Comparison of spiral-in/out and spiral-out BOLD fMRI at 1.5 and 3 T

Spiral-in/out functional magnetic resonance imaging (fMRI) methods acquire one image before the echo time (TE) and a second image after TE during each scan. Weighted combination of the two images provides a time series with reduced susceptibility dropout in frontal and medial temporal regions as well as increased signal-to-noise ratio (SNR) in regions of uniform cortex. In this study, task activation with the spiral-in/out method was compared to that with conventional spiral-out acquisitions at two field strengths (1.5 and 3.0 T) using episodic memory encoding, verbal working memory, and affective processing tasks in eight human volunteers. With the conventional spiral-out sequence, greater signal dropout is observed in lateral and medial prefrontal, amygdalar, and medial temporal regions at 3 T relative to 1.5 T, whereas such dropout at 3 T is reduced or mitigated with the spiral-in/out method. Similarly, activation volumes for frontal, amygdalar, and medial temporal regions are reduced for spiral-out acquisitions relative to spiral-in/out, and this difference is more apparent at 3 T than at 1.5 T. In addition, significant regionally specific increases in Z scores are obtained with the spiral-in/out sequence relative to spiral-out acquisitions at both field strengths. It is concluded the spiral-in/out sequence may provide significant advantages over conventional spiral methods, especially at 3 T.     

An fMRI Investigation of Cortical Contributions to Spatial and Nonspatial Visual Working Memory

The experiments presented in this report were designed to test the hypothesis that visual working memory for spatial stimuli and for object stimuli recruits separate neuronal networks in prefrontal cortex. We acquired BOLD fMRI data from subjects while they compared each serially presented stimulus to the one that had appeared two or three stimuli previously. Three experiments failed to reject the null hypothesis that prefrontal cortical activity associated with spatial working memory performance cannot be dissociated from prefrontal cortical activity associated with nonspatial working memory performance. Polymodal regions of parietal cortex (inferior and superior parietal lobules), as well as cortex surrounding the superior frontal sulcus (and encompassing the frontal eye fields), also demonstrated equivalent levels of activation in the spatial and object conditions. Posterior cortical regions associated with the ventral visual processing stream (portions of lingual, fusiform, and inferior temporal gyri), however, demonstrated greater object than spatial working memory-related activity, particularly when stimuli varied only along spatial or featural dimensions. These experiments, representing fMRI studies of spatial and object working memory in which the testing procedure and the stimuli were identical in the two conditions, suggest that domain-specific visual working memory processing may be mediated by posterior regions associated with domain-specific sensory processing.     

Practice-induced changes of brain function during visual attention: a parametric fMRI study at 4 Tesla

A parametric functional MRI (fMRI) study with three levels of task difficulty was performed to determine the effect of practice and attentional load on brain activation during visual attention tasks. Brief practice during repeat fMRI scanning (20 min) did not change performance accuracy or reaction times (RT), but decreased activation bilaterally in the inferior, middle, and superior frontal gyri, superior temporal gyrus, thalamus, and cerebellum. Increased attentional load decreased performance accuracy but not RT, and increased activation bilaterally in the inferior, posterior, and superior parietal cortices, thalamus, cerebellum, and frontal gyri. These changes suggest that practice decreases dependency on thalamus, cerebellum, and the frontal cortices for controlled task processing possibly due to increased efficiency of the attentional network. Since short-term practice-effects in the prefrontal cortex may be similar to attentional load-effects, studies of attentional load need to take practice effects into account.     

Working Memory of Identification of Emotional Vocal Expressions: An fMRI Study

The distribution of brain activation during working memory processing of emotional vocal expressions was studied using functional magnetic resonance imaging (fMRI) in eight female subjects performing n-back tasks with three load levels (0-back, 1-back, and 2-back tasks). The stimuli in the n-back tasks were the Finnish female name [Saara] uttered in an astonished, angry, frightened, commanding, and scornful mode, and the subjects were instructed to memorize the emotional connotation of the stimuli. Subregions in the prefrontal, parietal, and visual association areas were load-dependently activated during the performance of the n-back tasks. The most consistently activated areas in the prefrontal region were detected in the inferior frontal gyrus corresponding to Brodmann's areas (BAs) 44 and 45 and in the middle and superior frontal gyri (BAs 6/8). Activation was also found in the inferior parietal lobe and intraparietal sulcus (BAs 40/7) and visual association areas including the lingual and fusiform gyri. The results suggest that a distributed neuronal network in occipital, parietal, and frontal areas is involved in working memory processing of emotional content of aurally presented information.     

