The role of area V4 in the perception and recognition of visual objects

摘要 在杂乱的自然视觉环境中，目标识别能力可能会受到严重限制。这可能反映了 与多个邻近刺激的视觉皮质编码相关的限制。或者，可怜的对象 在杂乱中的识别，特别是在自闭症患者中的深刻识别，可能是由于对 注意力控制和物体解码依赖于视觉皮质和额叶皮质之间的相互作用。我们 我不知道在拥挤的场景中是什么神经机制限制了物体识别，因为 神经生理学研究通常一次呈现一个或两个刺激，因此不受限制 由自然场景中的杂乱造成的。此外，很少有研究研究视觉额叶的作用。 物体识别中的交互作用。我们将在清醒的猴子身上使用单一神经元研究的组合， 视觉两个中层阶段的行为操纵、可逆失活和计算模型 大脑皮质，V2和V4，以及前额叶皮质(PFC)，以确定：(目标1)V2和V4神经元如何编码 杂乱中的视觉刺激，以及编码如何依赖于偏心率和注意力 参与；(目标2)PFC反馈如何影响V2和V4的编码，以及这些大脑区域是如何 这些因素共同导致了杂乱中的形状辨别。我们将考虑三个假设。第一，视觉编码 可能在杂乱中具有有限的分辨率：当许多对象位于附近时，无论这些对象是什么， 视觉系统可能无法分割和编码单个对象。第二，在中级阶段的处理可以 设计为仅对显著对象进行编码，即相对于以下对象表现出足够的特征对比度的对象 相邻的图像区域。在这种情况下，信息丢失可能与同质图像中的对象有关 区域反映了优先对突出的对象进行编码的代表性策略。第三，有可能 所有对象都被准确地分段和编码，即使在杂乱的情况下也是如此，但容量限制由 注意力的解决或影响物体解码的其他下游过程。我们的研究将解决 在理解主导自然视觉的多对象显示方面存在着根本的差距 编码在中层视觉皮质。他们将揭示编码策略在不同的偏心程度上是如何变化的 可能与老年性黄斑变性等疾病有关，黄斑中心凹代表 有选择地妥协了。最后，我们的结果将提供有关V4和PFC如何 通信对于杂波中的目标识别至关重要，以及两者之间的通信是如何减少的 会影响人们的行为。这对指导自闭症谱系障碍的翻译工作可能很重要。

ABSTRACT In cluttered natural visual environments object recognition capacity can be severely limited. This may reflect limitations associated with the visual cortical encoding of multiple nearby stimuli. Alternatively, poor object recognition in clutter, especially profound in patients with autism, may result from limited resolution of attentional control and object decoding that rely on interactions between visual cortex and frontal cortex. We do not know what neuronal mechanisms limit object recognition in crowded scenes because neurophysiological studies typically present one or two stimuli at a time, and are thus free from the constraints imposed by clutter in natural scenes. In addition, studies seldom investigate the role of visual-frontal interactions in object recognition. We will use a combination of single neuron studies in awake monkeys, behavioral manipulations, reversible inactivation and computational modelling in two mid-level stages of visual cortex, V2 and V4, and the prefrontal cortex (PFC), to determine: (Aim 1) how V2 and V4 neurons encode visual stimuli in the presence of clutter, and how the encoding depends on eccentricity and on attentional engagement; (Aim 2) how PFC feedback influences encoding in V2 and V4, and how these brain regions together contribute to shape discrimination in clutter. We will consider three hypotheses. First, visual encoding may have limited resolution in clutter: when many objects are nearby, regardless of what those objects are, the visual system may fail to segment and encode individual objects. Second, processing in mid-level stages may be designed to encode only salient objects, i.e., objects that exhibit sufficient feature contrast relative to neighboring image regions. In this case, loss of information may pertain to objects in homogeneous image regions reflecting a representational strategy to preferentially encode objects that stand out. Third, it is possible that all objects are segmented and encoded faithfully, even in clutter, but the capacity limits are dictated by the resolution of attention or other downstream processes that influence object decoding. Our studies will address a fundamental gap in the understanding of how multi-objects displays, which dominate natural vision, are encoded in mid-level visual cortex. They will reveal how encoding strategies vary across eccentricity and this could be relevant for diseases like age-related macular degeneration, where foveal representations are compromised selectively. Finally, our results will provide fundamental insights into how V4 and PFC communication is critical for object recognition in clutter and how diminished communication between the two could influence behavior. This could be important for guiding translational work on autism spectrum disorder.