Post-lesion plasticity in the auditory central nervous system

对中枢神经系统（CNS）损伤的再生反应可以通过两种类型的机制引起。一种是损伤神经元的再生发芽或轴突再生，另一种是完整神经元的侧枝发芽。侧枝发芽广泛发生在中枢神经系统以及周围神经系统中。另一方面，在哺乳动物中枢神经系统中，轴突再生通常是流产的。本研究观察了小鼠下丘连合（CIC）切断后轴突再生的情况。虽然有关CNS的形态学重组的证据正在积累，但对随后在细胞水平上的功能恢复知之甚少。本研究的目的是观察再生的CIC轴突是否能与下丘神经元重建突触。如果突触重新建立，我们关心的是它们的功能特征。在手术小鼠和未手术对照组的两个神经元群体之间发现了一些统计学差异。然而，重新建立的突触似乎被适当地重新组织成新建立的神经回路，这可能与完整动物中的神经回路相似。这意味着即使在哺乳动物脑内的轴突被机械切断后，突触完整性的恢复也会发生。

Regenerative responses to damage in the central nervous system (CNS) can be elicited may two types of mechanisms. One is regenerative sprouting or axonal regeneration from damaged neurons and the other is collateral sprouting from intact neurons. Collateral sprouting occurs widely in the CNS, as well as in the peripheral nervous system. On the other band, in the mammalian CNS, axonal regeneration is usually abortive. In this study, we observed axonal regeneration in the commissure of the inferior colliculus (CIC) of mice following its transection. While evidence concerning morphological re-organization of the CNS is accumulating, little is known about the consequent recovery of function at the cellular level. The purpose of this study was to examine whether the regenerated CIC axons could re-establish synapses with neurons in the inferior colliculus (IC). If the synapses were re-established, our concern was their functional features. Some statistical differences were found between the two neuronal populations of the operated mice and the unoperated controls. However, the re-established synapses seem to be properly re-organized into newly established neural circuits which may be similar to those in the intact animals. This means the restitution of synaptic integrity occurs even after mechanical transection of the axons within mammalian brain.