首发精神分裂症患者威斯康星卡片分类测验中的脑功能障碍研究

目的:探讨首发未服药精神分裂症患者进行威斯康星卡片分类测验(WCST)操作时的脑功能状态特点。方法:20名健康受试者(对照组)和20名首发未服药精神分裂症患者(患者组)操作WCST和颜色卡片分类测验(CCST)时进行脑功能磁共振成像(fMRI),比较2组激活脑区的激活体积。结果:对照组WCST和CCST功能图像相减获得的脑活动功能图像显示,激活主要分布在双侧前额叶,尤其是背外侧部以及顶叶后下部皮质和前扣带回。患者组WCST操作成绩较对照组差,有显著性差异(P<0.01)。与对照组相比,患者组的左侧前额叶背外侧部、左前扣带回皮质激活低下,左顶叶后下部皮质激活增加(P<0.01或0.05)。结论:双侧前额叶,尤其是背外侧部,以及顶叶后下部皮质和前扣带回皮质参与WCST操作的高级认知过程。精神分裂症患者在未治疗前就存在执行功能缺陷,其前额叶和扣带回功能低下,可能与患者执行功能障碍相关;后顶叶皮质功能亢进,可能对前额叶功能低下有补偿作用。     

Prolonged reaction time to a verbal working memory task predicts increased power of posterior parietal cortical activation

We used multislice functional magnetic resonance imaging (fMRI) to investigate the association between behavioral and neurophysiological measures of working memory task performance in 20 right-handed male healthy volunteers. Images were acquired over a 5-min period at 1.5 Tesla. We used a periodic design, alternating 30-s blocks of the "n-back" working memory task with 30-s blocks of a sensorimotor control task to activate verbal working memory systems. The power of functional response to the task was estimated by sinusoidal regression at each voxel. The relationship between power of fMRI response and mean reaction time over all 11 working memory trials was explored by multiple regression, with age and mean reaction time to the control task as covariates, at voxel and regional levels of analysis. All subjects were able to perform the n-back task accurately. A spatially distributed network was activated, including dorsolateral prefrontal cortex, inferior frontal gyrus, lateral premotor cortex, and supplementary motor area (SMA) in the frontal lobes. More posteriorly, there were major foci of activation in parietal and occipitoparietal cortex, precuneus, lingual, and fusiform gyri of the ventral occipital lobe, inferior temporal gyrus, and cerebellum. The power of functional response was positively correlated with reaction time in bilateral posterior parietal cortex (Talairach coordinates in x, y, z (mm) 35, -44, 37 and -32, -56, 42), indicating that subjects who found the task difficult, and responded with a slower reaction time, tended to activate these regions more powerfully. One interpretation of this regionally specific relationship between prolonged reaction time and increased power of posterior parietal activation is consistent with prior studies identifying similar areas of parietal cortex as the site of the phonological storage function in verbal working memory.     

汉字与英文字形辨认的脑功能磁共振成像初步研究

目的:探讨功能磁共振成像(fMRI)技术研究人脑汉字与英文字形辨认方面的价值。材料与方法:12例(男5例,女7例)母语为汉语且裸眼视力正常的大学生参加实验。设备为GE Signa 1.5T MR仪,采用EPI序列,BOLD法行脑功能磁共振扫描。实验任务分别将汉字与英文(真字、假字、非字)投射到屏幕上,受试者通过头线圈反光镜观看屏幕并辨认。数据分析使用SPM 99升级软件,经过数据采集、预处理和建立模型显示结果。结果:汉字真字刺激在左额叶、中央前回(BA6)及枕叶(BA18)显著激活;左顶叶、中央后回(BA3)、右额下回(BA9)及双侧颞叶少量激活。英文真字刺激时左额中回、中央前回、左额下回显著激活;左颞梭状回(BA37)、右枕语言回(BA18)及左顶叶(BA40)也有激活。汉字和英文假字与非字只引起少量激活(P>0.05)。汉字与英文刺激左大脑半球的激活体积明显大于右半球;除枕叶外,英文在额、颞及顶叶引起的激活体积均大于汉字。结论:fMRI是研究人脑汉字和英文语言加工理想的无创性影像学方法,其脑加工优势半球均为左半球;母语为汉语者,其英文脑处理过程需更多的脑活动来参与和完成。     

