参与不同难度数字计算的脑区——脑功能磁共振成像研究

本研究用功能磁共振成像技术观察了人脑进行不同难度数字加减计算时的脑区激活情况,并探讨大脑皮层和皮层下结构在数字计算中的作用.用Siemens 1.5 Tesla磁共振机对16名右利手健康志愿者进行简单及复杂数字加减任务的fMRI扫描.实验采用组块设计.刺激任务分为简单加减计算任务、复杂加减计算任务和基线任务.用SPM99软件进行数据分析和脑功能区定位.分别比较同一任务各个脑区平均激活强度和同一脑区在两种任务中的激活强度.结果显示,简单及复杂加减计算激活的被试者的脑区基本相同,激活的皮层区主要见于额叶、顶叶、枕叶、扣带回、丘脑及小脑;简单及复杂加减计算激活的皮层下结构包括两侧尾状核、左纹状体边缘区等基底核结构和丘脑.在简单及复杂计算中,纹状体与皮质结构(额叶、顶叶)间激活强度均无显著性差异.简单计算与复杂计算比较,右顶叶,在复杂任务时出现激活,在简单任务时未出现激活.上述结果提示,完成数字计算任务的脑区除了额叶、顶叶、扣带回等皮层结构外,大脑皮层下的一些结构如纹状体、纹状体边缘区,也是参与数字计算的重要部位.皮层下结构纹状体和优势半球的纹状体边缘区参与了数字工作记忆,可能是进行数字计算神经环路的重要组成部位.右项叶(缘上回)只在复杂任务出现激活,该区可能是视空间记忆和加工的重要部位.     

纹状体神经通路与运动调控

纹状体(striatum)是机体运动中枢的关键组成部分,对机体随意运动、非意识性运动、肌张力、身体姿态、精细运动等调节均发挥重要作用。纹状体功能异常导致运动失调:一类为运动减少,肌张力亢进,如帕金森病;另一类为运动过多,肌张力不足,如舞蹈病。一般认为,纹状体接收大脑运动皮层传来的运动相关信号,经其加工处理后,经丘脑返传回运动皮层,最终由运动皮层发出运动执行信号,经锥体系完成运动。可见,纹状体的运动调控功能有赖于复杂的神经通路系统。本文综述近几年来有关纹状体神经通路与运动调控的研究进展,以期更深入理解纹状体运动调控神经机制及其与临床疾病的关系。     

脑功能成像用于疼痛相关情绪的研究进展

本文综述了近年来脑功能成像技术应用于疼痛情绪研究的进展,介绍了不同的皮层亚区和皮层下结构在疼痛相关情绪的产生和调控中的作用.指明了扣带回、前额叶皮质、岛叶、海马结构和杏仁核在疼痛相关情绪产生以调控过程中所起的作用.     

SOCS-3基因在Balb/c小鼠脑组织中的表达与脑不对称性

为探讨细胞因子信号传导抑制因子-3（suppresso of cytokine signaling-3, SOCS-3）在Balb/c小鼠皮层、海马、下丘脑中的表达及其与脑不对称性的关系.通过伸爪取食法将Balb/c小鼠分为左利组和右利组,取左、右侧皮层,左、右侧海马及下丘脑,以RT-PCR法间接测定SOCS-3 mRNA水平.结果表明：a.在左利鼠右侧皮层中,SOCS-3基因表达水平显著高于左侧皮层(P＜0.05);右利鼠左侧皮层SOCS-3表达显著高于左利鼠左侧皮层(P＜0.05).b.海马中SOCS-3表达：左利鼠右侧海马SOCS-3表达显著高于左侧海马(P＜0.05);右利鼠左侧海马SOCS-3表达显著高于左利鼠左侧海马(P＜0.05).c.右利鼠下丘脑中SOCS-3显著高于左利鼠(P＜0.05).上述研究结果提示,Balb/c小鼠脑中SOCS-3表达与脑不对称性有关.     

