Depoortere R, Sandner G, Di Scala G
D.N.B.C., Centre de Neurochimie du C.N.R.S., Strasbourg, France.
Physiol Behav. 1990 Mar;47(3):561-7. doi: 10.1016/0031-9384(90)90127-p.
Electrical stimulation of the so-called "mesencephalic locomotor region" (MLR) in the acute mesencephalic and restrained rat is known to induce locomotion. In the intact and freely moving rat, electrical stimulation of an area coextensive with MLR is reported to elicit an apparently aversive type of behavioral response. Indeed, the description of this behavioral response is very similar to the description of the prototypical escape reaction elicited by electrical stimulation of the periaqueductal gray (PAG), a structure of the so-called "brain aversive system." In this study, we investigated if, as is the case for PAG stimulations, these MLR electrical stimulations are also aversive in nature. To that end, MLR-stimulated rats were subjected to the switch-off test, in which the stimulated rat learns to interrupt the stimulation by pressing a bar. It was found that electrical stimulation of MLR sites, positive for apparently aversive behavior, supports the learning of the switch-off behavior, which demonstrates the aversive nature of such stimulations. Furthermore, the switch-off latency (time elapsed between the onset of the stimulation and its offset by a press of the bar) was shown to decrease when the intensity of the electrical stimulation is increased or when the interpulse interval is decreased, which suggests that the generated aversive state is graded by the strength of the stimulation. It is, hence, proposed to extend the "brain aversive system" to the MLR.
已知在急性中脑且受束缚的大鼠中，电刺激所谓的“中脑运动区”（MLR）可诱发运动。据报道，在完整且自由活动的大鼠中，电刺激与MLR范围一致的区域会引发一种明显的厌恶型行为反应。实际上，这种行为反应的描述与电刺激导水管周围灰质（PAG）所引发的典型逃避反应的描述非常相似，PAG是所谓“脑厌恶系统”的一个结构。在本研究中，我们调查了与PAG刺激的情况一样，这些MLR电刺激在本质上是否也具有厌恶性质。为此，对接受MLR刺激的大鼠进行了关闭测试，在该测试中，受刺激的大鼠学会通过按压杠杆来中断刺激。结果发现，对明显具有厌恶行为的MLR部位进行电刺激，能支持关闭行为的学习，这证明了此类刺激的厌恶性质。此外，当电刺激强度增加或脉冲间隔减小时，关闭潜伏期（从刺激开始到通过按压杠杆使其停止之间经过的时间）会缩短，这表明所产生的厌恶状态是由刺激强度分级的。因此，有人提议将“脑厌恶系统”扩展至MLR。
