2016. © 2016 Wiley Periodicals, Inc.     

Resting‐state functional connectivity of the human hypothalamus

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 35:6088–6096, 2014. © 2014 Wiley Periodicals, Inc.     

Corticostriatal connectivity fingerprints: Probability maps based on resting‐state functional connectivity

Over the last decade, structure–function relationships have begun to encompass networks of brain areas rather than individual structures. For example, corticostriatal circuits have been associated with sensorimotor, limbic, and cognitive information processing, and damage to these circuits has been shown to produce unique behavioral outcomes in Autism, Parkinson's Disease, Schizophrenia and healthy ageing. However, it remains an open question how abnormal or absent connectivity can be detected at the individual level. Here, we provide a method for clustering gross morphological structures into subregions with unique functional connectivity fingerprints, and generate network probability maps usable as a baseline to compare individual cases against. We used connectivity metrics derived from resting‐state fMRI (N = 100), in conjunction with hierarchical clustering methods, to parcellate the striatum into functionally distinct clusters. We identified three highly reproducible striatal subregions, across both hemispheres and in an independent replication dataset (N = 100) (dice‐similarity values 0.40–1.00). Each striatal seed region resulted in a highly reproducible distinct connectivity fingerprint: the putamen showed predominant connectivity with cortical and cerebellar sensorimotor and language processing areas; the ventromedial striatum cluster had a distinct limbic connectivity pattern; the caudate showed predominant connectivity with the thalamus, frontal and occipital areas, and the cerebellum. Our corticostriatal probability maps agree with existing connectivity data in humans and non‐human primates, and showed a high degree of replication. We believe that these maps offer an efficient tool to further advance hypothesis driven research and provide important guidance when investigating deviant connectivity in neurological patient populations suffering from e.g., stroke or cerebral palsy. Hum Brain Mapp 38:1478–1491, 2017. © 2016 Wiley Periodicals, Inc.     

Fluctuations of the EEG‐fMRI correlation reflect intrinsic strength of functional connectivity in default mode network

Both functional magnetic resonance imaging (fMRI) and electrophysiological recordings have revealed that resting‐state functional connectivity is temporally variable in human brain. Combined full‐band electroencephalography‐fMRI (fbEEG‐fMRI) studies have shown that infraslow (<.1 Hz) fluctuations in EEG scalp potential are correlated with the blood‐oxygen‐level‐dependent (BOLD) fMRI signals and that also this correlation appears variable over time. Here, we used simultaneous fbEEG‐fMRI to test the hypothesis that correlation dynamics between BOLD and fbEEG signals could be explained by fluctuations in the activation properties of resting‐state networks (RSNs) such as the extent or strength of their activation. We used ultrafast magnetic resonance encephalography (MREG) fMRI to enable temporally accurate and statistically robust short‐time‐window comparisons of infra‐slow fbEEG and BOLD signals. We found that the temporal fluctuations in the fbEEG‐BOLD correlation were dependent on RSN connectivity strength, but not on the mean signal level or magnitude of RSN activation or motion during scanning. Moreover, the EEG‐fMRI correlations were strongest when the intrinsic RSN connectivity was strong and close to the pial surface. Conversely, weak fbEEG‐BOLD correlations were attributable to periods of less coherent or spatially more scattered intrinsic RSN connectivity, or RSN activation in deeper cerebral structures. The results thus show that the on‐average low correlations between infra‐slow EEG and BOLD signals are, in fact, governed by the momentary coherence and depth of the underlying RSN activation, and may reach systematically high values with appropriate source activities. These findings further consolidate the notion of slow scalp potentials being directly coupled to hemodynamic fluctuations.     

