Mesulam M M
Ann Neurol. 1981 Oct;10(4):309-25. doi: 10.1002/ana.410100402.
Unilateral neglect reflects a disturbance in the spatial distribution of directed attention. A review of unilateral neglect syndromes in monkeys and humans suggests that four cerebral regions provide an integrated network for the modulation of directed attention within extrapersonal space. Each component region has a unique functional role that reflects its profile of anatomical connectivity, and each gives rise to a different clinical type of unilateral neglect when damaged. A posterior parietal component provides an internal sensory map and perhaps also a mechanism for modifying the extent of synaptic space devoted to specific portions of the external world; a limbic component in the cingulate gyrus regulates the spatial distribution of motivational valence; a frontal component coordinates the motor programs for exploration, scanning, reaching, and fixating; and a reticular component provides the underlying level of arousal and vigilance. This hypothetical network requires at least three complementary and interacting representations of extrapersonal space: a sensory representation in posterior parietal cortex, a schema for distributing exploratory movements in frontal cortex, and a motivational map in the cingulate cortex. Lesions in only one component of this network yield partial unilateral neglect syndromes, while those that encompass all the components result in profound deficits that transcend the mass effect of the larger lesion. This network approach to the localization of complex functions offers an alternative to more extreme approaches, some of which stress an exclusive concentration of function within individual centers in the brain and others which advocate a more uniform (equipotential or holistic) distribution. In human beings, unilateral neglect syndromes are more frequent and severe after lesions in the right hemisphere. Also, right hemisphere mechanisms appear more effective in the execution of attentional tasks. Furthermore, the attentional functions of the right hemisphere span both hemispaces, while the left hemisphere seems to contain the neural apparatus mostly for contralateral attention. This evidence indicates that the right hemisphere of dextrals has a functional specialization for the distribution of directed attention within extrapersonal space.
单侧忽视反映了定向注意力空间分布的紊乱。对猴子和人类单侧忽视综合征的综述表明，四个脑区为调节个人空间外定向注意力提供了一个整合网络。每个组成区域都有独特的功能作用，反映了其解剖连接特征，并且每个区域受损时都会引发不同临床类型的单侧忽视。后顶叶部分提供内部感觉图谱，或许还提供一种机制来改变分配给外部世界特定部分的突触空间范围；扣带回中的边缘部分调节动机效价的空间分布；额叶部分协调探索、扫描、伸手和注视的运动程序；网状部分提供觉醒和警觉的基础水平。这个假设的网络至少需要三种关于个人空间外的互补且相互作用的表征：后顶叶皮质中的感觉表征、额叶皮质中用于分布探索性运动的图式以及扣带回皮质中的动机图谱。该网络中仅一个组成部分受损会产生部分单侧忽视综合征，而那些累及所有组成部分的损伤则会导致严重缺陷，这种缺陷超越了较大损伤的占位效应。这种针对复杂功能定位的网络方法为更极端的方法提供了一种替代方案，其中一些方法强调功能仅集中在大脑中的单个中心，而另一些方法则主张更均匀（等势或整体）的分布。在人类中，右侧半球受损后单侧忽视综合征更常见且更严重。此外，右侧半球机制在执行注意力任务时似乎更有效。而且，右侧半球的注意力功能跨越两个半空间，而左侧半球似乎主要包含用于对侧注意力的神经机制。这一证据表明，右利手者的右侧半球在个人空间外定向注意力的分布方面具有功能特化。
