Neural Substrates Of Stimulus Recognition And Associatio

NIMH神经心理学实验室的学习和记忆神经生物学部分研究感知、学习、记忆和其他认知过程的神经机制。为此，我们研究了选择性脑消融和切断对猕猴不同类型学习和记忆的影响。概述。“腹侧视觉流”是一组致力于处理物体视觉信息的纹状、前纹状和下颞皮质区。虽然视觉信息的处理是由这些视觉皮层区进行的，但猴子的视觉表征的实际存储似乎在很大程度上取决于位于内侧颞叶底部的皮质带。该区域由内嗅皮层和外嗅皮层组成，在这里简称为“鼻皮层”。鼻皮层似乎对准确的刺激识别、刺激识别和刺激-刺激关联（包括模内刺激-刺激关联和跨模内刺激-刺激关联）至关重要。此外，在没有内侧颞叶边缘结构、杏仁核和海马体的情况下，鼻皮质可以介导这些类型的信息存储。鼻皮层与大脑其他区域相互作用，将储存的刺激表征与情绪和行动联系起来。过去一年的成就。最近，我们假设，周围皮层包含神经元，代表视觉刺激特征的复杂连接，因此，该区域对于在高度特征重叠的条件下区分物体是重要的。特征重叠的一个例子是当一个给定的视觉特征或一组特征是两个需要区分的不同对象的一部分时。我们已经测试了这个想法，并发现当我们通过实验增加“特征重叠”时，无论是通过使用软件变形或“混合”两种不同的刺激，还是通过专门构建具有许多共同特征的视觉刺激，嗅周皮层对于区分物体确实很重要。相比之下，当特征重叠很少或没有重叠时，周围皮层对视觉识别物体是不需要的。因此，周围皮层作为腹侧视觉流或“什么”通路的一部分，帮助处理和存储有关物体的信息。我们认为，它对这种处理的特殊贡献是特征的复杂连接的表示，而不是它可能拥有的任何特殊计算功能。一旦识别出一个视觉项目，它就可以与其他类型的信息联系起来，例如情绪（或情感价）、空间位置和反应。该实验室和其他实验室最近的研究表明，杏仁核在将视觉刺激与其情感效价联系起来方面很重要，而且，杏仁核必须与眶前额叶皮层相互作用，才能使动物在行动结果可能变好或变坏的情况下做出有利的选择。另外的研究通过检查不同的前额皮质区域在视觉刺激与特定行为的关联中的作用，扩展了视觉信息处理和存储的工作。这种学习可能是语言习得的基础，尤其是书面文字和产生语言所必需的运动程序之间的联系。至少有两个前额皮质区域，腹侧前额皮质和眶前额皮质，对于建立这种快速、任意的视觉刺激与行动的联系是重要的。据我们所知，前额叶区域的必要作用是将视觉和行动联系起来，并获得指导这些行为的规则，而不是对物体的视觉识别或产生反应本身。在过去的一年中，我们发表了13篇报告，其中包括4篇同行评审的初级研究文章以及几篇参考评论和百科全书文章。对生物医学研究和心理健康的意义。记忆丧失通常伴随着中风和脑部病毒感染，是某些疾病（如阿尔茨海默病和艾滋病痴呆复合体）的主要特征。我们的研究一直致力于了解涉及信息存储的关键大脑区域的功能，包括鼻皮质、杏仁核和海马体。通过更好地了解这些区域的正常功能组织，我们希望揭示理解记忆障碍的方法，并有可能找到改善记忆障碍的方法。

The Section on the Neurobiology of Learning & Memory of the Laboratory of Neuropsychology, NIMH, studies the neural mechanisms underlying perception, learning, memory, and other cognitive processes. To this end, we have examined the effects of selective cerebral ablations and disconnections on different types of learning and memory in macaque monkeys. Overview. The "ventral visual stream" is a group of striate, prestriate, and inferior temporal cortical fields devoted to processing visual information about objects. While the processing of visual information is carried out by these visual cortical fields, the actual storage of visual representations in monkeys appears to depend in large part on a strip of cortex lying at the base of the medial temporal lobe. This region is comprised of the entorhinal cortex and perirhinal cortex, abbreviated here as "rhinal cortex". The rhinal cortex appears to be critical for accurate stimulus identification, stimulus recognition, and stimulus-stimulus association, including both intramodal stimulus-stimulus associations and crossmodal ones. Furthermore, the rhinal cortex can mediate these types of information storage in the absence of the medial temporal lobe limbic structures, the amygdala and hippocampus. The rhinal cortex interacts with other brain regions to link stored stimulus representations with emotion and action. Accomplishments of the past year. Recently we have hypothesized that the perirhinal cortex contains neurons that represent complex conjunctions of visual stimulus features, and, as a consequence, that this region is important for discriminating objects under conditions of high feature overlap. An example of feature overlap is when a given visual feature or set of features is part of two different objects that need to be differentiated. We have tested this idea and have found that the perirhinal cortex is indeed important for discriminating objects when we increase "feature overlap" experimentally, either by using software to morph or "blend" two different stimuli or by specially constructing visual stimuli that have a number of features in common. By contrast, the perirhinal cortex is not necessary for visual discrimination objects when there is little or no feature overlap. Thus, the perirhinal cortex operates as part of the ventral visual stream or "what" pathway, in helping to process and store information about objects. We suggest that its special contribution to this kind of processing is the representation of complex conjunctions of features, as opposed to any special computational function it might possess. Once a visual item is identified, it can be associated with other kinds of information, for example with emotions (or affective valence), spatial locations and responses. Recent work from this and other laboratories indicates that the amygdala is important for associating a visual stimulus with its affective valence, and further, that the amygdala must interact with the orbital prefrontal cortex to enable animals to choose advantageously under conditions in which the outcome of their actions may be changing for the better or worse. Additional studies have extended the work on visual information processing and storage by examining the role of various prefrontal cortical fields in associating visual stimuli with specific actions. This kind of learning probably underlies the acquisition of language, especially the association between the written word and the motor programs necessary to produce speech. At least two prefrontal cortical areas, the ventral prefrontal cortex and the orbital prefrontal cortex, are important for establishing this kind of rapid, arbitrary linking of visual stimuli with actions. As far as we can discern, the necessary roles for the prefrontal areas is the association between vision and action, and the acquisition of rules guiding those kinds of behavior, as opposed to the visual identification of the object or the production of the response, per se. In the past year we have published 13 reports, including 4 peer-reviewed primary research articles together with several refereed review and encyclopedia articles. Significance to biomedical research and mental health. Memory loss typically accompanies strokes and viral infections of the brain, and is a central feature of certain diseases such as Alzheimer's Disease and AIDS dementia complex. Our research has been dedicated to understanding the functions of the key brain areas involved in information storage, including the rhinal cortex, amygdala, and hippocampus. By gaining a better understanding of the normal functional organization of these regions, we hope to reveal ways in which the disorders of memory can be understood and, potentially, ways in which the disorders can be ameliorated.