Duloxetine effects on striatal resting‐state functional connectivity in patients with major depressive disorder

Reward deficits and associated striatal circuitry disturbances have been implicated in the onset and progression of major depressive disorder (MDD). However, no studies have been conducted to investigate how the striatal circuitry changes during standard antidepressant, which is important for development of novel and targeted treatments for MDD. We examined the seed‐to‐whole‐brain functional connectivity (FC) for six striatal subregions based on resting‐state fMRI data of 23 MDD patients before and after 8‐week duloxetine, a serotonin, and noradrenaline reuptake inhibitor. Twenty‐three healthy controls (HCs) were also scanned twice with an 8‐week interval. After the analysis of covariance, we observed significant group‐by‐time interaction on FC of the dorsal caudate (DC), ventral striatum (VS), and putamen seeds. Post hoc analyses revealed that the FC between several right striatal seeds and left superior frontal gyrus (SFG), between right DC and left precuneus, between right superior VS and left inferior parietal lobe, were significantly higher in MDD patients compared to HCs at baseline and were reduced after treatment. Conversely, the FC between right inferior VS and left cerebellum was lower in MDD patients and was increased after treatment. Patients with larger reduction in right superior VS—left SFG FC exhibited larger alleviation of rumination. These findings suggest that duloxetine modulates the striatal FC with dorsolateral prefrontal cortex, posterior default mode network, and cerebellum, and partly, these changes underlie symptomatic improvement. This study adds to our understanding of antidepressant mechanism and future therapeutic development might benefit from considering these striatal circuitry as potential targets.     

Altered intra‐ and inter‐network functional coupling of resting‐state networks associated with motor dysfunction in stroke

Motor functions are supported through functional integration across the extended motor system network. Individuals following stroke often show deficits on motor performance requiring coordination of multiple brain networks; however, the assessment of connectivity patterns after stroke was still unclear. This study aimed to investigate the changes in intra‐ and inter‐network functional connectivity (FC) of multiple networks following stroke and further correlate FC with motor performance. Thirty‐three left subcortical chronic stroke patients and 34 healthy controls underwent resting‐state functional magnetic resonance imaging. Eleven resting‐state networks were identified via independent component analysis (ICA). Compared with healthy controls, the stroke group showed abnormal FC within the motor network (MN), visual network (VN), dorsal attention network (DAN), and executive control network (ECN). Additionally, the FC values of the ipsilesional inferior parietal lobule (IPL) within the ECN were negatively correlated with the Fugl‐Meyer Assessment (FMA) scores (hand + wrist). With respect to inter‐network interactions, the ipsilesional frontoparietal network (FPN) decreased FC with the MN and DAN; the contralesional FPN decreased FC with the ECN, but it increased FC with the default mode network (DMN); and the posterior DMN decreased FC with the VN. In sum, this study demonstrated the coexistence of intra‐ and inter‐network alterations associated with motor‐visual attention and high‐order cognitive control function in chronic stroke, which might provide insights into brain network plasticity following stroke.     

Functional connectivity in amygdalar‐sensory/(pre)motor networks at rest: new evidence from the Human Connectome Project

The word ‘e‐motion’ derives from the Latin word ‘ex‐moveo’ which literally means ‘moving away from something/somebody’. Emotions are thus fundamental to prime action and goal‐directed behavior with obvious implications for individual's survival. However, the brain mechanisms underlying the interactions between emotional and motor cortical systems remain poorly understood. A recent diffusion tensor imaging study in humans has reported the existence of direct anatomical connections between the amygdala and sensory/(pre)motor cortices, corroborating an initial observation in animal research. Nevertheless, the functional significance of these amygdala‐sensory/(pre)motor pathways remain uncertain. More specifically, it is currently unclear whether a distinct amygdala‐sensory/(pre)motor circuit can be identified with resting‐state functional magnetic resonance imaging (rs‐fMRI). This is a key issue, as rs‐fMRI offers an opportunity to simultaneously examine distinct neural circuits that underpin different cognitive, emotional and motor functions, while minimizing task‐related performance confounds. We therefore tested the hypothesis that the amygdala and sensory/(pre)motor cortices could be identified as part of the same resting‐state functional connectivity network. To this end, we examined independent component analysis results in a very large rs‐fMRI data‐set drawn from the Human Connectome Project (n = 820 participants, mean age: 28.5 years). To our knowledge, we report for the first time the existence of a distinct amygdala‐sensory/(pre)motor functional network at rest. rs‐fMRI studies are now warranted to examine potential abnormalities in this circuit in psychiatric and neurological diseases that may be associated with alterations in the amygdala‐sensory/(pre)motor pathways (e.g. conversion disorders, impulse control disorders, amyotrophic lateral sclerosis and multiple sclerosis).     

