Division of Neurosciences, Pablo de Olavide University, Seville-41013, Spain.
J Neurosci. 2012 Aug 29;32(35):12129-43. doi: 10.1523/JNEUROSCI.1782-12.2012.
The red nucleus (RN) is a midbrain premotor center that has been suggested as being involved in the acquisition and/or performance of classically conditioned nictitating membrane/eyelid responses. We recorded in rabbits the activity of RN and pararubral neurons during classical eyeblink conditioning using a delay paradigm. Neurons were identified by their antidromic activation from contralateral facial and accessory abducens nuclei and by their synaptic activation from the ipsilateral motor cortex (MC) and the contralateral cerebellar interpositus (IP) nucleus. For conditioning, we used a tone as a conditioned stimulus (CS) followed 250 ms later by a 100 ms air puff as an unconditioned stimulus (US) coterminating with it. Conditioned responses (CRs) were determined from the evoked changes in the electromyographic activity of the orbicularis oculi (OO) muscle. Recorded neurons were classified by their antidromic activation and by their changes in firing rate during the CS-US interval. Identified neurons increased their firing rates in relation to the successive conditioning sessions, but their discharge rates were related more to the EMG activity of the OO muscle than to the learning curves. Reversible inactivation of the IP nucleus with lidocaine during conditioning evoked a complete disappearance of both conditioned and unconditioned eyelid responses, and a progressive decrease in CR-related activity of RN neurons. In contrast, MC inactivation evoked a decrease in the acquisition process and an initial disfacilitation of neuronal firing (which was later recovered), together with the late appearance of CRs. Thus, RN neurons presented learning-dependent changes in activity following MC inactivation.
红核（RN）是中脑的一个运动前中枢，它被认为参与了经典条件反射眨眼/眼睑反应的获得和/或表现。我们使用延迟范式在兔子中记录了经典眨眼条件反射过程中 RN 和旁正中核神经元的活动。神经元通过对侧面面神经核和副外展神经核的逆行激活以及同侧运动皮层（MC）和对侧小脑中间核（IP）核的突触激活来识别。对于条件反射，我们使用声音作为条件刺激（CS），250 毫秒后用 100 毫秒的空气喷射作为非条件刺激（US）与之同时终止。CR 是从眼轮匝肌（OO）的肌电图诱发变化中确定的。根据 CS-US 期间的逆行激活和放电率变化对记录神经元进行分类。鉴定出的神经元的放电率随着连续的条件反射过程而增加，但它们的放电率与 OO 肌肉的肌电图活动相关，而不是与学习曲线相关。在条件反射过程中用利多卡因可逆性失活 IP 核会引起条件和非条件眨眼反应完全消失，以及 RN 神经元与 CR 相关的活动逐渐减少。相比之下，MC 失活会引起获得过程的减少和神经元放电的初始去适应（随后恢复），以及 CR 的后期出现。因此，MC 失活后，RN 神经元的活动表现出与学习相关的变化。
