Dysfunction in the Fronto-Parietal Network in Attention Deficit Hyperactivity Disorder (ADHD): An fMRI Study

ADHD is associated with spatial working memory deficits, thought to be subserved by dysfunction of neural circuits. In this study we aimed to further examine fronto-parietal dysfunction in ADHD by examining brain activation associated with the Raven’s Progressive Matrices task, a visuo-spatial pattern sequencing task involving relational reasoning and thereby placing high-demand loading on the prefrontal cortex. Functional MRI was conducted on twelve right-handed 8–12 year old boys with ADHD-combined type and 12 right-handed, age and performance IQ-matched, healthy boys as they completed items from the Raven’s Progressive Matrices. Our findings further confirm striatum and parietal lobe dysfunction in ADHD. Furthermore, dysfunction in lateral prefrontal regions was found. In addition to lateral prefrontal, striatum and posterior parietal regions, the temporal lobe was also less active. These findings suggest deficits in a widespread ‘functional network’ in ADHD that may be fundamental for visuo-spatial information processing and relational reasoning.     

抑郁症患者眶额叶皮层功能连接偏离的研究

目的 通过功能磁共振成像技术,研究抑郁症患者和健康对照组在情感处理时眶额叶皮层的功能连接偏离,为抑郁症的早期诊断和疗效评估提供影像学依据.方法 对25例重度抑郁症患者和15名健康对照组在执行面貌一致性任务时进行功能性磁共振成像.结果 和健康对照组相比重度抑郁症患者的背侧前扣带回皮层、楔前叶、小脑与眶额叶的活动连接减少;抑郁症患者的眶额叶皮层和背外侧前额叶皮层、右额叶岛盖部、左运动区之间的功能连接比健康对照组有所增加.结论 眶额叶皮层在抑郁症的病理生理学机制中发挥着关键作用.眶额叶皮层连接的失衡似乎代表加工偏离的神经机制.从神经生物学的角度来看,楔前叶和扣带回的连接解离活动与眶额叶皮层的自我架构规则的问题相关,而背外侧前额叶皮层到眶额叶的连接增加可能代表更高消极刺激的神经反应.     

Effects of heartbeat and respiration on macaque fMRI: Implications for functional connectivity

The use of functional magnetic resonance imaging (fMRI) in non-human primates is on the increase. It is known that the blood-oxygen-level-dependent (BOLD) signal varies not only as a function of local neuronal energy consumption but also as a function of cardiac and respiratory activity. We mapped these cyclic cardiac and respiratory artifacts in anesthetized macaque monkeys and present an objective analysis of their impact on estimates of functional connectivity (fcMRI). Voxels with significant cardiac and respiratory artifacts were found in much the same regions as previously reported for awake humans. We show two example seeds where removing the artifacts clearly decreased the number of false positive and false negative correlations. In particular, removing the artifacts reduced correlations in the so-called resting state network. Temporal bandpass filtering or spatial smoothing may help to reduce the effects of artifacts in some cases but are not an adequate replacement for an algorithm that explicitly models and removes cyclic cardiac and respiratory artifacts.     

Psychogenic nonepileptic seizures: A current overview

Psychogenic nonepileptic seizures (PNES) resemble epilepsy, but no pathophysiological explanation has been established. Although there have been recent advances in PNES research and various hypotheses as to the psychopathology, no theory has achieved general acceptance. In this overview of selected literature on PNES, we highlight the often contradictory findings that underline the challenges that confront both practitioner and researcher. We first provide a synopsis of the history, diagnosis, treatment, and outcomes, as well as patient characteristics of PNES and the relevance of communication in the clinical context. In the subsequent sections we discuss recent research that may advance the understanding and diagnosis of this disorder. These themes include the use of qualitative methods as a viable research option, the application of nonlinear methods to analyze heterogeneous observations during diagnosis, recent advances in neuroimaging of PNES, and the development of international databases.     