Functional connectivity associated with gait velocity during walking and walking‐while‐talking in aging: A resting‐state fMRI study

Gait decline is common among older adults and is a risk factor for adverse outcomes. Poor gait performance in dual‐task conditions, such as walking while performing a secondary cognitive interference task, is associated with increased risk of frailty, disability, and death. Yet, the functional neural substrates that support locomotion are not well established. We examined the functional connectivity associated with gait velocity in single‐ (normal pace walking) and dual‐task (walking while talking) conditions using resting‐state functional Magnetic Resonance Imaging (fMRI). We acquired 6 minutes of resting‐state fMRI data in 30 cognitively healthy older adults. Independent components analyses were performed to separate resting‐state fMRI data into group‐level statistically independent spatial components that correlated with gait velocity in single‐ and dual‐task conditions. Gait velocity in both task conditions was associated with similar functional connectivity in sensorimotor, visual, vestibular, and left fronto‐parietal cortical areas. Compared to gait velocity in the single‐task condition, the networks associated with gait velocity in the dual‐task condition were associated with greater functional connectivity in supplementary motor and prefrontal regions. Our findings show that there are partially overlapping functional networks associated with single‐ and dual‐task walking conditions. These initial findings encourage the future use of resting‐state fMRI as tool in developing a comprehensive understanding of age‐related mobility impairments. Hum Brain Mapp 36:1484–1493, 2015. © 2014 Wiley Periodicals, Inc.     

Realistic models of apparent dynamic changes in resting‐state connectivity in somatosensory cortex

Variations over time in resting‐state correlations in blood oxygenation level‐dependent (BOLD) signals from different cortical areas may indicate changes in brain functional connectivity. However, apparent variations over time may also arise from stationary signals when the sample duration is finite. Recently, a vector autoregressive (VAR) null model has been proposed to simulate real functional magnetic resonance imaging (fMRI) data, which provides a robust stationary model for identifying possible temporal dynamic changes in functional connectivity. In this work, we propose a simpler model that uses a filtered stationary dataset. The filtered stationary model generates statistically stationary time series from random data with a single prescribed correlation coefficient that is calculated as the average over the entire time series. In addition, we propose a dynamic model, which is better able to replicate real fMRI connectivity, estimated from monkey brain studies, than the two stationary models. We compare simulated results using these three models with the behavior of primary somatosensory cortex (S1) networks in anesthetized squirrel monkeys at high field (9.4 T), using a sliding window correlation analysis. We found that at short window sizes, both stationary models reproduced the distribution of correlations of real signals well, but at longer window sizes, a dynamic model reproduced the distribution of correlations of real signals better than the stationary models. While stationary models replicate several features of real data, a close representation of the behavior of resting‐state data acquired from somatosensory cortex of non‐human primates is obtained only when a dynamic correlation is introduced, suggesting dynamic variations in connectivity are real. Hum Brain Mapp 37:3897–3910, 2016. © 2016 Wiley Periodicals, Inc .     

Default‐mode network functional connectivity is closely related to metabolic activity

Over the last decade, the brain's default‐mode network (DMN) and its function has attracted a lot of attention in the field of neuroscience. However, the exact underlying mechanisms of DMN functional connectivity, or more specifically, the blood‐oxygen level‐dependent (BOLD) signal, are still incompletely understood. In the present study, we combined 2‐deoxy‐2‐[¹⁸F]fluoroglucose positron emission tomography (FDG‐PET), proton magnetic resonance spectroscopy (¹H‐MRS), and resting‐state functional magnetic resonance imaging (rs‐fMRI) to investigate more directly the association between local glucose consumption, local glutamatergic neurotransmission and DMN functional connectivity during rest. The results of the correlation analyzes using the dorsal posterior cingulate cortex (dPCC) as seed region showed spatial similarities between fluctuations in FDG‐uptake and fluctuations in BOLD signal. More specifically, in both modalities the same DMN areas in the inferior parietal lobe, angular gyrus, precuneus, middle, and medial frontal gyrus were positively correlated with the dPCC. Furthermore, we could demonstrate that local glucose consumption in the medial frontal gyrus, PCC and left angular gyrus was associated with functional connectivity within the DMN. We did not, however, find a relationship between glutamatergic neurotransmission and functional connectivity. In line with very recent findings, our results lend further support for a close association between local metabolic activity and functional connectivity and provide further insights towards a better understanding of the underlying mechanism of the BOLD signal. Hum Brain Mapp 36:2027–2038, 2015. © 2015 Wiley Periodicals, Inc.     

