颞叶内侧癫癎海马功能连接的功能磁共振成像研究

目的研究颞叶内侧癫癎患者右侧海马与全脑,尤其是默认网络功能连接的关系,探讨颞叶内侧癫癎患者默认网络异常的机制及其形成的颞叶癫癎网络。方法23例颞叶内侧癫癎患者,采用静息功能连接的功能磁共振成像,选择右侧海马作为兴趣区,获得正常对照组和颞叶内侧癫癎组受试者的脑功能连接激活图,观察其右侧海马与全脑的功能连接。结果正常对照组受试者默认网络包括海马、后扣带回和（或）楔前叶、前扣带回和（或）前额叶内侧、角回及前颞叶。颞叶内侧癫癎组患者右侧海马与默认网络的正向功能连接明显减弱,与右侧额下回、颞上回及第一运动感觉皮质下部的正向功能连接增强;与前额叶背侧、顶间沟及第一运动感觉皮质上部的负向功能连接减弱。结论在颞叶内侧癫癎患者功能连接网络中,默认网络及部分正向功能连接网络受损,提示患者存在广泛的、与海马相关的生理功能丧失;与右侧额下回、颞上回及第一感觉运动皮质下部的功能连接增强则可能与颞叶癫癎网络有关。     

颞叶内侧癫(癎)海马功能连接的功能磁共振成像研究

目的 研究颞叶内侧癫(癎)患者右侧海马与全脑,尤其是默认网络功能连接的关系,探讨颞叶内侧癫(癎)患者默认网络异常的机制及其形成的颞叶癫(癎)网络.方法 23例颞叶内侧癫(癎)患者,采用静息功能连接的功能磁共振成像,选择右侧海马作为兴趣区,获得正常对照组和颞叶内侧癫(癎)组受试者的脑功能连接激活图,观察其右侧海马与全脑的功能连接.结果 正常对照组受试者默认网络包括海马、后扣带回和(或)楔前叶、前扣带回和(或)前额叶内侧、角回及前颞叶.颞叶内侧癫(癎)组患者右侧海马与默认网络的正向功能连接明显减弱,与右侧额下回、颞上回及第一运动感觉皮质下部的正向功能连接增强;与前额叶背侧、顶间沟及第一运动感觉皮质上部的负向功能连接减弱.结论 在颞叶内侧癫(癎)患者功能连接网络中,默认网络及部分正向功能连接网络受损,提示患者存在广泛的、与海马相关的生理功能丧失;与右侧额下回、颞上回及第一感觉运动皮质下部的功能连接增强则可能与颞叶癫(癎)网络有关.     

基于功能连接的复发缓解型多发性硬化患者默认网络静息态功能磁共振成像

目的 采用静息态功能磁共振成像(rs-fMRI)基于种子点相关性分析技术对复发缓解型多发性硬化(RRMS)患者默认网络的功能连接改变进行研究.方法 使用3.0T磁共振采集RRMS组和健康对照组(各27例)rs-fMRI数据.数据经预处理后,选择后扣带回(-5,-49,40)为种子点,采用基于种子点相关性分析技术进行功能连接分析,分别在默认网络内和默认网络外脑区比较两组功能连接的差异.分析差异脑区与临床参数如临床扩展残疾量表、同步听觉连续加法测验评分(PASAT)、脑实质分数、T2可见病灶数和病程的相关性.结果 基于种子点相关性分析技术构建的RRMS患者默认网络包含脑区主要有前额叶皮质腹侧、双侧顶下叶、后扣带回及楔前叶等脑区.在默认网络内比较,RRMS患者较健康对照组右侧额上回功能连接下降;右侧小脑后叶、右侧小脑脚、右侧颞中回、右侧额中回、左侧楔前叶及扣带回、右侧角回、右侧扣带回功能连接增高.RRMS患者组默认网络内差异脑区中,右侧颞中回功能连接系数(0.387±0.216)与PASAT呈负相关(r=-0.590,P =0.001);患者右侧额上回功能连接系数(0.039±0.293)与病程之间呈负相关(r=-0.390,P=0.041).在默认网络外比较,RRMS组后扣带回功能连接下降脑区有右侧额上回、左侧枕中回、左侧中央前回;功能连接增高脑区有右侧小脑前叶(含齿状核)、右侧额叶白质区.RRMS组后扣带回与左侧中央前回、右侧小脑前叶功能连接系数(-0.924±0.253和0.217±0.208)分别与病程之间存在正相关(r =0.650,P=0.000;r =0.436,P=0.023).结论 RRMS患者默认网络内和默认网络外均出现后扣带回静息态功能连接的异常改变,表明患者存在功能下降和代偿的复杂过程.RRMS患者存在有限功能重构或重组,以维持默认网络的功能稳定.     

