Mechanisms of neglect: Implications for rehabilitation

Abstract

Unilateral neglect is not a unitary disorder, nor does it reflect injury to a single modular structure or element of a distributed neural network. Rather, neglect characterises a set of syndromes that share a characteristic (laterally biased) pattern of malfunction. Specifically, neglect syndromes arise on account of a basic design characteristic of the bisymmetrically organised nervous system: Interaction between opponent processors, which determines the moment-to-moment status of certain parameters. Among these are the opponent systems that implement changes in the direction of attention along the lateral (right-left) axis. Such systems are widespread among both vertebrates and non-vertebrates, at multiple levels of the neuroaxis (Kinsbourne, 1974). Negative feedback interactions between the opponent processors in each half brain enable the individual to shift attention along the lateral plane in a graduated fashion, in a direction contralateral to the more activated processor. Thus there is a gradient of attention along the lateral plane, with its focus moving rightwards under left brain influence and leftwards under right brain influence.