RT Journal Article
SR Electronic
T1 Operant Conditioning of Rat Soleus H-Reflex Oppositely Affects Another H-Reflex and Changes Locomotor Kinematics
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 11370
OP 11375
DO 10.1523/JNEUROSCI.1526-11.2011
VO 31
IS 31
A1 Chen, Yi
A1 Chen, Lu
A1 Wang, Yu
A1 Wolpaw, Jonathan R.
A1 Chen, Xiang Yang
YR 2011
UL http://www.jneurosci.org/content/31/31/11370.abstract
AB H-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 (SOLR and SOLL) and right quadriceps (QDR), and stimulating cuffs on both posterior tibial (PT) nerves and right posterior femoral nerve. When SOLR EMG remained in a defined range, PTR stimulation just above M-response threshold elicited the SOLR H-reflex. Analogous procedures elicited the QDR and SOLL H-reflexes. After a control period, each rat was exposed for 50 d to a protocol that rewarded SOLR H-reflexes that were above (HRup rats) or below (HRdown rats) a criterion. HRup conditioning increased the SOLR H-reflex to 214 ± 37% (mean ± SEM) of control (p = 0.02) and decreased the QDR H-reflex to 71 ± 26% (p = 0.06). HRdown conditioning decreased the SOLR H-reflex to 69 ± 2% (p < 0.001) and increased the QDR H-reflex to 121 ± 7% (p = 0.02). These changes remained during locomotion. The SOLL 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 QDR 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 SOLR H-reflex pathway. The changes in joint angles, coupled with the preservation of hip height, suggest that compensatory plasticity did occur.