@article {3383,
	title = {Persistent beneficial impact of H-reflex conditioning in spinal cord-injured rats.},
	journal = {J Neurophysiol},
	volume = {112},
	year = {2014},
	month = {11/2014},
	pages = {2374-81},
	abstract = {<p>Operant conditioning of a spinal cord reflex can improve locomotion in rats and humans with incomplete spinal cord injury. This study examined the persistence of its beneficial effects. In rats in which a right lateral column contusion injury had produced asymmetric locomotion, up-conditioning of the right soleus H-reflex eliminated the asymmetry while down-conditioning had no effect. After the 50-day conditioning period ended, the H-reflex was monitored for 100 [{\textpm}9 (SD)] (range 79-108) more days and locomotion was then reevaluated. After conditioning ended in up-conditioned rats, the H-reflex continued to increase, and locomotion continued to improve. In down-conditioned rats, the H-reflex decrease gradually disappeared after conditioning ended, and locomotion at the end of data collection remained as impaired as it had been before and immediately after down-conditioning. The persistence (and further progression) of H-reflex increase but not H-reflex decrease in these spinal cord-injured rats is consistent with the fact that up-conditioning improved their locomotion while down-conditioning did not. That is, even after up-conditioning ended, the up-conditioned H-reflex pathway remained adaptive because it improved locomotion. The persistence and further enhancement of the locomotor improvement indicates that spinal reflex conditioning protocols might supplement current therapies and enhance neurorehabilitation. They may be especially useful when significant spinal cord regeneration becomes possible and precise methods for retraining the regenerated spinal cord are needed.</p>},
	keywords = {H-reflex conditioning, Learning, Locomotion, Memory, Motor control, Rehabilitation, spinal cord injury, spinal cord plasticity},
	issn = {1522-1598},
	doi = {10.1152/jn.00422.2014},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/25143542},
	author = {Yi Chen and Lu Chen and Wang, Yu and Jonathan Wolpaw and Xiang Yang Chen}
}
@article {3188,
	title = {Effects of H-reflex up-conditioning on GABAergic terminals on rat soleus motoneurons.},
	journal = {The European journal of neuroscience},
	volume = {28},
	year = {2008},
	month = {08/2008},
	pages = {668{\textendash}674},
	abstract = {To explore the role of spinal cord plasticity in motor learning, we evaluated the effects of H-reflex operant conditioning on GABAergic input to rat spinal motoneurons. Previous work indicated that down-conditioning of soleus H-reflex increases GABAergic input to soleus motoneurons. This study explored the effect of H-reflex up-conditioning on GABAergic input. Of nine rats exposed to H-reflex up-conditioning, up-conditioning was successful (H-reflex increase >or= 20\%) in seven and failed (change < 20\%) in two. These rats and eight naive control (i.e. unconditioned) rats were injected with cholera toxin subunit B-conjugated Alexa fluor 488 into the soleus muscle to retrogradely label soleus motoneurons. Sections containing soleus motoneurons were processed for GAD(67) [one of the two principal forms of the GABA-synthesizing enzyme glutamic acid decarboxylase (GAD)] with an ABC-peroxidase system. Two blinded independent raters counted and measured GABAergic terminals on these motoneurons. Unlike successful down-conditioning, which greatly increased the number of identifiable GABAergic terminals on the motoneurons, up-conditioning did not significantly change GABAergic terminal number. Successful up-conditioning did produce slight but statistically significant increases in GABAergic terminal diameter and soma coverage. These results are consistent with other data indicating that up- and down-conditioning are not mirror images of each other, but rather have different mechanisms. Although the marked changes in GABAergic terminals with down-conditioning probably contribute to H-reflex decrease, the modest changes in GABAergic terminals associated with up-conditioning may be compensatory or reactive plasticity, rather than the plasticity responsible for H-reflex increase. As a variety of spinal and supraspinal GABAergic neurons innervate motoneurons, the changes found with up-conditioning may be in terminals other than those affected in successful down-conditioning.},
	keywords = {activity-dependent plasticity, Learning, Memory, Motor control, Spinal Cord},
	issn = {1460-9568},
	doi = {10.1111/j.1460-9568.2008.06370.x},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/18657184},
	author = {Pillai, Shreejith and Wang, Yu and Jonathan Wolpaw and Xiang Yang Chen}
}
@article {3193,
	title = {Motor learning changes GABAergic terminals on spinal motoneurons in normal rats.},
	journal = {The European journal of neuroscience},
	volume = {23},
	year = {2006},
	month = {01/2006},
	pages = {141{\textendash}150},
	abstract = {The 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.},
	keywords = {activity-dependent plasticity, GABA, H-Reflex, Memory, Motor control, Spinal Cord},
	issn = {0953-816X},
	doi = {10.1111/j.1460-9568.2005.04547.x},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/16420424},
	author = {Wang, Yu and Pillai, Shreejith and Jonathan Wolpaw and Xiang Yang Chen}
}
@article {3066,
	title = {Operant conditioning of H-reflex can correct a locomotor abnormality after spinal cord injury in rats.},
	journal = {The Journal of neuroscience : the official journal of the Society for Neuroscience},
