Durkin T P, Toumane A
Laboratoire de Neurosciences Comportementales et Cognitives, URA CNRS n. 339, Université de Bordeaux 1, UFR de Biologie, Talence, France.
Behav Brain Res. 1992 Sep 28;50(1-2):43-52. doi: 10.1016/s0166-4328(05)80286-4.
We previously showed that the initial acquisition session of a spatial discrimination (mixed reference/working memory) test in an 8-arm radial maze induced differential activations in the ascending cholinergic septo-hippocampal and nBM-cortical pathways in mice. This data showed that the duration of post-test cholinergic activation was longer in the nBM-cortical pathway than in the septo-hippocampal projection. Moreover, the post-test durations but not the immediate post-test amplitudes of activation in each pathway decreased progressively as a function of repeated daily acquisition sessions. In the present study we have thus tested the hypotheses that the time-courses of post-test cholinergic activation in the septo-hippocampal and nBM-cortical pathways may vary both as a function of the type of memory used (working vs. reference) and according to the duration of repeated daily testing. Cholinergic activity in vivo in the hippocampus or frontal cortex of mice was quantified using measures of sodium-dependent high-affinity choline uptake at two different times (30 s and 15 min) following specific spatial working or reference memory testing in an 8-arm radial maze. The memory tests were administered daily over a 13-day period to attain high levels of performance in each type of task. In comparison to control groups both types of memory testing induced significant post-test cholinergic activations in each brain region on Day 15. However, cholinergic activity remained elevated in frontal cortex at 15 min post-test following reference memory testing, whereas significantly shorter durations of cortical and hippocampal cholinergic activation were observed following working memory testing using short (1 min) retention intervals. The possible significance of these differential modifications to the time-course of the post-test activations in these cholinergic pathways in working and reference memory processes and the putative transsynaptic mechanisms involved are discussed.
我们先前表明，在八臂放射状迷宫中进行空间辨别（混合参考/工作记忆）测试的初始获取阶段，会在小鼠的胆碱能上升性隔海马通路和基底前脑-皮质通路中引起不同的激活。该数据表明，基底前脑-皮质通路中测试后胆碱能激活的持续时间比隔海马投射中的更长。此外，随着每日重复获取阶段的进行，各通路中测试后的激活持续时间而非测试后即刻的激活幅度逐渐降低。因此，在本研究中，我们检验了以下假设：隔海马和基底前脑-皮质通路中测试后胆碱能激活的时间进程可能会因所使用的记忆类型（工作记忆与参考记忆）以及每日重复测试的持续时间而有所不同。在八臂放射状迷宫中进行特定的空间工作或参考记忆测试后的两个不同时间点（30秒和15分钟），通过测量钠依赖性高亲和力胆碱摄取来量化小鼠海马体或额叶皮质中的体内胆碱能活性。在13天的时间里每天进行记忆测试，以使每种任务类型都达到高水平的表现。与对照组相比，两种类型的记忆测试在第15天均在每个脑区引起了显著的测试后胆碱能激活。然而，在参考记忆测试后15分钟时，额叶皮质中的胆碱能活性仍然升高，而在使用短（1分钟）保留间隔的工作记忆测试后，观察到皮质和海马体胆碱能激活的持续时间明显较短。讨论了这些胆碱能通路中测试后激活时间进程的差异变化在工作记忆和参考记忆过程中的可能意义以及所涉及的假定跨突触机制。
