Zhang Wei, Linden David J
Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
J Neurosci. 2006 Jun 28;26(26):6935-44. doi: 10.1523/JNEUROSCI.0784-06.2006.
Several lines of evidence have indicated that the deep cerebellar nuclei (DCN) are a site of memory storage for certain forms of motor learning, most notably associative eyelid conditioning. In particular, these experiments, together with network models, have implicated the excitatory glutamatergic synapse between mossy fibers and DCN neurons in this memory trace. However, to date, evidence for persistent use-dependent change in the strength of this synapse has been almost entirely absent. Here, we report that high-frequency burst stimulation of mossy fibers, either alone or paired with postsynaptic depolarization, gives rise to long-term depression (LTD) of the mossy fiber-DCN synapse. This form of LTD is not associated with changes in the paired-pulse ratio and is blocked by loading with a postsynaptic Ca2+ chelator but not by bath application of an NMDA receptor antagonist. Mossy fiber-DCN LTD requires activation of a group I metabotropic glutamate receptor (mGluR) and protein translation. Unlike mGluR/translation-dependent LTD in other brain regions, this form of LTD requires mGluR1 and is mGluR5 independent.
多项证据表明，小脑深部核团（DCN）是某些形式的运动学习的记忆存储位点，最显著的是联合性眼睑条件反射。具体而言，这些实验以及网络模型表明，苔藓纤维与DCN神经元之间的兴奋性谷氨酸能突触参与了这一记忆痕迹。然而，迄今为止，几乎完全没有证据表明这种突触的强度存在持续的使用依赖性变化。在此，我们报告，单独或与突触后去极化配对的苔藓纤维高频爆发刺激会导致苔藓纤维 - DCN突触的长时程抑制（LTD）。这种形式的LTD与双脉冲比率的变化无关，并且可被突触后Ca2 +螯合剂加载所阻断，但不能被浴应用NMDA受体拮抗剂所阻断。苔藓纤维 - DCN LTD需要激活I组代谢型谷氨酸受体（mGluR）和蛋白质翻译。与其他脑区中mGluR/翻译依赖性LTD不同，这种形式的LTD需要mGluR1且不依赖于mGluR5。
