Chen Xiang Yang, Wang Yu, Chen Yi, Chen Lu, Wolpaw Jonathan R
National Center for Adaptive Neurotechnologies, Wadsworth Center, New York State Department of Health, Albany, New York;
Department of Biomedical Sciences, State University of New York, Albany, New York.
J Neurophysiol. 2016 Oct 1;116(4):1946-1955. doi: 10.1152/jn.00085.2016. Epub 2016 Aug 17.
The inferior olive (IO) is essential for operant down-conditioning of the rat soleus H-reflex, a simple motor skill. To evaluate the role of the IO in long-term maintenance of this skill, the H-reflex was down-conditioned over 50 days, the IO was chemically ablated, and down-conditioning continued for up to 102 more days. H-reflex size just before IO ablation averaged 62(±2 SE)% of its initial value (P < 0.001 vs. initial). After IO ablation, H-reflex size rose to 75-80% over ∼10 days, remained there for ∼30 days, rose over 10 days to above its initial value, and averaged 140(±14)% for the final 10 days of study (P < 0.01 vs. initial). This two-stage loss of down-conditioning maintenance correlated with IO neuronal loss (r = 0.75, P < 0.01) and was similar to the loss of down-conditioning that follows ablation of the cerebellar output nuclei dentate and interpositus. In control (i.e., unconditioned) rats, IO ablation has no long-term effect on H-reflex size. These results indicate that the IO is essential for long-term maintenance of a down-conditioned H-reflex. With previous data, they support the hypothesis that IO and cortical inputs to cerebellum combine to produce cerebellar plasticity that produces sensorimotor cortex plasticity that produces spinal cord plasticity that produces the smaller H-reflex. H-reflex down-conditioning appears to depend on a hierarchy of plasticity that may be guided by the IO and begin in the cerebellum. Similar hierarchies may underlie other motor learning.
下橄榄核（IO）对于大鼠比目鱼肌H反射（一种简单的运动技能）的操作性消退条件作用至关重要。为了评估IO在这种技能长期维持中的作用，H反射在50天内进行消退条件作用，对IO进行化学损毁，然后消退条件作用再持续长达102天。IO损毁前H反射大小平均为其初始值的62（±2标准误）%（与初始值相比，P<0.001）。IO损毁后，H反射大小在约10天内升至75 - 80%，在该水平维持约30天，在接下来的10天内升至高于其初始值，在研究的最后10天平均为140（±14）%（与初始值相比，P<0.01）。这种消退条件作用维持的两阶段丧失与IO神经元丧失相关（r = 0.75，P<0.01），并且与小脑输出核齿状核和间位核损毁后消退条件作用的丧失相似。在对照（即未条件化）大鼠中，IO损毁对H反射大小没有长期影响。这些结果表明，IO对于消退条件化H反射的长期维持至关重要。结合先前的数据，它们支持这样的假设，即IO和大脑皮层输入到小脑共同产生小脑可塑性，进而产生感觉运动皮层可塑性，再产生脊髓可塑性，从而产生较小的H反射。H反射消退条件作用似乎依赖于一种可塑性层级，该层级可能由IO引导并始于小脑。类似的层级可能是其他运动学习的基础。
