Altered cerebro-cerebellum resting-state functional connectivity in HIV-infected male patients

In addition to the role of planning and executing movement, the cerebellum greatly contributes to cognitive process. Numerous studies have reported structural and functional abnormalities in the cerebellum for HIV-infected patients, but little is known about the altered functional connectivity of particular cerebellar subregions and the cerebrum. Therefore, this study aimed to explore the resting-state functional connectivity (rsFC) changes of the cerebellum and further analyze the relationship between the rsFC changes and the neuropsychological evaluation. The experiment involved 26 HIV-infected men with asymptomatic neurocognitive impairment (ANI) and 28 healthy controls (HC). We selected bilateral hemispheric lobule VI and lobule IX as seed regions and mapped the whole-brain rsFC for each subregion. Results revealed that right lobule VI showed significant increased rsFC with the anterior cingulate cortex (ACC) in HIV-infected subjects. In addition, the correlation analysis on HIV-infected subjects illustrated the increased rsFC was negatively correlated with the attention/working memory score. Moreover, significantly increased cerebellar rsFCs were also observed in HIV-infected patients related to right inferior frontal gyrus (IFG) and right superior medial gyrus (SMG) while decreased rsFC was just found between right lobule VI and the left hippocampus (HIP). These findings suggested that, abnormalities of cerebro-cerebellar functional connectivity might be associated with cognitive dysfunction in HIV-infected men, particularly working memory impairment. It could also be the underlying mechanism of ANI, providing further evidence for early injury in the neural substrate of HIV-infected patients.     

Neurological Soft Signs Are Associated With Altered Cerebellar-Cerebral Functional Connectivity in Schizophrenia

Cerebellar dysfunction is associated with neurological soft signs (NSS), which is a promising endophenotype for schizophrenia spectrum disorders. However, the relationship between cerebellar-cerebral resting-state functional connectivity (rsFC) and NSS is largely unexplored. Moreover, both NSS and cerebellar-cerebral rsFC have been found to be correlated with negative symptoms of schizophrenia. Here, we investigated the correlations between NSS and cerebellar-cerebral rsFC, explored their relationship with negative symptoms in a main dataset, and validated the significant findings in a replication dataset. Both datasets comprised schizophrenia patients and healthy controls. In schizophrenia patients, we found positive correlations between NSS and rsFC of the cerebellum with the inferior frontal gyrus and the precuneus, and negative correlations between NSS and rsFC of the cerebellum with the inferior temporal gyrus. In healthy controls, NSS scores were positively correlated with rsFC of the cerebellum with the superior frontal gyrus and negatively correlated with rsFC between the cerebellum and the middle occipital gyrus. Cerebellar-prefrontal rsFC was also positively correlated with negative symptoms in schizophrenia patients. These findings were validated in the replication dataset. Our results suggest that the uncoupling of rsFC between the cerebellum and the cerebral cortex may underlie the expression of NSS in schizophrenia. NSS-related cerebellar-prefrontal rsFC may be a potential neural pathway for possible neural modulation to alleviate negative symptoms.     

Cerebellar Neural Circuits Involving Executive Control Network Predict Response to Group Cognitive Behavior Therapy in Social Anxiety Disorder

Some intrinsic connectivity networks including the default mode network (DMN) and executive control network (ECN) may underlie social anxiety disorder (SAD). Although the cerebellum has been implicated in the pathophysiology of SAD and several networks relevant to higher-order cognition, it remains unknown whether cerebellar areas involved in DMN and ECN exhibit altered resting-state functional connectivity (rsFC) with cortical networks in SAD. Forty-six patients with SAD and 64 healthy controls (HC) were included and submitted to the baseline resting-state functional magnetic resonance imaging (fMRI). Seventeen SAD patients who completed post-treatment clinical assessments were included after group cognitive behavior therapy (CBT). RsFC of three cerebellar subregions in both groups was assessed respectively in a voxel-wise way, and these rsFC maps were compared by two-sample t tests between groups. Whole-brain voxel-wise regression was performed to examine whether cerebellar connectivity networks can predict response to CBT. Lower rsFC circuits of cerebellar subregions compared with HC at baseline (p < 0.05, corrected by false discovery rate) were revealed. The left Crus I rsFC with dorsal medial prefrontal cortex was negatively correlated with symptom severity. The clinical assessments in SAD patients were significantly decreased after CBT. Higher pretreatment cerebellar rsFC with angular gyrus and dorsal lateral frontal cortex corresponded with greater symptom improvement following CBT. Cerebellar rsFC circuits involving DMN and ECN are possible neuropathologic mechanisms of SAD. Stronger pretreatment cerebellar rsFC circuits involving ECN suggest potential neural markers to predict CBT response.     

