Ghose Geoffrey M, Ts'o Daniel Y
University of Minnesota, Department of Neuroscience, Center for Magnetic Resonance Research, Minneapolis, Minnesota, United States.
SUNY Upstate Medical University, Department of Neurosurgery, Syracuse, New York, United States.
Neurophotonics. 2017 Jul;4(3):031216. doi: 10.1117/1.NPh.4.3.031216. Epub 2017 May 27.
Functional specialization within the extrastriate areas of the ventral pathway associated with visual form analysis is poorly understood. Studies comparing the functional selectivities of neurons within the early visual areas have found that there are more similar than different between the areas. We simultaneously imaged visually evoked activation over regions of V2 and V4 and parametrically varied three visual attributes for which selectivity exists in both areas: color, orientation, and size. We found that color selective regions were observed in both areas and were of similar size and spatial distribution. However, two major areal distinctions were observed: V4 contained a greater number and diversity of color-specific regions than V2 and exhibited a higher degree of overlap between domains for different functional attributes. In V2, size and color regions were largely segregated from orientation domains, whereas in V4 both color and size regions overlapped considerably with orientation regions. Our results suggest that higher-order composite selectivities in the extrastriate cortex may arise organically from the interactions afforded by an overlap of functional domains for lower order selectivities.
与视觉形态分析相关的腹侧通路纹外区域内的功能特化目前还知之甚少。比较早期视觉区域内神经元功能选择性的研究发现，这些区域之间的相似之处多于不同之处。我们同时对V2和V4区域的视觉诱发激活进行成像，并对两个区域中都存在选择性的三种视觉属性进行参数变化：颜色、方向和大小。我们发现，两个区域都观察到了颜色选择性区域，且其大小和空间分布相似。然而，观察到了两个主要的区域差异：V4中颜色特异性区域的数量和多样性比V2更多，并且不同功能属性的区域之间表现出更高程度的重叠。在V2中，大小和颜色区域在很大程度上与方向区域分离，而在V4中，颜色和大小区域都与方向区域有相当大的重叠。我们的结果表明，纹外皮层中的高阶复合选择性可能源自低阶选择性功能域重叠所提供的相互作用。
