Neglect and Neural Mechanisms of Magnitude Estimation

本研究的目的是为当代的空间忽视理论增加一个量化因素，并将不同的理论整合到一个模型中。理论发展可以带来更好的治疗。忽视每年影响着大量的中风患者，目前的治疗效果有限。当代的忽视理论从心理上对空间、空间注意力和空间定向运动的表征来看待这种混乱。它们无法解决最近一些与震级估计相关的经验性观察--对大小、响度、重量等的错误感知。我们认为，除了空间的心理表征外，刺激强度的心理表征也是由大脑中的神经系统构建的，这两种类型的表征都会在忽视中发生变化。进一步，我们提出刺激强度的表示是根据比例比例的心理物理原理来建立的，这是进行幅度估计的基础。对刺激强度的描述增加了当代忽视理论中缺失的定量因素。我们预计，这一新概念将极大地推进有关忽视的理论，并导致研究的新方向。它也直接适用于治疗，例如，通过比率比例的直接训练来恢复刺激强度的表现。提出了六个实验。受试者将是右半球和左半球病变的患者。缺血性中风后，根据(1)忽视的临床症状和(2)与忽视相关的特定神经系统损害而被选择的患者。非患者对照受试者将在年龄、性别和种族方面进行匹配。实验一验证了这一假设，即在忽视患者中，刺激强度的表征在多种感觉方式下都会发生变化。实验二测试了注意将空间表征和刺激强度联系在一起的假设。实验三验证了刺激强度的表征是在每个大脑半球构建的假设。实验IV-VI检验了忽略患者中改变比例比例的其他解释。最后，我们建议在这一建议的过程中开发和测试比率比例的数学模型。

The goal of this research is to add a quantitative element to contemporary theories of spatial neglect and to combine disparate theories into one model. Theoretical development can lead to improved treatment. Neglect affects a large number of stroke patients each year, and current treatments are of limited benefit. Contemporary theories of neglect view the disorder in terms of mental representations of space, spatial attention, and spatially- directed movements. They cannot address a number of recent empiric observations related to magnitude estimation -- misperceiving size, loudness, weight, and the like. We propose that mental representations of stimulus intensity are constructed by neural systems in the brain, in addition to mental representations of space, and that both types of representations are altered in neglect. Further, we propose that representations of stimulus intensity are developed in accordance with the psychophysical principle of ratio scaling, which is the basis for magnitude estimation. Representations of stimulus intensity add the quantitative element that is missing in contemporary theories of neglect. We anticipate this new concept will significantly advance theories concerning neglect and lead to new directions in research. It is also directly applicable to treatment, e.g., rehabilitating representations of stimulus intensity through direct training in ratio scaling. Six experiments are proposed. Subjects will be patients with right and left hemisphere lesions . following ischemic stroke who are selected for (1) clinical signs of neglect and (2) damage to a specific, neural system associated with neglect. Non-patient control subjects will be matched for age, gender, and race. Experiment I tests the hypothesis that representations of stimulus intensity are altered in multiple sensory modalities among patients with neglect. Experiment II tests the hypothesis that attention binds representations of space and stimulus intensity together. Experiment III tests the hypothesis that representation of stimulus intensity are constructed in each cerebral hemisphere. Experiments IV-VI examine alternative explanations for altered ratio scaling among patients with neglect. Finally, we propose to develop and test a mathematical model of ratio scaling during the course of this proposal.