语言控制和一般领域认知控制的脑机制的重合和分离

双语者能根据不同的场合和交流对象选择目标语言进行交流.已有的研究发现,双语者需要通过抑制控制选择合适的语言.本研究使用功能性核磁共振(f MRI)技术,扫描22名汉-英双语者完成语言切换任务和西蒙切换任务时的脑活动状况,通过联合分析和分离分析的方法,揭示了双语产生过程中语言控制与一般领域的认知控制的脑机制的重合与分离.结果发现,双语产生过程中,语言控制需要使用一般领域的施加抑制和解除抑制机制.其中,语言控制与施加抑制共同涉及了额上回、前辅助运动区/背侧前扣带回、壳核和右侧顶上小叶的活动;语言控制与解除抑制都需要左侧顶上小叶的参与.此外发现,双语控制相比于一般领域的控制,需要特异性地激活左侧中央后回、左侧颞上回、左侧楔前叶、中后部扣带回、后辅助运动区、右侧颞中回、右侧舌回、右侧缘上回和双侧小脑等脑区,以发挥与发音动作、词汇提取、语义记忆有关的认知控制功能.这表明,语言控制与一般领域的认知控制既存在重合的脑机制,也存在分离的脑机制.     

反应抑制的额叶-基底神经节模型

额叶-基底神经节模型构成运动控制网络,其网络主要由额下回、辅助运动区、初级运动皮层、初级躯体感觉皮层及基底神经节亚区组成,是调节反应抑制能力的主要网络。目前,评测反应抑制能力的范式主要包括Go/No-Go与Stop-signal范式。多项研究发现,这两种实验范式在进行抑制任务时额叶及基底神经节亚区存在不同的激活,提示其抑制机制可能有所不同。其中,Go/No-Go任务是否由超直接通路调控抑制过程还有待探讨,Stop-signal任务则可能需要间接通路、超直接通路实现对抑制过程的调控。运动控制网络与感觉运动网络、默认模式网络之间的交互作用可能在治疗反应抑制缺陷与其他脑功能疾病中发挥调节作用。     

去胡须对大鼠行为及桶状皮层的影响

目的:研究外周去胡须后大鼠行为及桶状皮层(barrel cortex,BC)的可塑性变化。方法:SD大鼠随机分组(n=4):正常对照(A组),出生后第2天去除双侧颊脂垫组(B组),出生后第2天去除右侧颊脂垫组(C组),出生后1～5d每天剪右侧胡须,从出生后第5天起不剪由其胡须自由生长组(D组)。出生后第30天时称体重,测量左侧D2胡须长度,观测行为学变化(如狭缝实验、自由探索行为和趋壁行为)。采用细胞色素氧化酶组织化学法研究barrel排列与发育情况。结果:A组能迅速辨别出正确狭缝并钻入,平均用时(5.6±2.3)s;B组大鼠只有当鼻尖碰到狭缝壁时才会钻入狭缝。C组大鼠当其右侧脸颊靠近狭缝时,不能辨别出狭缝,只有当其掉转身体,用左侧胡须探测时才可能迅速钻入正确的狭缝。D组的表现同C组,B、C、D组大鼠进入正确狭缝的所用时间均显著长于A组(P0.01,P0.05,P0.01)。去除双侧颊脂垫的大鼠其左趋壁时间、右趋壁时间以及总趋壁时间均较正常大鼠短。去除右侧颊脂垫组的大鼠右趋壁时间也显著短于正常(P0.05)。四组大鼠左侧D2胡须长度以及体重均无显著差异。从出生后第2天时一直剪除右侧胡须的小鼠在出生后第30天时发现其barrel变小,排列较混乱,barrel之间的界限不清,皮层细胞色素氧化酶(CO)反应的灰度明显变淡。结论:外周去传入不引起大鼠体重改变及残留胡须长度的代偿性改变,但可引起其趋触及探索行为方面的改变。外周去传入可导致barrel形状及排列的可塑性变化。     

慢性疼痛患者静息态脑功能磁共振的默认网络研究

运用静息态功能磁共振成像技术(resting-state fMRI)研究慢性疼痛患者脑默认网络结构.通过选择双侧膝骨性关节炎(knee osteoarthritis,KOA)患者20例和正常志愿者20名,以后扣带回(posterior cingulated cortex,PCC)为种子点,分别进行fMRI扫描,分析配对两组受试者的脑功能连接情况.结果显示相对正常受试者,KOA患者存在异常脑功能连接,主要表现为PCC呈负激活,边缘叶、脑岛呈正激活.     

