@article {3390,
	title = {Locomotor impact of beneficial or nonbeneficial H-reflex conditioning after spinal cord injury.},
	journal = {J Neurophysiol},
	volume = {111},
	year = {2014},
	month = {03/2014},
	pages = {1249-58},
	abstract = {When new motor learning changes neurons and synapses in the spinal cord, it may affect previously learned behaviors that depend on the same spinal neurons and synapses. To explore these effects, we used operant conditioning to strengthen or weaken the right soleus H-reflex pathway in rats in which a right spinal cord contusion had impaired locomotion. When up-conditioning increased the H-reflex, locomotion improved. Steps became longer, and step-cycle asymmetry (i.e., limping) disappeared. In contrast, when down-conditioning decreased the H-reflex, locomotion did not worsen. Steps did not become shorter, and asymmetry did not increase. Electromyographic and kinematic analyses explained how H-reflex increase improved locomotion and why H-reflex decrease did not further impair it. Although the impact of up-conditioning or down-conditioning on the H-reflex pathway was still present during locomotion, only up-conditioning affected the soleus locomotor burst. Additionally, compensatory plasticity apparently prevented the weaker H-reflex pathway caused by down-conditioning from weakening the locomotor burst and further impairing locomotion. The results support the hypothesis that the state of the spinal cord is a "negotiated equilibrium" that serves all the behaviors that depend on it. When new learning changes the spinal cord, old behaviors undergo concurrent relearning that preserves or improves their key features. Thus, if an old behavior has been impaired by trauma or disease, spinal reflex conditioning, by changing a specific pathway and triggering a new negotiation, may enable recovery beyond that achieved simply by practicing the old behavior. Spinal reflex conditioning protocols might complement other neurorehabilitation methods and enhance recovery.},
	keywords = {Animals, Conditioning, Operant, Female, H-Reflex, Learning, Locomotion, Male, Rats, Rats, Sprague-Dawley, Spinal Cord Injuries},
	issn = {1522-1598},
	doi = {10.1152/jn.00756.2013},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/24371288},
	author = {Yi Chen and Lu Chen and Liu, Rongliang and Wang, Yu and Xiang Yang Chen and Jonathan Wolpaw}
}
@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 {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 {3159,
	title = {Corticospinal tract transection prevents operantly conditioned H-reflex increase in rats.},
	journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale},
	volume = {144},
	year = {2002},
	month = {05/2002},
	pages = {88{\textendash}94},
	abstract = {Operant conditioning of the H-reflex, the electrical analog of the spinal stretch reflex, in freely moving rats is a relatively simple model for studying long-term supraspinal control over spinal cord function. Motivated by food reward, rats can gradually increase (i.e., up-condition) or decrease (i.e., down-condition) the soleus H-reflex. Earlier work showed that corticospinal tract transection prevents acquisition and maintenance of H-reflex down-conditioning while transection of other major spinal cord tracts does not. This study explores the effects on acquisition of up-conditioning of the right soleus H-reflex of mid-thoracic transection of: the right lateral column (LC, five rats) (containing the rubrospinal, vestibulospinal, and reticulospinal tracts); the entire dorsal column (DC, six rats) [containing the main corticospinal tract (CST) and the dorsal ascending tract (DA)]; the CST alone (five rats); or the DA alone (seven rats). After initial (i.e., control) H-reflex amplitude was determined, the rat was exposed for 50 days to the up-conditioning mode in which reward was given when the H-reflex was above a criterion value. H-reflex amplitude at the end of up-conditioning was compared to initial H-reflex amplitude. An increase > or =20\% was defined as successful up-conditioning. In intact rats, H-reflex amplitude at the end of up-conditioning averaged 164\% (+/-10\%, SE), and 81\% were successful. In the present study, LC and DA rats were similar to intact rats in final H-reflex amplitude and percent successful. In contrast, results for DC and CST rats were significantly different from those of intact rats. In the six DC rats, final H-reflex amplitude averaged 105\% (+/-3)\% of control and none was successful; and in the five CST rats, final H-reflex amplitude averaged 94\% (+/-3)\% and none was successful. The results indicate that the main CST, located in the dorsal column, is essential for H-reflex up-conditioning as it is for down-conditioning, while the dorsal column ascending tract and the ipsilateral lateral column (containing the main rubrospinal, vestibulospinal, and reticulospinal tracts) do not appear to be essential.},
	keywords = {dorsal column, lateral column, Learning, plasticity, spinal cord injury},
	issn = {0014-4819},
	doi = {10.1007/s00221-002-1026-8},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/11976762},
	author = {Xiang Yang Chen and Jonathan S. Carp and Lu Chen and Jonathan Wolpaw}
}
@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}
}
