人們學(xué)習(xí)某項運動技能的時候,，有時學(xué)得快忘得也快，而有時雖然學(xué)得慢,，卻能長久不忘,，這種現(xiàn)象并非偶然，而是有其生理基礎(chǔ),。據(jù)美國物理學(xué)家組織網(wǎng)近日報道,，南加利福尼亞大學(xué)科學(xué)家首次揭示了在運動記憶形成過程中，短期記憶和長期記憶共同作用但卻互相競爭的生理機制,。該發(fā)現(xiàn)不僅有助于制定科學(xué)合理的個人訓(xùn)練計劃,，也為中風(fēng)病人康復(fù)帶來了希望。相關(guān)論文發(fā)表在近期出版的《神經(jīng)生理學(xué)雜志》上,。
該項目由加利福尼亞大學(xué)生物運動機能學(xué)與物理療法分部的尼古拉斯-斯格威霍夫領(lǐng)導(dǎo),。研究小組在對中風(fēng)患者進行空間工作記憶測試時發(fā)現(xiàn)，中風(fēng)后病人的短期記憶被破壞,，長期記憶卻更好地保留下來,，這是因為他們不得不依賴長期記憶的緣故。研究人員由此發(fā)現(xiàn),，運動記憶現(xiàn)象是由兩個過程組成,，對某項技能建立起記憶，是長期記憶和短期記憶共同作用的結(jié)果,。
研究人員解釋說,，假如你在學(xué)習(xí)某些運動技能，比如兩種上手投球,，分別學(xué)這兩種,，可能會掌握得很快，但一段時間后,，卻很可能把這兩種動作都忘了,。但如果你把時間輪流分配在多種運動技能訓(xùn)練上，比如同時學(xué)習(xí)兩種不同的投球，你或許學(xué)得更慢,，但在以后卻可能將這兩種都記住,。這一現(xiàn)象稱為“背景干擾效應(yīng)”。
斯格威霍夫解釋說,，“背景干擾效應(yīng)”是短期運動記憶和長期運動記憶競爭的結(jié)果,，雖然人們早就知道存在這種效應(yīng)，但新研究首次揭示了這種效應(yīng)背后的生理機制,。
“不斷地清除運動短期記憶有助于更新長期記憶,。”斯格威霍夫說，如果大腦是靠短期記憶去記住一項運動任務(wù),，記住了之后,，該任務(wù)卻還沒能建立起長期記憶。如果人們在此時不停下來,，繼續(xù)學(xué)習(xí)另一項任務(wù),，并在兩項任務(wù)之間交替輪換地學(xué)習(xí)，將會進一步建立起長期記憶,。雖然這要花更長時間,，但以后不會忘記。“學(xué)習(xí)兩種運動技能更加困難,。但在無序訓(xùn)練中,，我們還沒發(fā)現(xiàn)忘記的情況。”
斯格威霍夫表示,，從長遠來看,，該發(fā)現(xiàn)有助于為中風(fēng)病人找到最優(yōu)的康復(fù)療法，以及為每個人制定最有效的訓(xùn)練方案,。(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.
