@article {3382,
	title = {Electrocorticographic activity over sensorimotor cortex and motor function in awake behaving rats.},
	journal = {J Neurophysiol},
	volume = {113},
	year = {2015},
	month = {04/2015},
	pages = {2232-41},
	abstract = {<p>Sensorimotor cortex exerts both short-term and long-term control over the spinal reflex pathways that serve motor behaviors. Better understanding of this control could offer new possibilities for restoring function after central nervous system trauma or disease. We examined the impact of ongoing sensorimotor cortex (SMC) activity on the largely monosynaptic pathway of the H-reflex, the electrical analog of the spinal stretch reflex. In 41 awake adult rats, we measured soleus electromyographic (EMG) activity, the soleus H-reflex, and electrocorticographic activity over the contralateral SMC while rats were producing steady-state soleus EMG activity. Principal component analysis of electrocorticographic frequency spectra before H-reflex elicitation consistently revealed three frequency bands: μβ (5-30 Hz), low γ (γ1; 40-85 Hz), and high γ (γ2; 100-200 Hz). Ongoing (i.e., background) soleus EMG amplitude correlated negatively with μβ power and positively with γ1 power. In contrast, H-reflex size correlated positively with μβ power and negatively with γ1 power, but only when background soleus EMG amplitude was included in the linear model. These results support the hypothesis that increased SMC activation (indicated by decrease in μβ power and/or increase in γ1 power) simultaneously potentiates the H-reflex by exciting spinal motoneurons and suppresses it by decreasing the efficacy of the afferent input. They may help guide the development of new rehabilitation methods and of brain-computer interfaces that use SMC activity as a substitute for lost or impaired motor outputs.</p>},
	keywords = {brain-computer interface, cortex, H-Reflex, Motor control, Spinal Cord},
	issn = {1522-1598},
	doi = {10.1152/jn.00677.2014},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/25632076},
	author = {Chadwick B. Boulay and Xiang Yang Chen and Jonathan Wolpaw}
}
@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 {3100,
	title = {Reflex conditioning: a new strategy for improving motor function after spinal cord injury.},
	journal = {Annals of the New York Academy of Sciences},
	volume = {1198 Suppl 1},
	year = {2010},
	month = {06/2010},
	pages = {E12{\textendash}E21},
	abstract = {Spinal reflex conditioning changes reflex size, induces spinal cord plasticity, and modifies locomotion. Appropriate reflex conditioning can improve walking in rats after spinal cord injury (SCI). Reflex conditioning offers a new therapeutic strategy for restoring function in people with SCI. This approach can address the specific deficits of individuals with SCI by targeting specific reflex pathways for increased or decreased responsiveness. In addition, once clinically significant regeneration can be achieved, reflex conditioning could provide a means of reeducating the newly (and probably imperfectly) reconnected spinal cord.},
	keywords = {H-Reflex, learning and memory, Locomotion, plasticity, reflex conditioning, Rehabilitation, spinal cord injury},
	issn = {1749-6632},
	doi = {10.1111/j.1749-6632.2010.05565.x},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/20590534},
	author = {Xiang Yang Chen and Yi Chen and Wang, Yu and Thompson, Aiko and Jonathan S. Carp and Segal, Richard L. and Jonathan Wolpaw}
}
@article {3109,
	title = {Acquisition of a simple motor skill: task-dependent adaptation plus long-term change in the human soleus H-reflex.},
	journal = {The Journal of neuroscience : the official journal of the Society for Neuroscience},
	volume = {29},
	year = {2009},
	month = {05/2009},
	pages = {5784{\textendash}5792},
	abstract = {Activity-dependent plasticity occurs throughout the CNS. However, investigations of skill acquisition usually focus on cortex. To expand the focus, we analyzed in humans the development of operantly conditioned H-reflex change, a simple motor skill that develops gradually and involves plasticity in both the brain and the spinal cord. Each person completed 6 baseline and 24 conditioning sessions over 10 weeks. In each conditioning session, the soleus H-reflex was measured while the subject was or was not asked to increase (HRup subjects) or decrease (HRdown subjects) it. When the subject was asked to change H-reflex size, immediate visual feedback indicated whether a size criterion had been satisfied. Over the 24 conditioning sessions, H-reflex size gradually increased in six of eight HRup subjects and decreased in eight of nine HRdown subjects, resulting in final