共查询到20条相似文献，搜索用时 46 毫秒
1.
自信是现代人优秀的个性品质,也是自信进取性的重要构成要素.为研究自信的神经起源,采用静息态功能磁共振成像技术,以大脑自发神经活动的低频振幅、功能连接分析来探究与自信相关的脑区及脑网络.结果发现:左侧颞中回、右侧颞下回和中央后回的低频振幅值与自信有紧密关系;右侧颞下回与左侧中央前回和右侧中央后回之间的连接强度与自信正相关,该脑区与双侧额中回、右侧额上回、左侧顶上小叶和左侧扣带回之间的连接强度与自信负相关;右侧中央后回与双侧脑岛、右侧颞中回、左侧颞上回、左侧额上回的连接强度与自信正相关,与左侧楔前叶的连接强度和自信负相关.这些大脑区域连接与自信的关系表明自信品质具有广泛的脑功能网络基础,为自信及相关研究提供了新证据. 相似文献
2.
为探讨符号和非符号数量加工的特异性和非特异性问题以及二者间相互转换的神经机制,利用功能性近红外光谱成像技术(fNIRS)对30名成人进行测量,实验中让被试完成数量适应范式任务,结果发现:(1)非符号数量加工主要激活脑区为右顶上叶、右额上回和左右额中回,而符号数量加工则主要在左额中回有显著激活,且只有符号数量加工中出现了距离效应;(2)非符号向符号数量转换由左右顶上叶、左额上回和左右额中回负责,而符号向非符号数量转换则是由左顶上叶和左右额上回负责.研究结果既支持了符号和非符号数量加工的特异性观点,又进一步揭示符号和非符号数量相互转换有着不同的神经机制. 相似文献
3.
The human frontal cortex helps mediate working memory, a system that is used for temporary storage and manipulation of information and that is involved in many higher cognitive functions. Working memory includes two components: short-term storage (on the order of seconds) and executive processes that operate on the contents of storage. Recently, these two components have been investigated in functional neuroimaging studies. Studies of storage indicate that different frontal regions are activated for different kinds of information: storage for verbal materials activates Broca's area and left-hemisphere supplementary and premotor areas; storage of spatial information activates the right-hemisphere premotor cortex; and storage of object information activates other areas of the prefrontal cortex. Two of the fundamental executive processes are selective attention and task management. Both processes activate the anterior cingulate and dorsolateral prefrontal cortex. 相似文献
4.
Miyashita Y 《Science (New York, N.Y.)》2004,306(5695):435-440
A brain-wide distributed network orchestrates cognitive memorizing and remembering of explicit memory (i.e., memory of facts and events). The network was initially identified in humans and is being systematically investigated in molecular/genetic, single-unit, lesion, and imaging studies in animals. The types of memory identified in humans are extended into animals as episodic-like (event) memory or semantic-like (fact) memory. The unique configurational association between environmental stimuli and behavioral context, which is likely the basis of episodic-like memory, depends on neural circuits in the medial temporal lobe, whereas memory traces representing repeated associations, which is likely the basis of semantic-like memory, are consolidated in the domain-specific regions in the temporal cortex. These regions are reactivated during remembering and contribute to the contents of a memory. Two types of retrieval signal reach the cortical representations. One runs from the frontal cortex for active (or effortful) retrieval (top-down signal), and the other spreads backward from the medial temporal lobe for automatic retrieval. By sending the top-down signal to the temporal cortex, frontal regions manipulate and organize to-be-remembered information, devise strategies for retrieval, and also monitor the outcome, with dissociated frontal regions making functionally separate contributions. The challenge is to understand the hierarchical interactions between these multiple cortical areas, not only with a correlational analysis but also with an interventional study demonstrating the causal necessity and the direction of the causality. 相似文献
5.
