NEURAL MECHANISMS OF SIZE PERCEPTION

尺寸是物体的基本属性。 许多神经元非常 选择性的对象的大小呈现在其经典的接受 场（CRF）;然而，对象大小的感知也取决于 视觉上下文，包括字段中其他元素的大小和 物体与观察者的距离。我们建议调查 黄斑部大小知觉的调节机制 对象视觉、V1、V2、V4和IT的皮层区域的表征 在清醒的、行为正常的猕猴（Macaca mulatta）身上。在我们的初步调查中 我们发现了两类主要的距离调节神经元： 细胞，其中响应随着接近猴子而增加，以及 farness细胞，其中响应随着与 猴子.这些神经元通常被调整到相同的视网膜图像大小 在不同的距离。我们将完成我们的调查的影响， 距离和寻找具有真实大小恒定性的神经元， 即在不同距离处调整到绝对对象大小的单元。 我们还计划通过参与测试注意力的可能影响， 猴子在大小比较的任务中。 我们将确定视觉环境如何影响 神经元对CRF内呈现的不同大小的刺激。我们计划2 通过艾宾浩斯错觉和 虚拟实验室每一个都提供了一种方法来探测非 经典感受野（非CRF），以揭示其在机制中的作用 大小感知。物体的感知大小受 艾宾浩斯错觉中周围物体的大小。我们将测试 非CRF在大小选择性细胞中的影响， 大小和形状的刺激在周围，同时测量响应 在CRF中呈现的不同大小的刺激。在另一项测试中， 视觉环境的影响，我们将创建一个虚拟实验室 以计算机图形模型的形式展示了我们的实际实验装置- 起来计算机图形模型的优点是， 深度和视角可以作为独立的参数变化，以测试 这些线索对猴子感知大小的影响， 它们对神经元的距离调制或大小恒定性的影响 在V1，V2，V4和IT中。我们还将测试双眼视差的影响 和透视与线框风格的图像，其中颜色，背景 阴影和纹理将从计算机图形显示中去除。 最后，我们将通过掩蔽绘制周围非CRF的范围 部分的视觉上下文显示，同时测量的反应， 不同大小的刺激呈现在CRF内。

Size is a fundamental attribute of objects. Many neurons are very selective for the size of objects presented in their classical receptive fields (CRFs); however, the perception of object size also depends on the visual context including the size of other elements in the field and the distance of the object from the observer. We propose to investigate the mechanisms for the mediation of size perceptIon in the macular representations in cortical areas for object vision, V1, V2, V4, and IT in awake, behaving macaque monkeys (Macaca mulatta). In our preliminary studies we found 2 main classes of distance modulated neurons: nearness cells in which the response increases with proximity to the monkey, and farness cells in which the response increases with distance from the monkey. These neurons typically are tuned to the same retinal image size at different distances. We will complete our survey of the influence of distance and also search for neurons that exhibit true size constancy, i.e. cells that are tuned to absolute object size at different distances. We also plan to test for the possible influence of attention by engaging the monkeys in size comparison tasks. We will determine how the visual context influences the responses of neurons to different sized stimuli presented within the CRF. We plan 2 approaches to this problem through the Ebbinghaus illusion and the virtual laboratory. Each of these provides a way to probe the non- classical receptive field (non-CRF) to reveal its role in the mechanisms of size perception. The perceived size of objects is influenced by the size of surrounding objects in the Ebbinghaus illusion. We will test the influence of the non-CRF in size-selective cells by presenting different sized and shaped stimuli in the surround while measuring the responses to different sized stimuli presented within the CRF. In another test of the influence of the visual context, we will create a virtual laboratory in the form of a computer graphics model of our actual experimental set- up. The advantage of the computer graphics model is that stereoscopic depth and perspective can be varied as independent parameters to test the influence of these cues on the monkey's perception of size as well as their influence on the distance modulation or size constancy of neurons in V1,V2,V4 and IT. We will also test the effects of binocular disparity and perspective with wire-frame style images in which color, background shading and texture will be removed from the computer graphics display. Finally, we will map the extent of the surrounding non-CRF by masking parts of the visual contextual display while measuring the responses to different sized stimuli presented within the CRF.