	volume = {26},
	year = {2006},
	month = {11/2006},
	pages = {12537{\textendash}12543},
	abstract = {<p>This study asked whether operant conditioning of the H-reflex can modify locomotion in spinal cord-injured rats. Midthoracic transection of the right lateral column of the spinal cord produced a persistent asymmetry in the muscle activity underlying treadmill locomotion. The rats were then either exposed or not exposed to an H-reflex up-conditioning protocol that greatly increased right soleus motoneuron response to primary afferent input, and locomotion was reevaluated. H-reflex up-conditioning increased the right soleus burst and corrected the locomotor asymmetry. In contrast, the locomotor asymmetry persisted in the control rats. These results suggest that appropriately selected reflex conditioning protocols might improve function in people with partial spinal cord injuries. Such protocols might be especially useful when significant regeneration becomes possible and precise methods for reeducating the regenerated spinal cord neurons and synapses are needed for restoring effective function.</p>},
	keywords = {H-reflex conditioning, Learning, Locomotion, Memory, Motor control, Rehabilitation, spinal cord injury, spinal cord plasticity},
	issn = {1529-2401},
	doi = {10.1523/JNEUROSCI.2198-06.2006},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/17135415},
	author = {Yi Chen and Xiang Yang Chen and Jakeman, Lyn B. and Lu Chen and Stokes, Bradford T. and Jonathan Wolpaw}
}
@article {3233,
	title = {Operant conditioning of rat H-reflex: effects on mean latency and duration.},
	journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale},
	volume = {136},
	year = {2001},
	month = {01/2001},
	pages = {274{\textendash}279},
	abstract = {We are currently studying the mechanisms of operantly conditioned changes in the H-reflex in the rat. Primate data suggest that H-reflex decrease is due to a positive shift in motoneuron firing threshold and a small decrease in the monosynaptic excitatory postsynaptic potential (EPSP), and that increase might be due to change in group-I oligosynaptic (especially disynaptic) input. To further evaluate the possibility of conditioned change in oligosynaptic input, we compared the mean latency (i.e., the average latency of the entire H-reflex) and the duration of control (i.e., pre-conditioning) H-reflexes with those of H-reflexes after up-conditioning or down-conditioning. Up-conditioning was associated with small, statistically significant increases in H-reflex mean latency [+0.11+/-0.05 (+/-SE) ms] and duration (+0.32+/-0.16 ms). The mean latency of the H-reflex increase (i.e., the part added to the H-reflex by up-conditioning) was 0.28+/-0.14 (+/-SE) ms greater than that of the control H-reflex. Down-conditioning had no significant effect on mean latency or duration. While these results indicate that operant conditioning does not greatly change H-reflex mean latency or duration, the effects detected with up-conditioning are consistent with the hypothesis that decreased inhibition, or increased excitation, by homonymous and heteronymous group-I oligosynaptic input contributes to the H-reflex increase produced by up-conditioning. Several other mechanisms might also account for these small effects.},
	keywords = {conditioning, H-Reflex, Memory, plasticity, Spinal Cord},
	issn = {0014-4819},
	doi = {10.1007/s002210000609},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/11206291},
	author = {Jonathan Wolpaw and Xiang Yang Chen}
}
@article {3231,
	title = {Time course of H-reflex conditioning in the rat.},
	journal = {Neuroscience letters},
	volume = {302},
	year = {2001},
	month = {04/2001},
	pages = {85{\textendash}88},
	abstract = {This 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.},
	keywords = {conditioning, Learning, Memory, plasticity, rat, Reflex, Spinal Cord},
	issn = {0304-3940},
	doi = {10.1016/S0304-3940(01)01658-5},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/11290393},
	author = {Xiang Yang Chen and Lu Chen and Jonathan Wolpaw}
}
@article {3255,
	title = {Operantly conditioned plasticity and circadian rhythm in rat H-reflex are independent phenomena.},
	journal = {Neuroscience letters},
	volume = {195},
	year = {1995},
	month = {08/1995},
	pages = {109{\textendash}112},
	abstract = {Recent studies indicate that rats can increase or decrease H-reflex amplitude in response to an operant conditioning paradigm. In addition, rats also display a circadian rhythm in H-reflex amplitude. As part of the development of H-reflex conditioning in the rat as a new model for defining the plasticity underlying a simple form of learning, this study examined the relationship in the rat between operantly conditioned H-reflex change and the H-reflex circadian rhythm. When H-reflex amplitude increased or decreased in response to the operant conditioning program, its circadian rhythm showed no changes in phase and minimal change in amplitude. Furthermore, animals did not alter daily performance schedule so as to use the rhythm to increase reward probability. Thus, in the rat, H-reflex operant conditioning and the H-reflex circadian rhythm appear to be independent phenomena. The circadian rhythm should not be a significant complicating factor in studies of operantly conditioned H-reflex change.},
	keywords = {circadian rhythm, H-Reflex, Learning, Memory, operant conditioning, Rats},
	issn = {0304-3940},
	doi = {10.1016/0304-3940(95)11793-V},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/7478262},
	author = {Xiang Yang Chen and Jonathan Wolpaw}
}