Conversion of new memories into a lasting form may involve the gradual refinement and linking together of neural representations stored widely throughout neocortex. This consolidation process may require coordinated reactivation of distributed components of memory traces while the cortex is "offline," i.e., not engaged in processing external stimuli. Simultaneous neural ensemble recordings from four sites in the macaque neocortex revealed such coordinated reactivation. In motor, somatosensory, and parietal cortex (but not prefrontal cortex), the behaviorally induced correlation structure and temporal patterning of neural ensembles within and between regions were preserved, confirming a major tenet of the trace-reactivation theory of memory consolidation. 相似文献
6.
McGaugh JL 《Science (New York, N.Y.)》2000,287(5451):248-251
The memory consolidation hypothesis proposed 100 years ago by Müller and Pilzecker continues to guide memory research. The hypothesis that new memories consolidate slowly over time has stimulated studies revealing the hormonal and neural influences regulating memory consolidation, as well as molecular and cellular mechanisms. This review examines the progress made over the century in understanding the time-dependent processes that create our lasting memories. 相似文献
7.
Little is known about the neuronal mechanisms that subserve long-term memory persistence in the brain. The components of the remodeled synaptic machinery, and how they sustain the new synaptic or cellwide configuration over time, are yet to be elucidated. In the rat cortex, long-term associative memories vanished rapidly after local application of an inhibitor of the protein kinase C isoform, protein kinase M zeta (PKMzeta). The effect was observed for at least several weeks after encoding and may be irreversible. In the neocortex, which is assumed to be the repository of multiple types of long-term memory, persistence of memory is thus dependent on ongoing activity of a protein kinase long after that memory is considered to have consolidated into a long-term stable form. 相似文献
8.
A method is developed for evaluating the effects of cosmic rays on computer memories and is applied to some typical memory devices. The sea-level flux of cosmic-ray particles is reviewed and the interaction of each type of particle with silicon is estimated, with emphasis on processes that produce bursts of charge. These charge pulses are then related to typical computer large-scale integrated circuit components and cosmic-ray-induced errors are estimated. The effects of shielding (such as building ceilings and walls), altitude, and solar cycle are estimated. Cosmic-ray nucleons and muons can cause errors in current memories at a level of marginal significance, and there may be a very significant effect in the next generation of computer memory circuitry. Error rates increase rapidly with altitude, which may be used for testing to make electronic devices less sensitive to cosmic rays. 相似文献
9.
Stephan KE Marshall JC Friston KJ Rowe JB Ritzl A Zilles K Fink GR 《Science (New York, N.Y.)》2003,301(5631):384-386
The principles underlying human hemispheric specialization are poorly understood. We used functional magnetic resonance imaging of letter and visuospatial decision tasks with identical word stimuli to address two unresolved problems. First, hemispheric specialization depended on the nature of the task rather than on the nature of the stimulus. Second, analysis of frontal candidate regions for cognitive control showed increased coupling between left anterior cingulate cortex (ACC) and left inferior frontal gyrus during letter decisions, whereas right ACC showed enhanced coupling with right parietal areas during visuospatial decisions. Cognitive control is thus localized in the same hemisphere as task execution. 相似文献
10.
Traumatic fear memories can be inhibited by behavioral therapy for humans, or by extinction training in rodent models, but are prone to recur. Under some conditions, however, these treatments generate a permanent effect on behavior, which suggests that emotional memory erasure has occurred. The neural basis for such disparate outcomes is unknown. We found that a central component of extinction-induced erasure is the synaptic removal of calcium-permeable α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors (AMPARs) in the lateral amygdala. A transient up-regulation of this form of plasticity, which involves phosphorylation of the glutamate receptor 1 subunit of the AMPA receptor, defines a temporal window in which fear memory can be degraded by behavioral experience. These results reveal a molecular mechanism for fear erasure and the relative instability of recent memory. 相似文献
11.