sizes of 140 +/- 12 and 69 +/- 6\% of baseline size, respectively. The final H-reflex change was the sum of within-session (i.e., task-dependent) adaptation and across-session (i.e., long-term) change. Task-dependent adaptation appeared within four to six sessions and persisted thereafter, averaging +13\% in HRup subjects and -15\% in HRdown subjects. In contrast, long-term change began after 10 sessions and increased gradually thereafter, reaching +27\% in HRup subjects and -16\% in HRdown subjects. Thus, the acquisition of H-reflex conditioning consists of two phenomena, task-dependent adaptation and long-term change, that together constitute the new motor skill. In combination with previous data, this new finding further elucidates the interaction of plasticity in brain and spinal cord that underlies the acquisition and maintenance of motor skills.},
	keywords = {H-Reflex, motor learning, motor skill, operant conditioning, plasticity, Spinal Cord},
	issn = {1529-2401},
	doi = {10.1523/JNEUROSCI.4326-08.2009},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/19420246},
	author = {Thompson, Aiko K. and Xiang Yang Chen and Jonathan Wolpaw}
}
@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 {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 {3162,
	title = {Effects of chronic nerve cuff and intramuscular electrodes on rat triceps surae motor units.},
	journal = {Neuroscience letters},
	volume = {312},
	year = {2001},
	month = {10/2001},
	pages = {1{\textendash}4},
	abstract = {In order to assess the long-term effects of implanted electrodes on motor unit properties, we studied triceps surae (TS) motor units in rats implanted for 3-10 months with a tibial nerve cuff electrode for H-reflex elicitation and intramuscular electrodes for recording TS electromyographic activity. Motor units with sag from implanted rats displayed greater tetanic force than those from unimplanted rats. Motor units without sag had shorter twitch contraction times. This disrupted the relationship between sag and contraction time that was always present in unimplanted rats. These differences were consistent with a small degree of muscle denervation and subsequent reinnervation. Further analyses ascribed this effect to the nerve cuff rather than to the intramuscular electrodes. Comparable changes in motor unit properties may occur in humans with implanted nerve cuffs.},
	keywords = {chronic recording, contraction time, H-Reflex, implanted electrodes, motor units, nerve cuff, reinnervation, sag},
	issn = {0304-3940},
	doi = {10.1016/S0304-3940(01)02183-8},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/11578831},
	author = {Jonathan S. Carp and Xiang Yang Chen and Sheikh, H. and Jonathan Wolpaw}
}
@article {3161,
	title = {Motor unit properties after operant conditioning of rat H-reflex.},
	journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale},
	volume = {140},
	year = {2001},
	month = {10/2001},
	pages = {382{\textendash}386},
	abstract = {Operant conditioning of the H-reflex produces plasticity at several sites in the spinal cord, including the motoneuron. This study assessed whether this spinal cord plasticity is accompanied by changes in motor unit contractile properties. Thirty-one adult male Sprague-Dawley rats implanted for chronic recording of triceps surae electromyographic activity and H-reflex elicitation were exposed for at least 40 days to HRup or HRdown training, in which reward occurred when the H-reflex was greater than (12 HRup rats) or less than (12 HRdown rats) a criterion value, or continued under the control mode in which the H-reflex was simply measured (7 HRcon rats). At the end of H-reflex data collection, rats were anesthetized and the contractile properties of 797 single triceps surae motor units activated by intraaxonal (or intramyelin) current injection were determined. Motor units were classified as S, FR, Fint, or FF on the basis of sag and fatigue properties. Maximum tetanic force and twitch contraction time were also measured. HRdown rats exhibited a significant increase in the fatigue index of fast-twitch motor units. This resulted in a significant decrease in the percentage of Fint motor units and a significant increase in that of FR motor units. HRup conditioning had no effect on fatigue index. Neither HRup nor HRdown conditioning affected maximum tetanic force or twitch contraction time. These data are consistent with the hypothesis that conditioning mode-specific change in motoneuron firing patterns causes activity-dependent change in muscle properties.},
	keywords = {H-Reflex, motor unit type, operant conditioning, plasticity, triceps surae},
	issn = {0014-4819},
