@article {3172,
	title = {Operant conditioning of the primate H-reflex: factors affecting the magnitude of change.},
	journal = {Experimental brain research. Experimentelle Hirnforschung. Exp{\'e}rimentation c{\'e}r{\'e}brale},
	volume = {97},
	year = {1993},
	month = {12/1993},
	pages = {31{\textendash}39},
	abstract = {Primates can gradually increase or decrease H-reflex amplitude in one leg when reward depends on that amplitude. The magnitude of change varies greatly from animal to animal. This study sought to define the factors that control this magnitude. It evaluated the influence of animal age, muscle size (absolute and relative), background electromyographic activity (EMG) level, M response amplitude, initial H-reflex amplitude, performance intensity, and behavior of the contralateral leg. Fifty-four animals (Macaca nemestrina) underwent operant conditioning of the triceps surae H-reflex in one leg (the trained leg). Twenty-eight were rewarded for larger H-reflexes (HRup animals), and 26 were rewarded for smaller H-reflexes (HRdown animals). In the HRup animals, H-reflex amplitude in the trained leg rose to an average final value of 177\% of its initial amplitude. Magnitude of increase varied widely across animals. Nine animals rose to 120-140\%, 11 to 160-240\%, three to 300\% or more, and five remained within 20\% of initial amplitude. In the HRdown animals, H-reflex amplitude in the trained leg decreased to an average of 69\% of initial amplitude. Magnitude of decrease varied widely. Five animals decreased to 20-40\%, seven to 40-60\%, six to 60-80\%, and eight remained within 20\% of initial amplitude. Animal age, as assessed by weight, markedly affected HRdown conditioning, but not HRup conditioning. Heavy HRdown animals (> or = 6 kg) were more successful than light HRdown animals (< 6 kg). Thirteen of 14 heavy animals and only five of 12 light animals decreased to less than 80\% of initial amplitude.(ABSTRACT TRUNCATED AT 250 WORDS)},
	keywords = {H-Reflex, monkey, operant conditioning, plasticity, Spinal Cord},
	issn = {0014-4819},
	doi = {10.1007/BF00228815},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/8131830},
	author = {Jonathan Wolpaw and Herchenroder, P. A. and Jonathan S. Carp}
}
@article {3269,
	title = {Operant conditioning of H-reflex in freely moving monkeys.},
	journal = {Journal of neuroscience methods},
	volume = {31},
	year = {1990},
	month = {02/1990},
	pages = {145{\textendash}152},
	abstract = {The H-reflex, the electrical analog of the stretch reflex or tendon jerk, is the simplest behavior of the primate CNS. It is subserved by a wholly spinal two-neuron reflex arc. Recent studies show that this reflex can be increased or decreased by operant conditioning, and that such conditioning causes plastic changes in the spinal cord itself. Thus, H-reflex conditioning provides a powerful new model for investigating primate memory traces. The key feature of this model, the conditioning task, originally required animal restraint. This report describes a new tether-based design that allows H-reflex measurement and conditioning without restraint. This design integrates the conditioning task into the life of the freely moving animal.},
	keywords = {conditioning, H-Reflex, Memory, plasticity, primate, spinal reflex, stretch reflex},
	issn = {0165-0270},
	doi = {10.1016/0165-0270(90)90159-D},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/2319815},
	author = {Jonathan Wolpaw and Herchenroder, P. A.}
}