精神分裂症患者基底节功能连接的静息态fMRI研究

目的通过功能磁共振(fMRI)技术,探讨精神分裂症患者静息状态下与基底节异常连接的脑区。方法采用3.0T功能磁共振成像技术检测15例精神分裂症患者与12例正常对照组在静息状态下的全脑功能活动。采用功能连接分析对比两组被试的基底节(双侧尾状核、壳核和苍白球共6个区域)与全脑功能连接的差异。结果与对照组相比,精神分裂症患者的内侧额上回、后扣带与尾状核的功能连接上升;左侧额上回、右侧前扣带与左侧苍白球功能连接上升;左内侧额上回与右侧苍白球功能连接上升;左侧额上回与左侧壳核功能连接上升。差异均有统计学意义。结论精神分裂症患者的基底节区域与默认网络的重要节点功能连接上升,提示基底节-默认网络环路出现异常,这可能与精神分裂症的病理机制有关。     

无认知功能障碍的终末期肾病患者全脑皮质厚度变化研究

目的观察终末期肾病患者大脑皮质厚度变化,并探讨其与肾功能的相关性。方法共35例终末期肾病患者,测量收缩压、舒张压、血红蛋白、血清肌酐、尿素氮、总胆固醇、血清钾和血清钙,并行头部MRI检查,观察大脑皮质厚度变化,Pearson相关分析探讨其与肾功能的相关性。结果与正常对照者相比,终末期肾病患者右侧前额叶皮质[包括4个局部峰值顶点,即外侧前额叶皮质(峰值1和2)、内侧前额叶皮质(峰值3)和腹侧前额叶皮质(峰值4)]厚度减少(均P0.05,RFT校正)。Pearson相关分析显示,终末期肾病患者外侧前额叶皮质厚度(峰值1:r=-0.344,P=0.043;峰值2:r=-0.335,P=0.049)和内侧前额叶皮质厚度(峰值3:r=-0.387,P=0.021)与血清肌酐呈负相关;外侧前额叶皮质厚度(峰值1:r=-0.384,P=0.023;峰值2:r=-0.380,P=0.024)、内侧前额叶皮质厚度(峰值3:r=-0.470,P=0.004)和腹侧前额叶皮质厚度(峰值4:r=-0.440,P=0.009)与血清尿素氮呈负相关;内侧前额叶皮质厚度(峰值3)与血红蛋白呈正相关(r=0.339,P=0.046),与血清钾呈负相关(r=-0.335,P=0.049);外侧前额叶皮质厚度(峰值2)与校正血清钙呈正相关(r=0.354,P=0.037)。结论终末期肾病患者右侧前额叶皮质(包括外侧前额叶皮质、内侧前额叶皮质和腹侧前额叶皮质)厚度减少,且与肾功能具有一定相关性,为终末期肾病患者灰质形态学异常提供有力证据,同时也表明肾功能可能是预测脑结构改变的关键因素。     

