Prefrontal -> Top Down Contribution to Object Recognition

高效的视觉识别对我们生活和理解的许多方面都至关重要 IL是如何实现的，对于任何完整的大脑理论来说都是至关重要的。一个主要的 物体识别效率的原因在于它通过自上而下的反馈来促进 流程。我们一直在尝试一种自上而下的促进模式，根据 从早期视觉区域快速提取粗略、低空间频率的图像 投射到眶前叶皮质，在那里Agisr的信息被用来产生 关于潜在刺激身份的预测。然后，预测被反馈给 颞叶下部皮质中的物体识别区域，以帮助在 腹侧视觉流。我们之前的研究已经揭示了一个认识到 在该网络中，皮质事件的时空动力学，以及初级 信息交换，符合OIF自上而下的促进模式。这些 研究结果提出了一系列重要的问题，涉及结构、功能和 自上而下促进网络的通信特性。特别是，我们建议 应用我们的多模式成像方法。充分利用优势互补 心理物理范式、功能和弥散磁共振成像，以及 脑磁图实现以下具体目的：1)研究自然界 参与促进物体识别的前额叶皮质表征； 2)开始研究调节自上而下促进作用的通路的特性； 以及3)揭示自上而下的预测是如何生成的并与 自下而上的河流。预计这里提出的六个实验的结果将是 提供基础，并随后将刺激这些目标的关键扩展。 我们预计，这些机制的特征将为临床模型提供参考 几种疾病的潜在原因。例如，巨细胞途径异常 与精神分裂症和阅读障碍的视力障碍有关。此外， 拟议的皮质视觉通路检查将增强我们对 视觉障碍，如视觉失认和失范、面容失认症和 色觉减退。最后，拟议的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.