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1.
The human mirror system: a motor resonance theory of mind-reading   总被引:6,自引:0,他引:6  
Electrophysiological data confirm the existence of neurons that respond to both motor and sensory events in the macaque brain. These mirror neurons respond to execution and observation of goal-orientated actions. It has been suggested that they comprise a neural basis for encoding an internal representation of action. In this paper the evidence for a parallel system in humans is reviewed and the implications for human theory of mind processing are discussed. Different components of theory of mind are discussed; the evidence for mirror activity within subtypes is addressed. While there is substantial evidence for a human mirror system, there are weaknesses in the attempts to localize such a system in the brain. Preliminary evidence indicates that mirror neurons may be involved in theory of mind; however, these data by their very nature are reliant on the presence, and precise characterization, of the human mirror system.  相似文献
2.
BACKGROUND: Oxytocin is known to reduce anxiety and stress in social interactions as well as to modulate approach behavior. Recent studies suggest that the amygdala might be the primary neuronal basis for these effects. METHODS: In a functional magnetic resonance imaging study using a double-blind, placebo-controlled within-subject design, we measured neural responses to fearful, angry, and happy facial expressions after intranasal application of 24 IU oxytocin compared with placebo. RESULTS: Oxytocin reduced right-sided amygdala responses to all three face categories even when the emotional content of the presented face was not evaluated explicitly. Exploratory whole brain analysis revealed modulatory effects in prefrontal and temporal areas as well as in the brainstem. CONCLUSIONS: Results suggest a modulatory role of oxytocin on amygdala responses to facial expressions irrespective of their valence. Reduction of amygdala activity to positive and negative stimuli might reflect reduced uncertainty about the predictive value of a social stimulus and thereby facilitates social approach behavior.  相似文献
3.
It is now widely accepted that visual cortical areas are active during normal tactile perception, but the underlying mechanisms are still not clear. The goal of the present study was to use functional magnetic resonance imaging (fMRI) to investigate the activity and effective connectivity of parietal and occipital cortical areas during haptic shape perception, with a view to potentially clarifying the role of top-down and bottom-up inputs into visual areas. Subjects underwent fMRI scanning while engaging in discrimination of haptic shape or texture, and in separate runs, visual shape or texture. Accuracy did not differ significantly between tasks. Haptic shape-selective regions, identified on a contrast between the haptic shape and texture conditions in individual subjects, were found bilaterally in the postcentral sulcus (PCS), multiple parts of the intraparietal sulcus (IPS) and the lateral occipital complex (LOC). The IPS and LOC foci tended to be shape-selective in the visual modality as well. Structural equation modelling was used to study the effective connectivity among the haptic shape-selective regions in the left hemisphere, contralateral to the stimulated hand. All possible models were tested for their fit to the correlations among the observed time-courses of activity. Two equivalent models emerged as the winners. These models, which were quite similar, were characterized by both bottom-up paths from the PCS to parts of the IPS, and top-down paths from the LOC and parts of the IPS to the PCS. We conclude that interactions between unisensory and multisensory cortical areas involve bidirectional information flow.  相似文献
4.
Self–other discrimination is fundamental to social interaction,however, little is known about the neural systems underlyingthis ability. In a previous functional magnetic resonance imagingstudy, we demonstrated that a right fronto-parietal networkis activated during viewing of self-faces as compared with thefaces of familiar others. Here we used image-guided repetitivetranscranial magnetic stimulation (rTMS) to create a ‘virtuallesion’ over the parietal component of this network totest whether this region is necessary for discriminating self-facesfrom other familiar faces. The current results indeed show that1 Hz rTMS to the right inferior parietal lobule (IPL) selectivelydisrupts performance on a self–other discrimination task.Applying 1 Hz rTMS to the left IPL had no effect. It appearsthat activity in the right IPL is essential to the task, thusproviding for the first time evidence for a causal relationbetween a human brain area and this high-level cognitive capacity.  相似文献
5.
