@article {3176,
	title = {Operantly conditioned plasticity in spinal cord.},
	journal = {Annals of the New York Academy of Sciences},
	volume = {627},
	year = {1991},
	month = {08/1991},
	pages = {338{\textendash}348},
	abstract = {Recent work has shown that the monosynaptic pathway of the SSR can be operantly conditioned, and that a significant part of the plasticity responsible for the behavioral change resides in the spinal cord. The most likely sites of this activity-driven plasticity are the synapse of the Ia afferent neuron on the motoneuron and/or the motoneuron itself. Because the SSR pathway is the simplest and most accessible stimulus-response pathway in the vertebrate CNS, it may provide a valuable experimental model for elucidating activity-driven CNS changes responsible for learning.},
	keywords = {Spinal Cord},
	issn = {0077-8923},
	doi = {10.1111/j.1749-6632.1991.tb25936.x},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/1883143},
	author = {Jonathan Wolpaw and Lee, C. L. and Jonathan S. Carp}
}
@article {3271,
	title = {Memory traces in primate spinal cord produced by operant conditioning of H-reflex.},
	journal = {Journal of neurophysiology},
	volume = {61},
	year = {1989},
	month = {03/1989},
	pages = {563{\textendash}572},
	abstract = {1. Study of memory traces in higher animals requires experimental models possessing well-localized and technically accessible memory traces{\textendash}plasticity responsible for behavioral change, not dependent on control from elsewhere, and open to detailed investigation. Our purpose has been to develop such a model based on the wholly spinal, largely monosynaptic path of the spinal stretch reflex. Previous studies described operant conditioning of this reflex and of its electrical analog, the H-reflex. In this study, we sought to determine whether conditioning causes changes in the spinal cord that affect the reflex and are not dependent on continued supraspinal influence, and thus qualify as memory traces. 2. Sixteen monkeys underwent chronic conditioning of the triceps surae H-reflex. Eight were rewarded for increasing H-reflex amplitude (HR increases mode), and eight were rewarded for decreasing it (HR decreases mode). In each animal, the other leg was an internal control. Over several months of conditioning, H-reflex amplitude in the conditioned leg rose in HR increases animals and fell in HR decreases animals. H-reflex amplitude in the control leg changed little. 3. After HR increases or HR decreases conditioning, each animal was deeply anesthetized and surgically prepared. The reflex response to supramaximal dorsal root stimulation was measured from the triceps surae nerve as percent of response to supramaximal ventral root stimulation, which was the maximum possible response. Data from both legs were collected before and for up to 3 days after thoracic (T9-10) cord transection. The animal remained deeply anesthetized throughout and was killed by overdose. 4. The reflex asymmetries produced by conditioning were still present several days after transection removed supraspinal influence: reflexes of HR increases animals were significantly larger in HR increases legs than in control legs and reflexes of HR decreases animals were significantly smaller in HR decreases legs than in control legs. 5. Reflex amplitude was much greater in the control legs of anesthetized HR decreases animals than in the control legs of anesthetized HR increases animals. 6. Chronic conditioning had at least two effects on the spinal cord. The first effect, task-appropriate reflex asymmetry, was evident both in the awake behaving animal and in the anesthetized transected animal. The second effect, larger control leg reflexes in HR decreases than in HR increases animals, was evident only in the anesthetized animal. By removing supraspinal control, anesthesia and transection revealed a previously hidden effect of conditioning.(ABSTRACT TRUNCATED AT 400 WORDS)},
	keywords = {Spinal Cord},
	issn = {0022-3077},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/2709100},
	author = {Jonathan Wolpaw and Lee, C. L.}
}
@article {3178,
	title = {Memory traces in spinal cord produced by H-reflex conditioning: effects of post-tetanic potentiation.},
	journal = {Neuroscience letters},
	volume = {103},
	year = {1989},
	month = {08/1989},
	pages = {113{\textendash}119},
