Leal-Campanario Rocío, Fairén Alfonso, Delgado-García José M, Gruart Agnès
División de Neurociencias, Universidad Pablo de Olavide, 41013 Sevilla, Spain.
Proc Natl Acad Sci U S A. 2007 Jul 3;104(27):11459-64. doi: 10.1073/pnas.0704548104. Epub 2007 Jun 25.
We have studied the role of rostral medial prefrontal cortex (mPFC) on reflexively evoked blinks and on classically conditioned eyelid responses in alert-behaving rabbits. The rostral mPFC was identified by its afferent projections from the medial half of the thalamic mediodorsal nuclear complex. Classical conditioning consisted of a delay paradigm using a 370-ms tone as the conditioned stimulus (CS) and a 100-ms air puff directed at the left cornea as the unconditioned stimulus (US). The CS coterminated with the US. Electrical train stimulation of the contralateral rostral mPFC produced a significant inhibition of air-puff-evoked blinks. The same train stimulation of the rostral mPFC presented during the CS-US interval for 10 successive conditioning sessions significantly reduced the generation of conditioned responses (CRs) as compared with values reached by control animals. Interestingly, the percentage of CRs almost reached control values when train stimulation of the rostral mPFC was removed from the fifth conditioning session on. The electrical stimulation of the rostral mPFC in well conditioned animals produced a significant decrease in the percentage of CRs. Moreover, the stimulation of the rostral mPFC was also able to modify the kinematics (latency, amplitude, and velocity) of evoked CRs. These results suggest that the rostral mPFC is a potent inhibitor of reflexively evoked and classically conditioned eyeblinks but that activation prevents only the expression of CRs, not their latent acquisition. Functional and behavioral implications of this inhibitory role of the rostral mPFC are discussed.
我们研究了家兔警觉行为时，吻内侧前额叶皮质（mPFC）在反射性诱发眨眼及经典条件性眼睑反应中的作用。吻内侧前额叶皮质是通过丘脑背内侧核复合体内侧半的传入投射来确定的。经典条件反射采用延迟模式，以370毫秒的纯音作为条件刺激（CS），以100毫秒的空气脉冲吹向左眼角膜作为非条件刺激（US）。条件刺激与非条件刺激同时结束。对侧吻内侧前额叶皮质的电串刺激显著抑制了空气脉冲诱发的眨眼。在条件刺激-非条件刺激间隔期间，对吻内侧前额叶皮质进行同样的串刺激，并持续10个连续的条件反射训练 sessions，与对照动物相比，条件反应（CRs）的产生显著减少。有趣的是，从第五次条件反射训练开始去除吻内侧前额叶皮质的串刺激后，条件反应的百分比几乎达到对照值。对训练良好的动物进行吻内侧前额叶皮质的电刺激，条件反应的百分比显著降低。此外，吻内侧前额叶皮质的刺激还能够改变诱发的条件反应的运动学特征（潜伏期、幅度和速度）。这些结果表明，吻内侧前额叶皮质是反射性诱发和经典条件性眨眼的有效抑制剂，但激活仅能阻止条件反应的表达，而非其潜在获得。文中讨论了吻内侧前额叶皮质这一抑制作用的功能和行为学意义。
