[Attention systems and unilateral neglect].

Abstract

Unilateral neglect can be defined as an impairment to detect, refer, orient or respond to stimuli presented contralaterally to a cerebral lesion, without any impairments in sensory-motor elementary functions. Development. The first descriptions were those of Hughlings Jackson (1876) and Anton (1893). The most important feature of the syndrome is a lateralization bias, which is directional in nature independently of the visual fields. It can be classified in: 1. Attentional (sensory neglect). 2. Intentional (motor neglect). The lesions that may be responsible for the neglect syndromes are usually found in the inferior parietal cortex of the right cerebral hemisphere (superior parietal when optic ataxia is prominent), and the right frontal lobe. Extinction is more frequently related to subcortical lesions (right lenticular nucleus, anterior aspects of peri-ventricular white matter). Unilateral neglect comprises a set of features that may coexist or be isolated traits: 1. Attentional neglect: hemi-inattention, allesthesia, allochiria, anosognosia (with/without somato-paraphrenia or misoplegia), and anoso-diaphoria, sensory extinction. 2. Intentional neglect: hemi-akinesia, directional hypokinesia, motor impersistence, motor extinction. Different theories try to explain the patho-physiology of these phenomena: the attentional-intentional model, the neural network model, the vectorial model, the representational model, and the premotor model, among others.