Gilbert C D
The Rockefeller University, New York, New York, USA.
Physiol Rev. 1998 Apr;78(2):467-85. doi: 10.1152/physrev.1998.78.2.467.
There are many influences on our perception of local features. What we see is not strictly a reflection of the physical characteristics of a scene but instead is highly dependent on the processes by which our brain attempts to interpret the scene. As a result, our percepts are shaped by the context within which local features are presented, by our previous visual experiences, operating over a wide range of time scales, and by our expectation of what is before us. The substrate for these influences is likely to be found in the lateral interactions operating within individual areas of the cerebral cortex and in the feedback from higher to lower order cortical areas. Even at early stages in the visual pathway, cells are far more flexible in their functional properties than previously thought. It had long been assumed that cells in primary visual cortex had fixed properties, passing along the product of a stereotyped operation to the next stage in the visual pathway. Any plasticity dependent on visual experience was thought to be restricted to a period early in the life of the animal, the critical period. Furthermore, the assembly of contours and surfaces into unified percepts was assumed to take place at high levels in the visual pathway, whereas the receptive fields of cells in primary visual cortex represented very small windows on the visual scene. These concepts of spatial integration and plasticity have been radically modified in the past few years. The emerging view is that even at the earliest stages in the cortical processing of visual information, cells are highly mutable in their functional properties and are capable of integrating information over a much larger part of visual space than originally believed.
有许多因素会影响我们对局部特征的感知。我们所看到的并非严格意义上场景物理特征的反映，而是高度依赖于大脑尝试解读该场景的过程。因此，我们的感知受到局部特征呈现的背景、我们过去在广泛时间尺度上积累的视觉经验以及我们对眼前事物的预期的影响。这些影响的基础可能存在于大脑皮层各个区域内的侧向相互作用以及从高阶到低阶皮层区域的反馈中。即使在视觉通路的早期阶段，细胞的功能特性也比之前认为的更加灵活。长期以来，人们一直认为初级视觉皮层中的细胞具有固定的特性，将一种刻板操作的产物传递到视觉通路的下一个阶段。任何依赖视觉经验的可塑性都被认为局限于动物生命早期的一个时期，即关键期。此外，人们认为轮廓和表面组合成统一的感知是在视觉通路的高级阶段进行的，而初级视觉皮层中细胞的感受野在视觉场景中代表的是非常小的窗口。在过去几年里，这些关于空间整合和可塑性的概念已经发生了根本性的改变。新出现的观点是，即使在视觉信息皮层处理的最早阶段，细胞的功能特性也具有高度的可变性，并且能够在比最初认为的大得多的视觉空间范围内整合信息。