基于功能磁共振成像的抗抑郁药对情绪加工神经环路作用机制的研究进展北大核心CSCD

诸多功能磁共振成像（functional magnetic resonance imaging, fMRI）研究显示前额叶．边缘系统（杏仁核）情绪加工环路异常是抑郁症主要的病理机制,主要表现为前额叶皮质网络如背外侧前额叶皮质、腹外侧前额叶皮质、背侧前扣带回活动异常降低,以及边缘系统如海马、下丘脑、杏仁核、腹侧前扣带回活动过度激活[1]。     

首发未用药青少年抑郁障碍患者静息态脑功能磁共振研究

目的探讨首次发病未用药青少年抑郁障碍患者静息态脑功能的异常变化。方法应用静息态功能磁共振局部一致性方法,对19例首发未用药青少年抑郁障碍患者和24名健康对照的静息态脑功能磁共振图像进行比较。结果青少年抑郁障碍患者在双侧眶额叶(t=-4.379,P0.001)、双侧内侧前额叶(t=-4.379,P0.001)、右侧额下回(t=-6.057,P0.001)的局部一致性值高于对照组,差异有统计学意义。结论首发未用药的青少年抑郁障碍患者在双侧眶额叶、双侧内侧前额叶、右侧额下回静息态脑功能存在异常,这些脑区的功能异常可能与青少年抑郁障碍的病理生理机制有关。     

轻型颅脑损伤静息态脑网络变化的研究

目的通过对轻型颅脑损伤病人进行静息态功能磁共振检查并采用低频振幅的方法进行数据分析,观察其脑网络异常激活区域。方法收集16例轻型颅脑损伤病人作为轻型颅脑损伤组,同时将23例正常志愿者作为正常对照组。采用低频振幅分析方法对两组进行静息态功能磁共振数据分析。结果与正常对照组比较,轻型颅脑损伤组脑网络出现6个异常激活脑区,主要分布于胼胝体前部、右侧额叶的前部及后部皮质、右侧顶枕联合皮质、左侧小脑半球底部、右侧枕极、双侧颞叶底部、双侧颞中回后部、双侧颞枕联合皮质及双侧额叶前部内侧皮质。结论轻型颅脑损伤病人静息态脑网络存在异常激活区域,静息态功能磁共振可能成为临床治疗中的重要诊断方法。     

早发青少年精神分裂症患者皮质下脑结构协变连接异常的研究北大核心CSCD

目的 探讨早发青少年精神分裂症患者皮质下脑结构体积和协变连接异常变化.方法 对39例首次发病未用药的早发青少年（12～18周岁）精神分裂症患者（患者组）以及31名年龄、性别及受教育程度与之相匹配的健康志愿者（对照组）进行全脑磁共振扫描;采用Freesurfer软件对T1加权脑结构像进行图像分割配准处理,并提取皮质下脑体积进行双样本t检验分析,利用组水平线性相关构建皮质下脑区之间的协变连接,对协变连接r值进行Fisher r-to-z变换后进行组间Z检验比较分析.结果 患者组（n=35）左侧丘脑（7755 mm^3与7955 mm^3,t=-2.16,P〈0.05未校正）、左侧海马（4200 mm^3与4331 mm^3,t=-2.01,P〈0.05未校正）相对于对照组（n=29）体积减少;患者组皮质下脑区协变连接在左侧苍白球与壳核、左侧海马与杏仁核、右侧杏仁核与丘脑、右侧杏仁核与壳核、左侧壳核与右侧丘脑之间显著降低（Z=1.88～2.87,P〈0.05 FDR校正）.结论 早发青少年精神分裂症患者皮质下局部脑体积减少以及协变连接降低,这可能提示患者皮质下边缘系统、基底节脑区的结构协同发育异常.     

