Chapter 28 Visual pathways to perception and action

Abstract

There appears to be important integrative areas within the superior temporal sulcus in the monkey where a great deal of the necessary interaction to ensure behavioral and perceptual unity. Indeed there are many polysensory neurons in these areas, such that not only visual but also cross-modal perceptual integration may be enabled by these networks. Despite the crosstalk between the dorsal and ventral streams, the chapter discusses that each stream uses visual information in different ways. Both streams process information about orientation and shape, and probably about spatial relationships, including depth; and both are subject to the modulatory influences of an animal's shifting spatial attention. The ventral stream provide object-centered coding, while the dorsal provide entirely viewer-centered information: the former would enable a monkey to identify an object as being of an edible type, the latter to guide its actions in picking it up. Although there will be differences in the ways that visual information is processed in the two systems, these differences are not a reflection of some biologically arbitrary separation of inputs, but rather a consequence of the special transformations required for perception and action, respectively.