Increased Cerebellar Functional Connectivity With the Default-Mode Network in Unaffected Siblings of Schizophrenia Patients at Rest

The default-mode network (DMN) is vital in the neurobiology of schizophrenia, and the cerebellum participates in the high-order cognitive network such as the DMN. However, the specific contribution of the cerebellum to the DMN abnormalities remains unclear in unaffected siblings of schizophrenia patients. Forty-six unaffected siblings of schizophrenia patients and 46 healthy controls were recruited for a resting-state scan. The images were analyzed using the functional connectivity (FC) method. The siblings showed significantly increased FCs between the left Crus I and the left superior medial prefrontal cortex (MPFC), as well as between the lobule IX and the bilateral MPFC (orbital part) and right superior MPFC compared with the controls. No significantly decreased FC was observed in the siblings relative to the controls. The analyses were replicated in 49 first-episode, drug-naive patients with schizophrenia, and the results showed that the siblings and the patients shared increased FCs between the left Crus I and the left superior MPFC, as well as between the lobule IX and the left MPFC (orbital part) compared with the controls. These findings suggest that increased cerebellar-DMN connectivities emerge earlier than illness onset, which highlight the contribution of the cerebellum to the DMN alterations in unaffected siblings. The shared increased cerebellar-DMN connectivities between the patients and the siblings may be used as candidate endophenotypes for schizophrenia.Key words: unaffected siblings of schizophrenia patients, schizophrenia, cerebellum, functional connectivity, default-mode network     

Accelerated HF-rTMS in treatment-resistant unipolar depression: Insights from subgenual anterior cingulate functional connectivity

Objectives. Intensified repetitive transcranial magnetic stimulation (rTMS) applied to the left dorsolateral prefrontal cortex (DLPFC) may result in fast clinical responses in treatment resistant depression (TRD). In these kinds of patients, subgenual anterior cingulate cortex (sgACC) functional connectivity (FC) seems to be consistently disturbed. So far, no de novo data on the relationship between sgACC FC changes and clinical efficacy of accelerated rTMS were available. Methods. Twenty unipolar TRD patients, all at least stage III treatment resistant, were recruited in a randomized sham-controlled crossover high-frequency (HF)-rTMS treatment study. Resting-state (rs) functional MRI scans were collected at baseline and at the end of treatment. Results. HF-rTMS responders showed significantly stronger resting-state functional connectivity (rsFC) anti-correlation between the sgACC and parts of the left superior medial prefrontal cortex. After successful treatment an inverted relative strength of the anti-correlations was observed in the perigenual prefrontal cortex (pgPFC). No effects on sgACC rsFC were observed in non-responders. Conclusions. Strong rsFC anti-correlation between the sgACC and parts of the left prefrontal cortex could be indicative of a beneficial outcome. Accelerated HF-rTMS treatment designs have the potential to acutely adjust deregulated sgACC neuronal networks in TRD patients.     

Learning-driven cerebellar intrinsic functional connectivity changes in men

Learning involves distributed but coordinated activity among the widespread connected brain areas. Increase in areas connections' strength may be established offline, that is, aside from the task itself, in a resting-state. The resulting functional connectivity may hence constitute a neural trace of the learning episode. The present study examined whether a conditional visuomotor learning task previously shown to activate the cerebellum would modify cerebellar intrinsic connectivity in groups of young and older male subjects. In the group of young subjects, resting-state connectivity within several cerebellar networks (fronto-cerebellar, temporo-cerebellar, cerebello-cerebellar) was modified following the task. In most cases, modulation resulted in increased anticorrelations between cerebellar and cortical areas and the amplitude of changes was correlated with learning efficacy. The group of older subjects drastically differed, with sparser modifications of resting-state functional connectivity and no cerebellar networks involved. The findings of this exploratory study indicate that associative learning modifies the strength of intrinsic connectivity in young subjects but to a lesser degree in older subjects. They further suggest that functional connectivity within cerebellar networks may play an operative role in this kind of learning.     

