NEURAL BASIS OF SHAPE REPRESENTATION AND RECOGNITION

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 我实验室的研究目标是了解视觉刺激是如何在视觉皮质的神经活动模式中编码的，以及这种表征是如何支持物体识别的。在一组实验中，我们正在研究部分遮挡物体是如何编码的。在日常情况下，物体通常会被部分遮挡，但我们的视觉系统会稳健而高效地识别物体，尽管部分遮挡会导致视网膜图像失真。为了发现这是如何在灵长类动物的大脑中实现的，我们在两只注视着的猴子身上进行了实验，以研究V4区的活动，并比较当一个物体被隔离时与当被暗示部分闭塞的上下文刺激毗邻时的表征。我们的结果表明，V4神经元的反应更接近于感知到的刺激，即V4神经元不编码由于部分遮挡而可能在视网膜图像中出现的轮廓。在第二个实验中，我们训练了一只动物在有封闭器的情况下执行形状匹配任务。我们将在几周后开始对这只动物进行录音，以研究动物在执行任务时V4神经元的活动。在单一试验的基础上，神经活动和动物行为之间的相关性将为如何利用V4活动识别对象提供重要的见解。最后，我们在V4中发现了一类新的细胞，它们在等照度下优先对有色刺激做出反应。当刺激和背景之间的对比度增加时，神经元受到抑制。我们目前正在研究这种神经元是如何影响颜色知觉的。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The goal of research in my laboratory is to understand how visual stimuli are encoded in the neural activity patterns in the visual cortex and how this representation underlies object recognition. In one set of experiments we are investigating how partially occluded objects are encoded. In everyday situations objects are often partially occluded but our visual system recognizes objects robustly and efficiently despite retinal image distortions due to partial occlusion. To discover how this is achieved in the primate brain, we have conducted experiments in two fixating monkeys to study activity in area V4 and compare representations when an object is isolated versus when adjoined by a contextual stimulus that suggests partial occlusion. Our results indicate that responses of V4 neurons more closely resemble the perceived stimulus, i.e. V4 neurons do not encode contours that are likely to arise in the retinal image as a result of partial occlusion. In a second experiment, we have trained an animal to perform a shape matching task in the presence of occluders. We will start recording from this animal in a few weeks to study activity of V4 neurons as the animal performs the task. Correlation between neural activity and animal behavior on a single trial basis will provide important insights into how V4 activity is utilized for recognizing objects. Finally, we have found a new class of cells in V4 that respond preferentially to colored stimuli at isoluminance. When the contrast between the stimulus and background increases the neuron is suppressed. We are currently investigating how this neuron contributes to color perception.