目的应用超高场磁共振功能成像技术进行手术前后研究脑躯体感觉功能区肿瘤与功能区的定位,辅助切除躯体感觉功能区胶质瘤。方法5例邻近或累及躯体感觉功能区的胶质瘤患者,术前行双手持物对接刺激策略,在3.0T磁共振采用血氧水平依赖(BOLD)原理进行图像采集,经工作站(Leonardo syngo 2003A,Siemens)提供的BOLD功能图像分析软件包进行分析获得脑运动功能区的激活图像,参与神经外科手术方案的制定。所有患者均在唤醒麻醉下进行显微外科手术,在术前脑功能磁共振图像指导下利用皮质直接电刺激定位感觉区与运动区。在保护脑功能区功能不受损的前提下,最大程度地切除胶质瘤。术前、术后均行KPS评分,判断患者的状态。结果(1)5例躯体感觉功能区胶质瘤,通过此项技术获得了较好的BOLD功能磁共振成像感觉功能区激活图像,定位躯体感觉功能区。(2)患者在唤醒麻醉下,在术前脑功能磁共振图像指导下利用直接皮质电刺激快捷、准确进行中央后回定位,两者具有良好的一致性。结论应用3.0T MRI可以于术前更好地利用BOLD技术显示躯体感觉功能区与脑胶质瘤的解剖关系,以指导唤醒麻醉下直接皮质电刺激定位躯体感觉功能区的手术,实现最大程度保护患者重要的功能并最大程度地切除肿瘤。  相似文献
6.
功能磁共振与皮层电刺激定位感觉运动区的比较   总被引:2,自引:1,他引:1  
目的 通过功能磁共振(fMRI)与皮层电刺激做点对点的比较,以判断fMRI对感觉运动区定位的精确性,从而评价其在功能定位中的意义及其临床应用价值.方法 对14例EEG示异常放电部位位于感觉运动区的难治性癫痫患者,术前采用双手握拳-伸缩运动任务进行血氧依赖水平(BOLD)扫描,运用BOLD技术的fMRI定位皮质感觉运动区.皮层电极植入术后给予头颅连续无间断CT扫描获取电极与颅骨的对应关系,通过神经导航仪将CT、fMRI影像与导航序列MRI图像融合后,得出含有皮层激活区和电极的融合图像建立三维立体图像,与皮层电刺激.结果进行比较,以评价fMRI定位皮质感觉运动区的准确性.结果 14例fMRI可见激活部位主要分布于对侧中央区、辅助运动区和小脑.其中11例成功完成皮层电刺激,结果显示fMRI与电刺激的吻合率为91.7%.结论 BOLD技术具有较高的敏感性和精确率,对感觉运动区定位有重要的临床应用价值.  相似文献
7.
EEG source localization in focal epilepsy: Where are we now?   总被引:2,自引:0,他引:2  
Plummer C  Harvey AS  Cook M 《Epilepsia》2008,49(2):201-218
Electroencephalographic source localization (ESL) by noninvasive means is an area of renewed interest in clinical epileptology. This has been driven by innovations in the computer-assisted modeling of dipolar and distributed sources for the investigation of focal epilepsy; a process fueled by the ever-increasing computational power available to researchers for the analysis of scalp EEG recordings. However, demonstration of the validity and clinical utility of these mathematically derived source modeling techniques has struggled to keep pace. This review evaluates the current clinical "fitness' of ESL as applied to the focal epilepsies by examining some of the key studies performed in the field, with emphasis given to clinical work published in the last five years. In doing so, we discuss why ESL techniques have not made an impact on routine epilepsy practice, underlining some of the current problems and controversies in the field. We conclude by examining where ESL currently sits alongside magnetoencephalography and combined EEG-functional magnetic resonance imaging in the investigation of focal epilepsy.  相似文献
8.
