Classical conditioning and brain systems: The role of awareness
Classical conditioning and brain systems: The role of awareness
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DOI：
10.1126/science.280.5360.77
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发表时间：
1998-04-03
期刊：
影响因子：
56.9
通讯作者：
Squire, LR
中科院分区：
文献类型：
--
作者：
Clark, RE;Squire, LR
经典条件反射的眨眼反应，也许是最好的研究例子，在脊椎动物的联想学习，是相对自动和反射，并与标准程序（简单的延迟条件反射），它是完整的海马损伤的动物。在延迟条件反射中，一个音调[条件刺激（CS）]就在空气喷向眼睛[非条件刺激（US）]之前出现。然后呈现US，并且两个刺激共同终止。在描记条件反射中，标准范例的一种变体，在CS的偏移和US的开始之间插入短间期（500至1000 ms）。海马损伤的动物不能获得跟踪条件反射。对海马结构受损的痴呆患者和正常志愿者进行了两种版本的延迟条件反射和两种版本的跟踪条件反射测试，然后评估他们意识到CS和US之间的时间关系的程度。癫痫患者获得延迟条件反射在正常的速度，但未能获得跟踪条件反射。对于正常志愿者来说，意识与成功的延迟条件反射无关，但却是成功的痕迹条件反射的先决条件。痕迹条件反射是海马体依赖的，因为在陈述性记忆的其他任务中，意识知识必须在训练过程中获得。在当前关于多个记忆系统和海马体功能的观点的背景下，痕迹条件反射可能为研究非人类动物的意识提供一种手段。
Classical conditioning of the eye-blink response, perhaps the best studied example of associative learning in vertebrates, is relatively automatic and reflexive, and with the standard procedure (simple delay conditioning), it is intact in animals with hippocampal lesions. In delay conditioning, a tone [the conditioned stimulus (CS)] is presented just before an air puff to the eye [the unconditioned stimulus (US)]. The US is then presented, and the two stimuli coterminate. In trace conditioning, a variant of the standard paradigm, a short interval (500 to 1000 ms) is interposed between the offset of the CS and the onset of the US. Animals with hippocampal lesions fail to acquire trace conditioning. Amnesic patients with damage to the hippocampal formation and normal volunteers were tested on two versions of delay conditioning and two versions of trace conditioning and then assessed for the extent to which they became aware of the temporal relationship between the CS and the US. Amnesic patients acquired delay conditioning at a normal rate but failed to acquire trace conditioning. For normal volunteers, awareness was unrelated to successful delay conditioning but was a prerequisite for successful trace conditioning, Trace conditioning is hippocampus dependent because, as in other tasks of declarative memory, conscious knowledge must be acquired across the training session. Trace conditioning may provide a means for studying awareness in nonhuman animals, in the context of current ideas about multiple memory systems and the function of the hippocampus.