Long-term potentiation in freely moving rats reveals asymmetries in thalamic and cortical inputs to the lateral amygdala
Long-term potentiation in freely moving rats reveals asymmetries in thalamic and cortical inputs to the lateral amygdala
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DOI：
10.1046/j.1460-9568.2003.02707.x
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发表时间：
2003-06-01
影响因子：
3.4
通讯作者：
LeDoux, JE
中科院分区：
文献类型：
--
作者：
Doyère, V;Schafe, GE;LeDoux, JE
巴甫洛夫恐惧条件作用下的长期记忆被认为涉及杏仁外侧核(LA)感觉输入突触的可塑性。长时程增强(LTP)是研究突触可塑性的一个有用的生理模型。LTP在LA中的研究仅在体外或在麻醉的大鼠中进行。在这里，我们测试了LTP是否可以在清醒大鼠的LA的听觉输入通路中诱导，如果是的话，它是否持续数天。在长期植入的大鼠中，利用测试模拟和输入/输出(I/O)曲线，比较了刺激听觉丘脑和听觉联系皮质在LA中诱发的胞外场电位在同一动物中单独强直或联合强直后的情况。对于这两条途径，LTP都是特定于输入的，并且持续时间很长。皮层输入的LTP在早期时间点(24小时)变化最大，但在3天内逐渐消失。相反，丘脑输入的LTP虽然最初比皮质LTP小，但至少在6天内保持稳定。I/O曲线的比较表明，这两条途径可能依赖于不同的机制来维持LTP，并可能从它们的共同激活中获得不同的好处。这是在清醒动物中LTP在LA的感觉输入的第一次报道。这些结果揭示了恐惧记忆神经元回路中突触可塑性的重要特征，这是体外实验无法揭示的，并表明丘脑和大脑皮层听觉传入在恐惧条件性长期记忆中的不同作用。
Long-term memory underlying Pavlovian fear conditioning is believed to involve plasticity at sensory input synapses in the lateral nucleus of the amygdala (LA). A useful physiological model for studying synaptic plasticity is long-term potentiation (LTP). LTP in the LA has been studied only in vitro or in anaesthetized rats. Here, we tested whether LTP can be induced in auditory input pathways to the LA in awake rats, and if so, whether it persists over days. In chronically implanted rats, extracellular field potentials evoked in the LA by stimulation of the auditory thalamus and the auditory association cortex, using test simulations and input/output (I/O) curves, were compared in the same animals after tetanization of either pathway alone or after combined tetanization. For both pathways, LTP was input-specific and long lasting. LTP at cortical inputs exhibited the largest change at early time points (24 h) but faded within 3 days. In contrast, LTP at thalamic inputs, though smaller initially than cortical LTP, remained stable until at least 6 days. Comparisons of I/O curves indicated that the two pathways may rely on different mechanisms for the maintenance of LTP and may benefit differently from their coactivation. This is the first report of LTP at sensory inputs to the LA in awake animals. The results reveal important characteristics of synaptic plasticity in neuronal circuits of fear memory that could not have been revealed with in vitro preparations, and suggest a differential role of thalamic and cortical auditory afferents in long-term memory of fear conditioning.