@article {3389,
	title = {The simplest motor skill: mechanisms and applications of reflex operant conditioning.},
	journal = {Exerc Sport Sci Rev},
	volume = {42},
	year = {2014},
	month = {04/2014},
	pages = {82-90},
	abstract = {Operant conditioning protocols can change spinal reflexes gradually, which are the simplest behaviors. This article summarizes the evidence supporting two propositions: that these protocols provide excellent models for defining the substrates of learning and that they can induce and guide plasticity to help restore skills, such as locomotion, that have been impaired by spinal cord injury or other disorders.},
	keywords = {Animals, Conditioning, Operant, H-Reflex, Humans, Motor Skills, Muscle, Skeletal, Neuronal Plasticity, Reflex, Spinal Cord, Spinal Cord Injuries},
	issn = {1538-3008},
	doi = {10.1249/JES.0000000000000010},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/24508738},
	author = {Thompson, Aiko K and Jonathan Wolpaw}
}
@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 {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 {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 {3195,
	title = {Ablation of cerebellar nuclei prevents H-reflex down-conditioning in rats.},
	journal = {Learning \& memory (Cold Spring Harbor, N.Y.)},
	volume = {12},
	year = {2005},
	month = {05/2005},
	pages = {248{\textendash}254},
	abstract = {While studies of cerebellar involvement in learning and memory have described plasticity within the cerebellum, its role in acquisition of plasticity elsewhere in the CNS is largely unexplored. This study set out to determine whether the cerebellum is needed for acquisition of the spinal cord plasticity that underlies operantly conditioned decrease in the H-reflex, the electrical analog of the spinal stretch reflex. Rats in which the cerebellar output nuclei dentate and interpositus (DIN) had been ablated were exposed for 50 d to the H-reflex down-conditioning protocol. DIN ablation, which in itself had no significant long-term effect on H-reflex size, entirely prevented acquisition of a smaller H-reflex. Since previous studies show that corticospinal tract (CST) transection also prevents down-conditioning while transection of the rubrospinal tract and other major descending tracts does not, this result implies that DIN output that affects cortex is essential for generation of the CST activity that induces the spinal cord plasticity, which is, in turn, directly responsible for the smaller H-reflex. The result extends the role of the cerebellum in learning and memory to include participation in induction of plasticity elsewhere in the CNS, specifically in the spinal cord. The cerebellum might simply support processes in sensorimotor cortex or elsewhere that change the spinal cord, or the cerebellum itself might undergo plasticity similar to that occurring with vestibulo-ocular reflex (VOR) or eyeblink conditioning.},
	keywords = {Reflex, Vestibulo-Ocular},
	issn = {1072-0502},
	doi = {10.1101/lm.91305},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/15930503},
	author = {Xiang Yang 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}
}
@article {3239,
	title = {What do reflex and voluntary mean? Modern views on an ancient debate.},
	journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale},
	volume = {130},
	year = {2000},
	month = {02/2000},
	pages = {417{\textendash}432},
	abstract = {Are the words reflex and voluntary useful scientific concepts, or are they prescientific terms that should be discarded? Physiologists use these words routinely in their publications, in laboratory experiments and, indeed, like most lay people, in their daily lives. The tacit assumption is that we all know, more or less, what they mean. However, the issue has a rich history of philosophical and scientific debate; and, as this article demonstrates, present-day researchers still cannot reach a consensus on the meaning of the words and on whether it is possible to draw a scientific distinction between them. The five authors present five quite different analyses. In broad terms, they split into two camps: those who equate voluntary behaviours with consciousness and suppressibility and those who view all behaviours as sensorimotor interactions, the complexity of which determines whether they are reflexive or voluntary. According to the first view, most movements of daily life are neither purely reflex nor purely voluntary. They fall into the middle ground of automatic motor programs. According to the second view, as neuroscience advances the class of reflex behaviours will grow and the class of voluntary behaviours will shrink.},
	keywords = {Consciousness, Reflex, voluntary},
	issn = {0014-4819},
	doi = {10.1007/s002219900250},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/10717785},
	author = {Prochazka, A. and Clarac, F. and Loeb, G. E. and Rothwell, J. C. and Jonathan Wolpaw}
}
@article {3171,
	title = {The volitional nature of the simplest reflex.},
	journal = {Acta neurobiologiae experimentalis},
	volume = {53},
	year = {1993},
	pages = {103{\textendash}111},
