@article {3258,
	title = {Acquisition and maintenance of the simplest motor skill: investigation of CNS mechanisms.},
	journal = {Medicine and science in sports and exercise},
	volume = {26},
	year = {1994},
	month = {12/1994},
	pages = {1475{\textendash}1479},
	abstract = {The spinal stretch reflex (SSR), or tendon jerk, is the simplest behavior of the vertebrate nervous system. It is mediated primarily by a wholly spinal, two-neuron pathway. Recent studies from several laboratories have shown that primates, human and nonhuman, can gradually increase or decrease the size of the SSR when reward depends on such change. Evidence of this training remains in the spinal cord after all supraspinal influence is removed. Thus, the learning of this simple motor skill changes the spinal cord itself. Comparable spinal plasticity probably plays a role in the acquisition of many complex motor skills. Intracellular physiological and anatomical studies are seeking the location and nature of this spinal cord plasticity. Attention focuses on the most probable sites of change, the group Ia afferent synapse on the alpha motoneuron and the motoneuron itself. Results to date indicate that modifications are present at several places in the spinal cord. Current clinical studies are investigating the use of spinal cord adaptive plasticity as a basis for a new therapeutic approach to spasticity and other forms of abnormal spinal reflex function that result from spinal cord injury, stroke, or other neurological disorders. In the future, understanding of spinal reflex plasticity may lead to development of improved training methods for a variety of motor skills.},
	keywords = {conditioning, Learning, Memory, Motor control, plasticity, primate, Spinal Cord, training},
	issn = {0195-9131},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/7869882},
	author = {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 {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.}
}
@article {3273,
	title = {Chronic exposure of primates to 60-Hz electric and magnetic fields: I. Exposure system and measurements of general health and performance.},
	journal = {Bioelectromagnetics},
	volume = {10},
	year = {1989},
	month = {01/1989},
	pages = {277{\textendash}288},
	abstract = {We exposed pigtailed macaques (Macaca nemestrina) to electric (E) and magnetic (B) fields at strengths of 3 kV/m and 0.1 G, 10 kV/m and 0.3 G, and 30 kV/m and 0.9 G for three 21 day segments. These three exposure segments were preceded and followed by 21 day sham exposure segments. Additional animals received only sham exposure for five 21 day segments. Detailed description of the exposure chamber and field generation apparatus is given. We evaluated measures of animal well-being, including weight, blood chemistry, blood cell counts, and performance on a simple motor task, and performed postmortem examinations. Reliable and consistent results were obtained throughout data collection. None of the measures evaluated was significantly affected by E- and B-field exposures. Data obtained during actual exposure segments were not distinguishable from those obtained during the initial and final sham exposure segments, nor were they different from data obtained from the sham-exposed animals. Thus, field exposure had no apparent effects on general health or performance.},
	keywords = {60-Hz fields, central nervous system, electric field, magnetic field, primate},
	issn = {0197-8462},
	doi = {10.1002/bem.2250100306},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/2751702},
	author = {Jonathan Wolpaw and Seegal, R. F. and Dowman, R.}
}
@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 {3280,
	title = {Spinal stretch reflex and cortical evoked potential amplitudes versus muscle stretch amplitude in the monkey arm.},
	journal = {Electroencephalography and clinical neurophysiology},
	volume = {69},
	year = {1988},
	month = {04/1988},
	pages = {394{\textendash}397},
	abstract = {While investigating operant conditioning of the primate spinal stretch reflex (SSR), we studied SSR amplitude and cortical somatosensory evoked potential (SEP) amplitude as stretch amplitude changed in the monkey arm. Initial muscle length and background EMG activity remained constant. With change in stretch amplitude (and proportional change in stretch velocity and acceleration), changes in SSR and SEP amplitudes were respectively 0.75 and 0.66 as great. The lesser change in SSR amplitude may reflect saturation of Ia afferents, while that in SEP amplitude may also reflect participation of other peripheral receptors.},
	keywords = {muscle stretch, primate, Somatosensory Cortex, somatosensory evoked potential, spinal reflex, stretch reflex},
	issn = {0013-4694},
	doi = {10.1016/0013-4694(88)90011-9},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/2450738},
	author = {Jonathan Wolpaw and Dowman, R.}
}
@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.}
}
@article {3285,
	title = {Adaptive plasticity in the spinal stretch reflex: an accessible substrate of memory?.},
	journal = {Cellular and molecular neurobiology},
	volume = {5},
	year = {1985},
	month = {06/1985},
	pages = {147{\textendash}165},
	abstract = {The study of the substrates of memory in higher vertebrates is one of the major problems of neurobiology. A simple and technically accessible experimental model is needed. Recent studies have demonstrated long-term adaptive plasticity, a form of memory, in the spinal stretch reflex (SSR). The SSR is due largely to a two-neuron monosynaptic arc, the simplest, best-defined, and most accessible pathway in the primate central nervous system (CNS). Monkeys can slowly change SSR amplitude without a change in initial muscle length or alpha motoneuron tone, when reward is made contingent on amplitude. Change occurs over weeks and months and persists for long periods. It is relatively specific to the agonist muscle and affects movement. The salient features of SSR adaptive plasticity, combined with clinical and laboratory evidence indicating spinal cord capacity for intrinsic change, suggest that SSR change eventually involves persistent segmental alteration. If this is the case, SSR plasticity should be a powerful model for studying the neuronal and synaptic substrates of memory in a primate.},
	keywords = {Learning, Memory, plasticity, primate, spinal reflex, stretch reflex},
