Plasticity in the mediodorsal thalamo-prefrontal cortical transmission in behaving mice
Plasticity in the mediodorsal thalamo-prefrontal cortical transmission in behaving mice
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DOI：
10.1152/jn.1999.82.5.2827
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发表时间：
1999-11-01
影响因子：
2.5
通讯作者：
Garcia, R
中科院分区：
文献类型：
--
作者：
Herry, C;Vouimba, RM;Garcia, R
我们研究了行为小鼠在低频刺激丘脑中背侧（MD）和条件恐惧反应消失后丘脑-前额叶皮层传递的变化。MD的电刺激诱导内侧前额叶皮层（mPFC）的保持电位，其特征是两个初始的负正复合物（N1-P1和N2-P2），随后是两个正负复合物（P2-N3和P3-N4）。N1-P1和N2-P2复合物分别由正负和反负前额叶激活产生。由于这两种复合物通常不容易分离，前额叶突触传递的可塑性被认为是由N1-P2振幅的变化引起的。低频丘脑刺激（1200次2hz脉冲）产生长期（至少32分钟）的N1-P2振幅抑制或增强。小鼠在恐惧条件反射（音调-休克关联）下，在灭绝的第一天（音调单独呈现）表现出强烈的冻结行为，逐渐减少，但第二天仍然很高。条条性恐惧的消除在第一天伴随着前额叶传导的抑制，第二天转化为增强。在恐惧消除过程的第二天，前额叶传导的增强持续了至少24小时。综上所述，低频丘脑刺激可以使行为正常的小鼠前额叶突触传递抑制或增强。在消失的第一天观察到的前额叶突触传递减少可能反映了厌恶条件刺激（CS）对危险（非条件刺激：US）的高度预测性的加工。然而，mPFC中随后的传输增强可能与认知信息的处理有关，例如，即使对CS的情绪反应（冻结）仍然很高，CS将不再被美国跟随。
We studied changes in thalamo-prefrontal cortical transmission in behaving mice following both low-frequency stimulation of the mediodorsal thalamus (MD) and during extinction of a conditioned fear response. Electrical stimulation of the MD induces a held potential in the medial prefrontal cortex (mPFC) characterized by two initial negative-positive complexes (N1-P1 and N2-P2) followed by two positive-negative complexes (P2-N3 and P3-N4). The N1-P1 and N2-P2 complexes were identified as resulting from orthodromic and antidromic prefrontal activation, respectively. Because the two complexes were not often easily dissociated, plasticity in the prefrontal synaptic transmission was considered to result from changes in N1-P2 amplitude. Low-frequency thalamic stimulation (1,200 pulses at 2 Hz) produced either long-term (at least 32 min) depression or potentiation of the N1-P2 amplitude. Mice submitted to fear conditioning (tone-shock association), displayed on the first day of extinction (tone-alone presentations) a strong freezing behavior, which decreased progressively, but was still high the following day. Extinction of conditioned fear was accompanied the first day by a depression of prefrontal transmission, which was converted into potentiation the following day. Potentiation of prefrontal transmission lasted at least 24 h following the second day of the fear extinction procedure. In conclusion, low-frequency thalamic stimulation can produce, in behaving mice, either depression or potentiation of prefrontal synaptic transmission. Decrease in prefrontal synaptic transmission observed during the first day of extinction may reflect processing of the high degree of predictiveness of danger (unconditioned stimulus: US) by the aversive conditioned stimulus (CS). However, the subsequent potentiation of transmission in the mPFC may be related to processing of cognitive information such as the CS will no longer be followed by the US, even if emotional response (freezing) to the CS is still high.