Horn G
Dept of Zoology, University of Cambridge, UK.
Trends Neurosci. 1998 Jul;21(7):300-5. doi: 10.1016/s0166-2236(97)01219-8.
To understand the neural bases of memory it is necessary to localize the regions storing information. Part of the hyperstriatum ventrale (IMHV) serves such a function for the learning process of imprinting in domestic chicks. Chicks exposed to an object learn its characteristics, and in doing so, the responsiveness of IMHV neurones to that object is selectively enhanced. Imprinting is associated with both pre- and postsynaptic changes in the region. Postsynaptic changes involve increases in the length of the postsynaptic density on dendritic spines and in the numbers of NMDA receptors; presynaptically, converging evidence points to an early and persistent enhancement of neurotransmitter release. Increases in the amounts of certain neural cell adhesion molecules a day after training might serve to stabilize the synaptic changes associated with a particular memory by strengthening pre- to postsynaptic adhesion, and by more strongly interconnecting the cytoskeletal frameworks of the dendritic spine and the synaptic terminal. Learning-related increases in the number of neurones staining positive for the transcription factor Fos in the IMHV give promise of identifying the neurones engaged in memory functions and of analysing their connections.
为了理解记忆的神经基础，有必要确定存储信息的区域。家禽雏鸡印记学习过程中，腹侧上纹状体的一部分（IMHV）起到这样的作用。接触某一物体的雏鸡会了解其特征，在此过程中，IMHV神经元对该物体的反应性会选择性增强。印记学习与该区域突触前和突触后的变化都有关。突触后变化包括树突棘上突触后致密物长度增加以及NMDA受体数量增加；在突触前，越来越多的证据表明神经递质释放会出现早期且持续的增强。训练一天后某些神经细胞黏附分子数量的增加，可能通过加强突触前到突触后的黏附作用，以及更紧密地连接树突棘和突触终末的细胞骨架框架，来稳定与特定记忆相关的突触变化。IMHV中对转录因子Fos染色呈阳性的神经元数量在学习相关过程中的增加，有望确定参与记忆功能的神经元并分析它们之间的联系。
