Hippocampal function during behaviorally silent associative learning: dissociation of memory storage and expression.
Hippocampal function during behaviorally silent associative learning: dissociation of memory storage and expression.
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行为沉默联想学习期间的海马功能：记忆存储和表达的分离。
DOI：
10.1002/hipo.10098
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
Matzel,LouisD
中科院分区：
文献类型：
--
作者：
Talk,AndrewC;Gandhi,ChetanC;Matzel,LouisD
在实验室研究中，记忆的评估通常与明显的行为反应有关。因此，很难确定通常伴随记忆形成的海马感觉诱发电位的增强是记忆“痕迹”的神经生理学表现还是记忆行为表达的次级产物。我们通过检查感觉预处理过程中诱发海马场电位的变化来解决这个问题，感觉预处理是一种行为沉默关系学习的形式，需要完整的海马来执行。大鼠暴露于以音调（S2）终止的白色噪声（S1）。这些表面上“中性”的刺激配对并没有支持噪音引起的行为变化。然而，如果随后将音调与轻度足电击（US）配对，则噪声会引起持续舔行为（表示恐惧）的抑制，表明动物已将噪声与音调（S1-S2）相关联，并代表了噪声-音调-电击（S1-S2-US）关系。海马的训练前神经毒性损伤对音-休克（S2-US）配对后对音的条件性抑制没有影响，但破坏了音-休克配对后对噪声（S1）的持续抑制的表达。在第二个实验中，用细胞外电极记录背侧海马中的感觉诱发场电位。在噪声和音调配对后，没有观察到由白色噪声诱发的海马反应的变化，即，没有证据显示有记忆痕迹。相比之下，在音调与足电击配对后，噪声诱发场反应中的两个短潜伏期负电位的幅度增加，这种反应通常被认为反映了记忆储存的神经生理学相关性。总的来说，这些结果表明，虽然海马对行为沉默联想记忆的处理有重要贡献，但海马感觉诱发场电位的幅度变化在存储感觉经验之间关系的表征方面可能没有作用。海马2002;12：648-656.© 2002 Wiley利斯公司
In laboratory studies, the assessment of memory is typically associated with overt behavioral responses. Thus, it has been difficult to determine whether the enhancement of hippocampal sensory‐evoked potentials that often accompany memory formation are the neurophysiological manifestation of a memory “trace” or are a secondary product of the behavioral expression of the memory. We addressed this issue by examining changes in evoked hippocampal field potentials during sensory preconditioning, a form of behaviorally silent relational learning that requires an intact hippocampus for execution. Rats were exposed to presentations of a white noise (S1) that terminated with a tone (S2). These pairings of ostensibly “neutral” stimuli supported no change in the behavior elicited by the noise. However, if the tone was subsequently paired with mild footshock (US), suppression of ongoing licking behavior (indicative of fear) was elicited by the noise, indicating that the animal had associated the noise with tone (S1‐S2), and had represented the noise‐tone‐shock (S1‐S2‐US) relationship. Pre‐training neurotoxic lesions of the hippocampus had no effect on conditioned suppression to tone after tone‐shock (S2‐US) pairings, but disrupted the expression of continued suppression to noise (S1) after tone‐shock pairings. In a second experiment, sensory‐evoked field potentials in the dorsal hippocampus were recorded with extracellular electrodes. No changes in the hippocampal response evoked by white noise were observed after pairings of noise and tone, i.e., no evidence for a memory trace could be detected. In contrast, after tone was paired with footshock, two short‐latency negative potentials within the noise‐evoked field response increased in amplitude, a response often presumed to reflect a neurophysiological correlate of memory storage. In total, these results suggest that although the hippocampus critically contributes to the processing of a behaviorally silent associative memory, there may be no role for changes in the amplitude of hippocampal sensory‐evoked field potentials in storing representations of the relationships between sensory experiences. Hippocampus 2002;12:648–656. © 2002 Wiley‐Liss, Inc.