Dominey P F, Lelekov T, Ventre-Dominey J, Jeannerod M
Centre National de la Recherche Scientifique UPR 9075, Institut des Sciences Cognitives, 67 Boulevard Pinel, Lyon, 69675, FR.
J Cogn Neurosci. 1998 Nov;10(6):734-51. doi: 10.1162/089892998563130.
A sensorimotor sequence may contain information structure at several different levels. In this study, we investigated the hypothesis that two dissociable processes are required for the learning of surface structure and abstract structure, respectively, of sensorimotor sequences. Surface structure is the simple serial order of the sequence elements, whereas abstract structure is defined by relationships between repeating sequence elements. Thus, sequences ABCBAC and DEFEDF have different surface structures but share a common abstract structure, 123213, and are therefore isomorphic. Our simulations of sequence learning performance in serial reaction time (SRT) tasks demonstrated that (1) an existing model of the primate fronto-striatal system is capable of learning surface structure but fails to learn abstract structure, which requires an additional capability, (2) surface and abstract structure can be learned independently by these independent processes, and (3) only abstract structure transfers to isomorphic sequences. We tested these predictions in human subjects. For a sequence with predictable surface and abstract structure, subjects in either explicit or implicit conditions learn the surface structure, but only explicit subjects learn and transfer the abstract structure. For sequences with only abstract structure, learning and transfer of this structure occurs only in the explicit group. These results are parallel to those from the simulations and support our dissociable process hypothesis. Based on the synthesis of the current simulation and empirical results with our previous neuropsychological findings, we propose a neuro-physiological basis for these dissociable processes: Surface structure can be learned by processes that operate under implicit conditions and rely on the fronto-striatal system, whereas learning abstract structure requires a more explicit activation of dissociable processes that rely on a distributed network that includes the left anterior cortex.
一个感觉运动序列可能包含几个不同层次的信息结构。在本研究中，我们调查了这样一种假设，即感觉运动序列的表面结构和抽象结构的学习分别需要两个可分离的过程。表面结构是序列元素的简单顺序，而抽象结构则由重复序列元素之间的关系定义。因此，序列ABCBAC和DEFEDF具有不同的表面结构，但共享一个共同的抽象结构123213，因此是同构的。我们在序列反应时（SRT）任务中对序列学习表现的模拟表明：（1）灵长类前额叶-纹状体系统的现有模型能够学习表面结构，但无法学习抽象结构，这需要额外的能力；（2）表面结构和抽象结构可以通过这些独立的过程独立学习；（3）只有抽象结构能够迁移到同构序列中。我们在人类受试者中测试了这些预测。对于具有可预测表面结构和抽象结构的序列，无论是明确条件还是隐含条件下的受试者都能学习表面结构，但只有明确条件下的受试者能学习并迁移抽象结构。对于只有抽象结构的序列，这种结构的学习和迁移仅发生在明确组中。这些结果与模拟结果一致，并支持了我们的可分离过程假设。基于当前模拟和实证结果与我们之前神经心理学发现的综合，我们提出了这些可分离过程的神经生理学基础：表面结构可以通过在隐含条件下运行并依赖前额叶-纹状体系统的过程来学习，而学习抽象结构则需要更明确地激活依赖包括左前皮质在内的分布式网络的可分离过程。