Mapping the altered patterns of cerebellar resting-state function in longitudinal amnestic mild cognitive impairment patients

The cerebellum is known to be a relatively well preserved structure, but subtle alterations may occur early in the evolution of Alzheimer's disease (AD). Amnestic mild cognitive impairment (aMCI) patients appear to be particularly vulnerable to AD. However, little is currently known whether altered patterns of cerebellar function occur in aMCI patients. 26 aMCI patients and 18 well-matched healthy controls underwent a baseline resting-state functional magnetic resonance imaging (fMRI) scan. After a mean follow-up period of 20 months, the subjects who successfully completed baseline fMRI scans underwent a further follow-up scan, while spontaneous activation and functional connectivity of the cerebellum were explored by using resting-state fMRI. Compared to controls, increased amplitude of low frequency fluctuation of the posterior cerebellar lobe may contribute to the underlying mechanisms affected, while greater decreased functional connections to the posterior cerebellar lobe were identified in the longitudinal study of aMCI patients. This suggests that abnormal functional connectivity of the cerebellum may offer a more sensitive and possibly preferred index of functional disturbance than regional activity measures in aMCI patients. The cerebellum may be partly related to the underlying mechanisms of aMCI, and it could help guide subsequent investigations designed to specify the precise functional role of cerebellum in aMCI patients.     

Reduction in gray matter of cerebellum in schizophrenia and its influence on static and dynamic connectivity

Pathophysiological and atrophic changes in the cerebellum have been well‐documented in schizophrenia. Reduction of gray matter (GM) in the cerebellum was confirmed across cognitive and motor cerebellar modules in schizophrenia. Such abnormalities in the cerebellum could potentially have widespread effects on both sensorimotor and cognitive symptoms. In this study, we investigated how reduction change in the cerebellum affects the static and the dynamic functional connectivity (FC) between the cerebellum and cortical/subcortical networks in schizophrenia. Reduction of GM in the cerebellum was confirmed across the cognitive and motor cerebellar modules in schizophrenic subjects. Results from this study demonstrates that the extent of reduction of GM within cerebellum correlated with increased static FCs between the cerebellum and the cortical/subcortical networks, including frontoparietal network (FPN), and thalamus in patients with schizophrenia. Decreased GM in the cerebellum was also associated with a declined dynamic FC between the cerebellum and the FPN in schizophrenic subjects. The severity of patients' positive symptom was related to these structural‐functional coupling score of cerebellum. These findings identified potential cerebellar driven functional changes associated with positive symptom deficits. A post hoc analysis exploring the effect of changed FC within cerebellum, confirmed that a significant positive relationship, between dynamic FCs of cerebellum–thalamus and intracerebellum existed in patients, but not in controls. The reduction of GM within the cerebellum might be associated with modulation of cerebellum–thalamus, and contributes to the dysfunctional cerebellar‐cortical communication in schizophrenia. Our results provide a new insight into the role of cerebellum in understanding the pathophysiological of schizophrenia.     

Increased grey matter volume and associated resting-state functional connectivity in chronic spontaneous urticaria: A structural and functional MRI study

