人们学习某项运动技能的时候，有时学得快忘得也快，而有时虽然学得慢，却能长久不忘，这种现象并非偶然，而是有其生理基础。据美国物理学家组织网近日报道，南加利福尼亚大学科学家首次揭示了在运动记忆形成过程中，短期记忆和长期记忆共同作用但却互相竞争的生理机制。该发现不仅有助于制定科学合理的个人训练计划，也为中风病人康复带来了希望。相关论文发表在近期出版的《神经生理学杂志》上。
该项目由加利福尼亚大学生物运动机能学与物理疗法分部的尼古拉斯-斯格威霍夫领导。研究小组在对中风患者进行空间工作记忆测试时发现，中风后病人的短期记忆被破坏，长期记忆却更好地保留下来，这是因为他们不得不依赖长期记忆的缘故。研究人员由此发现，运动记忆现象是由两个过程组成，对某项技能建立起记忆，是长期记忆和短期记忆共同作用的结果。
研究人员解释说，假如你在学习某些运动技能，比如两种上手投球，分别学这两种，可能会掌握得很快，但一段时间后，却很可能把这两种动作都忘了。但如果你把时间轮流分配在多种运动技能训练上，比如同时学习两种不同的投球，你或许学得更慢，但在以后却可能将这两种都记住。这一现象称为“背景干扰效应”。
斯格威霍夫解释说，“背景干扰效应”是短期运动记忆和长期运动记忆竞争的结果，虽然人们早就知道存在这种效应，但新研究首次揭示了这种效应背后的生理机制。
“不断地清除运动短期记忆有助于更新长期记忆。”斯格威霍夫说，如果大脑是靠短期记忆去记住一项运动任务，记住了之后，该任务却还没能建立起长期记忆。如果人们在此时不停下来，继续学习另一项任务，并在两项任务之间交替轮换地学习，将会进一步建立起长期记忆。虽然这要花更长时间，但以后不会忘记。“学习两种运动技能更加困难。但在无序训练中，我们还没发现忘记的情况。”
斯格威霍夫表示，从长远来看，该发现有助于为中风病人找到最优的康复疗法，以及为每个人制定最有效的训练方案。(生物谷 Bioon.com)
doi:10.?1152/?jn.?00399.?2011
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Mechanisms of the contextual interference effect in individuals post-stroke
Nicolas Schweighofer, Jeong-Yoon Lee, Hui-Ting Goh, Younggeun Choi, Sungshin Kim, Jill C Stewart, Rebecca Lewthwaite, and Carolee J. Winstein
Although intermixing different motor learning tasks via random schedules enhances long-term retention compared to "blocked" schedules, the mechanism underlying this contextual interference effect has been unclear. Furthermore, previous studies have reported inconclusive results in individuals post-stroke. We instructed participants to learn to produce three grip force patterns in either random or blocked schedules, and measured the contextual interference effect by long-term forgetting: the change in performance between immediate and 24-hour post-tests. Non-disabled participants exhibited the contextual interference effect: no forgetting in the random condition, but forgetting in the blocked condition. Participants at least 3 months post-stroke exhibited no forgetting in the random condition, but marginal forgetting in the blocked condition. However, in participants post-stroke, the integrity of visuo-spatial working memory modulated long-term retention after blocked schedule training: participants with poor visuo-spatial working memory exhibited little forgetting at 24 hours. These counter-intuitive results were predicted by a computational model of motor memory that contains a common fast process and multiple slow processes, which are competitively updated by motor errors. In blocked schedules, the fast process quickly improved performance, therefore reducing error-driven update of the slow processes, and thus poor long-term retention. In random schedules, interferences in the fast process led to slower change in performance, therefore increasing error-driven update of slow processes and thus good long-term retention. Increased forgetting rates in the fast process, as would be expected in individuals with visuo-spatial working memory deficits, led to small updates of the fast process during blocked schedules, and thus better long-term retention.
