Barkai Edi
Sagol Department of Neurobiology, University of Haifa, Haifa, Israel.
Prog Brain Res. 2014;208:253-74. doi: 10.1016/B978-0-444-63350-7.00010-3.
Rats that are trained in a particularly difficult olfactory discrimination task demonstrate a dramatic increase in their capability to acquire memories of new odors once they have learned the first discrimination task. Such high-skill learning, termed "rule learning" or "learning set" (see Saar et al., 1998, 2001) is accompanied by a series postsynaptic cellular modifications which have three major traits: a.They are widespread throughout the piriform cortex network. Both physiological and morphological modifications are found in most of the studied neurons.b.The time course in which these modifications appear and disappear is strongly correlated with the time course in which the skill is acquired and decayed. However, memories for specific odors outlast these modifications by far. Thus, the identified modifications are related to rule learning (learning how to learn), rather than to long-term memory for the specific odors for which the rats are trained.c.While the above-mentioned changes act to enhance single-cell excitability, others reduced it; synaptic inhibition is enhanced after learning and the subunit composition of the NMDA receptor is modified in a manner that favors activity-induced synaptic weakening over synaptic enhancement.
在一项特别困难的嗅觉辨别任务中接受训练的大鼠，一旦学会了第一个辨别任务，它们获取新气味记忆的能力就会显著提高。这种高技能学习，被称为“规则学习”或“学习集”（见萨尔等人，1998年，2001年），伴随着一系列突触后细胞修饰，这些修饰具有三个主要特征：a.它们广泛分布于梨状皮层网络。在大多数被研究的神经元中都发现了生理和形态上的修饰。b.这些修饰出现和消失的时间进程与技能获得和衰退的时间进程密切相关。然而，特定气味的记忆远远超过这些修饰的持续时间。因此，所确定的修饰与规则学习（学习如何学习）有关，而不是与大鼠所训练的特定气味的长期记忆有关。c.虽然上述变化会增强单细胞兴奋性，但其他变化会降低它；学习后突触抑制增强，NMDA受体的亚基组成发生改变，这种改变有利于活动诱导的突触减弱而非突触增强。