Background and purposeChronic itch is one of the most common irritating sensations, yet its mechanisms have not been fully elucidated. Although some studies have revealed relationships between itching and brain function, the structural changes in the brain induced by chronic itching, such as those accompanying chronic spontaneous urticaria (CSU), remain unclear. In this study, we aimed to explore the potential changes in brain structure and the associated functional circuitry in CSU patients to generate insights to aid chronic itch management.MethodsForty CSU patients and forty healthy controls (HCs) were recruited. Seven-day urticaria activity score (UAS7) values were collected to evaluate clinical symptoms. Voxel-based morphometry (VBM) and seed-based resting-state functional connectivity (rs-FC) analysis were used to assess structural changes in the brain and associated changes in functional circuitry.ResultsCompared with HCs, CSU patients had significantly increased grey matter (GM) volume in the right premotor cortex, left fusiform cortex, and cerebellum. UAS7 values were positively associated with GM volume in the left fusiform cortex. In CSU patients relative to HCs, the left fusiform cortex as extracted by VBM analysis demonstrated decreased functional connectivity with the right orbitofrontal cortex, medial prefrontal cortex (mPFC), premotor cortex, primary motor cortex (MI), and cerebellum and increased functional connectivity with the right posterior insular cortex, primary somatosensory cortex (SI), and secondary somatosensory cortex (SII). The left cerebellum as extracted from VBM analysis demonstrated decreased functional connectivity with the right supplementary motor area (SMA) and MI in CSU patients relative to HCs.ConclusionsOur findings indicate that patients suffering from chronic itching conditions, such as CSU, are likely to demonstrate altered GM volume in some brain regions. These changes may affect not only the sensorimotor area but also brain regions associated with cognitive function.     

Altered cerebellar functional connectivity mediates potential adaptive plasticity in patients with multiple sclerosis

BACKGROUND: The cerebellum is of potential interest for understanding adaptive responses in motor control in patients with multiple sclerosis because of the high intrinsic synaptic plasticity of this brain region. OBJECTIVE: To assess the relative roles of interactions between the neocortex and the cerebellum using measures of functional connectivity. METHODS: A role for altered neocortical-cerebellar functional connectivity in adaptive responses to injury from multiple sclerosis was tested using 1.5 T functional magnetic resonance imaging (fMRI) during figure writing with the dominant right hand in patients with predominantly early relapsing-remitting multiple sclerosis. RESULTS: Patients (n = 14) showed a more bihemispheric pattern of activation in motor cortex than healthy controls (n = 11). Correlations between task related signal changes in neocortical and cerebellar regions of interest were used as a measure of functional connectivity. Healthy controls showed strong functional connectivity between the left motor cortex and the right cerebellar dentate nucleus. Significant connectivity between the left primary motor cortex and the right dentate was not found in patients. However, patients had significant connectivity between the left premotor neocortex and the ipsilateral (left) cerebellar cortex (crus I), which was not found in healthy controls. CONCLUSIONS: Changes in apparent cerebellar-neocortical functional connectivity may mediate potentially adaptive changes in brain motor control in patients with multiple sclerosis. Similar changes in the cerebellum and premotor cortex have been reported in the healthy brain during motor learning, suggesting that common mechanisms may contribute to normal motor learning and motor recovery after injury from multiple sclerosis.     

Resting-state functional connectivity abnormalities in patients with obsessive–compulsive disorder and their healthy first-degree relatives

Background

Obsessive–compulsive disorder (OCD) is a common, heritable neuropsychiatric disorder, hypothetically underpinned by dysfunction of brain cortical–striatal–thalamic–cortical (CSTC) circuits; however, the extent of brain functional abnormalities in individuals with OCD is unclear, and the genetic basis of this disorder is poorly understood. We determined the whole brain functional connectivity patterns in patients with OCD and their healthy first-degree relatives.

Methods

We used resting-state fMRI to measure functional connectivity strength in patients with OCD, their healthy first-degree relatives and healthy controls. Whole brain functional networks were constructed by measuring the temporal correlations of all brain voxel pairs and further analyzed using a graph theory approach.

Results

We enrolled 39 patients with OCD, 20 healthy first-degree relatives and 39 healthy controls in our study. Compared with healthy controls, patients with OCD showed increased functional connectivity primarily within the CSTC circuits and decreased functional connectivity in the occipital cortex, temporal cortex and cerebellum. Moreover, patients with OCD and their first-degree relatives exhibited overlapping increased functional connectivity strength in the bilateral caudate nucleus, left orbitofrontal cortex (OFC) and left middle temporal gyrus.

Limitations

Potential confounding factors, such as medication use, heterogeneity in symptom clusters and comorbid disorders, may have impacted our findings.

Conclusion

Our preliminary results suggest that patients with OCD have abnormal resting-state functional connectivity that is not limited to CSTC circuits and involves abnormalities in additional large-scale brain systems, especially the limbic system. Moreover, resting-state functional connectivity strength abnormalities in the left OFC, bilateral caudate nucleus and left middle temporal gyrus may be neuroimaging endophenotypes for OCD.     

