Chapter 1 Neural mechanisms of visual orienting responses

Abstract

This chapter focuses on the neural mechanisms of visual orienting responses. Orienting has several components—(1) the reflexive response triggered by the appearance of an object in the visual field; (2) the internally programmed, exploratory motor search that may occur without a specific visual target; and (3) the shift of attention that accompanies both reflex and search. The chapter distinguishes three components of the orienting response—(1) targeting (directional), (2) arousal, and (3) perceptual. Orienting is a function for exploration of the environment by telereceptors of eyes, ears, and nose and by receptors on the body surface; thus, it is multimodal in operation-olfaction, vision, acoustic, and somesthetic. The recognition that SNR is a part of a neural orienting system that comprise cortex, striatum, nigra, superior colliculus, and thalamus in several species. Understanding the neural mechanisms of the colliculus in visual orienting is enhanced by the demonstration that this laminated structure can be divided into superficial and deep layers, on the basis of both structure and function in the tree shrew.