	doi = {10.1007/s002210100830},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/11681314},
	author = {Jonathan S. Carp and Xiang Yang Chen and Sheikh, H. and Jonathan Wolpaw}
}
@article {3163,
	title = {Operant conditioning of rat H-reflex affects motoneuron axonal conduction velocity.},
	journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale},
	volume = {136},
	year = {2001},
	month = {01/2001},
	pages = {269{\textendash}273},
	abstract = {This study assessed the effects of operant conditioning of the H-reflex on motoneuron axonal conduction velocity in the rat. After measurement of the control H-reflex size, rats were either exposed for at least 40 days to the HRup or HRdown conditioning mode, in which reward occurred only if the soleus H-reflex was greater than (HRup mode) or less than (HRdown mode) a criterion or continued under the control condition (HRcon mode) in which the H-reflex was simply measured. We then measured axonal conduction velocity of triceps surae motor units of HRup, HRdown, and HRcon rats by stimulating the axon in the ventral root and recording from the tibial nerve. Conduction velocity was 8\% less in successful HRdown rats than in HRcon rats (P=0.02). Conduction velocity in HRup rats and unsuccessful HRdown rats was not significantly different from that in HRcon rats. Since recording bypassed the intra-spinal portion of the motoneuron, the change was clearly in the axon. This decrease was similar to the 6\% decrease previously found in successful HRdown monkeys. Unsuccessful HRdown rats and monkeys did not show this decrease. This result suggests that the mechanism of HRdown conditioning is similar in rats and monkeys and provides further support for the hypothesis that HRdown conditioning decreases motoneuron excitability by producing a positive shift in firing threshold. While traditional theories of learning emphasize synaptic plasticity, neuronal plasticity may also contribute to operantly conditioned behavioral changes.},
	keywords = {conduction velocity, H-Reflex, motoneuron, plasticity, Spinal Cord},
	issn = {0014-4819},
	doi = {10.1007/s002210000608},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/11206290},
	author = {Jonathan S. Carp and Xiang Yang Chen and Sheikh, H. 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 {3240,
	title = {Operant conditioning of H-reflex increase in spinal cord{\textendash}injured rats.},
	journal = {Journal of neurotrauma},
	volume = {16},
	year = {1999},
	month = {02/1999},
	pages = {175{\textendash}186},
	abstract = {Operant conditioning of the spinal stretch reflex or its electrical analog, the H-reflex, is a new model for exploring the mechanisms of long-term supraspinal control over spinal cord function. Primates and rats can gradually increase (HRup conditioning mode) or decrease (HRdown conditioning mode) the H-reflex when reward is based on H-reflex amplitude. An earlier study indicated that HRdown conditioning of the soleus H-reflex in rats is impaired following contusion injury to thoracic spinal cord. The extent of impairment was correlated with the percent of white matter lost at the injury site. The present study investigated the effects of spinal cord injury on HRup conditioning. Soleus H-reflexes were elicited and recorded with chronically implanted electrodes from 14 rats that had been subjected to calibrated contusion injuries to the spinal cord at T8. At the lesion epicenter, 12-39\% of the white matter remained. After control-mode data were collected, each rat was exposed to the HRup conditioning mode for 50 days. Final H-reflex amplitudes after HRup conditioning averaged 112\% (+/-22\% SD) of control. This value was significantly smaller than that for 13 normal rats exposed to HRup conditioning, in which final amplitude averaged 153\% (+/-51\%) SD of control. As previously reported for HRdown conditioning after spinal cord injury, success was inversely correlated with the severity of the injury as assessed by white matter preservation and by time to return of bladder function. HRup and HRdown conditioning are similarly sensitive to injury. These results further demonstrate that H-reflex conditioning is a sensitive measure of the long-term effects of injury on supraspinal control over spinal cord functions and could prove a valuable measure of therapeutic efficacy.},
	keywords = {H-Reflex, operant conditioning, plasticity, rat, soleus muscle, spinal cord injury},
	issn = {0897-7151},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/10098962},
	author = {Xiang Yang Chen and Jonathan Wolpaw and Jakeman, L. B. and Stokes, B. T.}
}
@article {3250,
	title = {Operant conditioning of H-reflex in spinal cord-injured rats.},