	abstract = {Operant conditioning of the wholly spinal, largely monosynaptic triceps surae H-reflex in monkeys causes changes in lumbosacral spinal cord that persist after removal of supraspinal influence. We evaluated the interaction between post-tetanic potentiation and these memory traces. Animals in which the triceps surae H-reflex in one leg had been increased or decreased by conditioning were deeply anesthetized, and monosynaptic reflexes to L6-S1 dorsal root stimulation were recorded before and after tetanization from both legs for 3 days after thoracic cord transection. Animals remained anesthetized throughout and were sacrificed by overdose. Reflex asymmetries consistent with the effect of H-reflex conditioning were present after transection and persisted through the 3 days of study. Tetanization affected conditioned leg and control leg reflexes similarly. This finding suggests that, while post-tetanic potentiation and probably H-reflex conditioning alter Ia synaptic transmission, the two phenomena have different mechanisms.},
	keywords = {conditioning, Learning, Memory, motoneuron, potentiation, primate, spinal reflex},
	issn = {0304-3940},
	doi = {10.1016/0304-3940(89)90495-3},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/2779852},
	author = {Jonathan Wolpaw and Jonathan S. Carp and Lee, C. L.}
}
@article {3274,
	title = {Operant conditioning of primate triceps surae H-reflex produces reflex asymmetry.},
	journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale},
	volume = {75},
	year = {1989},
	month = {03/1989},
	pages = {35{\textendash}39},
	abstract = {Monkeys are able to increase or decrease triceps surae H-reflex when reward depends on reflex amplitude. Operantly conditioned change occurs over weeks and produces persistent alterations in the lumbosacral spinal cord which should be technically accessible substrates of primate memory. Previous work monitored and conditioned triceps surae H-reflex in one leg. To determine whether H-reflex conditioning in one leg affects the control leg, the present study monitored H-reflexes in both legs while the reflex in one leg underwent HR increases or HR decreases conditioning. Under the HR increases mode, H-reflex increase was much greater in the HR increases leg than in the control leg. Under the HR decreases mode, H-reflex decrease was confined to the HR decreases leg. By showing that conditioning of one leg{\textquoteright}s H-reflex produces H-reflex asymmetry, the data further define the phenomenon and indicate that the other leg can serve as an internal control for physiologic and anatomic studies exploring the sites and mechanisms of the spinal cord memory substrates.},
	keywords = {Learning, Memory, monosynaptic reflex, operant conditioning, plasticity, Spinal Cord, spinal reflex},
	issn = {0014-4819},
	doi = {10.1007/BF00248527},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/2707354},
	author = {Jonathan Wolpaw and Lee, C. L. and Calaitges, J. G.}
}
@article {3281,
	title = {Retrograde transport of the lectin Phaseolus vulgaris leucoagglutinin (PHA-L) by rat spinal motoneurons.},
	journal = {Neuroscience letters},
	volume = {86},
	year = {1988},
	month = {03/1988},
	pages = {133{\textendash}138},
	abstract = {The lectin Phaseolus vulgaris leucoagglutinin (PHA-L) has been used primarily as an anterograde transport tracer in the CNS. We present evidence of PHA-L retrograde transport by rat spinal motoneurons after injection into the triceps brachii. Labelled motoneurons were localized in specific and well-defined neuron pools in the ventral horn. Primary afferent labelling was not seen in the spinal gray matter. Dorsal rhizotomy did not eliminate or decrease motoneuron labelling. The retrograde transport rate was about 8 mm/day. PHA-L can clearly undergo retrograde, as well as anterograde, transport.},
	keywords = {lectin, phaseolus vulgaris leucoagglutinin (PHA-L), rat, retrograde transport, spinal motoneuron},
	issn = {0304-3940},
	doi = {10.1016/0304-3940(88)90559-9},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/2453002},
	author = {Lee, C. L. and Dennis J. McFarland and Jonathan Wolpaw}
}
@article {3283,
	title = {Motoneuron response to dorsal root stimulation in anesthetized monkeys after spinal cord transection.},
	journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale},
	volume = {68},
	year = {1987},
	month = {10/1987},
	pages = {428{\textendash}433},
	abstract = {In preparation for studying the spinal cord alterations produced by operant conditioning of spinal reflexes, we studied peripheral nerve responses to supramaximal dorsal root stimulation in the lumbosacral cord of deeply anesthetized monkeys before and after thoracic cord transection. Except for variable depression in the first few minutes, reflex responses were not reduced or otherwise significantly affected by transection in the hour immediately following the lesion or for at least 50 h. The results suggest that reduction in muscle spindle sensitivity and/or in polysynaptic motoneuron excitation contributes to stretch reflex depression after cord transection.},
	keywords = {monosynaptic reflex, primate, Spinal Cord, spinal cord injury, spinal reflex, spinal shock},
	issn = {0014-4819},
	doi = {10.1007/BF00248809},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/3480233},
	author = {Jonathan Wolpaw and Lee, C. L.}
}