Pattern separation, the process of transforming similar representations or memories into highly dissimilar, nonoverlapping representations, is a key component of many functions ascribed to the hippocampus. Computational models have stressed the role of the hippocampus and, in particular, the dentate gyrus and its projections into the CA3 subregion in pattern separation. We used high-resolution (1.5-millimeter isotropic voxels) functional magnetic resonance imaging to measure brain activity during incidental memory encoding. Although activity consistent with a bias toward pattern completion was observed in CA1, the subiculum, and the entorhinal and parahippocampal cortices, activity consistent with a strong bias toward pattern separation was observed in, and limited to, the CA3/dentate gyrus. These results provide compelling evidence of a key role of the human CA3/dentate gyrus in pattern separation. 相似文献
12.
Ferroelectric memories 总被引：1，自引：0，他引：1
In the past year it has become possible to fabricate ferroelectric thin-film memories onto standard silicon integrated circuits that combine very high speed (30-nanosecond read/erase/rewrite operation), 5-volt standard silicon logic levels, very high density (2 by 2 micrometer cell size), complete nonvolatility (no standby power required), and extreme radiation hardness. These ferroelectric random-access memories are expected to replace magnetic core memory, magnetic bubble memory systems, and electrically erasable read-only memory for many applications. The switching kinetics of these films, 100 to 300 nanometers thick, are now well understood, with switching times that fit an activation field dependence that scales applied field and temperature. Earlier problems of fatigue and retention failure are also now understood and have been improved to acceptable levels. 相似文献
13.
The hippocampus is crucial for spatial memory formation, yet it does not store long-lasting memories. By combining functional brain imaging and region-specific neuronal inactivation in mice, we identified prefrontal and anterior cingulate cortices as critical for storage and retrieval of remote spatial memories [correction]. Imaging of activity-dependent genes also revealed an involvement of parietal and retrosplenial cortices during consolidation of remote memory. Long-term memory storage within some of these neocortical regions was accompanied by structural changes including synaptogenesis and laminar reorganization, concomitant with a functional disengagement of the hippocampus and posterior cingulate cortex [correction]. Thus, consolidation of spatial memory requires a time-dependent hippocampal-cortical dialogue, ultimately enabling widespread cortical networks to mediate effortful recall and use of cortically stored remote memories independently. 相似文献
14.
采用事件相关电位技术(ERP),探讨了具有两个叉的三叉戟不可能图形加工的脑内时程动态变化,结果表明:首先在250～310ms事件窗口内,与PC(不可能条件,Possible Condition)相比,IC(可能条件,Impossible Condition)诱发了一个更正的波形(P250～310),对差异波(IC—PC)进行偶极子溯源分析,结果显示,P250～310可能起源于海马旁回.因此,P250～310可能与知觉加工过程中,将物体的各个分散特征,整合成空间上相关的物体表征的过程有关;其次,在400～500ms时间窗口内,IC比PC诱发了一个更负的波形,对差异波(IC—PC)进行偶极子溯源分析,结果显示,N400～500可能起源于扣带前回(anterior cingulate cortex,ACC)和右侧颞叶(temporallobe),因此,N400～500可能与认知冲突(不可能图形中所包含的空间结构与个体三维知识经验相违背)的监测与控制有关;最后,在500～600ms时间窗口内,IC比PC诱发了一个更正的波形(P500～600),此波形可能与工作记忆中对不可能图形的空间结构的推测有关(通过空间结构推理,... 相似文献
15.
Bissiere S Zelikowsky M Ponnusamy R Jacobs NS Blair HT Fanselow MS 《Science (New York, N.Y.)》2011,331(6013):87-91
The role of electrical synapses in synchronizing neuronal assemblies in the adult mammalian brain is well documented. However, their role in learning and memory processes remains unclear. By combining Pavlovian fear conditioning, activity-dependent immediate early gene expression, and in vivo electrophysiology, we discovered that blocking neuronal gap junctions within the dorsal hippocampus impaired context-dependent fear learning, memory, and extinction. Theta rhythms in freely moving rats were also disrupted. Our results show that gap junction-mediated neuronal transmission is a prominent feature underlying emotional memories. 相似文献
16.