Functionally linked resting‐state networks reflect the underlying structural connectivity architecture of the human brain

During rest, multiple cortical brain regions are functionally linked forming resting‐state networks. This high level of functional connectivity within resting‐state networks suggests the existence of direct neuroanatomical connections between these functionally linked brain regions to facilitate the ongoing interregional neuronal communication. White matter tracts are the structural highways of our brain, enabling information to travel quickly from one brain region to another region. In this study, we examined both the functional and structural connections of the human brain in a group of 26 healthy subjects, combining 3 Tesla resting‐state functional magnetic resonance imaging time‐series with diffusion tensor imaging scans. Nine consistently found functionally linked resting‐state networks were retrieved from the resting‐state data. The diffusion tensor imaging scans were used to reconstruct the white matter pathways between the functionally linked brain areas of these resting‐state networks. Our results show that well‐known anatomical white matter tracts interconnect at least eight of the nine commonly found resting‐state networks, including the default mode network, the core network, primary motor and visual network, and two lateralized parietal‐frontal networks. Our results suggest that the functionally linked resting‐state networks reflect the underlying structural connectivity architecture of the human brain. Hum Brain Mapp 2009. © 2009 Wiley‐Liss, Inc.     

Neuronal mechanism of mirror movements caused by dysfunction of the motor cortex

Mirror movements (MMs) are often observed in hemiplegic patients after stroke, and are supposed to reflect some aspects of their recovery process. Therefore, understanding the neuronal mechanism of MMs is important, but from the currently available evidence in human case studies, the mechanism of MMs has not been clearly understood. Here we found that in monkeys, after reversible inactivation of the right primary motor cortex (M1) by microinjection of muscimol, MMs were induced in the right hand during voluntary grasping with the left hand, which were partially affected by the injection. Using this animal model, we investigated the origin of MMs after dysfunction of the M1. We found the MMs thus induced were completely abolished by additional blockade of the left M1. Electromyogram (EMG) activities in some homonymous muscle pairs in bilateral hands were co‐activated. Detailed analysis of EMG activities suggested that the enhanced activation of the left M1, which led to MMs in the right hand, was not directly driven by the activity of the right M1, whose activity was likely to be affected by the injection. Rather, the present finding has suggested that common drive of bilateral M1 from higher‐order structures and reduction in commissural inhibition from the affected side concomitantly enhanced the activity of the cortico‐motoneuronal pathway of the intact side, and led to the MMs.     

Altered resting‐state connectivity during interictal generalized spike‐wave discharges in drug‐naïve childhood absence epilepsy

Purpose: To investigate the intrinsic brain connections at the time of interictal generalized spike‐wave discharges (GSWDs) to understand their mechanism of effect on brain function in untreated childhood absence epilepsy (CAE). Methods: The EEG‐functional MRI (fMRI) was used to measure the resting state functional connectivity during interictal GSWDs in drug‐naïve CAE, and three different brain networks—the default mode network (DMN), cognitive control network (CCN), and affective network (AN)—were investigated. Results: Cross‐correlation functional connectivity analysis with priori seed revealed decreased functional connectivity within each of these three networks in the CAE patients during interictal GSWDS. It included precuneus‐dorsolateral prefrontal cortex (DLPFC), dorsomedial prefrontal cortex (DMPFC), and inferior parietal lobule in the DMN; DLPFC‐inferior frontal junction (IFJ), and pre‐supplementary motor area (pre‐SMA) subregions connectivity disruption in CCN; ACC‐ventrolateral prefrontal cortex (VLPFC) and DMPFC in AN; There were also some regions, primarily the parahippcampus, paracentral in AN, and the left frontal mid orb in the CCN, which showed increased connectivity. Conclusions: The current findings demonstrate significant alterations of resting‐state networks in drug naïve CAE subjects during interictal GSWDs and interictal GSWDs can cause dysfunction in specific networks important for psychosocial function. Impairment of these networks may cause deficits both during and between seizures. Our study may contribute to the understanding of neuro‐pathophysiological mechanism of psychosocial function impairments in patients with CAE. Hum Brain Mapp, 2013. © 2012 Wiley Periodicals, Inc.     