A developmental fMRI study of the Stroop color-word task

We used fMRI to investigate developmental changes in brain activation during a Stroop color-word interference task. A positive correlation was observed between age and Stroop-related activation (n = 30) in the left lateral prefrontal cortex, the left anterior cingulate, and the left parietal and parieto-occipital cortices. No regions showed a negative correlation between activation and age. We further investigated age-related differences by stratifying the sample into three age groups: children (ages 7-11), adolescents (ages 12-16), and young adults (ages 18-22). Young adult subjects (n = 11) displayed significant activation in the inferior and middle frontal gyri bilaterally, the left anterior cingulate, and bilateral inferior and superior parietal lobules. Between-group comparisons revealed that young adults had significantly greater activation than adolescent subjects (n = 11) in the left middle frontal gyrus and that young adults showed significantly greater activation than children (n = 8) in the anterior cingulate and left parietal and parieto-occipital regions, as well as in the left middle frontal gyrus. Compared to children, both adult and adolescent subjects exhibited significantly greater activation in the parietal cortex. Adult and adolescent groups, however, did not differ in activation for this region. Together, these data suggest that Stroop task-related functional development of the parietal lobe occurs by adolescence. In contrast, prefrontal cortex function contributing to the Stroop interference task continues to develop into adulthood. This neuromaturational process may depend on increased ability to recruit focal neural resources with age. Findings from this study, the first developmental fMRI investigation of the Stroop interference task, provide a template with which normal development and neurodevelopmental disorders of prefrontal cortex function can be assessed.     

Optimized voxel-based morphometry in children with developmental dyscalculia

Developmental dyscalculia (DD) is a specific learning disability affecting the normal acquisition of arithmetic skills. Current studies estimate that 3-6% of the school population is affected by DD. Genetic, neurobiological, and epidemiologic evidence indicates that dyscalculia is a brain-based disorder. Imaging studies suggest the involvement of parietal and prefrontal cortices in arithmetic tasks. The aim of the present study was to analyze if children with DD show structural differences in parietal, frontal, and cingulate areas compared to typically achieving children. Magnetic resonance imaging was obtained from 12 children with DD aged 9.3+/-0.2 years and 12 age-matched control children without any learning disabilities on a 1.5 T whole-body scanner. Voxel-based morphometry analysis with an optimization of spatial segmentation and normalization procedures was applied to compare the two groups in order to find differences in cerebral gray and white matter. Compared to controls, children with DD show significantly reduced gray matter volume in the right intraparietal sulcus (IPS), the anterior cingulum, the left inferior frontal gyrus, and the bilateral middle frontal gyri. White matter comparison demonstrates clusters with significantly less volume in the left frontal lobe and in the right parahippocampal gyrus in dyscalculic children. The decreased gray and white matter volumes in the frontoparietal network might be the neurological substrate of impaired arithmetic processing skills. The white matter volume decrease in parahippocampal areas may have influence on fact retrieval and spatial memory processing.     

Evidence of enhancement of spatial attention during inhibition of a visuo-motor response

A visuo-motor task was used as the setting for a study into inhibition in six healthy volunteers using fMRI. The task involved responding to colored stimuli, which appeared at random positions in the left and right visual field, with the corresponding hand. The volunteers were asked to respond to green colored stimuli ("go" response) and to inhibit responses to red stimuli ("no-go" response). The task was presented in a block design with blocks of three types; only "go" trials, a pseudo-random mixture of "go" and "no-go" tasks ("go/no-go" block), and "visual control." ANCOVA analysis of the fMRI data was performed within the framework of SPM99. Increased activation in the go vs visual control comparison was found in the bilateral motor and medial premotor cortices associated with the action of the button press response, as well as parietal regions attending to the task of identifying the visual field. The go/no-go vs visual control comparison showed a similar pattern, plus additional prefrontal areas that have previously been shown to be associated with inhibition. The direct comparison of the go and go/no-go blocks highlighted large differences not only in the prefrontal cortices, associated with inhibition, but also particularly in the right parietal cortex. We interpret the increased parietal activation, during inhibition, as representing a heightened spatial attention required for the correct execution of the inhibition task.     

