Welbourne Stephen R, Ralph Matthew A Lambon
Department of Psychology, University of Manchester, Oxford Road, Manchester M13 9PL, England.
Cogn Affect Behav Neurosci. 2005 Mar;5(1):77-92. doi: 10.3758/cabn.5.1.77.
The effect of retraining a damaged connectionist model of single-word reading was investigated with the aim of establishing whether plasticity-related changes occurring during the recovery process can contribute to our understanding of the pattern of dissociations found in brain-damaged patients. In particular, we sought to reproduce the strong frequency x consistency interactions found in surface dyslexia. A replication of Plaut, McClelland, Seidenberg, and Patterson's (1996) model of word reading was damaged and then retrained, using a standard backpropagation algorithm. Immediately after damage, there was only a small frequency x consistency interaction. Retraining the damaged model crystallized out these small differences into a strong dissociation, very similar to the pattern found in surface dyslexic patients. What is more, the percentage of regularization errors, always high in surface dyslexics, increased greatly over the retraining period, moving from under 10% to over 80% in some simulations. These results suggest that the performance patterns of brain-damaged patients can owe as much to the substantial changes in the pattern of connectivity occurring during recovery as to the original premorbid structure. This finding is discussed in relation to the traditional cognitive neuropsychological assumptions of subtractivity and transparency.
本研究旨在探讨重新训练受损的单字阅读联结主义模型的效果，以确定恢复过程中发生的与可塑性相关的变化是否有助于我们理解脑损伤患者中发现的分离模式。特别是，我们试图重现表层失读症中发现的强频率×一致性交互作用。我们对Plaut、McClelland、Seidenberg和Patterson（1996）的单词阅读模型进行复制，使其受损，然后使用标准反向传播算法进行重新训练。损伤后立即出现的频率×一致性交互作用很小。对受损模型进行重新训练，将这些微小差异明确为强烈的分离，这与表层失读症患者中发现的模式非常相似。此外，正则化误差的百分比在表层失读症患者中一直很高，在重新训练期间大幅增加，在某些模拟中从低于10%升至超过80%。这些结果表明，脑损伤患者的表现模式可能同样归因于恢复过程中连接模式的实质性变化，以及原始病前结构。我们将结合减法性和透明性的传统认知神经心理学假设来讨论这一发现。
