DTI和功能磁共振成像对精神分裂症患者脑功能连接强度的临床研究

摘要 目的：探讨DTI和功能磁共振成像对精神分裂症患者脑功能连接强度的临床研究。方法：选取2017年9月-2021年3月在我院精神科就诊的精神分裂患者96例。将纳入的96例患者作为精神分裂组,选择同时期招募的96例健康志愿者作为对照组。使用FMRIB软件库进行结构数据预处理和脑解剖网络构建,并进行相关的分析。结果：精神分裂组较对照组枕叶模块功能连接强度增强,较对照组皮质模块和额顶叶模块功能连接强度减弱（P<0.05）,精神分裂组与对照组的默认模块和中央模块功能连接强度比较无差异（P>0.05）。精神分裂组与对照组各模块的结构连接强度比较无差异（P>0.05）。精神分裂组较对照组默认模式模块和中央模块的结构-功能连接程度增加,精神分裂组较对照组枕叶模块和皮质模块的结构-功能连接程度降低（P<0.05）,额顶叶模块结构-功能连接程度两组比较无差异（P>0.05）。在精神分裂症组中,枕叶模块的结构-功能连接评分与疾病持续时间（r=-0.528,P=0.006）和PANSS总体症状相关（r=-0.174,P=0.003）,皮质模块的结构-功能连接评分也与PANSS整体症状（r=-0.405,P=0.034）显著负相关。皮质模块的结构-功能连接评分与疾病持续时间之间显著负相关（r=-0.336,P=0.029）。结论：精神分裂症患者的脑功能连接强度（功能模块水平上结构-功能耦合）发生改变,其结构-功能耦合的畸变与精神分裂症的临床特征相关。     

Cross-Modal Multivariate Pattern Analysis

Multivariate pattern analysis (MVPA) is an increasingly popular method of analyzing functional magnetic resonance imaging (fMRI) data^1-4. Typically, the method is used to identify a subject''s perceptual experience from neural activity in certain regions of the brain. For instance, it has been employed to predict the orientation of visual gratings a subject perceives from activity in early visual cortices⁵ or, analogously, the content of speech from activity in early auditory cortices⁶.Here, we present an extension of the classical MVPA paradigm, according to which perceptual stimuli are not predicted within, but across sensory systems. Specifically, the method we describe addresses the question of whether stimuli that evoke memory associations in modalities other than the one through which they are presented induce content-specific activity patterns in the sensory cortices of those other modalities. For instance, seeing a muted video clip of a glass vase shattering on the ground automatically triggers in most observers an auditory image of the associated sound; is the experience of this image in the "mind''s ear" correlated with a specific neural activity pattern in early auditory cortices? Furthermore, is this activity pattern distinct from the pattern that could be observed if the subject were, instead, watching a video clip of a howling dog?In two previous studies^7,8, we were able to predict sound- and touch-implying video clips based on neural activity in early auditory and somatosensory cortices, respectively. Our results are in line with a neuroarchitectural framework proposed by Damasio^9,10, according to which the experience of mental images that are based on memories - such as hearing the shattering sound of a vase in the "mind''s ear" upon seeing the corresponding video clip - is supported by the re-construction of content-specific neural activity patterns in early sensory cortices.     

Letter to the Editor: Seasonal Pattern of Births in Patients with Optic Neuritis

Attentional processes are fundamental to good cognitive functioning of human operators. The purpose of this study was to analyze the activity of neuronal networks involved in the orienting attention and executive control processes from the perspective of diurnal variability. Twenty-three healthy male volunteers meeting magnetic resonance (MR) inclusion criteria performed the Stroop Color-Word task (block design) in the MR scanner five times/day (06:00, 10:00, 14:00, 18:00, 22:00 h). The first scanning session was scheduled 1–1.5 h after waking. Between MR sessions, subjects performed simulated driving tasks in stable environmental conditions, with controlled physical activity and diet. Significant activation was found in brain regions related to the orienting attentional system: the parietal lobe (BA40) and frontal eye-fields (FEFs). There were also activations in areas of the executive control system: the fronto-insular cortex (FIC), dorsal anterior cingulate cortex (dACC), presupplementary motor area (preSMA), supplementary motor area (SMA), basal ganglia, middle temporal (MT; BA21), and dorsolateral prefrontal cortex (DLPFC), as a part of the central executive network. Significant deactivations were observed in the rostral anterior cingulate cortex (rACC), posterior cingulate cortex (PCC), superior frontal gyrus (SF), parietal lobe (BA39), and parahippocampal that are thought to comprise the default mode network (DMN). Additionally, the activated regions included bilaterally lingual gyrus and fusiform gyrus. The insula was bilaterally deactivated. Visual attention controlled by the goal-oriented attention system and comprising top-down and bottom-up mechanisms, activated by Stroop-like task, turned out to be prone to diurnal changes. The study results show the occurrence of time-of-day–related variations in neural activity of brain regions linked to the orienting attentional system (left parietal lobe—BA40, left and right FEFs), simultaneously providing arguments for temporal stability of the executive system and default mode network. These results also seem to suggest that the involuntary, exogenous (bottom-up) mechanism of attention is more vulnerable to circadian and fatigue factors than the voluntary (top-down) mechanism, which appear to be maintained at the same functional level during the day. The above phenomena were observed at the neural level. (Author correspondence: marek@uj.edu.pl)     