熟练蒙汉双语者语义加工脑机制的fMRI分析

目的探讨熟练蒙汉双语者在蒙语和汉语语义信息加工的脑机制。方法对15右利手、蒙汉双语熟练的健康志愿者(男8名,女7名)进行fMRI测试,分析采用蒙语及汉语词语的语义判断任务。应用AFNI软件分析两种语言任务的脑功能激活情况及其差异。结果在汉语及蒙语语义信息加工过程中,语义加工的经典脑区均被激活,包括左侧颞中回、左侧后顶叶、左侧前额叶等区域。比较加工蒙语及汉语的语义信息过程,蒙语任务下左侧楔回及右侧梭状回的激活显著增加,汉语任务下在左侧颞中回后部、左侧额中回及额下回三角部、左侧顶上小叶的脑激活比蒙语显著增加。结论熟练蒙汉双语者在加工蒙语及汉语时,存在功能加工脑区的分离。fMRI研究能为双语者的语言加工脑机制提供影像学依据。     

精神分裂症空间工作记忆任务的fMRI研究

目的采用fMRI技术探讨精神分裂症患者空间工作记忆损害的神经机制。方法收集18例精神分裂症患者和18名正常受试者进行空间n-back任务的fMRI扫描。采用SPM 8进行数据预处理和统计分析,单样本t-检验用于分析两组各自脑激活结果,双样本t-检验用于工作记忆相关脑激活的组间比较。采用FDR方法进行多重比较校正。利用SPSS 17.0软件对工作记忆任务中的行为学结果 (正确率和反应时间)进行组间比较。结果与对照组相比,精神分裂症患者空间工作记忆任务反应时间延长(882.00±50.31)ms,正确率下降(83.60±2.90)%(P0.05)。精神分裂症患者在n-back空间工作记忆任务时所激活的脑区分布与对照组基本一致,主要包括双侧前额皮层、颞顶叶皮层及部分基底核团。但组间比较显示精神分裂症患者多个脑区激活强度及范围明显增加,包括双侧前额皮层背外侧、双侧后顶叶皮层、右侧中央前回、左侧颞中回、右扣带回和双侧小脑(FDR校正,P0.05)。结论执行空间工作记忆任务时精神分裂症患者脑区激活增加,但行为学表现下降,提示患者脑区活动效率低下,可能是工作记忆能力损害的神经基础。     

Brain activation in response to bladder filling and simultaneous stimulation of the dorsal clitoral nerve--an fMRI study in healthy women

AIMS: Using functional magnetic resonance imaging (fMRI) we investigated the cortical and subcortical representations during bladder filling and the effect of simultaneous stimulation of the dorsal clitoral nerve on these cortical and subcortical structures. METHODS: After approval of the local ethics committee, 8 healthy females were included. Prior to scanning, subjects were catheterized and the bladder was filled until first desire to void occurred. In a block design protocol we performed repetitive manual bladder filling (FILLING) and emptying of additional 80 ml saline, alternating with rest conditions (REST) of constant bladder volume. The protocol was repeated with simultaneous stimulation of the dorsal clitoral nerve during the filling periods (COMBINED). Activation maps were calculated by means for 3 different contrasts: 1) FILLING>REST, 2) COMBINED>REST and 3) FILLING>COMBINED. RESULTS: A group analysis of contrast 1) showed activation of the right prefrontal and orbitofrontal cortices, the insula bilaterally, the left precuneus, the parietal operculum bilaterally, the cerebellum bilaterally (q(FDR)< or =0.001), the right anterior cingulate gyrus (q(FDR)< or =0.005) and the right anterior mid pons (q(FDR)< or =0.05). Contrast 2) showed activation in the right frontal area, the left insula, the parietal operculum bilaterally and the left cerebellum (q(FDR)< or =0.001). Deactivations were found in the middle frontal gyrus bilaterally and the post- and paracentral gyri bilaterally. Contrast 3) revealed stronger activation during FILLING in the bilateral frontal and prefrontal areas, the right anterior cingulated gyrus, and the right putamen (q(FDR)< or =0.05). Only the right insula showed stronger activation during the COMBINED condition. CONCLUSION: Simultaneous dorsal clitoral nerve stimulation during bladder filling reduced the activation of certain cortical areas suggesting a neuromodulatory effect of this stimulation on supraspinal centres involved in lower urinary tract control.     