胚胎型大脑后动脉与脑白质病之间的关系

目的:探讨胚胎型大脑后动脉(Fetal origin of the posterior cerebral artery,FTP)与脑白质病之间的关系。方法:收集2013年1月~2014年6月在我院住院患者共485例,所有患者均行头颅磁共振平扫及血管成像,观察脑白质病变、急性脑梗死及FTP存在与否,并分为观察组(脑白质病组)和对照组(无脑白质病组),比较FTP的发生率。结果:观察组和对照组分别为232例和253例,观察组共发现53例FTP患者(左侧、右侧、双侧FTP分别为15例、19例、19例),FTP总发生率为22.8%,左侧、右侧、双侧FTP发生率分别为6.5%、8.2%、8.2%;对照组98例FTP患者(左侧、右侧、双侧FTP分别为26例、44例、28例),FTP总发生率为38.7%,左侧、右侧、双侧FTP发生率分别为10.3%、17.4%、11.1%,观察组FTP总发生率及右侧FTP发生率明显低于对照组(P0.001和P0.01)。232例观察组中急性脑梗死患者共156例,无急性脑梗死患者76例,其中急性脑梗死组有28例FTP患者(左侧、右侧、双侧FTP分别为7例、15例、6例),FTP总发生率及左侧、右侧、双侧FTP发生率分别为17.9%、4.5%、9.6%、3.8%;而无急性脑梗死的患者中,有24例FTP患者(左侧、右侧、双侧FTP分别为8例、4例、12例),FTP总发生率及左侧、右侧、双侧FTP发生率分别为31.6%、10.5%、5.3%、15.8%,观察组FTP总发生率及双侧FTP发生率明显低于对照组(P0.05和P0.01)。结论:FTP的存在可能一定程度上降低脑白质病甚至脑梗死的发生。     

从合作的进化探讨植物与传粉者的相互作用

合作的进化为研究植物–传粉者相互关系提供了新的视角。植物与传粉者通过"报酬换服务"建立种间合作关系。这一合作关系从建立、维持到解体面临着3个关键问题:(1)在植物和传粉者不了解对方质量信息时,双方如何选择出最适伙伴,进而建立合作关系;(2)合作方如何限制欺骗策略(比如,盗蜜和欺骗性传粉)的扩散以维持合作关系;(3)什么过程可导致传粉合作关系的解体。植物与传粉者间信号博弈或筛选博弈可促进二者合作关系的建立。面对欺骗策略,传粉者和植物分别采用伙伴选择机制和防御机制加以应对。合作者与欺骗者的稳定共存也有助于植物–传粉者合作的维持。从合作转向对抗、转向新的伙伴和合作放弃3个过程可导致植物–传粉者的合作关系的解体。植物与传粉者合作关系的理论预期已经得到了部分实验结果支持,深化了我们对植物与传粉者合作过程中关键机制的理解。在今后的研究中,需要进一步探讨以下问题:(1)传粉者对植物信号诚实性的选择作用和植物对传粉者的筛选作用;(2)植物与传粉者各自应对欺骗策略的可能机制及其相对重要性;(3)合作者与欺骗者稳定共存的机制;(4)植物与传粉者合作系统对全球变化的响应。     

Differential neural responses to food images in women with bulimia versus anorexia nervosa

Background

Previous fMRI studies show that women with eating disorders (ED) have differential neural activation to viewing food images. However, despite clinical differences in their responses to food, differential neural activation to thinking about eating food, between women with anorexia nervosa (AN) and bulimia nervosa (BN) is not known.

Methods

We compare 50 women (8 with BN, 18 with AN and 24 age-matched healthy controls [HC]) while they view food images during functional Magnetic Resonance Imaging (fMRI).

