Eccles J C
J Physiol (Paris). 1986;81(4):312-7.
Long-term potentiation (LTP) of the hippocampus provides an excellent model on which to build hypotheses for the laying down of memories in the cerebral cortex. After repetitive activation, the primary happening seems to be the increase in transmitter sensitivity brought about by the increased Ca2+ in the recipient neurons. There may be secondary presynaptic changes. The extreme duration of the LTP may require structural changes of the synaptic spines. The hippocampus plays an essential role in the laying down of cognitive memories, the pathway to the frontal lobe being via the MD thalamus. The thalamo-cortical fibres activate stellate cells whose axons make climbing fibre-like ramifications up the apical dendrites of the pyramidal cells. On the Marr hypothesis repetitive conjunction of synaptic activation by these climbing fibres with synaptic activation by horizontal fibres on the apical dendrites produces prolonged potentiation of the horizontal fibre synapses, which is the neural basis of memory. Presumably this is a consequence of the raised Ca2+ of the apical dendrites, acting as it does on the hippocampal LTP. It will be considered how this elemental unit for cerebral memory can be developed into the varieties of cerebral memories that have been located by study of the regional cerebral blood flow during their retrieval. These sites for memory are in the frontal lobe, usually in the superior prefrontal area.
海马体的长时程增强（LTP）为构建大脑皮层中记忆形成假说提供了一个绝佳模型。在重复激活后，主要发生的似乎是受体神经元中Ca2+增加所导致的递质敏感性增强。可能还存在继发性突触前变化。LTP的极长时间可能需要突触棘的结构改变。海马体在认知记忆形成中起关键作用，通往额叶的通路是经由丘脑背内侧核。丘脑 - 皮质纤维激活星状细胞，其轴突在锥体细胞的顶端树突上形成类似攀爬纤维的分支。根据马尔假说，这些攀爬纤维的突触激活与顶端树突上水平纤维的突触激活反复结合，会使水平纤维突触产生长时间增强，这就是记忆的神经基础。据推测，这是顶端树突中升高的Ca2+作用的结果，就如同其在海马体LTP中所起的作用一样。接下来将探讨这个大脑记忆的基本单元如何发展成为通过研究记忆提取过程中局部脑血流所定位的各种大脑记忆。这些记忆位点位于额叶，通常在上额叶前部区域。