Altered regional homogeneity and connectivity in cerebellum and visual-motor relevant cortex in Parkinson's disease with rapid eye movement sleep behavior disorder

ObjectiveRapid eye movement sleep behavior disorder (RBD) frequently occurs in Parkinson's disease (PD), however, the exact pathophysiological mechanism underlying its occurrence is not clear. In this study, we explored whether there is abnormal spontaneous neuronal activities and connectivity maps in some brain areas under resting-state in PD patients with RBD.MethodsWe recruited 38 PD patients (19 PD with RBD and 19 PD without RBD), and 20 age- and gender-matched normal controls. We used resting-state functional magnetic resonance imaging (RS-fMRI) to analyze regional homogeneity (ReHo) and functional connectivity (FC), and further to reveal the neuronal activity in all subjects.ResultsCompared with the PD without RBD patients, the PD with RBD patients showed a significant increase in regional homogeneity in the left cerebellum, the right middle occipital region and the left middle temporal region, and decreased regional homogeneity in the left middle frontal region. The REM sleep behavioral disorders questionnaire scores were significantly positively correlated with the ReHo values of the left cerebellum. The functional connectivity analysis in which the four regions described above were used as regions of interest revealed increased functional activity between the left cerebellum and bilateral occipital regions, bilateral temporal regions and bilateral supplementary motor area.ConclusionThe pathophysiological mechanism of PD with RBD may be related to abnormal spontaneous neuronal activity patterns with strong synchronization of cerebellar and visual-motor relevant cortex, and the increased connectivity of the cerebellum with the occipital and motor regions.     

Abnormal Causal Connectivity by Structural Deficits in First-Episode,Drug-Naive Schizophrenia at Rest

Anatomical deficits and resting-state functional connectivity (FC) alterations in prefrontal-thalamic-cerebellar circuit have been implicated in the neurobiology of schizophrenia. However, the effect of structural deficits in schizophrenia on causal connectivity of this circuit remains unclear. This study was conducted to examine the causal connectivity biased by structural deficits in first-episode, drug-naive schizophrenia patients. Structural and resting-state functional magnetic resonance imaging (fMRI) data were obtained from 49 first-episode, drug-naive schizophrenia patients and 50 healthy controls. Data were analyzed by voxel-based morphometry and Granger causality analysis. The causal connectivity of the integrated prefrontal-thalamic (limbic)-cerebellar (sensorimotor) circuit was partly affected by structural deficits in first-episode, drug-naive schizophrenia as follows: (1) unilateral prefrontal-sensorimotor connectivity abnormalities (increased driving effect from the left medial prefrontal cortex [MPFC] to the sensorimotor regions); (2) bilateral limbic-sensorimotor connectivity abnormalities (increased driving effect from the right anterior cingulate cortex [ACC] to the sensorimotor regions and decreased feedback from the sensorimotor regions to the right ACC); and (3) bilateral increased and decreased causal connectivities among the sensorimotor regions. Some correlations between the gray matter volume of the seeds, along with their causal effects and clinical variables (duration of untreated psychosis and symptom severity), were also observed in the patients. The findings indicated the partial effects of structural deficits in first-episode, drug-naive schizophrenia on the prefrontal-thalamic (limbic)-cerebellar (sensorimotor) circuit. Schizophrenia may reinforce the driving connectivities from the left MPFC or right ACC to the sensorimotor regions and may disrupt bilateral causal connectivities among the sensorimotor regions.Key words: first-episode schizophrenia, causal effect, structural deficits, voxel-based morphometry, Granger causality analysis     

Acupuncture treatment modulates the corticostriatal reward circuitry in major depressive disorder