Results

In response to food (vs non-food) images, women with BN showed greater neural activation in the visual cortex, right dorsolateral prefrontal cortex, right insular cortex and precentral gyrus, women with AN showed greater activation in the right dorsolateral prefrontal cortex, cerebellum and right precuneus. HC women activated the cerebellum, right insular cortex, right medial temporal lobe and left caudate. Direct comparisons revealed that compared to HC, the BN group showed relative deactivation in the bilateral superior temporal gyrus/insula, and visual cortex, and compared to AN had relative deactivation in the parietal lobe and dorsal posterior cingulate cortex, but greater activation in the caudate, superior temporal gyrus, right insula and supplementary motor area.

Conclusions

Women with AN and BN activate top-down cognitive control in response to food images, yet women with BN have increased activation in reward and somatosensory regions, which might impinge on cognitive control over food consumption and binge eating.     

额叶冲突加工机制及年老化改变的事件相关电位研究

目的：探讨大脑额叶对冲突信息的加工处理机制及其年老化改变,探索敏感的事件相关电位（ERPs）指标。方法：研究对象为15例正常老年人（老年组）和15例青年成人（青年组）,ERPs检查采用改良的Eriksenflanker视觉刺激范式,记录32导脑电、正确率及反应时。结果：与青年组相比,老年组反应时明显延长,反应阶段干扰效应尤其明显。老年组N380出现时间窗延迟,平均波幅两组无差异,源定位分析（IDRETA）显示青年组可见双颞叶、双前额背外侧区域激活,以右侧明显;老年组主要见左颞叶、左前额背外侧、左前额内侧面区域激活。结论：在反应阶段出现冲突信息时,老年人额叶干扰控制功能减退,差异负波N380与老年人左前额背外侧、左侧颞叶等区域在反应选择、执行控制中的活动有关,且增龄改变明显。     

Neural responses during Valsalva maneuvers in obstructive sleep apnea syndrome.

The repetitive upper airway muscle atonic episodes and cardiovascular sequelae of obstructive sleep apnea (OSA) suggest dysfunction of specific neural sites that integrate afferent airway signals with autonomic and somatic outflow. We determined neural responses to the Valsalva maneuver by using functional magnetic resonance imaging. Images were collected during a baseline and three Valsalva maneuvers in 8 drug-free OSA patients and 15 controls. Multiple cortical, midbrain, pontine, and medullary regions in both groups showed intensity changes correlated to airway pressure. In OSA subjects, the left inferior parietal cortex, superior temporal gyrus, posterior insular cortex, cerebellar cortex, fastigial nucleus, and hippocampus showed attenuated signal changes compared with controls. Enhanced responses emerged in the left lateral precentral gyrus, left anterior cingulate, and superior frontal cortex of OSA patients. The anterior cingulate, cerebellar cortex, and posterior insula exhibited altered response timing patterns between control and OSA subjects. The response patterns in OSA subjects suggest deficits in particular neural pathways that normally mediate the Valsalva maneuver and compensatory actions in other structures.     

Hemispheric dominance of cortical activity evoked by focal electrogustatory stimuli.

Functional magnetic resonance imaging was used to observe cortical hemodynamic responses to electric taste stimuli applied separately to the right and left sides of the tongue tip. In 11 right-handed normal adults activation occurred primarily in the insular cortex, superior temporal lobe, inferior frontal lobe, including premotor regions, and in inferior parts of the postcentral gyrus. Unexpectedly, the location and laterality of activation were largely identical regardless of the side of the tongue stimulated. Activation in the superior insula, the presumed location of primary gustatory cortex, was predominantly, but not exclusively, in the right hemisphere, whereas central (more inferior) insular activations were more evenly bilateral. Right hemispheric dominance of activation also occurred in premotor regions (Brodmann areas 6 and 44), whereas left hemispheric dominance occurred only in the superior temporal cortex (Brodmann areas 22/42). The electric taste-evoked hemodynamic response pattern was more consistent with activation of the gustatory system than activation of somatosensory systems. The results suggest that the sites for cortical processing of electric taste information are dependent on hemispheric specialization.     

