@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 {3084,
	title = {Cortical stimulation causes long-term changes in H-reflexes and spinal motoneuron GABA receptors.},
	journal = {Journal of neurophysiology},
	volume = {108},
	year = {2012},
	month = {11/2012},
	pages = {2668{\textendash}2678},
	abstract = {The cortex gradually modifies the spinal cord during development, throughout later life, and in response to trauma or disease. The mechanisms of this essential function are not well understood. In this study, weak electrical stimulation of rat sensorimotor cortex increased the soleus H-reflex, increased the numbers and sizes of GABAergic spinal interneurons and GABAergic terminals on soleus motoneurons, and decreased GABA(A) and GABA(B) receptor labeling in these motoneurons. Several months after the stimulation ended the interneuron and terminal increases had disappeared, but the H-reflex increase and the receptor decreases remained. The changes in GABAergic terminals and GABA(B) receptors accurately predicted the changes in H-reflex size. The results reveal a new long-term dimension to cortical-spinal interactions and raise new therapeutic possibilities.},
	keywords = {Spinal Cord},
	issn = {1522-1598},
	doi = {10.1152/jn.00516.2012},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/22933718},
	author = {Wang, Yu and Yi Chen and Lu Chen and Jonathan Wolpaw and Xiang Yang Chen}
}
@article {3090,
	title = {Operant conditioning of rat soleus H-reflex oppositely affects another H-reflex and changes locomotor kinematics.},
	journal = {The Journal of neuroscience : the official journal of the Society for Neuroscience},
	volume = {31},
	year = {2011},
	month = {08/2011},
	pages = {11370{\textendash}11375},
	abstract = {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 (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 {\textpm} 37\% (mean {\textpm} SEM) of control (p = 0.02) and decreased the QD(R) H-reflex to 71 {\textpm} 26\% (p = 0.06). HRdown conditioning decreased the SOL(R) H-reflex to 69 {\textpm} 2\% (p < 0.001) and increased the QD(R) H-reflex to 121 {\textpm} 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.},
	keywords = {Rats, Sprague-Dawley},
	issn = {1529-2401},
	doi = {10.1523/JNEUROSCI.1526-11.2011},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/21813696},
	author = {Yi Chen and Lu Chen and Wang, Yu and Jonathan Wolpaw and Xiang Yang Chen}
}
@article {3095,
	title = {H-reflex up-conditioning encourages recovery of EMG activity and H-reflexes after sciatic nerve transection and repair in rats.},
	journal = {The Journal of neuroscience : the official journal of the Society for Neuroscience},
	volume = {30},
	year = {2010},
	month = {12/2010},
	pages = {16128{\textendash}16136},
	abstract = {Operant conditioning of the spinal stretch reflex or its electrical analog, the H-reflex, produces spinal cord plasticity and can thereby affect motoneuron responses to primary afferent input. To explore whether this conditioning can affect the functional outcome after peripheral nerve injury, we assessed the effect of up-conditioning soleus (SOL) H-reflex on SOL and tibialis anterior (TA) function after sciatic nerve transection and repair. Sprague Dawley rats were implanted with EMG electrodes in SOL and TA and stimulating cuffs on the posterior tibial nerve. After control data collection, the sciatic nerve was transected and repaired and the rat was exposed for 120 d to continued control data collection (TC rats) or SOL H-reflex up-conditioning (TU rats). At the end of data collection, motoneurons that had reinnervated SOL and TA were labeled retrogradely. Putative primary afferent terminals [i.e., terminals containing vesicular glutamate transporter-1 (VGLUT1)] on SOL motoneurons were studied immunohistochemically. SOL (and probably TA) background EMG activity recovered faster in TU rats than in TC rats, and the final recovered SOL H-reflex was significantly larger in TU than in TC rats. TU and TC rats had significantly fewer labeled motoneurons and higher proportions of double-labeled motoneurons than untransected rats. VGLUT1 terminals were significantly more numerous on SOL motoneurons of TU than TC rats. Combined with the larger H-reflexes in TU rats, this anatomical finding supports the hypothesis that SOL H-reflex up-conditioning strengthened primary afferent reinnervation of SOL motoneurons. These results suggest that H-reflex up-conditioning may improve functional recovery after nerve injury and repair.},
	keywords = {conditioning, peripheral nerve, plasticity, Reflex, regeneration, Spinal Cord},
	issn = {1529-2401},
	doi = {10.1523/JNEUROSCI.4578-10.2010},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/21123559},
	author = {Yi Chen and Wang, Yu and Lu Chen and Sun, Chenyou and English, Arthur W. and Jonathan Wolpaw and Xiang Yang Chen}
}
@article {3150,
	title = {Spinal and supraspinal effects of long-term stimulation of sensorimotor cortex in rats.},
	journal = {Journal of neurophysiology},
