Devauges V, Sara S J
Department de Psychophysiologie, Centre Nationale de la Recherche Scientifique, Gif-sur-Yvette, France.
Behav Brain Res. 1990 Jun 18;39(1):19-28. doi: 10.1016/0166-4328(90)90118-x.
The noradrenergic system was pharmacologically activated with the alpha 2 receptor antagonist, idazoxan (2 mg/kg i.p.), during the acquisition of a complex appetitive task requiring a shift in attention to stimulus dimension and in response strategy. Rats first learned a fixed path of 6 successive choices in a linear maze. The task was then changed to a visual discrimination task in which the spatial configuration of the correct path was indicated by visual cues and changed on each daily trial. During this part of the task, the rats were injected before each trial with idazoxan, a drug which increases the firing rate of neurons in the locus coeruleus and the release of noradrenaline in the cortex and hippocampus. Two control experiments showed that the drug treatment had no effect on the acquisition of either component of the task - the successive place learning or the visual discrimination. The drug was found to be effective only during the shift phase of the experiment, the idazoxan-treated rats taking fewer trials to reach criterion than the saline. A second experiment showed that idazoxan increased the amount of time spent investigating novel and unexpected objects in a familiar hole board. These results implicate the noradrenergic system in problem-solving which requires an attentional shift or a shift in responding from familiar to novel stimuli.
在一项复杂的奖赏任务获取过程中，使用α2受体拮抗剂咪唑克生（腹腔注射2毫克/千克）对去甲肾上腺素能系统进行药理学激活，该任务需要注意力转移到刺激维度和反应策略上。大鼠首先在直线迷宫中学习连续6次选择的固定路径。然后任务转变为视觉辨别任务，其中正确路径的空间配置由视觉线索指示，并且在每天的试验中都会改变。在任务的这一部分期间，大鼠在每次试验前注射咪唑克生，该药物可增加蓝斑中神经元的放电率以及皮质和海马中去甲肾上腺素的释放。两项对照实验表明，药物处理对任务的任何一个组成部分——连续位置学习或视觉辨别——的获取均无影响。发现该药物仅在实验的转换阶段有效，接受咪唑克生处理的大鼠比接受生理盐水处理的大鼠达到标准所需的试验次数更少。第二项实验表明，咪唑克生增加了在熟悉的洞板中探究新奇和意外物体所花费的时间。这些结果表明，去甲肾上腺素能系统参与了需要注意力转移或从熟悉刺激向新奇刺激反应转变的问题解决过程。
