Steidl Stephan, Veverka Kevin
Department of Psychology, Loyola University Chicago, 1032 West Sheridan Road, Chicago, IL 60626, United States.
Department of Psychology, Loyola University Chicago, 1032 West Sheridan Road, Chicago, IL 60626, United States.
Brain Res. 2015 Jul 21;1614:86-93. doi: 10.1016/j.brainres.2015.04.021. Epub 2015 Apr 21.
The laterodorsal tegmental nucleus (LDTg) importantly contributes to regulating firing activity of midbrain dopamine neurons and forebrain dopamine levels. Whether excitation of LDTg afferents to the ventral tegmental area (VTA) can reinforce operant behavior in rats is not known. Rats received adeno-associated viral vectors encoding channelrhodopsin2 (ChR2) and EYFP or EYFP only into the LDTg and were implanted with bilateral optic probes aimed at the VTA. LDTg ChR2-infected rats, but not LDTg EYFP-infected rats acquired lever pressing to obtain photostimulation into the VTA. During reversal testing, where contingencies between response levers were reversed, LDTg ChR2-infected rats learned to press the alternate, now reinforced, lever within one session. Following pretreatment with the broad-spectrum dopamine receptor blocker flupenthixol LDTg ChR2-infected rats initiated lever-pressing with normal latencies and lever-pressed normally for the first ten minutes of the session. Lever-pressing rates were strongly reduced thereafter. These results provide further support for an important role of LDTg inputs to the VTA in appetitively motivated behaviors.
外侧背盖区（LDTg）对调节中脑多巴胺能神经元的放电活动及前脑多巴胺水平起着重要作用。LDTg传入腹侧被盖区（VTA）的神经纤维兴奋是否能强化大鼠的操作性行为尚不清楚。将编码通道视紫红质2（ChR2）和增强型黄色荧光蛋白（EYFP）或仅含EYFP的腺相关病毒载体注入大鼠的LDTg，并植入双侧指向VTA的光学探针。感染ChR2的LDTg大鼠学会了按压杠杆以获得对VTA的光刺激，而感染EYFP的LDTg大鼠则未学会。在反转测试中，即反应杠杆之间的条件反转时，感染ChR2的LDTg大鼠在一个实验环节内就学会了按压另一个现在得到强化的杠杆。在用广谱多巴胺受体阻滞剂氟哌噻吨预处理后，感染ChR2的LDTg大鼠以正常潜伏期开始按压杠杆，并在实验环节的前10分钟正常按压杠杆。但此后按压杠杆的速率大幅降低。这些结果进一步支持了LDTg向VTA的输入在食欲驱动行为中起重要作用的观点。
