Hippocampal place cell firing patterns can induce long-term synaptic plasticity in vitro.
Hippocampal place cell firing patterns can induce long-term synaptic plasticity in vitro.
复制标题
DOI：
10.1523/jneurosci.0731-09.2009
复制
发表时间：
2009-05-27
期刊：
影响因子：
--
通讯作者：
Mellor JR
中科院分区：
文献类型：
--
作者：
Isaac JT;Buchanan KA;Muller RU;Mellor JR
在海马体中，锥体细胞之间的突触强度可通过 NMDA 受体 (NMDAR) 依赖性长期增强 (LTP) 和长期抑制 (LTD) 进行调节，这两者都需要一致的突触前和突触后活动。在体内，许多锥体细胞表现出位置特异性的活动模式，被称为“位置细胞”。这些因素的结合表明，在连接位置细胞和重叠放电场的突触处会诱导突触可塑性，因为当大鼠处于环境的特定部分时，这些细胞会同时放电。然而，这一预测对于如何使用长期突触可塑性来编码海马网络空间的模型很重要，但尚未得到测试。为了研究这一点，在成年海马切片的穿孔膜片钳记录期间，从自由活动的大鼠的位置细胞同时记录的动作电位时间序列被同时重播到突触后 CA1 锥体细胞和突触前输入。位置细胞放电模式诱导了大的、途径特异性、NMDAR 依赖的 LTP，并在几分钟内快速表达。然而，只有当两个位置细胞具有重叠的放电野并且通过胆碱能激动剂卡巴胆碱的沐浴恢复探索期间海马中存在的胆碱能张力时，位置细胞LTP才会被诱导。从未观察到LTD对位置细胞放电模式的反应。我们的研究结果表明，海马位置细胞的尖峰模式可以强烈诱导 NMDAR 依赖性 LTP，为支持空间距离被编码为位置细胞之间突触连接强度的模型提供了重要证据。
In the hippocampus, synaptic strength between pyramidal cells is modifiable by NMDA receptor (NMDAR)-dependent long-term potentiation (LTP) and long-term depression (LTD), both of which require coincident pre- and postsynaptic activity. In vivo, many pyramidal cells exhibit location-specific activity patterns and are known as “place cells”. The combination of these factors suggests that synaptic plasticity will be induced at synapses connecting place cells with overlapping firing fields, since such cells fire coincidentally when the rat is in a specific part of the environment. However this prediction, which is important for models of how long-term synaptic plasticity can be used to encode space in the hippocampal network, has not been tested. To investigate this, action potential time series recorded simultaneously from place cells in freely moving rats were replayed concurrently into postsynaptic CA1 pyramidal cells and presynaptic inputs during perforated patch-clamp recordings from adult hippocampal slices. Place cell firing patterns induced large, pathway-specific, NMDAR-dependent LTP that was rapidly expressed within a few minutes. However, place-cell LTP was induced only if the two place cells had overlapping firing fields and if the cholinergic tone present in the hippocampus during exploration was restored by bath application of the cholinergic agonist carbachol. LTD was never observed in response to place cell firing patterns. Our findings demonstrate that spike patterns from hippocampal place cells can robustly induce NMDAR-dependent LTP, providing important evidence in support of a model in which spatial distance is encoded as the strength of synaptic connections between place cells.