Load response functions in the human spatial working memory circuit during location memory updating

Previous studies have emphasized that the dorsolateral prefrontal cortex is important for manipulating information in working memory, although activations in other frontal and parietal areas are commonly observed under the same conditions. We conducted an fMRI experiment to examine brain responses as a parametric function of memory updating, which is considered as an elemental process in working memory. In a variant spatial delayed-response task, human subjects performed updating operations over a 9-second delay period, during which they mentally transform the location of a memorized target in a 4 by 4 grid according to 3 to 12 instruction cues. Activity increased monotonically with increasing updating load in numerous cortical and subcortical regions including the rostrodorsal premotor (rdPM), lateral precentral sulcus, lateral prefrontal, posterior associative, striatal and cerebellar areas. The rdPM and superior parietal were particularly sensitive to the updating manipulation. There were several main findings. First, updating spatial working memory involved mostly the same cortical and subcortical regions that were activated during maintenance of spatial information. Second, the updating load response functions of regions in the spatial working memory circuit showed a strong linear component. However, none shows significant increases in activity from 9 to 12 updating operations. Third, activity in the right rdPM and anterior inferior frontal gyrus correlated positively with working memory performance in the high updating load condition. Our findings suggest that updating and maintenance of spatial information may share similar processes and that the rostrodorsal premotor cortex and anterior inferior frontal gyrus may be important for the success of tracking spatial information in working memory.     

Linear and nonlinear prefrontal and parietal activity during multiple-item working memory

Most parts of the prefrontal and posterior parietal cortices show sustained activity during short-term maintenance of visual information and their activity increases with increasing memory set size. To investigate the interplay of feature selectivity, memory load and inter-item interaction (or interference) on sustained activity, we compared and contrasted fMRI signal during the retention of two items from the same or different visual feature categories (e.g., two line orientations versus a line and a color) relative to the retention of single items. Data from 16 young adults revealed three types of activation patterns in the prefrontal and posterior parietal cortices. First, among the prefrontal and posterior parietal areas that showed preferential responses to line orientations, some exhibited linear increases in sustained activity whereas others exhibited nonlinear increases in correspondence to the number of lines in the memory set. Second, the right lateral prefrontal and ventral posterior parietal areas, albeit not showing differential sustained activity relative to lines or colors, were disproportionately more active during holding two lines in comparison to holding a line and a color. Third, the left posterior intraparietal sulcus showed a weak effect of memory set size regardless of the items' visual features. These observations suggest that rather than number of items, a combination of factors such as visual feature and memory-set homogeneity may have the greater influence on prefrontal and parietal activity during multiple-item working memory. This is consistent with the view that working memory capacity is influenced by the level of interaction or interference between visual stimuli, which is stronger between items from the same feature category.     

Neurodevelopmental changes in verbal working memory load-dependency: an fMRI investigation

Development of working memory (WM) aptitude parallels structural changes in the frontal–parietal association cortices important for performance within this cognitive domain. The cerebellum has been proposed to function in support of the postulated phonological loop component of verbal WM, and along with frontal and parietal cortices, has been shown to exhibit linear WM load-dependent activation in adults. It is not known if these kinds of WM load-dependent relationships exist for cerebro-cerebellar networks in developmental populations, and whether there are age-related changes in the nature of load-dependency between childhood, adolescence, and adulthood. The present study used fMRI and a verbal Sternberg WM task with three load levels to investigate developmental changes in WM load-dependent cerebro-cerebellar activation in a sample of 30 children, adolescents, and young adults between the ages of 7 and 28. The neural substrates of linear load-dependency were found to change with age. Among adolescents and adults, frontal, parietal and cerebellar regions showed linear load-dependency, or increasing activation under conditions of increasing WM load. In contrast, children recruited only left ventral prefrontal cortex in response to increasing WM load. These results demonstrate that, while children, adolescents, and young adults activate similar cerebro-cerebellar verbal working memory networks, the extent to which they rely on parietal and cerebellar regions in response to increasing task difficulty changes significantly between childhood and adolescence.     

