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

本研究旨在研究灵长类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，携带不同种类的信息。这些通道一直被认为是分开的，因为它们通过大脑的各个层面传输信息。最后，在新皮层中，视觉信息沿着两条主要的信息流，一条从背侧到达顶叶皮层，另一条从腹侧到达颞叶皮层。根据最近的研究，我们质疑这种严格的隔离的途径，并建议研究如何相互作用之间发生的两个流和两个通道是否走到一起，在视觉通路的早期水平。我们还将检验我们的想法，在背侧流和腹侧流中，一个流是否真的可以门控另一个流，并决定什么通过另一个流。事实上，根据我们最近的研究，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显著方面的，而腹侧流似乎负责识别物体。在这个项目中，我们将严格检验这个想法。从各种证据来看，我们还认为，人类儿童在学习阅读时，会利用这种注意力聚光灯下的神经机制。由此可见，背侧通路的任何缺陷，或进入背侧通路的纤维和细胞的任何缺陷，都会导致阅读的困难。我们认为这是有阅读障碍儿童的根本问题。该项目将进行一些实验来检验这一想法。

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.