Mason S T, Fibiger H C
Brain Res. 1979 Feb 2;161(2):321-33. doi: 10.1016/0006-8993(79)90073-8.
The selective neurotoxin 6-hydroxydopamine was used to deplete forebrain noradrenaline to less than 5% of control values and the learning capabilities of the depleted animals examined on a two-way active avoidance task. Noradrenaline depleted animals learned the two-way active avoidance task more quickly than controls and required fewer training trials to reach acquisition criterion. Twenty-four hour retention was not altered by the lesion, but significant resistance to extinction was seen when electric footshock was no longer presented. More detailed analysis of the improved acquisition shown by the lesioned animals revealed that the major effect lay in a reduced freezing response to footshock. This freezing tended to slow down learning in the control animals, since it was incompatible with the required two-way active avoidance response. No alteration was seen in sensory detection thresholds for electric footshock or in spontaneous locomotor activity in the absence of shock. These results are discussed in relation to theories of noradrenaline function in learning and memory and, more recently, in fear and anxiety.
选择性神经毒素6-羟基多巴胺被用于将前脑去甲肾上腺素耗竭至对照值的5%以下，并检测了耗竭动物在双向主动回避任务中的学习能力。去甲肾上腺素耗竭的动物比对照组更快地学会了双向主动回避任务，并且达到习得标准所需的训练次数更少。损伤对24小时的记忆保持没有影响，但当不再施加电击足底刺激时，可见对消退有显著抗性。对损伤动物所表现出的改善的习得进行更详细的分析发现，主要影响在于对电击足底刺激的僵住反应减少。这种僵住往往会减缓对照动物的学习，因为它与所需的双向主动回避反应不相容。在电击足底刺激的感觉检测阈值或无刺激时的自发运动活动方面未观察到改变。结合去甲肾上腺素在学习和记忆中，以及最近在恐惧和焦虑中的功能理论对这些结果进行了讨论。
