Bisiach E, Ricci R, Mòdona M N
Dipartimento di Psicologia, Università di Torino, Italy.
Conscious Cogn. 1998 Sep;7(3):327-55. doi: 10.1006/ccog.1998.0361.
Ninety-one right brain-damaged patients with left neglect and 43 right brain-damaged patients without neglect were asked to extend horizontal segments, either left- or rightward, starting from their right or left endpoints, respectively. Earlier experiments based on similar tasks had shown, in left neglect patients, a tendency to overextend segments toward the left side. This seemingly paradoxical phenomenon was held to undermine current explanations of unilateral neglect. The results of the present extensive research demonstrate that contralesional overextension is also evident in most right brain-damaged patients without contralesional neglect. Furthermore, they show that in a minority of left neglect patients, the opposite behavior, i.e., right overextension can be found. The paper also reports the results of correlational analyses comprising the parameters of line-extension, line-bisection, and cancellation tasks, as well as the parameters relative to the Milner Landmark Task, by which a distinction is drawn between perceptual and response biases in unilateral neglect. A working hypothesis is then advanced about the brain dysfunction underlying neglect and an attempt is made at finding an explanation of neglect and the links between the mechanisms of space representation and consciousness through the study of the changes induced by unilateral brain lesions in the characteristics of space-coding neurons.
C, control group; GN+91, full group of neglect patients; GN+27, group of neglect patients with relative left overextension; GN+14, group of neglect patients with relative right overextension; GN-43, full group of non-neglect patients; GN-9, group of non-neglect patients with relative left overextension; H canc, H cancellation task; LE, left extension; LE/RE, ratio of left-right extension; N+, neglect patients; N-, non-neglect patients; PB Land-M, perceptual bias on Landmark motor task; PB Land-V, perceptual bias on Landmark verbal task; RB Land-M, response bias on Landmark motor task; RB Land-V, response bias on Landmark verbal task; RE, right extension.
91名患有左侧忽视的右脑损伤患者和43名无忽视症状的右脑损伤患者被要求分别从其右侧或左侧端点开始向左或向右延长水平线段。早期基于类似任务的实验表明，在左侧忽视患者中，存在一种线段向左侧过度延长的倾向。这种看似矛盾的现象被认为会削弱当前对单侧忽视的解释。本项广泛研究的结果表明，在大多数无对侧忽视的右脑损伤患者中，对侧过度延长现象也很明显。此外，研究结果还显示，在少数左侧忽视患者中，可以发现相反的行为，即右侧过度延长。本文还报告了相关性分析的结果，这些分析涉及线段延长、线段二等分和删除任务的参数，以及与米尔纳地标任务相关的参数，通过这些参数可以区分单侧忽视中的感知偏差和反应偏差。然后提出了一个关于忽视背后脑功能障碍的工作假设，并试图通过研究单侧脑损伤引起的空间编码神经元特征变化，来解释忽视以及空间表征和意识机制之间的联系。
C，对照组；GN+91，忽视患者全组；GN+27，相对左侧过度延长的忽视患者组；GN+14，相对右侧过度延长的忽视患者组；GN-43，无忽视患者全组；GN-9，相对左侧过度延长的无忽视患者组；H canc，H删除任务；LE，左侧延长；LE/RE，左右延长比例；N+，忽视患者；N-，无忽视患者；PB Land-M，地标运动任务的感知偏差；PB Land-V，地标言语任务的感知偏差；RB Land-M，地标运动任务的反应偏差；RB Land-V，地标言语任务的反应偏差；RE，右侧延长。
