Münte S, Kobbe I, Demertzis A, Lüllwitz E, Münte T F, Piepenbrock S, Leuwer M
Department of Anaesthesiology, Medical School of Hanover, Germany.
Anesthesiology. 1999 Mar;90(3):662-9. doi: 10.1097/00000542-199903000-00006.
In the absence of explicit memories such as the recall and recognition of intraoperative events, memory of auditory information played during general anesthesia has been demonstrated with several tests of implicit memory. In contrast to explicit memory, which requires conscious recollection, implicit memory does not require recollection of previous experiences and is evidenced by a priming effect on task performance. The authors evaluated the effect of a standardized anesthetic technique on implicit memory, first using a word stem completion task, and then a reading speed task in a subsequent study.
While undergoing lumbar disc surgery, 60 patients were exposed to auditory materials via headphones in two successive experiments. A balanced intravenous technique with propofol and alfentanil infusions and a nitrous oxide-oxygen mixture was used to maintain adequate anesthesia. In the first experiment, 30 patients were exposed randomly to one of the two lists of 34 repeated German nouns; in the second experiment, 30 patients were exposed to one of two tapes containing two short stories. Thirty control patients for each experiment heard the tapes without receiving anesthesia. All patients were tested for implicit memory 6-8 h later: A word stem completion task for the words and a reading speed task for the stories were used as measures of implicit memory.
The control group completed the word stems significantly more often with the words that they had heard previously, but no such effect was found in the anesthetized group. However, both the control and patient groups showed a decreased reading time of about 40 ms per word for the previously presented stories compared with the new stories. The patients had no explicit memory of intraoperative events.
Implicit memory was demonstrated after anesthesia by the reading speed task but not by the word stem completion task. Some methodologic aspects, such as using low frequency words or varying study and test modalities, may account for the negative results of the word stem completion task. Another explanation is that anesthesia with propofol, alfentanil, and nitrous oxide suppressed the word priming but not the reading speed measure of implicit memory. The reading speed paradigm seems to provide a stable and reliable measurement of implicit memory.
在缺乏对术中事件的回忆和识别等显性记忆的情况下，通过几种内隐记忆测试已证实了全身麻醉期间播放的听觉信息的记忆。与需要有意识回忆的显性记忆不同，内隐记忆不需要回忆先前的经历，而是通过对任务表现的启动效应来证明。作者首先使用词干补全任务，然后在后续研究中使用阅读速度任务，评估了标准化麻醉技术对内隐记忆的影响。
在接受腰椎间盘手术时，60例患者在两个连续的实验中通过耳机接触听觉材料。采用丙泊酚和阿芬太尼输注以及氧化亚氮 - 氧气混合气体的平衡静脉技术来维持适当的麻醉。在第一个实验中，30例患者随机接触34个重复的德语名词的两个列表中的一个；在第二个实验中，30例患者接触包含两个短篇小说的两盒磁带中的一盒。每个实验的30例对照患者听磁带但不接受麻醉。所有患者在6 - 8小时后进行内隐记忆测试：使用针对单词的词干补全任务和针对故事的阅读速度任务作为内隐记忆的测量指标。
对照组用他们之前听过的单词显著更频繁地完成词干，但在麻醉组中未发现这种效应。然而，与新故事相比，对照组和患者组对于之前呈现的故事都显示出每个单词约40毫秒的阅读时间减少。患者对术中事件没有显性记忆。
麻醉后通过阅读速度任务而非词干补全任务证明了内隐记忆。一些方法学方面的因素，如使用低频单词或改变学习和测试方式，可能是词干补全任务结果为阴性的原因。另一种解释是丙泊酚、阿芬太尼和氧化亚氮麻醉抑制了单词启动，但没有抑制内隐记忆的阅读速度测量指标。阅读速度范式似乎为内隐记忆提供了一种稳定可靠的测量方法。