部分性发作癫痫患者静息状态功能磁共振默认模式网络的功能连接改变

目的 应用静息状态功能磁共振成像(fMRI)探讨部分性发作癫痫患者静息状态下的脑功能改变.方法 对60例部分性发作癫痫患者(患者组)和60名性别、年龄和教育程度匹配的健康对照者(对照组),使用3.0T磁共振采集两组的静息状态下fMRI数据,采用功能连接方法分析计算脑区的默认模式网络的功能连接,利用SPM5软件分析比较患者组和对照组脑功能的差异.结果 患者组的默认模式网络的功能连接主要包括左侧楔前叶/后扣带回和角回、扣带回;对照组的功能连接主要包括左侧楔前叶/后扣带回和右侧角回,双侧内侧额叶和颞叶;患者组的左侧顶下小叶[坐标值(x,y,z):-57,-39,48;t=4.90,P＜0.01]、左侧缘上回[坐标值(x,y,z):-63,- 48,33;t=4.25,P＜0.01]、左侧海马旁回[坐标值(x,y,z):-30,-6,-21;t =4.05,P＜0.01]、左侧颞上回[坐标值(x,y,z):-48,-39,6;t=3.72,P＜0.01],左侧钩回[坐标值(x,y,z):-24,6,- 36;=4.56,P＜0.01]及右侧钩回[坐标值(x,y,z):33,-15,- 36;t=4.00,P＜0.01]的默认模式网络功能连接较对照组降低;未发现功能连接升高的脑区.结论 部分性发作癫痫患者静息状态下脑区的功能连接改变,可能是部分性发作癫痫潜在的病理生理机制.静息状态fMRI能发现常规MRI正常的癫痫患者的广泛脑功能异常,是一种无创的研究癫痫患者脑功能的有效方法.     

Dysconnectivity Within the Default Mode in First-Episode Schizophrenia: A Stochastic Dynamic Causal Modeling Study With Functional Magnetic Resonance Imaging

We report the first stochastic dynamic causal modeling (sDCM) study of effective connectivity within the default mode network (DMN) in schizophrenia. Thirty-three patients (9 women, mean age = 25.0 years, SD = 5) with a first episode of psychosis and diagnosis of schizophrenia—according to the Diagnostic and Statistic Manual of Mental Disorders, 4th edition, revised criteria—were studied. Fifteen healthy control subjects (4 women, mean age = 24.6 years, SD = 4) were included for comparison. All subjects underwent resting state functional magnetic resonance imaging (fMRI) interspersed with 2 periods of continuous picture viewing. The anterior frontal (AF), posterior cingulate (PC), and the left and right parietal nodes of the DMN were localized in an unbiased fashion using data from 16 independent healthy volunteers (using an identical fMRI protocol). We used sDCM to estimate directed connections between and within nodes of the DMN, which were subsequently compared with t tests at the between subject level. The excitatory effect of the PC node on the AF node and the inhibitory self-connection of the AF node were significantly weaker in patients (mean values = 0.013 and −0.048 Hz, SD = 0.09 and 0.05, respectively) relative to healthy subjects (mean values = 0.084 and −0.088 Hz, SD = 0.15 and 0.77, respectively; P < .05). In summary, sDCM revealed reduced effective connectivity to the AF node of the DMN—reflecting a reduced postsynaptic efficacy of prefrontal afferents—in patients with first-episode schizophrenia.Key words: brain connectivity, default mode network, dysconnectivity, first-episode schizophrenia, functional magnetic resonance imaging (fMRI), resting state, stochastic dynamic causal modeling (DCM)     

Functional disintegration in paranoid schizophrenia using resting-state fMRI

Functional disintegration has been observed in schizophrenia during task performance. We sought to investigate functional disintegration during rest because an intrinsic functional brain organization, including both "task-negative" (i.e., "default mode") and "task-positive" networks, has been suggested to play an important role in integrating ongoing information processing. Additionally, the brain regions that are involved in the intrinsic organization are believed to be abnormal in schizophrenia. Patients with paranoid schizophrenia (N=18) and healthy volunteers (N=18) underwent a resting-state fMRI scan. Functional connectivity analysis was used to identify the connectivity between each pair of brain regions within this intrinsic organization, and differences were examined in patients versus healthy volunteers. Compared to healthy volunteers, patients showed significant differences in connectivity within networks and between networks, most notably in the connectivities associated with the bilateral dorsal medial prefrontal cortex, the lateral parietal region, the inferior temporal gyrus of the "task-negative" network and with the right dorsolateral prefrontal cortex and the right dorsal premotor cortex of the "task-positive" network. These results suggested that the interregional functional connectivities in the intrinsic organization are altered in patients with paranoid schizophrenia. These abnormalities could be the source of abnormalities in the coordination of and competition between information processing activities in the resting brain of paranoid patients.     

