Boyd T E, Trepel C, Racine R J
Department of Psychology, McMaster University, 1280 Main Street West, Hamilton, L8S-4K1, Ontario, Canada.
Brain Res. 2000 Oct 20;881(1):28-36. doi: 10.1016/s0006-8993(00)02720-7.
The neocortex has proven resistant to LTP induction using standard in vitro and acute, in vivo preparations. Because the neocortex is widely thought to be involved in long-term information storage, this resistance raises questions about the validity of LTP as a memory model. Recently, we have shown that the neocortex of freely moving rats reliably supports LTP, provided that the stimulation is spaced and repeated over days. The following experiments were designed to evaluate the neuromodulatory role played by cholinergic systems in the induction of LTP in this preparation. Chronically implanted rats received either low- or high-intensity LTP-inducing tetani in combination with the administration of either a cholinergic agonist or antagonist injected systemically. Potentiation was evidenced as amplitude changes in both early and late components of the evoked field potential, the former including population spikes. The cholinergic agonist facilitated LTP induction in the late component of both high- and low-intensity groups. The cholinergic antagonist blocked LTP induction in the early component of the high-intensity group. The possibility that there are component-specific modulatory effects of cholinergic agents on the induction of neocortical LTP is discussed.
使用标准的体外和急性体内实验准备方法，新皮层已被证明对长时程增强（LTP）诱导具有抗性。由于普遍认为新皮层参与长期信息存储，这种抗性引发了关于LTP作为记忆模型有效性的问题。最近，我们发现自由活动大鼠的新皮层能够可靠地支持LTP，前提是刺激是间隔进行且持续数天。以下实验旨在评估胆碱能系统在该实验准备中对LTP诱导所起的神经调节作用。长期植入的大鼠接受低强度或高强度的LTP诱导强直刺激，并同时全身注射胆碱能激动剂或拮抗剂。通过诱发场电位早期和晚期成分的幅度变化来证明增强作用，前者包括群体峰电位。胆碱能激动剂促进了高强度和低强度组晚期成分中的LTP诱导。胆碱能拮抗剂阻断了高强度组早期成分中的LTP诱导。文中讨论了胆碱能药物对新皮层LTP诱导存在成分特异性调节作用的可能性。
