02364nas a2200217   4500008004100000022001400041245011800055210006900173260001200242300001800254490000700272520171000279653000901989653001901998100001302017700001302030700001302043700002102056700002102077856004802098       2011                        eng d  a1529-240100aOperant conditioning of rat soleus H-reflex oppositely affects another H-reflex and changes locomotor kinematics.0 aOperant conditioning of rat soleus Hreflex oppositely affects an  c08/2011  a11370–113750 v313 aH-reflex conditioning is a model for studying the plasticity associated with a new motor skill. We are exploring its effects on other reflexes and on locomotion. Rats were implanted with EMG electrodes in both solei (SOL(R) and SOL(L)) and right quadriceps (QD(R)), and stimulating cuffs on both posterior tibial (PT) nerves and right posterior femoral nerve. When SOL(R) EMG remained in a defined range, PT(R) stimulation just above M-response threshold elicited the SOL(R) H-reflex. Analogous procedures elicited the QD(R) and SOL(L) H-reflexes. After a control period, each rat was exposed for 50 d to a protocol that rewarded SOL(R) H-reflexes that were above (HRup rats) or below (HRdown rats) a criterion. HRup conditioning increased the SOL(R) H-reflex to 214 ± 37% (mean ± SEM) of control (p = 0.02) and decreased the QD(R) H-reflex to 71 ± 26% (p = 0.06). HRdown conditioning decreased the SOL(R) H-reflex to 69 ± 2% (p < 0.001) and increased the QD(R) H-reflex to 121 ± 7% (p = 0.02). These changes remained during locomotion. The SOL(L) H-reflex did not change. During the stance phase of locomotion, ankle plantarflexion increased in HRup rats and decreased in HRdown rats, hip extension did the opposite, and hip height did not change. The plasticity that changes the QD(R) H-reflex and locomotor kinematics may be inevitable (i.e., reactive) due to the ubiquity of activity-dependent CNS plasticity, and/or necessary (i.e., compensatory) to preserve other behaviors (e.g., locomotion) that would otherwise be disturbed by the change in the SOL(R) H-reflex pathway. The changes in joint angles, coupled with the preservation of hip height, suggest that compensatory plasticity did occur.10aRats10aSprague-Dawley1 aChen, Yi1 aChen, Lu1 aWang, Yu1 aWolpaw, Jonathan1 aChen, Xiang Yang  uhttp://www.ncbi.nlm.nih.gov/pubmed/21813696