Sensory-evoked LTP driven by dendritic plateau potentials in vivo
Sensory-evoked LTP driven by dendritic plateau potentials in vivo
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DOI：
10.1038/nature13664
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发表时间：
2014-11-06
期刊：
影响因子：
64.8
通讯作者：
Holtmaat, Anthony
中科院分区：
文献类型：
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作者：
Gambino, Frederic;Pages, Stephane;Holtmaat, Anthony
长时程突触增强（LTP）被认为是皮层突触网络可塑性和记忆形成的关键过程（1）。Hebbian形式的LTP依赖于强烈的突触后去极化，在许多模型中，这是由从索马传播回树突的动作电位产生的（2，3）。然而，局部树突状去极化已被证明介导这些形式的LTP以及（1，4，5）。由于躯体感觉皮层颗粒上层的锥体细胞很少发出尖峰（6-8），因此尚不清楚这两种机制中的哪一种在体内对这些细胞起主导作用。在小鼠体感觉皮层中使用全细胞记录，我们证明，有节奏的感觉须刺激有效地诱导突触LTP在层2/3（L2/3）锥体细胞在体棘波的情况下。LTP的诱导依赖于NMDAR（N-甲基-D-天冬氨酸受体）介导的持久去极化的发生，其与树突平台电位相似（9-13）。此外，我们发现，胡须刺激招募突触网络，起源于丘脑（POM）的后内侧复合体。光刺激通道视紫红质-2表达POm神经元产生NMDAR介导的平台电位，而在节律性触须刺激过程中抑制POm活性抑制了这些电位的产生，并阻止了触须诱发的LTP。两者合计，我们的数据提供了证据，感觉驱动的突触LTP在体内，在没有体细胞尖峰。相反，LTP由通过丘系和丘系突触回路的合作活动产生的平台电位介导（14-16）。
Long-term synaptic potentiation (LTP) is thought to be a key process in cortical synaptic network plasticity and memory formation(1). Hebbian forms of LTPdependon strong postsynaptic depolarization, which in many models is generated by action potentials that propagate back from the soma into dendrites(2,3). However, local dendritic depolarization has been shown to mediate these forms of LTP as well(1,4,5). As pyramidal cells in supragranular layers of the somatosensory cortex spike infrequently(6-8), it is unclear which of the two mechanisms prevails for those cellsin vivo. Using whole-cell recordings in the mouse somatosensory cortexin vivo, we demonstrate that rhythmic sensory whisker stimulation efficiently induces synaptic LTP in layer 2/3 (L2/3) pyramidal cells in the absence of somatic spikes. The induction of LTP depended on the occurrence of NMDAR(N-methyl-D-aspartate receptor)-mediated long-lasting depolarizations, which bear similarities to dendritic plateau potentials(9-13). In addition, we show that whisker stimuli recruit synaptic networks that originate from the posteromedial complex of the thalamus (POm). Photostimulation of channelrhodopsin-2 expressing POm neurons generated NMDAR mediated plateau potentials, whereas the inhibition of POm activity during rhythmic whisker stimulation suppressed the generation of those potentials and prevented whisker-evoked LTP. Taken together, our data provide evidence for sensory-driven synaptic LTP in vivo, in the absence of somatic spiking. Instead, LTP is mediated by plateau potentials that are generated through the cooperative activity of lemniscal and paralemniscal synaptic circuitry(14-16).