轻型缺血性卒中后认知障碍与脑动态功能连接状态改变的功能磁共振成像研究

目的 探索轻型缺血性卒中后有认知障碍（cognitive impairment,CI）患者和无认知障碍（no cognitive impairment,NCI）患者脑动态功能连接（functional connectivity,FC）状态的变化。 方法 选择2014年12月1日-2016年5月31日首都医科大学附属北京天坛医院神经病学中心就诊的 轻型急性缺血性卒中患者为研究对象,对所有患者进行神经心理学评估和多模态MRI检查,分为CI 组（15例）和NCI组（11例）,同时招募年龄、性别均匹配的志愿者作为健康对照（healthy control,HC）组 （29例）。基于静息态功能头颅MRI影像,利用动态功能网络连接方法构建一系列随时间变化的FC网络, 然后通过聚类方法划分为多个具有代表性的动态FC状态（分别为模块化连接状态、强连接状态、局 部连接状态和稀疏连接状态）,比较HC组、CI组与NCI组的FC动态特征（各状态的时间比例、驻留时间 及各状态间的转换次数）差异,并在两个时间点（基线和3个月随访期）探索CI组与NCI组动态FC状态 的变化。 结果 HC组、CI组和NCI组在基线和随访期各连接状态的时间比例差异均无统计学意义。基线CI组 和NCI组在稀疏连接状态的驻留时间比HC组更低,三组差异有统计学意义（P =0.035）,但两两比较 的结果均未通过Bonferroni校正;而在随访期,各连接状态的驻留时间差异均无统计学意义。纵向比 较中,与基线相比,CI组随访期在模块化连接状态的时间比例明显下降（P =0.035）,在稀疏连接状 态的时间比例明显上升（P =0.025）,在模块化连接状态的驻留时间明显降低（P =0.012）;而NCI 组 在两个时间点各连接状态的时间比例和驻留时间差异均无统计学意义。对于转换次数,所有组间的 差异均无统计学意义。 结论 轻型缺血性卒中患者急性期较对照人群有局部连接状态增多而稀疏连接状态减少的趋势, 但差异未达统计学意义;对于有认知障碍的轻型缺血性卒中患者,发病3个月时模块化连接状态和 稀疏连接状态均较急性期显著恢复;动态功能网络能够客观反映大脑功能的变化。     

Corticostriatal functional connectivity in non-medicated patients with obsessive-compulsive disorder

The basal ganglia represents a key component of the pathophysiological model for obsessive-compulsive disorder (OCD). This brain region is part of several neural circuits, including the orbitofronto-striatal circuit and dorsolateral prefronto-striatal circuit. There are, however, no published studies investigating those circuits at a network level in non-medicated patients with OCD. Resting state functional magnetic resonance imaging scans were obtained from 20 non-medicated patients with OCD and 23 matched healthy volunteers. Voxelwise statistical parametric maps testing strength of functional connectivity of three striatal seed regions of interest (ROIs) with remaining brain regions were calculated and compared between groups. We performed additional correlation analyses between strength of connectivity and the severity scores for obsessive-compulsive symptoms, depression, and anxiety in the OCD group. Positive functional connectivity with the ventral striatum was significantly increased (P_corrected <.05) in the orbitofrontal cortex, ventral medial prefrontal cortex and dorsal lateral prefrontal cortex of subjects with OCD. There was no significant correlation between measures of symptom severity and the strength of connectivity (P_uncorrected <.001). This is the first study to investigate the corticostriatal connectivity in non-medicated patients with OCD. These findings provide the first direct evidence supporting a pathophysiological model involving basal ganglia circuitry in OCD.     

Effects of Antidepressant Treatment on Sexual Arousal in Depressed Women: A Preliminary fMRI Study

Objective

There was a recent study to explore the cerebral regions associated with sexual arousal in depressed women using functional magnetic resonance imaging (fMRI). The purpose of this neuroimaging study was to investigate the effects of antidepressant treatment on sexual arousal in depressed women.

Methods

Seven depressed women with sexual arousal dysfunction (mean age: 41.7±13.8, mean scores of the Beck Depression Inventory (BDI) and the 17-item Hamilton Rating Scale for Depression (HAMD-17): 35.6±7.1 and 34.9±3.1, respectively) and nine healthy women (mean age: 40.3±11.6) underwent fMRI before and after antidepressant treatment. The fMRI paradigm contrasted a 1 minute rest period viewing non-erotic film with 4 minutes of sexual stimulation viewing an erotic video film. Data were analyzed by SPM 2. The relative number of pixels activated in each period was used as an index of activation. All depressed women were treated with mirtazapine (mean dosage: 37.5 mg/day) for 8 to 10 weeks.

Results

Levels of brain activity during sexual arousal in depressed women significantly increased with antidepressant treatment (p<0.05) in the regions of the hypothalamus (3.0% to 11.2%), septal area (8.6% to 27.8%) and parahippocampal gyrus (5.8% to 14.6%). Self-reported sexual arousal during visual sexual stimulation also significantly increased post-treatment, and severity of depressive symptoms improved, as measured by the BDI and HAMD-17 (p<0.05).