	journal = {Journal of neurotrauma},
	volume = {13},
	year = {1996},
	month = {12/1996},
	pages = {755{\textendash}766},
	abstract = {Operant conditioning of the spinal stretch reflex or its electrical analog, the H-reflex, is a new model for exploring the mechanisms of supraspinal control over spinal cord function. Both rats and primates can gradually increase (HRup conditioning mode) or decrease (HRdown conditioning mode) soleus H-reflex magnitude when exposed to an operant conditioning task. This study used H-reflex operant conditioning to assess and modify spinal cord function after injury. Soleus H-reflexes were elicited and recorded with chronically implanted electrodes from rats that had been subjected to calibrated contusion injuries to the spinal cord at T8. From 18 to 140 days after injury, background EMG, M response amplitude, and initial H-reflex amplitude were not significantly different from those of normal rats. HRdown conditioning was successful in some, but not all, spinal cord-injured rats. The H-reflex decrease achieved by conditioning was inversely correlated with the severity of the injury as assessed histologically or by time to return of bladder function. It was not correlated with the length of time between injury and the beginning of conditioning. The results confirm the importance of descending control from supraspinal structures in mediating operantly conditioned change in H-reflex amplitude. In conjunction with recent human studies, they suggest that H-reflex conditioning could provide a sensitive new means for assessing spinal cord function after injury, and might also provide a method for initiating and guiding functional rehabilitation.},
	keywords = {H-Reflex, operant conditioning, plasticity, rat, soleus muscle, spinal cord injury},
	issn = {0897-7151},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/9002061},
	author = {Xiang Yang Chen and Jonathan Wolpaw and Jakeman, L. B. and Stokes, B. T.}
}
@article {3253,
	title = {Reversal of H-reflex operant conditioning in the rat.},
	journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale},
	volume = {112},
	year = {1996},
	month = {11/1996},
	pages = {58{\textendash}62},
	abstract = {In response to an operant conditioning task, rats can gradually increase or decrease soleus H-reflex amplitude without change in background electromyographic activity or M response amplitude. Both increase (under the HRup mode) and decrease (under the HRdown mode) develop over weeks. The present study investigated reversal of conditioned H-reflex change. Following collection of control data, rats were exposed to one mode (HRup or HRdown) for 50 days, and then exposed to the opposite mode for up to 72 days. Rats responded to each mode exposure with gradual, mode-appropriate change in H-reflex amplitude. This finding is consistent with other evidence that H-reflex conditioning depends on spinal cord plasticity. The effects of exposure to the HRup (or HRdown) mode were not affected by whether exposure followed previous exposure to the HRdown (or HRup) mode. In accord with recent studies suggesting that HRup and HRdown conditioning have different spinal mechanisms, these results suggest that reversal of H-reflex change is due primarily to the superimposition of additional plasticity rather than to decay of the plasticity responsible for the initial change.},
	keywords = {H-Reflex, operant conditioning, plasticity, rat, soleus muscle, Spinal Cord},
	issn = {0014-4819},
	doi = {10.1007/BF00227178},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/8951407},
	author = {Xiang Yang 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}
}
@article {3261,
	title = {Circadian rhythm in rat H-reflex.},
	journal = {Brain research},
	volume = {648},
	year = {1994},
	month = {06/1994},
	pages = {167{\textendash}170},
	abstract = {We measured soleus H-reflex in the Sprague-Dawley rat as a function of time of day. H-reflex amplitude displayed a marked diurnal variation, even though background EMG and M-response amplitude were stable through the day. The H-reflex was largest in the late morning and smallest around midnight. Thus, its rhythm was opposite in phase to the circadian rhythm found in the primate H-reflex. This rhythm is a potentially confounding factor in studies of motor function. Furthermore, its existence implies that the CNS activity underlying a specific motor performance varies with time of day.},
	keywords = {circadian rhythm, electromyogram, H-Reflex, rat, soleus},
	issn = {0006-8993},
	doi = {10.1016/0006-8993(94)91918-6},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/7922520},
	author = {Xiang Yang Chen and Jonathan Wolpaw}
}
