Spatial Processing during Mental Imagery: A Neurofunctional Theory

Diverse methodologies, from animal research to neuroimaging, have begun to paint a coherent picture of the neural underpinnings of the human visual system. We outline a model that consists of seven coarsely defined processing subsystems. We begin with a discussion of the gating function of attention within a set of retinotopically mapped areas, which we call the visual buffer. This subsystem is implemented in the occipital lobe. Two major pathways lead forward, one going down to the inferior temporal lobe and the other up to the posterior parietal lobe. The functions of these systems are discussed, as are the roles of structures that integrate the two types of information and processes that use information to guide visual search. These same processes are used to generate visual mental images on the basis of stored information and to interpret patterns in images. We summarize a variety of types of evidence that support the putative role of each subsystem, as well as research investigating the anatomical localization of each subsystem.