Major depressive disorder (MDD) is a common disorder with a high prevalence and significant social and economic impacts. Nevertheless, the treatment of MDD is far from satisfactory. Acupuncture treatment has emerged as a promising method for treating MDD. However, the neural mechanism by which acupuncture reduces depressive symptoms is not fully understood. Studies have shown that the corticostriatal reward circuitry is associated with the pathophysiology of MDD; thus, we investigated the corticostriatal resting-state functional connectivity (rsFC) before and after real and sham acupuncture treatments combined with the antidepressant fluoxetine. Forty-six female major depressive patients were assigned to either verum acupuncture plus fluoxetine (n = 22) or sham acupuncture plus fluoxetine (n = 24) treatment for 8 weeks, and resting state functional magnetic resonance imaging (fMRI) data were collected before the first and after the last treatment sessions. The results showed that compared with sham acupuncture, the verum acupuncture group showed: (1) significantly increased rsFC between inferior ventral striatum and medial prefrontal cortex, ventral rostral putamen and amygdala/parahippocampus, as well as dorsal caudate and middle temporal gyrus; (2) significantly decreased rsFC between right ventral rostral putamen and right dorsolateral prefrontal cortex, and right dorsal caudate and bilateral cerebellar tonsil. The increased rsFC between the inferior ventral striatum and medial prefrontal cortex, ventral rostral putamen and amygdala/parahippocampus were significantly positively associated with decreased clinical scores (Montgomery–Åsberg Depression Rating Scale and Self-Rating Depression Scale scores) at the end of the eight-week treatment. Our findings suggest that acupuncture may achieve treatment effects by modulating the corticostriatal reward/motivation circuitry in MDD patients.     

Resting-State Functional Connectivity Changes Between Dentate Nucleus and Cortical Social Brain Regions in Autism Spectrum Disorders

Autism spectrum disorders (ASDs) are known to be characterized by restricted and repetitive behaviors and interests and by impairments in social communication and interactions mainly including “theory of mind” (ToM) processes. The cerebellum has emerged as one of the brain regions affected by ASDs. As the cerebellum is known to influence cerebral cortex activity via cerebello-thalamo-cortical (CTC) circuits, it has been proposed that cerebello-cortical “disconnection” could in part underlie autistic symptoms. We used resting-state (RS) functional magnetic resonance imaging (fMRI) to investigate the potential RS connectivity changes between the cerebellar dentate nucleus (DN) and the CTC circuit targets, that may contribute to ASD pathophysiology. When comparing ASD patients to controls, we found decreased connectivity between the left DN and cerebral regions known to be components of the ToM network and the default mode network, implicated in specific aspects of mentalizing, social cognition processing, and higher order emotional processes. Further, a pattern of overconnectivity was also detected between the left DN and the supramodal cerebellar lobules associated with the default mode network. The presented RS-fMRI data provide evidence that functional connectivity (FC) between the dentate nucleus and the cerebral cortex is altered in ASD patients. This suggests that the dysfunction reported within the cerebral cortical network, typically related to social features of ASDs, may be at least partially related to an impaired interaction between cerebellum and key cortical social brain regions.     

Cerebellar–cortical dysconnectivity in resting‐state associated with sensorimotor tasks in schizophrenia

Abnormalities of cerebellar function have been implicated in the pathophysiology of schizophrenia. Since the cerebellum has afferent and efferent projections to diverse brain regions, abnormalities in cerebellar lobules could affect functional connectivity with multiple functional systems in the brain. Prior studies, however, have not examined the relationship of individual cerebellar lobules with motor and nonmotor resting‐state functional networks. We evaluated these relationships using resting‐state fMRI in 30 patients with a schizophrenia‐spectrum disorder and 37 healthy comparison participants. For connectivity analyses, the cerebellum was parcellated into 18 lobular and vermal regions, and functional connectivity of each lobule to 10 major functional networks in the cerebrum was evaluated. The relationship between functional connectivity measures and behavioral performance on sensorimotor tasks (i.e., finger‐tapping and postural sway) was also examined. We found cerebellar–cortical hyperconnectivity in schizophrenia, which was predominantly associated with Crus I, Crus II, lobule IX, and lobule X. Specifically, abnormal cerebellar connectivity was found to the cerebral ventral attention, motor, and auditory networks. This cerebellar–cortical connectivity in the resting‐state was differentially associated with sensorimotor task‐based behavioral measures in schizophrenia and healthy comparison participants—that is, dissociation with motor network and association with nonmotor network in schizophrenia. These findings suggest that functional association between individual cerebellar lobules and the ventral attentional, motor, and auditory networks is particularly affected in schizophrenia. They are also consistent with dysconnectivity models of schizophrenia suggesting cerebellar contributions to a broad range of sensorimotor and cognitive operations.     

