Prefrontal -> Top Down Contribution to Object Recognition

有效的视觉识别对我们生活的许多方面都至关重要， 如何实现智能是任何完整的大脑理论的关键。一个主 物体识别效率的原因是自上而下的反馈 流程.我们一直在尝试一种自上而下的促进模型， 从早期视觉区域快速提取粗糙的低空间频率图像， 投射到眶额皮层，在那里，Agisr的信息被用来生成 关于潜在刺激身份的预测。然后将预测反馈给 下颞叶皮层中的物体识别区域，以帮助boltom-up处理 腹侧视觉流我们之前的研究已经发现 网络，其中皮层事件的时空动态，以及主要的 信息交换，符合OUF自上而下的促进模型。这些 研究结果提出了一系列关于结构、功能和 自上而下促进网络的沟通特性。特别是，我们建议 应用我们的多模式成像方法。发挥优势互补 心理物理学范式，功能和扩散MRI，以及 目的：1）研究脑磁图的性质， 前额叶皮层的表征参与了物体识别; 2)开始表征自上而下促进作用的通路的特性; 3）揭示自上而下的预测是如何产生的，并与 自底向上的流。预计本文提出的六项实验的结果将 提供了基础，并将随后刺激这些目标的重大扩展。 我们认为这些机制的特征将为临床模型提供信息。 导致了几种疾病例如，大细胞通路异常 与精神分裂症和阅读障碍的视觉缺陷有关。此外 对皮层视觉通路的拟议检查将增强我们对 视觉障碍，如视觉失认症和命名障碍、面孔失认症和 色盲最后，所提出的DTI实验可以为 治疗脱髓鞘疾病，如多发性硬化症、阿尔茨海默氏症和 帕金森氏症。

Efficient visual recognition is critical for many aspects of our lives, and understanding how il is accomplished is essential for any complete theory of the brain. One primary reason for the efficiency of object recognition is its facilitation by top-down, feedback processes. We have been tasting a top-down facilitation model according to which coarse, low spatial frequency, image is quickly extracted from early visual regions and projected to the orbitofrontal cortex, where this Agisr' information is used to generate predictions about potential stimulus identity. The predictions are then fed back to the object recognition areas in the inferior temporal cortex to aid the boltom-up processing in the ventral visual stream. Our previous studies have already revealed a recognition network in which the spatio-temporal dynamics of cortical events, and the primary information exchanged, are consistent with OUf top-down facilitation model. These findings raise a host of important questions about the structural, functional and communication properties of the top-down facilitation network. In particular, we propose to apply our multimodal imaging approach. capitalizing on the complementary strengths of psychophysical paradigms, functional and diffusion MRI, and magnetoencephalography to achieve the following specifiC aims: 1) To study the nature of the prefrontal cortex representations that participate in faCilitating object recognition; 2) To begin characterizing the properties of the pathways mediating top-down facilitation; and 3) To reveal how top-down predictions are generated and integrated with the bottom-up stream. It is expected that the outcome of the six experiments proposed here will provide the foundations and will subsequently stimulate a critical expansion of these aims. We antiCipate thai the characterization of these mechanisms will inform clinical mOdels underlying several disorders. For example, magnocellular pathway abnormalities have been associated with visual deficits in schizophrenia and dyslexia. In addition the proposed examination of the cortical visual pathways will enhance our understanding of visual impairments such as visual agnOSia and anomia, prosopagnosia and achromatopsia. Lastly, the proposed DTI experiments can contribute insights for the treatment of demyelination diseases, such as multiple sclerosis, Alzheimer's and Parkinson's diseases.