Altered resting‐state functional connectivity and effective connectivity of the habenula in irritable bowel syndrome: A cross‐sectional and machine learning study

Irritable bowel syndrome (IBS) is a disorder involving dysfunctional brain–gut interactions characterized by chronic recurrent abdominal pain, altered bowel habits, and negative emotion. Previous studies have linked the habenula to the pathophysiology of negative emotion and pain. However, no studies to date have investigated habenular function in IBS patients. In this study, we investigated the resting‐state functional connectivity (rsFC) and effective connectivity of the habenula in 34 subjects with IBS and 34 healthy controls and assessed the feasibility of differentiating IBS patients from healthy controls using a machine learning method. Our results showed significantly enhanced rsFC of the habenula‐left dorsolateral prefrontal cortex (dlPFC) and habenula‐periaqueductal grey (PAG, dorsomedial part), as well as decreased rsFC of the habenula‐right thalamus (dorsolateral part), in the IBS patients compared with the healthy controls. Habenula‐thalamus rsFC was positively correlated with pain intensity (r = .467, p = .005). Dynamic causal modeling (DCM) revealed significantly decreased effective connectivity from the right habenula to the right thalamus in the IBS patients compared to the healthy controls that was negatively correlated with disease duration (r = ?.407, p = .017). In addition, IBS was classified with an accuracy of 71.5% based on the rsFC of the habenula‐dlPFC, habenula‐thalamus, and habenula‐PAG in a support vector machine (SVM), which was further validated in an independent cohort of subjects (N = 44, accuracy = 65.2%, p = .026). Taken together, these findings establish altered habenular rsFC and effective connectivity in IBS, which extends our mechanistic understanding of the habenula's role in IBS.     

Amisulpride and l‐DOPA modulate subcortical brain nuclei connectivity in resting‐state pharmacologic magnetic resonance imaging

The precise understanding of the dopaminergic (DA) system and its pharmacological modifications is crucial for diagnosis and treatment of neuropsychiatric disorders, as well as for understanding basic processes, such as motivation and reward. We probed the functional connectivity (FC) of subcortical nuclei related to the DA system according to seed regions defined according to an atlas of subcortical nuclei. We conducted a large pharmaco‐fMRI study using a double‐blind, placebo‐controlled design, where we examined the effect of l ‐DOPA, a dopamine precursor, and amisulpride, a D2/D3‐receptor antagonist on resting‐state FC in 45 healthy young adults using a cross‐over design. We examined the FC of subcortical nuclei with connection to the reward system and their reaction to opposing pharmacological probing. Amisulpride increased FC from the putamen to the precuneus and from ventral striatum to precentral gyrus. l ‐DOPA increased FC from the ventral tegmental area (VTA) to the insula/operculum and between ventral striatum and ventrolateral prefrontal cortex and it disrupted ventral striatal and dorsal caudate FC with the medial prefrontal cortex. In an exploratory analysis, we demonstrated that higher self‐rated impulsivity goes together with a significant increase in VTA‐mid‐cingulate gyrus FC during l ‐DOPA‐challenge. Therefore, our DA challenge modulated distinct large‐scale subcortical connectivity networks. A dopamine‐boost can increase midbrain DA nuclei connectivity to the cortex. The involvement of the VTA‐cingulum connectivity in dependence of impulsivity has implications for diagnosis and therapy in disorders like ADHD.     