	volume = {98},
	year = {2007},
	month = {08/2007},
	pages = {878{\textendash}887},
	abstract = {Sensorimotor cortex (SMC) modifies spinal cord reflex function throughout life and is essential for operant conditioning of the H-reflex. To further explore this long-term SMC influence over spinal cord function and its possible clinical uses, we assessed the effect of long-term SMC stimulation on the soleus H-reflex. In freely moving rats, the soleus H-reflex was measured 24 h/day for 12 wk. The soleus background EMG and M response associated with H-reflex elicitation were kept stable throughout. SMC stimulation was delivered in a 20-day-on/20-day-off/20-day-on protocol in which a train of biphasic 1-ms pulses at 25 Hz for 1 s was delivered every 10 s for the on-days. The SMC stimulus was automatically adjusted to maintain a constant descending volley. H-reflex size gradually increased during the 20 on-days, stayed high during the 20 off-days, and rose further during the next 20 on-days. In addition, the SMC stimulus needed to maintain a stable descending volley rose steadily over days. It fell during the 20 off-days and rose again when stimulation resumed. These results suggest that SMC stimulation, like H-reflex operant conditioning, induces activity-dependent plasticity in both the brain and the spinal cord and that the plasticity responsible for the H-reflex increase persists longer after the end of SMC stimulation than that underlying the change in the SMC response to stimulation.},
	keywords = {Time Factors},
	issn = {0022-3077},
	doi = {10.1152/jn.00283.2007},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/17522179},
	author = {Xiang Yang Chen and Pillai, Shreejith and Yi Chen and Wang, Yu and Lu Chen and Jonathan S. Carp and Jonathan Wolpaw}
}
@article {3190,
	title = {Corticospinal tract transection permanently abolishes H-reflex down-conditioning in rats.},
	journal = {Journal of neurotrauma},
	volume = {23},
	year = {2006},
	month = {11/2006},
	pages = {1705{\textendash}1712},
	abstract = {Previous studies have shown that corticospinal tract (CST) transection, but not transection of other major spinal cord tracts, prevents down-conditioning of the H-reflex, the electrical analog of the spinal stretch reflex. This study set out to determine whether the loss of the capacity for H-reflex down-conditioning caused by CST transection is permanent. Female Sprague-Dawley rats received CST, lateral column (LC), or dorsal column ascending tract (DA) transection at T8-9; 9-10 months later, they were exposed to the H-reflex down-conditioning protocol for 50 days. In the LC and DA rats, H-reflex size fell to 60 (+/- 9 SEM)\% and 60 (+/- 19)\%, respectively, of its initial size. This down-conditioning was comparable to that of normal rats. In contrast, H-reflex size in the CST rats rose to 170 (+/- 42)\% of its initial size. A similar rise does not occur in rats exposed to down-conditioning shortly after CST transection. These results indicate that CST transection permanently eliminates the capacity for H-reflex down-conditioning and has gradual long-term effects on sensorimotor cortex function. They imply that H-reflex down-conditioning can be a reliable measure of CST function for long-term studies of the effects of spinal cord injury and/or for evaluations of the efficacy of experimental therapeutic procedures, such as those intended to promote CST regeneration. The results also suggest that the role of sensorimotor cortex in down-conditioning extends beyond generation of the essential CST activity.},
	keywords = {corticospinal tract, H-reflex conditioning, plasticity, rat, spinal cord injury},
	issn = {0897-7151},
	doi = {10.1089/neu.2006.23.1705},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/17115915},
	author = {Xiang Yang Chen and Yi Chen and Lu Chen and Tennissen, Ann M. and Jonathan Wolpaw}
}
@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 {3191,
	title = {Operant conditioning of reciprocal inhibition in rat soleus muscle.},
	journal = {Journal of neurophysiology},
	volume = {96},
	year = {2006},
	month = {10/2006},
	pages = {2144{\textendash}2150},
	abstract = {Operant conditioning of the H-reflex, the electrical analog of the spinal stretch reflex (SSR), induces activity-dependent plasticity in the spinal cord and might be used to improve locomotion after spinal cord injury. To further assess the potential clinical significance of spinal reflex conditioning, this study asks whether another well-defined spinal reflex pathway, the disynaptic pathway underlying reciprocal inhibition (RI), can also be operantly conditioned. Sprague-Dawley rats were implanted with electromyographic (EMG) electrodes in right soleus (SOL) and tibialis anterior (TA) muscles and a stimulating cuff on the common peroneal (CP) nerve. When background EMG in both muscles remained in defined ranges, CP stimulation elicited the TA H-reflex and SOL RI. After collection of control data for 20 days, each rat