Memory is thought to be encoded within networks of neurons within the brain, but the identity of the neurons involved and circuits they form have not been described for any memory. Previously, we used fos-tau-lacZ (FTL) transgenic mice to identify discrete populations of neurons in different regions of the brain which were specifically activated following fear conditioning. This suggested that these populations of neurons form nodes in a network that encodes fear memory. In particular, one population of learning activated neurons was found within a discrete region of the lateral amygdala (LA), a key nucleus required for fear conditioning. In order to provide evidence that this population is directly involved in fear conditioning, we have analysed the expression of a key molecular requirement for fear conditioning in LA, phosphorylated Extracellular Signal Regulated Kinase 1 and 2 (pERK1/2). The only neurons in LA that specifically expressed pERK1/2 following auditory fear conditioning were in the ventrolateral nucleus of the LA (LAvl), in the same discrete region where we found learning specific FTL+ neurons. Double labelling experiments in FTL mice showed that a substantial proportion of the learning activated neurons expressed both pERK1/2 and FTL. These experiments provide clear evidence that the learning specific neurons we identified within LAvl are directly involved in auditory fear conditioning. In addition, learning specific expression of pERK1/2 was found in a dense network of dendrites contained within the border region of the LAvl. This network of dendrites may represent an activated dendritic field involved in fear conditioning in LA.

中文翻译：

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外侧杏仁核中特定数量的神经元直接参与听觉恐惧学习和记忆的证据。

记忆被认为是在大脑内神经元网络内编码的，但是尚未对任何记忆描述涉及的神经元的身份及其形成的回路。以前，我们使用fos-tau-lacZ（FTL）转基因小鼠来识别大脑不同区域中离散的神经元种群，这些种群在恐惧调节后被特异性激活。这表明这些神经元群体在编码恐惧记忆的网络中形成节点。特别是，在外侧杏仁核（LA）的离散区域（恐惧调节所需的关键核）的不连续区域中发现了一群学习激活的神经元。为了提供证据表明该人群直接参与恐惧调节，我们分析了洛杉矶恐惧调节的关键分子要求的表达，磷酸化的细胞外信号调节激酶1和2（pERK1 / 2）。在听觉恐惧条件下，LA中唯一能特异性表达pERK1 / 2的神经元是在LA的腹外侧核（LAvl）中，在我们发现学习特定FTL +神经元的同一离散区域中。在FTL小鼠中进行的双标记实验表明，学习激活神经元中有很大一部分表达了pERK1 / 2和FTL。这些实验提供了明确的证据，表明我们在LAv1中识别出的学习特定神经元直接参与了听觉恐惧的调节。另外，在包含在LAv1的边界区域内的树突的致密网络中发现了pERK1 / 2的学习特异性表达。该树突网络可能代表一个激活的树突区域，参与了洛杉矶的恐惧调节。