01999nas a2200253   4500008004100000022001400041245005300055210005100108260001200159300001200171490000800183520136000191653001701551653001301568653001101581653001501592653000801607653001101615653001601626100002101642700001301663700002101676856004801697       2001                        eng d  a0304-394000aTime course of H-reflex conditioning in the rat.0 aTime course of Hreflex conditioning in the rat  c04/2001  a85–880 v3023 aThis study sought to define the course of operantly conditioned change in the rat soleus H-reflex and to determine whether, like H-reflex conditioning and spinal stretch reflex conditioning in the monkey, it develops in distinct phases. Data from 33 rats in which the right soleus H-reflex was trained up (i.e. HRup mode) and 38 in which it was trained down (i.e. HRdown mode) were averaged to define the courses of H-reflex increase and decrease. In HRup rats, the H-reflex showed a large phase I increase within the first 2 days followed by gradual phase II increase that continued for weeks. In HRdown rats, the H-reflex appeared to show a small phase I decrease and then showed a gradual phase II decrease over weeks. In combination with other recent work, the data suggest that H-reflex conditioning begins with a rapid mode-appropriate alteration in corticospinal tract influence over the spinal arc of the H-reflex, which causes phase I change, and that the continuation of this altered influence induces gradual spinal cord plasticity that is responsible for phase II change. The results further establish the similarity of H-reflex conditioning in primates and rats. Thus, they encourage efforts to produce a single coherent model of the phenomenon based on data from the two species and indicate the potential clinical relevance of the rat data.10aconditioning10aLearning10aMemory10aplasticity10arat10aReflex10aSpinal Cord1 aChen, Xiang Yang1 aChen, Lu1 aWolpaw, Jonathan  uhttp://www.ncbi.nlm.nih.gov/pubmed/11290393