was exposed for 50 days to up-conditioning (RIup mode) or down-conditioning (RIdown mode) in which food reward occurred if SOL RI evoked by CP stimulation was more (RIup mode) or less (RIdown mode) than a criterion. TA and SOL background EMG and TA M response remained stable. In every rat, RI conditioning was successful (i.e., change > or =20\% in the correct direction). In the RIup rats, final SOL RI averaged 171+/- 28\% (mean +/- SE) of control, and final TA H-reflex averaged 114 +/- 14\%. In the RIdown rats, final SOL RI averaged 37 +/- 13\% of control, and final TA H-reflex averaged 60 +/- 18\%. Final SOL RI and TA H-reflex sizes were significantly correlated. Thus like the SSR and the H-reflex, RI can be operantly conditioned; and conditioning one reflex can affect another reflex as well.},
	keywords = {Reflex, Stretch},
	issn = {0022-3077},
	doi = {10.1152/jn.00253.2006},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/16807351},
	author = {Xiang Yang Chen and Lu Chen and Yi Chen and Jonathan Wolpaw}
}
@article {3154,
	title = {Sensorimotor cortex ablation prevents H-reflex up-conditioning and causes a paradoxical response to down-conditioning in rats.},
	journal = {Journal of neurophysiology},
	volume = {96},
	year = {2006},
	month = {07/2006},
	pages = {119{\textendash}127},
	abstract = {Operant conditioning of the H-reflex, a simple model for skill acquisition, requires the corticospinal tract (CST) and does not require other major descending pathways. To further explore its mechanisms, we assessed the effects of ablating contralateral sensorimotor cortex (cSMC). In 22 Sprague-Dawley rats, the hindlimb area of left cSMC was ablated. EMG electrodes were implanted in the right soleus muscle and a stimulating cuff was placed around the right posterior tibial nerve. When EMG remained in a specified range, nerve stimulation just above the M response threshold elicited the H-reflex. In control mode, no reward occurred. In conditioning mode, reward occurred if H-reflex size was above (HRup mode) or below (HRdown mode) a criterion value. After exposure to the control mode for > or = 10 days, each rat was exposed for another 50 days to the control mode, the HRup mode, or the HRdown mode. In control and HRup rats, final H-reflex size was not significantly different from initial H-reflex size. In contrast, in HRdown rats, final H-reflex size was significantly increased to an average of 136\% of initial size. Thus like recent CST transection, cSMC ablation greatly impaired up-conditioning. However, unlike recent CST transection, cSMC produced a paradoxical response to down-conditioning: the H-reflex actually increased. These results confirm the critical role of cSMC in H-reflex conditioning and suggest that this role extends beyond producing essential CST activity. Its interactions with ipsilateral SMC or other areas contribute to the complex pattern of spinal and supraspinal plasticity that underlies H-reflex conditioning.},
	keywords = {Somatosensory Cortex},
	issn = {0022-3077},
	doi = {10.1152/jn.01271.2005},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/16598062},
	author = {Xiang Yang Chen and Jonathan S. Carp and Lu Chen and Jonathan Wolpaw}
}
@article {3196,
	title = {Conditioned H-reflex increase persists after transection of the main corticospinal tract in rats.},
	journal = {Journal of neurophysiology},
	volume = {90},
	year = {2003},
	month = {11/2003},
	pages = {3572{\textendash}3578},
	abstract = {The brain shapes spinal cord function throughout life. Operant conditioning of the H-reflex, the electrical analog of the spinal stretch reflex (SSR), is a relatively simple model for exploring the spinal cord plasticity underlying this functional change and may provide a new method for modifying spinal cord reflexes after spinal cord injury. In response to an operant conditioning protocol, rats can gradually increase (i.e., up-training mode) or decrease (i.e., down-training mode) the soleus H-reflex. This study explored the effects of midthoracic transection of the ipsilateral lateral column (LC) (rubrospinal, vestibulospinal, and reticulospinal tracts), the dorsal column corticospinal tract (CST), or the dorsal column ascending tract (DA) on maintenance of an H-reflex increase that has already occurred. Rats were implanted with EMG electrodes in the right soleus muscle and a nerve-stimulating cuff on the right posterior tibial nerve. After initial (i.e., control) H-reflex size was determined, the rats were exposed for 50 days to the up-training mode, in which reward was given when the H-reflex was above a criterion value. H-reflex size gradually rose to 168 +/- 12\% (mean +/- SE) of its initial value. Each rat then received an LC, CST, or DA transection and continued under the up-training mode for 50 more days. None of the transections abolished the H-reflex increase. H-reflex size increased further to 197 +/- 19\% of its initial value and did not differ significantly among LC, CST, and DA rats (P > 0.78 by ANOVA). Although earlier studies show that the main CST is needed for acquisition of H-reflex up-training and down-training and for maintenance of down-training, this study shows that it is not needed for maintenance of up-training. It adds to the evidence that H-reflex conditioning changes the spinal cord and that the spinal cord plasticity associated with up-training is different from that associated with down-training.},