Long‐lasting enhancements of memory and hippocampal‐cortical functional connectivity following multiple‐day targeted noninvasive stimulation

Noninvasive stimulation can alter the function of brain networks, although the duration of neuroplastic changes are uncertain and likely vary for different networks and stimulation parameters. We have previously shown that multiple‐day repetitive transcranial magnetic stimulation can influence targeted hippocampal‐cortical networks, producing increased functional MRI connectivity of these networks and concomitant improvements in memory that outlast stimulation by ～24 h. Here, we present new analyses showing that multiple‐day targeted stimulation of hippocampal‐cortical networks produces even longer‐lasting enhancement. The ability to learn novel, arbitrary face‐word pairings improved over five consecutive daily stimulation sessions, and this improvement remained robust at follow‐up testing performed an average of 15 days later. Furthermore, stimulation increased functional MRI connectivity of the targeted portion of the hippocampus with distributed regions of the posterior hippocampal‐cortical network, and these changes in connectivity remained robust at follow‐up testing. Neuroplastic changes of hippocampal‐cortical networks caused by multiple‐day noninvasive stimulation therefore persist for extended periods. These findings have implications for the design of multiple‐day stimulation experiments and for the development of stimulation‐based interventions for memory disorders. © 2015 Wiley Periodicals, Inc.     

Bilateral mirror writing movements (mirror dystonia) in a patient with writer's cramp: functional correlates.

A recent prospective analysis on writer's cramp showed that up to 44.6% of patients in a series of 65 presented mirror dystonia, defined as involuntary movements of the resting hand, abnormal posture, tremor, and jerks occurring while writing with the opposite hand. A clinical case is presented, with videotape evidence of right-handed writer's cramp, with mirror movements elicited while writing using either hand. Functional magnetic resonance imaging studies are compared both to those of a normal patient and to those from a patient with writer's cramp but lacking mirror dystonia. Widespread bilateral activation of cortical motor areas contralateral to the mirror movements in patients with writer's cramp and mirror movements suggests, that bilateral activation of the primary motor cortex may account for the appearance of these mirror movements. Further studies need to be conducted to determine whether mirror movements in dystonic patients appear as a result of loss of intra- and/or interhemispheric cortical inhibition or are simply a consequence of the sustained effort these patients need to exert while writing using a dystonic hand.     

Pelvic movements as rhythmic motor manifestation associated with restless legs syndrome.

Video-polysomnographic monitoring of a patient with a 4-year history of an unpleasant restless sensation originating in his lower abdomen showed stereotyped, repetitive, rhythmic pelvic body movements resembling coital behaviour at the wake-sleep transition. We discuss the association between restless legs syndrome and rhythmic movement disorder as a particular manifestation of a spectrum of rhythmic sleep-related movement disorders.     

Resting‐state functional MRI: Functional connectivity analysis of the visual cortex in primary open‐angle glaucoma patients

Purpose: To analyze functional connectivity (FC) of the visual cortex using resting‐state functional MRI in human primary open‐angle glaucoma (POAG) patients. Materials and Methods: Twenty‐two patients with known POAG and 22 age‐matched controls were included in this IRB‐approved study. Subjects were evaluated by 3 T MR using resting‐state blood oxygenation level dependent and three‐dimensional brain volume imaging (3D‐BRAVO) MRI. Data processing was performed with standard software. FC maps were generated from Brodmann areas (BA) 17/18/19/7 in a voxel‐wise fashion. Region of interest analysis was used to specifically examine FC among each pair of BA17/18/19/7. Results: Voxel‐wise analyses demonstrated decreased FC in the POAG group between the primary visual cortex (BA17) and the right inferior temporal, left fusiform, left middle occipital, right superior occipital, left postcentral, right precentral gyri, and anterior lobe of the left cerebellum. Increased FC was found between BA17 and the left cerebellum, right middle cerebellar peduncle, right middle frontal gyrus, and extra‐nuclear gyrus (P < 0.05). In terms of the higher visual cortices (BA18/19), positive FC was disappeared with the cerebellar vermis, right middle temporal, and right superior temporal gyri (P < 0.05). Negative FC was disappeared between BA18/19 and the right insular gyrus (P < 0.05). Region of interest analysis demonstrated no statistically significant differences in FC between the POAG patients relative to the controls (P > 0.05). Conclusion: Changes in FC of the visual cortex are found in patients with POAG. These include alterations in connectivity between the visual cortex and associative visual areas along with disrupted connectivity between the primary and higher visual areas. Hum Brain Mapp 34:2455–2463, 2013. © 2012 Wiley Periodicals, Inc.