Holahan Matthew R, Rekart Jerome L, Sandoval Jimena, Routtenberg Aryeh
Department of Psychology, Northwestern University, Evanston, Illinois 60208, USA.
Hippocampus. 2006;16(6):560-70. doi: 10.1002/hipo.20185.
Hebb (1949) proposed that after learning both presynaptic and postsynaptic structural changes form the neural substrate of long-lasting memory. Despite this, there are few instances linking presynaptic remodeling with learning. Here the authors demonstrate in two different rat strains that learning the location of a hidden platform induces expansion of the presynaptic hippocampal mossy fiber terminal field (MFTF) from the stratum lucidum to the distal stratum oriens (dSO). Prior to any training, Long Evans rats (LER) showed an extensive endogenous MFTF innervation of DSO, in contrast to Wistar rats (WR) that showed minimal innervation. LER showed better recall than WR on the hidden platform water maze task and a visible reversal water maze task. In both strains, significant MFTF expansion to dSO, spanning approximately 200 mum, was detected 7 days after training on the hidden platform task, but only LER showed significant MFTF expansion 24 h after training. It is attractive to think that the MFTF expansion to dSO contributes both to long-lasting memory formation and to facilitating spatial navigation strategies. The present results establish learning-induced axonal remodeling of the hippocampal MF system in adult rats as an especially useful system for exploring presynaptic morphological adjustments consequent to learning.
赫布（1949年）提出，学习后突触前和突触后的结构变化形成了长期记忆的神经基础。尽管如此，将突触前重塑与学习联系起来的实例却很少。在此，作者在两种不同的大鼠品系中证明，学习隐藏平台的位置会诱导海马苔藓纤维终末场（MFTF）从透明层扩展到远端的梨状层（dSO）。在任何训练之前，长 Evans 大鼠（LER）的dSO有广泛的内源性MFTF神经支配，而Wistar大鼠（WR）的神经支配则很少。在隐藏平台水迷宫任务和可见反转水迷宫任务中，LER的记忆表现优于WR。在两个品系中，隐藏平台任务训练7天后，均检测到MFTF向dSO有显著扩展，跨度约200μm，但只有LER在训练24小时后显示出显著的MFTF扩展。认为MFTF向dSO的扩展有助于长期记忆形成和促进空间导航策略，这很有吸引力。目前的结果表明，成年大鼠海马MF系统的学习诱导轴突重塑是探索学习后突触前形态调整的一个特别有用的系统。