Aberrant "default mode" functional connectivity in schizophrenia

OBJECTIVE: The "default mode" has been defined as a baseline condition of brain function and is of interest because its component brain regions are believed to be abnormal in schizophrenia. It was hypothesized that the default mode network would show abnormal activation and connectivity in patients with schizophrenia. METHOD: Patients with schizophrenia (N=21) and healthy comparison subjects (N=22) performed an auditory oddball task during functional magnetic resonance imaging (fMRI). Independent component analysis was used to identify the default mode component. Differences in the spatial and temporal aspects of the default mode network were examined in patients versus comparison subjects. RESULTS: Healthy comparison subjects and patients had significant spatial differences in the default mode network, most notably in the frontal, anterior cingulate, and parahippocampal gyri. In addition, activity in patients in the medial frontal, temporal, and cingulate gyri correlated with severity of positive symptoms. The patients also showed significantly higher frequency fluctuations in the temporal evolution of the default mode. CONCLUSIONS: Schizophrenia is associated with altered temporal frequency and spatial location of the default mode network. The authors hypothesized that this network may be under- or overmodulated by key regions, including the anterior and posterior cingulate cortex. In addition, the altered temporal fluctuations in patients may result from a change in the connectivity of these regions with other brain networks.     

Functional resting-state networks are differentially affected in schizophrenia

Neurobiological theories posit that schizophrenia relates to disturbances in connectivity between brain regions. Resting-state functional magnetic resonance imaging is a powerful tool for examining functional connectivity and has revealed several canonical brain networks, including the default mode, dorsal attention, executive control, and salience networks. The purpose of this study was to examine changes in these networks in schizophrenia. 42 patients with schizophrenia and 61 healthy subjects completed a RS-fMRI scanning session. Seed-based region-of-interest correlation analysis was used to identify the default mode, dorsal attention, executive control, and salience networks. Compared to healthy subjects, individuals with schizophrenia demonstrated greater connectivity between the posterior cingulate cortex, a key hub of the default mode, and the left inferior gyrus, left middle frontal gyrus, and left middle temporal gyrus. Interestingly, these regions were more strongly connected to the executive control network in healthy control subjects. In contrast to the default mode, patients demonstrated less connectivity in the executive control and dorsal attention networks. No differences were observed in the salience network. The results indicate that resting-state networks are differentially affected in schizophrenia. The alterations are characterized by reduced segregation between the default mode and executive control networks in the prefrontal cortex and temporal lobe, and reduced connectivity in the dorsal attention and executive control networks. The changes suggest that the process of functional specialization is altered in schizophrenia. Further work is needed to determine if the alterations are related to disturbances in white matter connectivity, neurodevelopmental abnormalities, and genetic risk for schizophrenia.     

Modular‐level alterations of structure–function coupling in schizophrenia connectome