The medial temporal lobe (MTL) is critical in forming new memories, but how subregions within the MTL carry out encoding and retrieval processes in humans is unknown. Using new high-resolution functional magnetic resonance imaging (fMRI) acquisition and analysis methods, we identified mnemonic properties of different subregions within the hippocampal circuitry as human subjects learned to associate names with faces. The cornu ammonis (CA) fields 2 and 3 and the dentate gyrus were active relative to baseline only during encoding, and this activity decreased as associations were learned. Activity in the subiculum showed the same temporal decline, but primarily during retrieval. Our results demonstrate that subdivisions within the hippocampus make distinct contributions to new memory formation. 相似文献
17.
Memories are thought to be attractor states of neuronal representations, with the hippocampus a likely substrate for context-dependent episodic memories. However, such states have not been directly observed. For example, the hippocampal place cell representation of location was previously found to respond continuously to changes in environmental shape alone. We report that exposure to novel square and circular environments made of different materials creates attractor representations for both shapes: Place cells abruptly and simultaneously switch between representations as environmental shape changes incrementally. This enables study of attractor dynamics in a cognitive representation and may correspond to the formation of distinct contexts in context-dependent memory. 相似文献
18.
In memory consolidation, the memory trace stabilizes and becomes resistant to certain amnesic agents. The textbook account is that for any memorized item, consolidation starts and ends just once. However, evidence has accumulated that upon activation in retrieval, the trace may reconsolidate. Whereas some authors reported transient renewed susceptibility of retrieved memories to consolidation blockers, others could not detect it. Here, we report that in both conditioned taste aversion in the rat and fear conditioning in the medaka fish, the stability of retrieved memory is inversely correlated with the control of behavior by that memory. This result may explain some conflicting findings on reconsolidation of activated memories. 相似文献
19.
D Dickson 《Science (New York, N.Y.)》1986,232(4746):13-14
Public controversy over genetic engineering research has prompted the West German government to propose that new safety guidelines in this area should be legally binding on industry, rather than remain voluntary as are the current regulations. Political reaction against biotechnology has been led by the Social Democrats and by the Greens, West Germany's environmental party, which has made opposition to all industrial uses of genetic engineering official party policy. While dismissing total rejection of genetic technologies as an emotional overreaction, researchers have begun to tell the public about their work and to organize meetings among themselves to discuss the issues. The increasing interest in control of genetic engineering has been attributed to memories of the eugenic experiments of the Nazis, debate over the growing links between industry and universities, and environmental concern over the release of genetically altered organisms. 相似文献
20.
Reduced numbers of somatostatin receptors in the cerebral cortex in Alzheimer's disease 总被引：9，自引：0，他引：9
M F Beal M F Mazurek V T Tran G Chattha E D Bird J B Martin 《Science (New York, N.Y.)》1985,229(4710):289-291
Somatostatin receptor concentrations were measured in patients with Alzheimer's disease and controls. In the frontal cortex (Brodmann areas 6, 9, and 10) and temporal cortex (Brodmann area 21), the concentrations of somatostatin in receptors in the patients were reduced to approximately 50 percent of control values. A 40 percent reduction was seen in the hippocampus, while no significant changes were found in the cingulate cortex, postcentral gyrus, temporal pole, and superior temporal gyrus. Scatchard analysis showed a reduction in receptor number rather than a change in affinity. Somatostatin-like immunoreactivity was significantly reduced in both the frontal and temporal cortex. Somatostatin-like immunoreactivity was linearly related to somatostatin-receptor binding in the cortices of Alzheimer's patients. These findings may reflect degeneration of postsynaptic neurons or cortical afferents in the patients' cerebral cortices. Alternatively, decreased somatostatin-like immunoreactivity in Alzheimer's disease might indicate increased release of somatostatin and down regulation of postsynaptic receptors. 相似文献