Interactions between afferent channels in vision: basic neurophysiology and implications for the pathology of dyslexia

我们打算研究灵长类动物视觉系统中不同信息通道之间的相互作用。从眼睛到大脑的通路由不同类型的神经纤维组成，这些神经纤维携带着不同种类的信息。这些通道被认为是分开的，因为它们通过大脑的不同层次传递信息。最后，在大脑新皮层中，视觉信息有两条主要的流向，一条是背侧的顶叶皮层，另一条是腹侧的颞叶皮层。基于最近的研究，我们质疑这种通路的严格隔离，并建议研究两种流之间的相互作用是如何发生的，以及两种通道是否在视觉通路的早期水平上结合在一起。我们还将测试我们的想法，在背侧和腹侧的水流中，是否有一条水流实际上是另一条水流的门，并决定什么通过另一条水流。事实上，从我们自己最近的研究来看，我们有理由相信，我们的注意力系统可能是通过背侧流选择进入腹侧流的东西来选择视觉场景的突出方面的，而腹侧流似乎负责识别物体。在提议的项目中，我们将严格检验这一想法。从各种各样的证据来看，我们还认为，当人类儿童学习阅读时，这种注意力聚光灯背后的神经机制被利用了。由此可见，任何背侧通路的缺陷，或者与之相关的纤维和细胞的缺陷，都将导致阅读困难。我们相信这是诵读困难儿童的潜在问题。该项目将进行一系列实验来验证这一想法。

We intend to study the interactions between different information channels in the primate visual system. The pathways from the eyes to the brain consist of different types of nerve fibres carrying distinct sorts of information. These channels have been believed to remain separate as they transmit the information through various levels of the brain. Finally, in the neocortex, it has been suggested that the visual information goes along two major streams, one dorsally to the parietal cortex and the other ventrally to the temporal cortex. Based upon recent studies, we question this strict segregation of the pathways and propose to study how interactions occur between the two streams and whether the two channels do come together at early levels of the visual pathway. We will also test our idea whether, of the dorsal and ventral streams, one stream might actually gate the other and decide what goes through the other stream. In fact, from our own recent studies, we have reason to believe that the way our attentional system might operate to select salient aspects of the visual scene may be through the dorsal stream selecting what goes into the ventral stream, which seems to be responsible for identifying objects. In the proposed project we will test this idea rigorously. From various lines of evidence, we also argue that the neural mechanisms that underlie this attentional spotlight is exploited by human children when they learn to read. It follows that any defect in the dorsal pathway or in the fibres and cells that feed into this will cause difficulties in reading. We believe this to be the underlying problem in dyslexic children. The project will undertake a number of experiments to test this idea.