Convergent evidences have revealed that schizophrenia is associated with brain dysconnectivity, which leads to abnormal network organization. However, discrepancies were apparent between the structural connectivity (SC) and functional connectivity (FC) studies, and the relationship between structural and functional deficits in schizophrenia remains largely unknown. In this study, resting‐state functional magnetic resonance imaging and structural diffusion tensor imaging were performed in 20 patients with schizophrenia and 20 matched healthy volunteers (patients/controls = 19/17 after head motion rejection). Functional and structural brain networks were obtained for each participant. Graph theoretical approaches were employed to parcellate the FC networks into functional modules. The relationships between the entries of SC and FC were estimated within each module to identify group differences and their correlations with clinical symptoms. Although five common functional modules (including the default mode, occipital, subcortical, frontoparietal, and central modules) were identified in both groups, the patients showed a significantly reduced modularity in comparison with healthy participants. Furthermore, we found that schizophrenia‐related aberrations of SC–FC coupling exhibited complex patterns among modules. Compared with controls, patients showed an increased SC–FC coupling in the default mode and the central modules. Moreover, significant SC–FC decoupling was demonstrated in the occipital and the subcortical modules, which was associated with longer duration of illness and more severe clinical manifestations of schizophrenia. Taken together, these findings demonstrated that altered module‐dependent SC–FC coupling may underlie abnormal brain function and clinical symptoms observed in schizophrenia and highlighted the potential for using new multimodal neuroimaging biomarkers for diagnosis and severity evaluation of schizophrenia. Hum Brain Mapp 38:2008–2025, 2017. © 2017 Wiley Periodicals, Inc.     

Spontaneous low-frequency fluctuations in the BOLD signal in schizophrenic patients: anomalies in the default network

Spontaneous low-frequency fluctuations in the blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (MRI) signal have been shown to reflect neural synchrony between brain regions. A "default network" of spontaneous low-frequency fluctuations has been described in healthy volunteers during stimulus-independent thought. Negatively correlated with this network are regions activated during attention-demanding tasks. Both these networks involve brain regions and functions that have been linked with schizophrenia in previous research. The present study examined spontaneous slow fluctuations in the BOLD signal at rest, as measured by correlation with low-frequency oscillations in the posterior cingulate, in 17 schizophrenic patients, and 17 comparable healthy volunteers. Healthy volunteers demonstrated correlation between spontaneous low-frequency fluctuations of the BOLD signal in the posterior cingulate and fluctuations in the lateral parietal, medial prefrontal, and cerebellar regions, similar to previous reports. Schizophrenic patients had significantly less correlation between spontaneous slow activity in the posterior cingulate and that in the lateral parietal, medial prefrontal, and cerebellar regions. Connectivity of the posterior cingulate was found to vary with both positive and negative symptoms in schizophrenic patients. Because these data suggest significant abnormalities in resting-state neural networks in schizophrenia, further investigations of spontaneous slow fluctuations of the BOLD signal seem warranted in this population.     

Key functional circuitry altered in schizophrenia involves parietal regions associated with sense of self

There is still no clear consensus as to which of the many functional and structural changes in the brain in schizophrenia are of most importance, although the main focus to date has been on those in the frontal and cingulate cortices. In the present study, we have used a novel holistic approach to identify brain‐wide functional connectivity changes in medicated schizophrenia patients, and functional connectivity changes were analyzed using resting‐state fMRI data from 69 medicated schizophrenia patients and 62 healthy controls. As far as we are aware, this is the largest population reported in the literature for a resting‐state study. Voxel‐based morphometry was also used to investigate gray and white matter volume changes. Changes were correlated with illness duration/symptom severity and a support vector machine analysis assessed predictive validity. A network involving the inferior parietal lobule, superior parietal gyrus, precuneus, superior marginal, and angular gyri was by far the most affected (68% predictive validity compared with 82% using all connections) and different components correlated with illness duration and positive and negative symptom severity. Smaller changes occurred in emotional memory and sensory and motor processing networks along with weakened interhemispheric connections. Our findings identify the key functional circuitry altered in schizophrenia involving the default network midline cortical system and the cortical mirror neuron system, both playing important roles in sensory and cognitive processing and particularly self‐processing, all of which are affected in this disorder. Interestingly, the functional connectivity changes with the strongest links to schizophrenia involved parietal rather than frontal regions. Hum Brain Mapp 35:123–139, 2014. © 2012 Wiley Periodicals, Inc.     

