CS-US非配对刺激易化豚鼠经典瞬目条件反射的建立

Pseudo-paired conditioned and unconditioned stimuli facilitates classical eyeblink conditioning in guinea pigs

目的探讨在豚鼠经典瞬目条件反射(eyeblink conditioning,EBC)中,条件刺激(conditioned stimulus,CS)与非条件刺激(unconditioned stimulus,US)先期的非配对训练对后续的CS-US配对训练结果是否存在易化效应,并分析其可能的神经机制。方法采用96只(4~5月龄,体质量500~550 g)健康雄性英国种白化豚鼠,以内侧前额叶或海马的微电流刺激作为中枢CS(m PFC CS或Hip.CS),以纯音刺激作为外周CS(Tone CS),以角膜吹气作为US,对实验组(8组,每组4只动物)和对照组(8组,每组8只动物)进行延迟性瞬目条件反射(delay EBC,DEBC)和痕迹性瞬目条件反射(trace EBC,TEBC)行为训练。其中实验组首先接受1周的非配对训练,包括中枢CS(m PFC CS或Hip.CS)及外周听觉CS(Tone CS)分别与角膜吹气的非配对训练,然后转换CS类型并进行与角膜吹气的配对训练,对照组直接接受中枢或外周CS与角膜吹气配对训练。结果在Tone CS与m PFC CS转换的情况下,无论对于DEBC还是TEBC模式,各实验组条件反应(conditioned responses,CR)的习得速率均快于对照组(P<0.05)。在Tone CS与Hip.CS转换的情况下,只有在TEBC模式下实验组的CR习得速率快于对照组(P<0.01);而在DEBC模式下,实验组习得CR的速率与对照组无显著差异(P>0.05)。结论先期的CS、US的非配对刺激对于后续EBC建立具有易化效应。两类非特异性刺激可能均不同程度地参与对于EBC的易化作用。

Objective To investigate whether pseudo-paired presentation of conditioned stimulus( CS) and unconditioned stimulus( US) can facilitate the subsequent CS-US paired training of classical eyeblink conditioning( EBC) in guinea pigs and to analyze the possible neural mechanisms of the facilitation effect. Methods Ninety-six health male albino Dunkin-Hartley guinea pigs( 4 to 5 months old,weighting500 to 550 g) were randomly assigned to receive behavioral training of delay eyeblink conditioning( DEBC) or trace eyeblink conditioning( TEBC). Micro-electrical stimulation of the medial prefrontal cortex( m PFC CS)or hippocampus( Hip CS) was selected as the central CS. A pure tone was used as the peripheral CS( Tone CS) and corneal air-puff was applied as US. The animals were divided into 8 experimental groups( n = 4) and8 control groups( n = 8). The animals in experimental groups were firstly given 1 week ’s pseudo-paired training with central or peripheral CS,and randomly presentation of US,then CS was switched from central to peripheral or vice versa,and paired with US to establish DEBC or TEBC. Animals in control groups were directly given paired training with central or peripheral CS and paired with US. Results( 1) After the in advance pseudo-paired training with m PFC CS or tone CS and randomly presentations of US,the acquisition rates of both DEBC and TEBC were greater in experimental groups than control groups during paired training in which CS were switched from m PFC stimulation to tone stimulation or vice versa and paired with US( P <0. 05).( 2) After the in advance pseudo-paired training with Hip CS or tone CS and randomly presentations of US,the acquisition rates of TEBC were greater in experimental groups than control groups( P < 0. 01),but the acquisition rate of DEBC was similar in the experimental groups and control groups( P > 0. 05) when CS was switched from Hip stimulation to tone or vice versa and paired with US. Conclusion The early CS-US pseudo-paired training has facilitating effect on the subsequent EBC establishment in CS-US paired training.Two types of non-specific stimulations of both CS and US may contribute to the facilitating effect for EBC in various degrees.