	issn = {0272-4340},
	doi = {10.1007/BF00711090},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/3161616},
	author = {Jonathan Wolpaw}
}
@article {3286,
	title = {Reduced day-to-day variation accompanies adaptive plasticity in the primate spinal stretch reflex.},
	journal = {Neuroscience letters},
	volume = {54},
	year = {1985},
	month = {03/1985},
	pages = {165{\textendash}171},
	abstract = {Monkeys can change the amplitude of the spinal stretch reflex (SSR), or M1, when reward is made contingent on amplitude. The present study demonstrates that reduced SSR day-to-day variation accompanies such adaptive SSR change. This finding supports the assumption that initial, phase I, SSR change results from contingency-appropriate stabilization of tonic activity in relevant descending spinal cord pathways.},
	keywords = {Learning, Memory, plasticity, primate, spinal reflex, stretch reflex},
	issn = {0304-3940},
	doi = {10.1016/S0304-3940(85)80073-2},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/3991057},
	author = {Jonathan Wolpaw and O{\textquoteright}Keefe, J. A. and Kieffer, V. A. and Sanders, M. G.}
}
@article {3288,
	title = {Adaptive plasticity and diurnal rhythm in the primate spinal stretch reflex are independent phenomena.},
	journal = {Brain research},
	volume = {300},
	year = {1984},
	month = {05/1984},
	pages = {385{\textendash}391},
	abstract = {Recent studies have revealed two phenomena producing considerable variation in amplitude of the initial, purely segmental, largely monosynaptic, response to sudden muscle stretch, the spinal stretch reflex (SSR), without change in background EMG activity or initial muscle length. The first is small and short-term, a modest diurnal rhythm in SSR amplitude. The second is large and long-term, marked adaptive change in SSR amplitude which occurs gradually over weeks and months when animals are rewarded for such change. This second phenomenon may involve persistent segmental alteration, and, if so, could constitute a technically accessible substrate of memory. The present study compared the two phenomena and sought evidence of interaction between them. The diurnal rhythm persisted, without change in phase and with only minimal change in amplitude, despite the occurrence of marked adaptive change. Animals did not utilize the rhythm to increase reward percentage by altering daily performance schedules. These results suggest that the mechanisms of the diurnal rhythm and of adaptive plasticity in SSR amplitude are separate and independent. The diurnal rhythm{\textquoteright}s effect on movement was not altered by adaptive change in SSR amplitude. This effect was comparable to adaptive change{\textquoteright}s effect on movement when both were expressed as change in movement/change in SSR amplitude.},
	keywords = {adaptive plasticity, diurnal rhythm, Learning, Memory, primate, stretch reflex},
	issn = {0006-8993},
	doi = {10.1016/0006-8993(84)90852-7},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/6539634},
	author = {Jonathan Wolpaw and Noonan, P. A. and O{\textquoteright}Keefe, J. A.}
}
@article {3292,
	title = {Adaptive plasticity in the primate spinal stretch reflex: reversal and re-development.},
	journal = {Brain research},
	volume = {278},
	year = {1983},
	month = {11/1983},
	pages = {299{\textendash}304},
	abstract = {Monkeys can gradually increase or decrease the amplitude of the segmentally mediated spinal stretch reflex (SSR) without change in initial muscle length or background EMG activity. Both increase (under the SSR increases mode) and decrease (under the SSR decreases mode) occur slowly, progressing steadily over weeks. The present study investigated reversal and re-development of SSR amplitude change. Over a period of months, following collection of control data, monkeys were exposed to one mode, then to the other, and then to the first mode again. Development, reversal, and re-development of change all took place over weeks, following very similar courses. These data are consistent with the hypothesis that persistent segmental alteration underlies SSR amplitude change. Such persistent segmental alteration would constitute a technically accessible substrate of memory.},
	keywords = {Learning, Memory, plasticity, primate, spinal reflex, stretch reflex},
	issn = {0006-8993},
	doi = {10.1016/0006-8993(83)90259-7},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/6640320},
	author = {Jonathan Wolpaw}
}
@article {3294,
	title = {Adaptive plasticity in the spinal stretch reflex.},
	journal = {Brain research},
	volume = {267},
	year = {1983},
	month = {05/1983},
	pages = {196{\textendash}200},
	abstract = {Monkeys can change the amplitude of the spinal stretch reflex without change in initial alpha motor neuron tone, as measured by EMG, or in initial muscle length. Change is apparent in 5-10 days, continues to develop over weeks, and persists during inactive periods. Spinal stretch reflex change may be a valuable system for studying the neuronal and synaptic bases of an adaptive change in primate CNS function.},
	keywords = {Learning, Memory, plasticity, primate, spinal reflex, stretch reflex},
	issn = {0006-8993},
	doi = {10.1016/0006-8993(83)91059-4},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/6860948},
	author = {Jonathan Wolpaw and Kieffer, V. A. and Seegal, R. F. and Braitman, D. J. and Sanders, M. G.}
}
@article {3329,
	title = {Diurnal rhythm in the spinal stretch reflex.},
	journal = {Brain research},
	volume = {244},
	year = {1982},
	month = {07/1982},
	pages = {365{\textendash}369},
	abstract = {We studied primate spinal stretch reflex (SSR) amplitude as a function of time of day. SSR amplitude was greatest around midnight and smallest around noon. The diurnal rhythm was not simply a function of number of trials, or of the lighting cycle. This rhythm offers an opportunity to study the neuronal and synaptic mechanisms producing a diurnal change in CNS function. Its existence indicates that the CNS response to a given limb disturbance, and thus the CNS activity underlying a given performance, varies with time of day.},
	keywords = {circadian rhythm, diurnal rhythm, muscle stretch, primate, spinal reflex, stretch reflex},
	issn = {0006-8993},
	doi = {10.1016/0006-8993(82)90099-3},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/6889452},
	author = {Jonathan Wolpaw and Seegal, R. F.}
}