Retrosplenial cortex connectivity in schizophrenia

In this paper, we build on our previous analysis [Bluhm, R.L., Miller, J., Lanius, R.A., Osuch, E.A., Boksman, K., Neufeld, R.W.J., et al., 2007 Spontaneous low-frequency fluctuations in the BOLD signal in schizophrenic patients: anomalies in the default network. Schizophrenia Bulletin 33, 1004–1012] of resting state connectivity in schizophrenia by examining alterations in connectivity of the retrosplenial cortex. We have previously demonstrated altered connectivity of the posterior cingulate/precuneus, particularly with other regions of the “default network” (which includes the medial prefrontal cortex and bilateral lateral parietal cortex). It was hypothesized that the retrosplenial cortex would show aberrant patterns of connectivity with regions of the default network and regions associated with memory. Patients with schizophrenia (N = 17) and healthy controls (N = 17) underwent a 5.5-min resting functional magnetic resonance imaging scan. Lower correlations were observed in patients with schizophrenia than in healthy controls between the retrosplenial cortex and both the temporal lobe and regions of the default network. In patients with schizophrenia, activity in the retrosplenial cortex correlated negatively with activity in bilateral anterior cingulate gyrus/medial prefrontal cortex (BA 32/10), despite the fact that these regions, as part of the default network, were expected to show positive correlations in activity. Connectivity of the retrosplenial cortex was greater in patients with more positive symptoms with areas previously associated with hallucinations, particularly the left superior temporal gyrus. These results suggest that spontaneous activity in the retrosplenial cortex during rest is altered in patients with schizophrenia. These alterations may help to explain alterations in self-oriented processing in this patient population.     

Dysfunctional neural networks associated with impaired social interactions in early psychosis: an ICA analysis

The “default mode”, or baseline of brain function is a topic of great interest in schizophrenia research. Recent neuroimaging studies report that the symptoms of chronic schizophrenia subjects are associated with temporal frequency alterations as well as with the disruption of local spatial patterns in the default mode network (DMN). Previous studies both on chronic and medicated subjects with psychosis suffered from limitations; on this basis, it was hypothesized that the default mode network showed abnormal activation and connectivity in young and neuroleptic-naïve patients with first-episode psychosis. This study investigated emotional responses to pleasant and unpleasant/disgusting visual stimuli by a resting-state analysis of fMRI-data from 12 untreated first-episode psychosis patients with prevalently negative symptomatology versus 12 healthy subjects. We chose this experimental task to explore the functional link between default mode network and hedonic processing which has been proposed as a marker of cerebral dysfunction in psychotic disorder and implicated in its pathophysiology. Independent Component Analysis (ICA) was used to identify the default mode component. Both healthy and first-episode subjects showed significant spatial differences in the default mode network. In first-episode subjects, medial frontal hypoactivity and cerebellar hyperactivity were correlated with the severity of negative symptoms.     

Disrupted Modular Architecture of Cerebellum in Schizophrenia: A Graph Theoretic Analysis

Recent studies of schizophrenia have revealed cognitive and memory deficits that are accompanied by disruptions of neuronal connectivity in cortical and subcortical brain regions. More recently, alterations of topological organization of structural networks in schizophrenia are also being identified using graph theoretical analysis. However, the role of the cerebellum in this network structure remains largely unknown. In this study, global network measures obtained from diffusion tensor imaging were computed in the cerebella of 25 patients with schizophrenia and 36 healthy volunteers. While cerebellar global network characteristics were slightly altered in schizophrenia patients compared with healthy controls, the patients showed a retained small-world network organization. The modular architecture, however, was changed mainly in crus II. Furthermore, schizophrenia patients had reduced correlations between modularity and microstructural integrity, as measured by fractional anisotropy (FA) in lobules I–IV and X. Finally, FA alterations were significantly correlated with the Positive and Negative Syndrome Scale symptom scores in schizophrenia patients. Taken together, our data suggest that schizophrenia patients have altered network architecture in the cerebellum with reduced local microstructural connectivity and that cerebellar structural abnormalities are associated symptoms of the disorder.Key words: cerebellum, diffusion tensor imaging, schizophrenia, structural connectivity, structural network, modular architecture