Kapur N
Wessex Neurological Centre, Southampton, UK.
Brain. 1996 Oct;119 ( Pt 5):1775-90. doi: 10.1093/brain/119.5.1775.
The aim in this review article is to document research findings that have shown paradoxical effects of nervous system changes, whereby direct or indirect neural damage may result in facilitation of behavioural functions. Such findings have often been ignored or undervalued in the brain-behaviour research literature. A further aim is to consider possible mechanisms and theoretical insights related to this facilitation. Analyses of relevant studies show that two major types of paradoxical functional facilitation (PFF) effects may be distinguished. (i) Situations where damage to intact brain tissue brings to normal or near normal a previously subnormal or abnormal level of functioning. I refer to improved levels of functioning in such contexts as restorative PFF effects. One of the best documented examples of such PFF effects is the 'Sprague effect', whereby collicular lesions may bring about an improvement in visual functioning following an initial occipital lesion. (ii) Situations where a subject with nervous system pathology or sensory loss performs better than normal control subjects on a particular task. I refer to improved levels of performance in these contexts as enhancing PFF effects. Restorative and enhancing PFF effects have been found in a range of domains, including memory, sensory and perceptual functions, and language functioning. A potential contribution of PFF effects is that they highlight two important neural mechanisms, i.e. inhibition and compensatory plasticity. Two broad classes of theoretical insights related to PFF effects are therefore discussed: (i) inhibitory mechanisms, which form part of an interactive view of brain function where competitive opponent-processing is a significant feature; (ii) 'compensatory augmentation', which occurs as a specific manifestation of CNS plasticity. Both of these mechanisms are considered in relation to paradoxical increases in CBF and anatomical annexation effects that are seen in neurological patients and in subjects with sensory loss. Paradoxical functional facilitation paradigms represent a powerful methodological tool for confirming or refuting hypotheses in brain-behaviour research. The counter-intuitive nature of PFF findings provides a particularly persuasive set of evidence in support of neural, conceptual or computational models of brain function that specifically predict paradoxical facilitation of cognitive functioning.
这篇综述文章的目的是记录研究结果，这些结果显示了神经系统变化的矛盾效应，即直接或间接的神经损伤可能导致行为功能的促进。在脑与行为研究文献中，这些发现常常被忽视或低估。另一个目的是考虑与这种促进相关的可能机制和理论见解。对相关研究的分析表明，可以区分出两种主要类型的矛盾性功能促进（PFF）效应。（i）完整脑组织受损使先前低于正常或异常的功能水平恢复到正常或接近正常水平的情况。我将这种情况下功能水平的提高称为恢复性PFF效应。这种PFF效应最有充分记录的例子之一是“斯普拉格效应”，即视丘病变可能在最初的枕叶病变后使视觉功能得到改善。（ii）患有神经系统病理学或感觉丧失的受试者在特定任务上的表现优于正常对照受试者的情况。我将这些情况下表现水平的提高称为增强性PFF效应。在包括记忆、感觉和知觉功能以及语言功能在内的一系列领域中都发现了恢复性和增强性PFF效应。PFF效应的一个潜在贡献是它们突出了两种重要的神经机制，即抑制和代偿性可塑性。因此，讨论了与PFF效应相关的两大类理论见解：（i）抑制机制，它是脑功能交互观点的一部分，其中竞争性对手处理是一个重要特征；（ii）“代偿性增强”，它作为中枢神经系统可塑性的一种特定表现而出现。这两种机制都与在神经病患者和感觉丧失受试者中看到的脑血流量矛盾增加和解剖学附加效应有关。矛盾性功能促进范式是在脑与行为研究中证实或反驳假设的有力方法工具。PFF发现的反直觉性质为支持专门预测认知功能矛盾促进的脑功能神经、概念或计算模型提供了一组特别有说服力的证据。