Functional neuroanatomy of auditory working memory in schizophrenia: relation to positive and negative symptoms

Functional brain imaging studies of working memory (WM) in schizophrenia have yielded inconsistent results regarding deficits in the dorsolateral prefrontal (DLPFC) and parietal cortices. In spite of its potential importance in schizophrenia, there have been few investigations of WM deficits using auditory stimuli and no functional imaging studies have attempted to relate brain activation during auditory WM to positive and negative symptoms of schizophrenia. We used a two-back auditory WM paradigm in a functional MRI study of men with schizophrenia (N = 11) and controls (N = 13). Region of interest analysis was used to investigate group differences in activation as well as correlations with symptom scores from the Brief Psychiatric Rating Scale. Patients with schizophrenia performed significantly worse and were slower than control subjects in the WM task. Patients also showed decreased lateralization of activation and significant WM related activation deficits in the left and right DLPFC, frontal operculum, inferior parietal, and superior parietal cortex but not in the anterior cingulate or superior temporal gyrus. These results indicate that in addition to the prefrontal cortex, parietal cortex function is also disrupted during WM in schizophrenia. Withdrawal-retardation symptom scores were inversely correlated with frontal operculum activation. Thinking disturbance symptom scores were inversely correlated with right DLPFC activation. Our findings suggest an association between thinking disturbance symptoms, particularly unusual thought content, and disrupted WM processing in schizophrenia.     

Males and females differ in brain activation during cognitive tasks

To examine the effect of gender on regional brain activity, we utilized functional magnetic resonance imaging (fMRI) during a motor task and three cognitive tasks; a word generation task, a spatial attention task, and a working memory task in healthy male (n = 23) and female (n = 10) volunteers. Functional data were examined for group differences both in the number of pixels activated, and the blood-oxygen-level-dependent (BOLD) magnitude during each task. Males had a significantly greater mean activation than females in the working memory task with a greater number of pixels being activated in the right superior parietal gyrus and right inferior occipital gyrus, and a greater BOLD magnitude occurring in the left inferior parietal lobe. However, despite these fMRI changes, there were no significant differences between males and females on cognitive performance of the task. In contrast, in the spatial attention task, men performed better at this task than women, but there were no significant functional differences between the two groups. In the word generation task, there were no external measures of performance, but in the functional measurements, males had a significantly greater mean activation than females, where males had a significantly greater BOLD signal magnitude in the left and right dorsolateral prefrontal cortex, the right inferior parietal lobe, and the cingulate. In neither of the motor tasks (right or left hand) did males and females perform differently. Our fMRI findings during the motor tasks were a greater mean BOLD signal magnitude in males in the right hand motor task, compared to females where males had an increased BOLD signal magnitude in the right inferior parietal gyrus and in the left inferior frontal gyrus. In conclusion, these results demonstrate differential patterns of activation in males and females during a variety of cognitive tasks, even though performance in these tasks may not vary, and also that variability in performance may not be reflected in differences in brain activation. These results suggest that in functional imaging studies in clinical populations it may be sensible to examine each sex independently until this effect is more fully understood.     

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.     

Watching social interactions produces dorsomedial prefrontal and medial parietal BOLD fMRI signal increases compared to a resting baseline

Some human brain areas are tonically active in a resting state when subjects are not engaged in any overt task. The activity of these areas decreases when subjects are engaged in a wide variety of laboratory tasks designed to study cognitive operations. It has been suggested that these areas, among them the medial parietal (precyneus) and the dorsomedial prefrontal cortices, may support a "default state" of the human brain. Passive visual observation of laboratory stimuli typically yields no change in activity in these default areas compared to rest. Here we report functional magnetic resonance imaging (fMRI) data on normal subjects watching realistic movie clips depicting everyday social interactions. In contrast with previous findings on default state brain areas, the observation of the relational segment of the movie clip, during which two persons interact, yielded increased activity in the medial parietal (precuneus) and dorsomedial prefrontal cortices, compared to rest and to observation of the segment of the movie clip depicting a single individual engaged in everyday activities. To the best of our knowledge, this is the first report of joint increased activity in medial parietal and dorsomedial prefrontal cortices. We suggest that the default state areas may participate in the processing of social relations in concert with regions previously identified as critical for social cognition that were also activated by our stimuli, including the inferior frontal cortex, the superior temporal cortex, and the fusiform gyrus.