Cortical correlates of perception and suppression of electrically induced pain

Two neuroimaging studies using fMRI were conducted in order to assess the cortical processes involved in the perception and suppression of pain. In the first study, 15 healthy subjects were stimulated with variable intensities of electrical pulses during a discrimination task. In the second study, the same subjects had to try to suppress the feeling of pain during tonic stimulation. The discrimination task resulted in cortical activation of contralateral SI, corresponding in extent to the intensity of the stimulus. Activation of contralateral operculum/posterior insula (SII) and non-dominant dorsolateral prefrontal cortex (DLPFC) with non-painful stimuli changed to activations of non-dominant anterior insula upon painful stimulation. In the second study, all subjects succeeded in suppressing the feeling of pain during previously painful levels of stimulation. During this suppression task, activations changed from anterior to posterior insula; also there was a suppression of activity in the anterior cingulated cortex (ACC) and caudate nucleus. Subjects seem to be able to suppress to a certain degree the feeling of pain under constant (and previously painful) stimulation. The cortical correlate seems to be a shift of cerebral activation from anterior to posterior right insula and a suppression of activity in the ACC and caudate nucleus.     

Construction of embedded fMRI resting-state functional connectivity networks using manifold learning

We construct embedded functional connectivity networks (FCN) from benchmark resting-state functional magnetic resonance imaging (rsfMRI) data acquired from patients with schizophrenia and healthy controls based on linear and nonlinear manifold learning algorithms, namely, Multidimensional Scaling, Isometric Feature Mapping, Diffusion Maps, Locally Linear Embedding and kernel PCA. Furthermore, based on key global graph-theoretic properties of the embedded FCN, we compare their classification potential using machine learning. We also assess the performance of two metrics that are widely used for the construction of FCN from fMRI, namely the Euclidean distance and the cross correlation metric. We show that diffusion maps with the cross correlation metric outperform the other combinations.     

Impact of BDNF Val66Met and 5-HTTLPR polymorphism variants on neural substrates related to sadness and executive function

The brain-derived neurotrophic factor (BDNF) Val(66) Met allelic variation is linked to both the occurrence of mood disorders and antidepressant response. These findings are not universally observed, and the mechanism by which this variation results in increased risk for mood disorders is unclear. One possible explanation is an epistatic relationship with other neurotransmitter genes associated with depression risk, such as the serotonin-transporter-linked promotor region (5-HTTLPR). Further, it is unclear how the coexistence of the BDNF Met and 5-HTTLPR S variants affects the function of the affective and cognitive control systems. To address this question, we conducted a functional magnetic resonance imaging (fMRI) study in 38 older adults (20 healthy and 18 remitted from major depressive disorder). Subjects performed an emotional oddball task during the fMRI scan and provided blood samples for genotyping. Our analyses examined the relationship between genotypes and brain activation to sad distractors and attentional targets. We found that 5-HTTLPR S allele carriers exhibited stronger activation in the amygdala in response to sad distractors, whereas BDNF Met carriers exhibited increased activation to sad stimuli but decreased activation to attentional targets in the dorsolateral prefrontal and dorsomedial prefrontal cortices. In addition, subjects with both the S allele and Met allele genes exhibited increased activation to sad stimuli in the subgenual cingulate and posterior cingulate. Our results indicate that the Met allele alone or in combination with 5-HTTLPR S allele may increase reactivity to sad stimuli, which might represent a neural mechanism underlying increased depression vulnerability.     

Modulation of Central Nociceptive Coding by Acupoint Stimulation

It is universally accepted that acupuncture or acupoint stimulation can produce analgesic effect on patients with painful disorders. The past decades has seen remarkable progress in exploring the central mechanisms of acupuncture-induced pain relief, including the neurotransmitter release and expression of particular receptors and genes in the spinal cord and the brain stem regions. Development of new techniques makes it possible to record and image the brain network patterns underlying pain perception and modulation, and to investigate the role of higher-level brain areas in mediating acupuncture analgesia. This review will present the current understanding of the neural network that is implicated in the modulation of pain by acupuncture. Special issue article in honor of Dr. Ji-Sheng Han.     

脑科学和脑功能MR成像

目的：在对大脑认知功能进行脑功能成像研究之中,随着磁共振成像技术的发展,人们现在可以对脑的认知功能,如视觉、运动、语言和记忆等功能中枢进行成像。本文首先介绍了脑科学的发展历程,并从脑功能MR成像的方法出发,分析了其成像机理,探讨了用脑功能MR成像为手段对脑科学—认知科学进行的方法研究,最后对脑功能MR成像应用于脑科学的研究作了展望。     

Imaging the premotor areas

Recent imaging studies of motor function provide new insights into the organization of the premotor areas of the frontal lobe. The pre-supplementary motor area and the rostral portion of the dorsal premotor cortex, the 'pre-PMd', are, in many respects, more like prefrontal areas than motor areas. Recent data also suggest the existence of separate functional divisions in the rostral cingulate zone.