Derrick B E, Martinez J L
Division of Life Sciences, The University of Texas, San Antonio 78249, USA.
Nature. 1996 May 30;381(6581):429-34. doi: 10.1038/381429a0.
Long-term potentiation (LTP) and long-term depression (LTD) are activity-dependent changes in synaptic strength that may serve as the cellular mechanisms of information storage in the vertebrate brain. The mossy fibre-CA3 synapse displays NMDA (M-methyl-D-aspartate) receptor-independent forms of LTP and LTD that were thought to be non-associative. Here we report that the mossy fibre-CA3 synapse displays each of the known types of LTD in vivo, including associative, heterosynaptic and homosynaptic LTD. These types of LTD are induced when only two of the three conditions necessary for mossy fibre LTP induction are provided. Because some of these conditions can be provided by convergent CA3 afferents, each type of LTD can be induced in an associative manner, which suggests that LTD is involved in associative information storage. Similar to the induction of NMDA receptor-dependent LTD and LTP at other cortical synapses, mossy fibre LTD occurs when synaptic conditions are insufficient to induce LTP, and both LTP and LTD induction are influenced by previous synaptic activity, consistent with the view that common principles govern activity-dependent plasticity at cortical synapses.
长时程增强（LTP）和长时程抑制（LTD）是突触强度的活动依赖性变化，可能是脊椎动物大脑中信息存储的细胞机制。苔藓纤维-CA3突触表现出不依赖N-甲基-D-天冬氨酸（NMDA）受体的LTP和LTD形式，这些形式曾被认为是非关联性的。在此我们报告，苔藓纤维-CA3突触在体内表现出每种已知类型的LTD，包括关联性、异突触性和同突触性LTD。当仅提供苔藓纤维LTP诱导所需的三个条件中的两个时，就会诱导出这些类型的LTD。由于其中一些条件可由汇聚的CA3传入纤维提供，因此每种类型的LTD都可以以关联性方式诱导，这表明LTD参与了关联性信息存储。与其他皮质突触处NMDA受体依赖性LTD和LTP的诱导类似，当突触条件不足以诱导LTP时，苔藓纤维LTD就会发生，并且LTP和LTD的诱导都受先前突触活动的影响，这与共同原则支配皮质突触处活动依赖性可塑性的观点一致。
