Spatial memory encoding depends in part on cholinergic modulation. How acetylcholine supports spatial memory encoding is not well understood. Prior studies indicate that acetylcholine release is correlated with exploration, including epochs of rearing onto hind legs. Here, to test whether elevated cholinergic tone increases the probability of rearing, we tracked rearing frequency and duration while optogenetically modulating the activity of choline acetyltransferase containing (i.e., acetylcholine producing) neurons of the medial septum in rats performing a spatial working memory task (n = 17 rats). The cholinergic neurons were optogenetically inhibited using halorhodopsin for the duration that rats occupied two of the four open arms during the study phase of an 8-arm radial arm maze win-shift task. Comparing rats' behaviour in the two arm types showed that rearing frequency was not changed, but the average duration of rearing epochs became significantly longer. This effect on rearing was observed during optogenetic inhibition but not during sham inhibition or in rats that received infusions of a fluorescent reporter virus (i.e., without halorhodopsin; n = 6 rats). Optogenetic inhibition of cholinergic neurons during the pretrial waiting phase had no significant effect on rearing, indicating a context-specificity of the observed effects. These results are significant in that they indicate that cholinergic neuron activity in the medial septum is correlated with rearing not because it motivates an exploratory state but because it contributes to the processing of information acquired while rearing.

中文翻译：

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执行空间记忆任务的大鼠饲养的胆碱能调节

空间记忆编码部分取决于胆碱能调制。乙酰胆碱如何支持空间记忆编码尚不清楚。先前的研究表明，乙酰胆碱的释放与探索相关，包括用后腿站立的时期。在这里，为了测试升高的胆碱能张力是否会增加站立的可能性，我们在执行空间工作记忆任务的大鼠中跟踪站立频率和持续时间，同时以光遗传学方式调节内侧隔膜中含有胆碱乙酰转移酶（即产生乙酰胆碱）的神经元的活性（n  = 17 只大鼠）。在 8 臂径向臂迷宫 win-shift 任务的研究阶段，当大鼠占据四个张开臂中的两个时，使用盐视紫红质对胆碱能神经元进行光遗传学抑制。比较两种臂型大鼠的行为表明，饲养频率没有改变，但饲养周期的平均持续时间明显更长。这种对饲养的影响在光遗传学抑制期间观察到，但在假抑制期间或在接受荧光报告病毒输注的大鼠中观察到（即，没有盐视紫红质；n  = 6只大鼠）。审前等待阶段胆碱能神经元的光遗传学抑制对饲养没有显着影响，表明观察到的效果具有背景特异性。这些结果很重要，因为它们表明内侧隔膜中的胆碱能神经元活动与抚养相关，不是因为它激发了探索状态，而是因为它有助于处理抚养时获得的信息。