Reduced cerebellar inhibition in schizophrenia: a preliminary study

OBJECTIVE: Postmortem and structural imaging studies suggest that patients with schizophrenia have disrupted cerebellar activity. It has been speculated that these abnormalities mediate disorganized thought processes and psychosis. The authors' goal was to use transcranial magnetic stimulation to measure cerebellar inhibition, a proxy of cerebellar activity, as the principal output of the cerebellum is inhibitory. METHOD: Cerebellar inhibition was accomplished by delivering a magnetic cerebellar conditioning stimulus 5-15 msec before a magnetic test stimulus to the motor cortex. The cerebellar conditioning stimulus inhibits the size of the motor evoked potential produced by the test stimulus by approximately 50%. Ten patients with schizophrenia and 10 healthy comparison subjects completed the cerebellar inhibition protocol. RESULTS: Patients with schizophrenia demonstrated significant deficits in cerebellar inhibition compared with healthy subjects. CONCLUSIONS: The authors conclude that deficits in cerebellar inhibitory activity in schizophrenia may be the result of an abnormality in the cerebellum or disrupted cerebellar-thalamic-cortical connectivity.     

Functional disconnection of the right anterior insula in obstructive sleep apnea

BackgroundThe right anterior insula (AIns) is an important node of the salience network and serves to switch between two major cognitive-related functional brain networks, ie, the central executive network (CEN) and the default mode network (DMN), both of which show functional deficits in obstructive sleep apnea (OSA) patients. However, the effect of OSA on functional connectivity of the right AIns remains uncertain.ObjectiveTo determine whether the resting-state functional connectivity (rsFC) between the right AIns and the CEN and DMN is disrupted in OSA patients, which may be associated with cognitive deficits in this disorder.MethodsTwenty-four male OSA patients and 21 matched healthy controls underwent functional MRI examinations and clinical and neuropsychologic assessments. The rsFCs between the right AIns and the CEN and DMN were compared between the two groups and were correlated with clinical and neuropsychologic assessments.ResultsCompared with healthy controls, OSA patients showed significantly weakened rsFC between the right AIns and the DMN. Moreover, the functional disconnection between the right AIns and the medial prefrontal cortex was correlated with the severity of the OSA; and the functional disconnection between the right AIns and the posterior cingulate cortex was correlated with depressive scores and working memory performance. However, there were no significant inter-group differences in the rsFC between the right AIns and the CEN.ConclusionsThese findings suggest that OSA selectively impairs the rsFC between the right AIns and the DMN, which may be a candidate substrate for cognitive impairment in OSA patients.     

Widespread functional disconnectivity in schizophrenia with resting-state functional magnetic resonance imaging

Using resting-state functional magnetic resonance imaging, we examined the functional connectivity throughout the entire brain in schizophrenia. The abnormalities in functional connectivity were identified by comparing the correlation coefficients of each pair of 116 brain regions between 15 patients and 15 controls. Then, the global distribution of the abnormal functional connectivities was examined. Experimental results indicated, in general, a decreased functional connectivity in schizophrenia during rest, and such abnormalities were widely distributed throughout the entire brain rather than restricted to a few specific brain regions. The results provide a quantitative support for the hypothesis that schizophrenia may arise from the disrupted functional integration of widespread brain areas.     

早发精神分裂症静息态脑功能低频振幅研究

目的通过静息态功能磁共振研究早发未用药精神分裂症患者局部脑功能低频振幅(amplitude of low-frequency fluctuation,ALFF)的变化,探讨其静息态下功能异常的脑区。方法收集20例早发未用药精神分裂症患者与20名性别、年龄、受教育年限相匹配的正常对照,分别对其进行全脑静息态功能磁共振扫描,计算ALFF值。结果与对照组相比,患者组左侧额上回、左侧楔前叶、左侧扣带回、左侧枕叶、左侧海马旁回、左侧距状沟ALFF值增高(P0.05,Alpha Sim校正),右侧颞上回和右侧小脑后叶ALFF值降低(P0.05,Alpha Sim校正)。结论早发精神分裂症患者在静息态下有多处脑区ALFF值改变,提示其在静息态下存在脑功能异常。