Department of Experimental Medical Science, Lund University, BMC F10, 22184 Lund, Sweden.
J Neurophysiol. 2010 Mar;103(3):1329-36. doi: 10.1152/jn.00524.2009. Epub 2009 Dec 23.
Pavlovian eyeblink conditioning is a useful experimental model for studying adaptive timing, an important aspect of skilled movements. The conditioned response (CR) is precisely timed to occur just before the onset of the expected unconditioned stimulus (US). The timing can be changed immediately, however, by varying parameters of the conditioned stimulus (CS). It has previously been shown that increasing the intensity of a peripheral CS or the frequency of a CS consisting of a train of stimuli to the mossy fibers shortens the latency of the CR. The adaptive timing of behavioral CRs probably reflects the timing of an underlying learned inhibitory response in cerebellar Purkinje cells. It is not known how the latency of this Purkinje cell CR is controlled. We have recorded form Purkinje cells in conditioned decerebrate ferrets while increasing the intensity of a peripheral CS or the frequency of a mossy fiber CS. We observe changes in the timing of the Purkinje cell CR that match the behavioral effects. The results are consistent with the effect of CS parameters on behavioral CR latency being caused by corresponding changes in Purkinje cell CRs. They suggest that synaptic temporal summation may be one of several mechanisms underlying adaptive timing of movements.
巴甫洛夫式眨眼条件反射是研究适应性计时的有用实验模型，适应性计时是熟练运动的一个重要方面。条件反应 (CR) 精确地定时发生，正好在预期的非条件刺激 (US) 出现之前。然而，通过改变条件刺激 (CS) 的参数，可以立即改变计时。先前已经表明，增加外周 CS 的强度或由刺激的串组成的 CS 的频率会缩短 CR 的潜伏期。行为性 CR 的适应性计时可能反映了小脑浦肯野细胞中潜在的学习性抑制反应的计时。尚不清楚如何控制这种浦肯野细胞 CR 的潜伏期。我们在条件性去大脑化雪貂中记录浦肯野细胞，同时增加外周 CS 的强度或苔藓纤维 CS 的频率。我们观察到与行为效应相匹配的浦肯野细胞 CR 计时的变化。结果与 CS 参数对行为性 CR 潜伏期的影响一致，这是由浦肯野细胞 CR 的相应变化引起的。它们表明突触时间总和可能是运动适应性计时的几种机制之一。
