@article {3155,
	title = {Diurnal H-reflex variation in mice.},
	journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale},
	volume = {168},
	year = {2006},
	month = {01/2006},
	pages = {517{\textendash}528},
	abstract = {Mice exhibit diurnal variation in complex motor behaviors, but little is known about diurnal variation in simple spinally mediated functions. This study describes diurnal variation in the H-reflex (HR), a wholly spinal and largely monosynaptic reflex. Six mice were implanted with tibial nerve cuff electrodes and electrodes in the soleus and gastrocnemius muscles, for recording of ongoing and nerve-evoked electromyographic activity (EMG). Stimulation and recording were under computer control 24 h/day. During a 10-day recording period, HR amplitude varied throughout the day, usually being larger in the dark than in the light. This diurnal HR variation could not be attributed solely to differences in the net ongoing level of descending and segmental excitation to the spinal cord or stimulus intensity. HRs were larger in the dark than in the light even after restricting the evoked responses to subsets of trials having similar ongoing EMG and M-responses. The diurnal variation in the HR was out of phase with that reported previously for rats, but was in phase with that observed in monkeys. These data, supported by those in other species, suggest that the supraspinal control of the excitability of the HR pathway varies throughout the day in a species-specific pattern. This variation should be taken into account in experimental and clinical studies of spinal reflexes recorded at different times of day.},
	keywords = {circadian rhythm, Electromyography, implanted electrodes, Monosynaptic, Reflex, Spinal Cord},
	issn = {0014-4819},
	doi = {10.1007/s00221-005-0106-y},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/16151781},
	author = {Jonathan S. Carp and Tennissen, Ann M. and 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}
}
