Chapter 39 Neurophysiologic tools to explore visual cognition

Abstract

Publisher Summary In primates, visual information is processed via two parallel visual pathways; the parvocellular (P) and magnocellular (M) pathways. The P-pathway is thought to be responsible for detecting form and color, because of its high spatial resolution, color sensitivity, low contrast sensitivity, and slow temporal resolution. The use of onset–offset mode rather than contrast reversal stimulus is more appropriate for the activation of the P-system. The M-system is considered to be responsible for detecting the dynamic form and motion, because of its fast temporal resolution, high contrast sensitivity, color insensitivity, and low spatial resolution. Several lines of evidence suggest that two systems exist in humans. The visual stimuli designed to preferentially stimulate each pathway has been developed and electrophysiological studies in humans have been carried out. This chapter discusses the recent finding on visual evoked potentials (VEPs), visual evoked magnetic fields (VEFs), and visual event related potentials (ERPs) with respect to visual cognition. The study suggests that the functional roles of the P- and M-systems can be evaluated electrophysiologically in humans, by using appropriate visual stimuli, revealing a combined use of VEPs, VEFs, and ERPs, is useful for exploring the visual cognition.