	keywords = {Spinal Cord Injuries},
	issn = {0022-3077},
	doi = {10.1152/jn.00264.2003},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/12917382},
	author = {Xiang Yang Chen and Lu Chen 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 {3197,
	title = {Corticospinal tract transection reduces H-reflex circadian rhythm in rats.},
	journal = {Brain research},
	volume = {942},
	year = {2002},
	month = {06/2002},
	pages = {101{\textendash}108},
	abstract = {In freely moving rats and monkeys, H-reflex amplitude displays a marked circadian variation without change in background motoneuron tone. In rats, the H-reflex is largest around noon and smallest around midnight. The present study evaluated in rats the effects on this rhythm of calibrated contusions of mid-thoracic spinal cord and mid-thoracic transection of specific spinal cord pathways. In 33 control rats, rhythm amplitude averaged 29.0(+/-2.6 S.E.)\% of H-reflex amplitude. Contusion injuries at T8-9 that destroyed 53-88\% of the white matter significantly reduced the rhythm to 18.9(+/-2.4)\% of H-reflex amplitude. Transection of the ipsilateral lateral column, which contains the rubrospinal, vestibulospinal, and reticulospinal tracts, or bilateral transection of the dorsal column ascending tract did not affect rhythm amplitude or phase. In contrast, bilateral transection of the main corticospinal tract significantly reduced the rhythm to 14.7(+/-6.6)\%. These results indicate that the H-reflex circadian rhythm depends in part on descending influence from the brain and that this influence is conveyed by the main corticospinal tract.},
	keywords = {circadian rhythms, corticospinal tract, diurnal rhythm, H-Reflex, rat, spinal cord injury},
	issn = {0006-8993},
	doi = {10.1016/S0006-8993(02)02702-6},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/12031858},
	author = {Xiang Yang Chen and Lu Chen and Jonathan Wolpaw and Jakeman, Lyn B.}
}
@article {3232,
	title = {Short-Term and medium-term effects of spinal cord tract transections on soleus H-reflex in freely moving rats.},
	journal = {Journal of neurotrauma},
	volume = {18},
	year = {2001},
	month = {03/2001},
	pages = {313{\textendash}327},
	abstract = {Spinal cord function is normally influenced by descending activity from supraspinal structures. When injury removes or distorts this influence, function changes and spasticity and other disabling problems eventually appear. Understanding how descending activity affects spinal cord function could lead to new means for inducing, guiding, and assessing recovery after injury. In this study, we investigated the short-term and medium-term effects of spinal cord bilateral dorsal column (DC), unilateral (ipsilateral) lateral column (LC), bilateral dorsal column ascending tract (DA), or bilateral dorsal column corticospinal tract (CST) transection at vertebral level T8-T9 on the soleus H-reflex in freely moving rats. Data were collected continuously for 10-20 days before and for 20-155 days after bilateral DC (13 rats), DA (10 rats), CST (eight rats), or ipsilateral LC (seven rats) transection. Histological examination showed that transections were 98(+/- 3 SD)\% complete for DC rats, 80(+/- 20)\% complete for LC rats, 91(+/- 13 SD)\% complete for DA rats, and 95(+/-13)\% complete for CST rats. LC, CST, and DA transections produced an immediate (i.e., first-day) increase in H-reflex amplitude. LC transection also produced a small decrease in background activity in the first few posttransection days. Other than this small decrease, none of the transections produced evidence for the phenomenon of spinal shock. For all transections, all measures returned to or neared pretransection values within 2 weeks. DA and LC transections were associated with modest increase in H-reflex amplitude 1-3 months after transection. These medium-term effects must be taken into account when assessing transection effects on operant conditioning of the H-reflex. At the same time, the results are consistent with other evidence that, while H-reflex rate dependence and H-reflex operant conditioning are sensitive measures of spinal cord injury, the H-reflex itself is not.},
	keywords = {corticospinal tract, dorsal column, dorsal column ascending tract, lateral column, rat, soleus activity, spinal cord injury},
	issn = {0897-7151},
	doi = {10.1089/08977150151070973},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/11284551},
	author = {Xiang Yang Chen and Feng-Chen, K. C. and Lu Chen and Stark, D. M. 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}
}
