Goodin D S, Aminoff M J, Ortiz T A
Department of Neurology, University of California, San Francisco 94143.
Neurology. 1993 Oct;43(10):2139-42. doi: 10.1212/wnl.43.10.2139.
We investigated the relationship between sensory discrimination and the selection of appropriate responses in subjects performing two different reaction-time tasks, in which three auditory stimuli were presented in random order and with a different likelihood of occurrence. Subjects anticipated the need to make different responses based on the likelihood that a particular stimulus would occur on a particular trial. This was determined by the occurrence and distribution of premovement potentials prior to the stimulus, which were consistent with preparation to respond to the most frequently occurring stimulus. These anticipatory cerebral events, however, could be altered after recognition that this frequent stimulus had not occurred. Thus, after the occurrence of a stimulus other than the anticipated frequent tone, the scalp distribution of cerebral potentials changed in a manner suggesting that the next most frequently occurring stimulus was anticipated. Nonetheless, subjects were able to respond to the least probable stimulus both accurately and rapidly despite a failure to anticipate it correctly, as judged by the cerebral "lateralized readiness potential." These results indicate that stimulus evaluation and response selection are integrated and dynamic cerebral processes, and raise doubt about the functional significance of the so-called premovement readiness potential.
我们研究了在执行两种不同反应时间任务的受试者中，感觉辨别与选择适当反应之间的关系。在这两种任务中，三种听觉刺激以随机顺序呈现，且出现的可能性不同。受试者根据特定刺激在特定试验中出现的可能性预期需要做出不同的反应。这由刺激前运动前电位的出现和分布决定，这些电位与准备对最常出现的刺激做出反应一致。然而，在认识到这种频繁出现的刺激未出现后，这些预期的大脑事件可能会改变。因此，在出现预期频繁音调以外的刺激后，脑电位的头皮分布发生变化，这表明预期的是下一个最常出现的刺激。尽管如此，根据大脑的“侧化准备电位”判断，尽管未能正确预期，但受试者仍能够准确且快速地对可能性最小的刺激做出反应。这些结果表明，刺激评估和反应选择是整合的、动态的大脑过程，并对所谓的运动前准备电位的功能意义提出了质疑。