Sex differences in neural activation to facial expressions denoting contempt and disgust

The facial expression of contempt has been regarded to communicate feelings of moral superiority. Contempt is an emotion that is closely related to disgust, but in contrast to disgust, contempt is inherently interpersonal and hierarchical. The aim of this study was twofold. First, to investigate the hypothesis of preferential amygdala responses to contempt expressions versus disgust. Second, to investigate whether, at a neural level, men would respond stronger to biological signals of interpersonal superiority (e.g., contempt) than women. We performed an experiment using functional magnetic resonance imaging (fMRI), in which participants watched facial expressions of contempt and disgust in addition to neutral expressions. The faces were presented as distractors in an oddball task in which participants had to react to one target face. Facial expressions of contempt and disgust activated a network of brain regions, including prefrontal areas (superior, middle and medial prefrontal gyrus), anterior cingulate, insula, amygdala, parietal cortex, fusiform gyrus, occipital cortex, putamen and thalamus. Contemptuous faces did not elicit stronger amygdala activation than did disgusted expressions. To limit the number of statistical comparisons, we confined our analyses of sex differences to the frontal and temporal lobes. Men displayed stronger brain activation than women to facial expressions of contempt in the medial frontal gyrus, inferior frontal gyrus, and superior temporal gyrus. Conversely, women showed stronger neural responses than men to facial expressions of disgust. In addition, the effect of stimulus sex differed for men versus women. Specifically, women showed stronger responses to male contemptuous faces (as compared to female expressions), in the insula and middle frontal gyrus. Contempt has been conceptualized as signaling perceived moral violations of social hierarchy, whereas disgust would signal violations of physical purity. Thus, our results suggest a neural basis for sex differences in moral sensitivity regarding hierarchy on the one hand and physical purity on the other.     

Can You Catch a Liar? How Negative Emotions Affect Brain Responses when Lying or Telling the Truth

The capacity to deceive others is a complex mental skill that requires the ability to suppress truthful information. The polygraph is widely used in countries such as the USA to detect deception. However, little is known about the effects of emotional processes (such as the fear of being found guilty despite being innocent) on the physiological responses that are used to detect lies. The aim of this study was to investigate the time course and neural correlates of untruthful behavior by analyzing electrocortical indexes in response to visually presented neutral and affective questions. Affective questions included sexual, shameful or disgusting topics. A total of 296 questions that were inherently true or false were presented to 25 subjects while ERPs were recorded from 128 scalp sites. Subjects were asked to lie on half of the questions and to answer truthfully on the remaining half. Behavioral and ERP responses indicated an increased need for executive control functions, namely working memory, inhibition and task switching processes, during deceptive responses. Deceptive responses also elicited a more negative N400 over the prefrontal areas and a smaller late positivity (LP 550–750 ms) over the prefrontal and frontal areas. However, a reduction in LP amplitude was also elicited by truthful affective responses. The failure to observe a difference in LP responses across conditions likely results from emotional interference. A swLORETA inverse solution was computed on the N400 amplitude (300–400 ms) for the dishonest – honest contrast. These results showed the activation of the superior, medial, middle and inferior frontal gyri (BA9, 11, 47) and the anterior cingulate cortex during deceptive responses. Our results conclude that the N400 amplitude is a reliable neural marker of deception.     

Brain Activity in Advantageous and Disadvantageous Situations: Implications for Reward/Punishment Sensitivity in Different Situations

Objective

This study modeled win and lose trials in a simple gambling task to examine the effect of entire win–lose situations (WIN, LOSS, or TIE) on single win/lose trials and related neural underpinnings.

Methods

The behavior responses and brain activities of 17 participants were recorded by an MRI scanner while they performed a gambling task. Different conditions were compared to determine the effect of the task on the behavior and brain activity of the participants. Correlations between brain activity and behavior were calculated to support the imaging results.

Results

In win trials, LOSS caused less intense posterior cingulate activity than TIE. In lose trials, LOSS caused more intense activity in the right superior temporal gyrus, bilateral superior frontal gyrus, bilateral anterior cingulate, bilateral insula cortex, and left orbitofrontal cortex than WIN and TIE.

Conclusions

The experiences of the participants in win trials showed great similarity among different win–lose situations. However, the brain activity and behavior responses of the participants in lose trials indicated that they experienced stronger negative emotion in LOSS. The participants also showed an increased desire to win in LOSS than in WIN or TIE conditions.     