Conclusion

These results show that sexual arousal dysfunction of depressed women may improve after treatment of depression, and that this improvement is associated with increased activation of the hypothalamus, septal area, and parahippocampal gyrus during sexual arousal.     

Maternal parenting behavior and functional connectivity development in children: A longitudinal fMRI study

Parenting behavior is associated with internalizing symptoms in children, and cross-sectional research suggests that this association may be mediated by the influence of parenting on the development of frontoamygdala circuitry. However, longitudinal studies are lacking. Moreover, there is a paucity of studies that have investigated parenting and large-scale networks implicated in affective functioning. In this longitudinal study, data from 95 (52 female) children and their mothers were included. Children underwent magnetic resonance imaging that included a 6 min resting state sequence at wave 1 (mean age = 8.4 years) and wave 2 (mean age = 9.9 years). At wave 1, observational measures of positive and negative maternal behavior were collected during mother-child interactions. Region-of-interest analysis of the amygdala, and independent component and dual-regression analyses of the Default Mode Network (DMN), Executive Control Network (ECN) and the Salience Network (SN) were carried out. We identified developmental effects as a function of parenting: positive parenting was associated with decreased coactivation of the superior parietal lobule with the ECN at wave 2 compared to wave 1. Thus our findings provide preliminary longitudinal evidence that positive maternal behavior is associated with maturation of the connectivity between higher-order control networks.     

Frequency-specific alterations in functional connectivity in treatment-resistant and -sensitive major depressive disorder

Major depressive disorder (MDD) may involve alterations in brain functional connectivity in multiple neural circuits and present large-scale network dysfunction. Patients with treatment-resistant depression (TRD) and treatment-sensitive depression (TSD) show different responses to antidepressants and aberrant brain functions. This study aims to investigate functional connectivity patterns of TRD and TSD at the whole brain resting state. Seventeen patients with TRD, 17 patients with TSD, and 17 healthy controls matched with age, gender, and years of education were recruited in this study. The brain was divided using an automated anatomical labeling atlas into 90 regions of interest, which were used to construct the entire brain functional networks. An analysis method called network-based statistic was used to explore the dysconnected subnetworks of TRD and TSD at different frequency bands. At resting state, TSD and TRD present characteristic patterns of network dysfunction at special frequency bands. The dysconnected subnetwork of TSD mainly lies in the fronto-parietal top-down control network. Moreover, the abnormal neural circuits of TRD are extensive and complex. These circuits not only depend on the abnormal affective network but also involve other networks, including salience network, auditory network, visual network, and language processing cortex. Our findings reflect that the pathological mechanism of TSD may refer to impairment in cognitive control, whereas TRD mainly triggers the dysfunction of emotion processing and affective cognition. This study reveals that differences in brain functional connectivity at resting state reflect distinct pathophysiological mechanisms in TSD and TRD. These findings may be helpful in differentiating two types of MDD and predicting treatment responses.     

Disrupted functional connectivity of default mode and salience networks in chronic pancreatitis patients

ObjectiveThe functional connectivity of the brain in chronic pancreatitis (CP) remains unknown. This study aimed to investigate functional connectivity in CP patients using resting state functional magnetic resonance imaging (fMRI) and explore the associations to clinical parameters and altered cerebral metabolites.MethodsSeed-based and ROI-to-ROI analyses were performed to assess connectivity within and between the default mode network (DMN) and salience network (SN). Additionally, functional connectivity in these networks were investigated in relation to clinical parameters (CP etiology, pain, medication, etc.) and cerebral glutamate/creatine level in the anterior cingulate cortex.ResultsThirty CP patients and 23 healthy controls were analyzed. CP patients showed hyper-connectivity in DMN and SN as compared to healthy controls. Furthermore, CP patients had reduced anti-correlated functional connectivity between DMN and SN (all P ≤ 0.009). The altered DMN connectivity correlated to glutamate/creatine level (r = 0.503, P = 0.020) in patients with pain, but not to the clinical parameters.ConclusionsCP patients had altered functional connectivity within and between brain networks. Altered DMN functional connectivity had an association to cerebral metabolic changes.SignificanceAltered functional connectivity in CP share similarities with other chronic pain conditions, and support our understanding of altered brain circuitry associated with the CP disease.