Purpose: Language functional magnetic resonance imaging (fMRI) is used to noninvasively assess hemispheric language specialization as part of the presurgical work-up in temporal lobe epilepsy (TLE). White matter asymmetries on diffusion tensor imaging (DTI) may be related to language specialization as shown in controls and TLE. To refine our understanding of the effect of epilepsy on the structure–function relationships, we focused on the arcuate fasciculus (ArcF) and the inferior occipitofrontal fasciculus (IOF) and tested the relationship between DTI- and fMRI-based lateralization indices in TLE.
Methods: fMRI with three language tasks and DTI were obtained in 20 patients (12 right and 8 left TLE). The ArcF, a major language-related tract, and the IOF were segmented bilaterally using probabilistic tractography to obtain fractional anisotropy (FA) lateralization indices. These were correlated with fMRI-based lateralization indices computed in the inferior frontal gyrus (Pearson's correlation coefficient).
Results: fMRI indices were left-lateralized in 16 patients and bilateral or right-lateralized in four. In the ArcF, FA was higher on the left than on the right side, reaching significance in right but not in left TLE. We found a positive correlation between ArcF anisotropy and fMRI-based lateralization indices in right TLE (p < 0.009), but not in left TLE patients. No correlation was observed for the IOF.
Conclusions: Right TLE patients with more left-lateralized functional activations also showed a leftward-lateralized arcuate fasciculus. The decoupling between the functional and structural indices of the ArcF underlines the complexity of the language network in left TLE patients.  相似文献
9.
Internal models are neural mechanisms that can mimic the input-output properties of controlled objects. Our studies have shown that: 1) an internal model for a novel tool is acquired in the cerebellum (Imamizu et al., 2000); 2) internal models are modularly organized in the cerebellum (Imamizu et al., 2003); 3) their outputs are sent to the premotor regions after learning (Tamada et al., 1999); and 4) the prefrontal and parietal regions contribute to the blending of the outputs (Imamizu et al., 2004). Here, we investigated changes in global neural networks resulting from the acquisition of a new internal model. Human subjects manipulated three types of rotating joystick whose cursor appeared at a position rotated 60 degrees, 110 degrees, or 160 degrees around the screen's center. In a pre-test after long-term training (5 days) for the 60 degrees and 160 degrees joysticks, brain activation was scanned during manipulation of the three joysticks. The subjects were then trained for the 110 degrees for only 25 min. In a post-test, activation was scanned using the same method as the pre-test. Comparisons of the post-test to the pre-test revealed that the volume of activation decreased in most of the regions where activation for the three rotations was observed. However, there was an increase in volume at a marginally significant level (p < .08) only in the inferior-lateral cerebellum and only for the 110 degrees joystick. In the cerebral cortex, activation related to 110 degrees decreased in the prefrontal and parietal regions but increased in the premotor and supplementary motor area (SMA) regions. These results can be explained by a model in which outputs of the 60 degrees and 160 degrees internal models are blended by prefrontal and parietal regions to cope with the novel 110 degrees joystick before the 25-minute training; after the acquisition within the cerebellum of an internal model for the 110 degrees, output is directly sent to the premotor and SMA regions, and activation in these regions increases.  相似文献
10.
Studies of categories of objects, including tools, have spurred the development of the sensory-motor model of object concept representation. According to this model, information about objects is represented in the same neural subsystems that are active when we perceive and use them. In turn, this model has provided insight into the brain mechanisms of tool use. For tools, three types of information are especially important for identification: the characteristic motion with which they move (such as the up and down motion of a hammer), their visual form, and the way that they are manipulated. Evidence from neuropsychological, non-human primates, and neuroimaging studies suggest a mapping between specific brain regions and these fundamental identifying properties of tools. We focus on neuroimaging studies of the left posterior middle temporal gyrus. This brain region is active both when subjects perceive moving tools and when they answer questions about tools, and is responsive to the type of visual motion characteristic of tools: rigid, unarticulated motion. We describe a simple model that explains how low-level receptive field properties like those known to exist in area MT/V5 could give rise to the high-level category-related representations observed in functional imaging experiments.  相似文献
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