Pavlovian reward prediction and receipt in schizophrenia: relationship to anhedonia

Reward processing abnormalities have been implicated in the pathophysiology of negative symptoms such as anhedonia and avolition in schizophrenia. However, studies examining neural responses to reward anticipation and receipt have largely relied on instrumental tasks, which may confound reward processing abnormalities with deficits in response selection and execution. 25 chronic, medicated outpatients with schizophrenia and 20 healthy controls underwent functional magnetic resonance imaging using a pavlovian reward prediction paradigm with no response requirements. Subjects passively viewed cues that predicted subsequent receipt of monetary reward or non-reward, and blood-oxygen-level-dependent signal was measured at the time of cue presentation and receipt. At the group level, neural responses to both reward anticipation and receipt were largely similar between groups. At the time of cue presentation, striatal anticipatory responses did not differ between patients and controls. Right anterior insula demonstrated greater activation for nonreward than reward cues in controls, and for reward than nonreward cues in patients. At the time of receipt, robust responses to receipt of reward vs. nonreward were seen in striatum, midbrain, and frontal cortex in both groups. Furthermore, both groups demonstrated responses to unexpected versus expected outcomes in cortical areas including bilateral dorsolateral prefrontal cortex. Individual difference analyses in patients revealed an association between physical anhedonia and activity in ventral striatum and ventromedial prefrontal cortex during anticipation of reward, in which greater anhedonia severity was associated with reduced activation to money versus no-money cues. In ventromedial prefrontal cortex, this relationship held among both controls and patients, suggesting a relationship between anticipatory activity and anhedonia irrespective of diagnosis. These findings suggest that in the absence of response requirements, brain responses to reward receipt are largely intact in medicated individuals with chronic schizophrenia, while reward anticipation responses in left ventral striatum are reduced in those patients with greater anhedonia severity.     

The ubiquity of deception and the ethics of deceptive research

Does the fact that deception is widely practised – even though there is a general prohibition against deception – provide insight into the ethics of deceptive methods in research, especially for social‐behavioral research? I answer in the affirmative. The ubiquity of deception argument, as I will call it, points to the need for a concrete and nuanced understanding of the variety of deceptive practices, and thus promises an alternative route of analysis for why some deception may be permissible in social‐behavioral research. As an alternative argument it also promises to break the stalemate that emerges in debates on the ethics of deceptive methods in social‐behavioral research. In the current paper I (1) motivate and articulate the ubiquity argument in order to clarify the significance of ubiquity and discharge some initial objections. Then, on the recommendations of the ubiquity argument, I (2) highlight the importance of interpersonal relationships for understanding the ethics of deception. Following this insight I (3) provide an analysis of several features of the researcher‐participant relationship relevant to the understanding of the ethics of deception in research. I then (4) conclude the argument with some recommendations for the ethical use of deceptive methods in social‐behavioral research.     

Racial Bias in Neural Empathic Responses to Pain

Recent studies have shown that perceiving the pain of others activates brain regions in the observer associated with both somatosensory and affective-motivational aspects of pain, principally involving regions of the anterior cingulate and anterior insula cortex. The degree of these empathic neural responses is modulated by racial bias, such that stronger neural activation is elicited by observing pain in people of the same racial group compared with people of another racial group. The aim of the present study was to examine whether a more general social group category, other than race, could similarly modulate neural empathic responses and perhaps account for the apparent racial bias reported in previous studies. Using a minimal group paradigm, we assigned participants to one of two mixed-race teams. We use the term race to refer to the Chinese or Caucasian appearance of faces and whether the ethnic group represented was the same or different from the appearance of the participant'' own face. Using fMRI, we measured neural empathic responses as participants observed members of their own group or other group, and members of their own race or other race, receiving either painful or non-painful touch. Participants showed clear group biases, with no significant effect of race, on behavioral measures of implicit (affective priming) and explicit group identification. Neural responses to observed pain in the anterior cingulate cortex, insula cortex, and somatosensory areas showed significantly greater activation when observing pain in own-race compared with other-race individuals, with no significant effect of minimal groups. These results suggest that racial bias in neural empathic responses is not influenced by minimal forms of group categorization, despite the clear association participants showed with in-group more than out-group members. We suggest that race may be an automatic and unconscious mechanism that drives the initial neural responses to observed pain in others.