02175nas a2200253   4500008004100000022001400041245008500055210006900140260001200209300001400221490000700235520145300242653003401695653000901729653001301738653001101751653001801762653001601780100001301796700002201809700002101831700002101852856004801873       2006                        eng d  a0953-816X00aMotor learning changes GABAergic terminals on spinal motoneurons in normal rats.0 aMotor learning changes GABAergic terminals on spinal motoneurons  c01/2006  a141–1500 v233 aThe role of spinal cord plasticity in motor learning is largely unknown. This study explored the effects of H-reflex operant conditioning, a simple model of motor learning, on GABAergic input to spinal motoneurons in rats. Soleus motoneurons were labeled by retrograde transport of a fluorescent tracer and GABAergic terminals on them were identified by glutamic acid decarboxylase (GAD)67 immunoreactivity. Three groups were studied: (i) rats in which down-conditioning had reduced the H-reflex (successful HRdown rats); (ii) rats in which down-conditioning had not reduced the H-reflex (unsuccessful HRdown rats) and (iii) unconditioned (naive) rats. The number, size and GAD density of GABAergic terminals, and their coverage of the motoneuron, were significantly greater in successful HRdown rats than in unsuccessful HRdown or naive rats. It is likely that these differences are due to modifications in terminals from spinal interneurons in lamina VI-VII and that the increased terminal number, size, GAD density and coverage in successful HRdown rats reflect and convey a corticospinal tract influence that changes motoneuron firing threshold and thereby decreases the H-reflex. GABAergic terminals in spinal cord change after spinal cord transection. The present results demonstrate that such spinal cord plasticity also occurs in intact rats in the course of motor learning and suggest that this plasticity contributes to skill acquisition.10aactivity-dependent plasticity10aGABA10aH-Reflex10aMemory10aMotor control10aSpinal Cord1 aWang, Yu1 aPillai, Shreejith1 aWolpaw, Jonathan1 aChen, Xiang Yang  uhttp://www.ncbi.nlm.nih.gov/pubmed/16420424