	abstract = {Recent studies suggest that none of the behaviors of the vertebrate CNS are fixed responses incapable of change. Even the simplest reflex of all, the two-neuron, monosynaptic spinal stretch reflex (SSR), undergoes adaptive change under appropriate circumstances. Operantly conditioned SSR change occurs gradually over days and weeks and is associated with a complex pattern of CNS plasticity at both spinal and supraspinal sites.},
	keywords = {behavior, Brain, conditioning, human physiology, Learning, Memory, motoneuron, nature, primate, Reflex, Spinal Cord, spinal site, supra spinal site, vertebrate},
	issn = {0065-1400},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/8317238},
	author = {Jonathan Wolpaw and Jonathan S. Carp}
}
@article {3277,
	title = {Jendrassik maneuver facilitates soleus H-reflex without change in average soleus motoneuron pool membrane potential.},
	journal = {Experimental neurology},
	volume = {101},
	year = {1988},
	month = {08/1988},
	pages = {288{\textendash}302},
	abstract = {Facilitation of spinal reflex amplitude by remote muscle contraction, otherwise known as the Jendrassik maneuver (JM), was first shown over 100 years ago, yet the mechanism by which this facilitation operates remains undetermined. Earlier work has eliminated participation of the muscle spindle in JM-induced spinal reflex facilitation, leaving changes in postsynaptic (e.g., change in average soleus motoneuron membrane potential) and presynaptic (e.g., inhibition of presynaptic inhibition) mechanisms as viable candidates. We recorded background EMG in the soleus muscle during JM-induced soleus H-reflex facilitation in humans. The JM in this experiment consisted of wrist muscle contraction. Soleus background EMG was maintained by the subject at either a zero level (e.g., relaxed) or a specified moderate level prior to and during the JM. The JM increased H-reflex amplitude by comparable amounts in both situations, but had no effect on soleus background EMG. Given the well-known relationship between the average motoneuron pool membrane potential and background EMG, we conclude that JM facilitation of the soleus H-reflex is not caused by an increase in background excitatory input to the soleus motoneuron pool. Remaining candidates for mediation of JM induced H-reflex facilitation include change in stimulus-evoked afferent input at some point proximal to the muscle spindle, such as reduction in presynaptic inhibition, or a change in motoneuron input resistance.},
	keywords = {Reflex, Stretch},
	issn = {0014-4886},
	doi = {10.1016/0014-4886(88)90012-X},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/3396646},
	author = {Dowman, R. and Jonathan Wolpaw}
}
@article {3332,
	title = {Change in short-latency response to limb displacement in primates.},
	journal = {Federation proceedings},
	volume = {41},
	year = {1982},
	month = {04/1982},
	pages = {2156{\textendash}2159},
	abstract = {When a muscle is stretched in an awake, behaving primate the earliest electromyographic (EMG) responses of the muscle consists of several reflex components. The earliest, M1, is mediated entirely at the segmental level and is largely monosynaptic. The next M2, is at least in part the result of an oligosynaptic transcortical loop to control the M1 response remains to be established. If primates can learn to control M1 amplitude, the M1 loop, which is the simplest and most accessible stimulus-response pathway in the primate central nervous system, may serve as a model for the study of mechanisms of memory. Preliminary evidence presented here strongly suggests that primates can control M1 gain without change in prestimulus EMG activity. The mechanisms of such change remain to be determined. Possibilities include change in gamma motor neuron tone, in Ia synaptic function, and in alpha motor neuron recruitment. The usefulness of learned M1 change as a model for memory will depend to a large extent on the nature of the responsible mechanism and on demonstration that the change can eventually become resident at the segmental level, without need for continued descending input.},
	keywords = {Reflex, Stretch},
	issn = {0014-9446},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/7075789},
	author = {Jonathan Wolpaw}
}
@article {3185,
	title = {The effects of phenytoin on motor function in awake cats.},
	journal = {Archives internationales de pharmacodynamie et de th{\'e}rapie},
	volume = {237},
	year = {1979},
	month = {01/1979},
	pages = {139{\textendash}148},
	abstract = {Adult cats were monitored for their performance of a variety of motor functions before and after acute administration of phenytoin (5, 10 or 20 mg/kg) in a schedule in which each animal received all drug doses. The only significant loss in motor function was balance and coordination. Half the animals could not balance or walk along a narrow-edged beam after 20 mg/kg of phenytoin although their performance was not impaired at lower drug doses or on wider surfaces. There were no effects of phenytoin on the righting reflex, flexor reflex, muscle strength, the hopping response, the blind placing response or visually aided placing. The data suggest that phenytoin has a selective effect on higher order neuronal systems involved with balance and locomotion rather than simple reflex pathways.},
	keywords = {Reflex},
	issn = {0003-9780},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/485678},
	author = {Jonathan S. Carp and Anderson, R. J.}
}
