02728nas a2200253   4500008004100000022001400041245003700055210003600092260001200128300001400140490000700154520210100161653002302262653001602285653001302301653001102314653001502325653001102340653001502351653001602366100002102382700002302403856004802426       2006                        eng d  a0301-008200aPlasticity from muscle to brain.0 aPlasticity from muscle to brain  c02/2006  a233–2630 v783 aRecognition that the entire central nervous system (CNS) is highly plastic, and that it changes continually throughout life, is a relatively new development. Until very recently, neuroscience has been dominated by the belief that the nervous system is hardwired and changes at only a few selected sites and by only a few mechanisms. Thus, it is particularly remarkable that Sir John Eccles, almost from the start of his long career nearly 80 years ago, focused repeatedly and productively on plasticity of many different kinds and in many different locations. He began with muscles, exploring their developmental plasticity and the functional effects of the level of motor unit activity and of cross-reinnervation. He moved into the spinal cord to study the effects of axotomy on motoneuron properties and the immediate and persistent functional effects of repetitive afferent stimulation. In work that combined these two areas, Eccles explored the influences of motoneurons and their muscle fibers on one another. He studied extensively simple spinal reflexes, especially stretch reflexes, exploring plasticity in these reflex pathways during development and in response to experimental manipulations of activity and innervation. In subsequent decades, Eccles focused on plasticity at central synapses in hippocampus, cerebellum, and neocortex. His endeavors extended from the plasticity associated with CNS lesions to the mechanisms responsible for the most complex and as yet mysterious products of neuronal plasticity, the substrates underlying learning and memory. At multiple levels, Eccles' work anticipated and helped shape present-day hypotheses and experiments. He provided novel observations that introduced new problems, and he produced insights that continue to be the foundation of ongoing basic and clinical research. This article reviews Eccles' experimental and theoretical contributions and their relationships to current endeavors and concepts. It emphasizes aspects of his contributions that are less well known at present and yet are directly relevant to contemporary issues.10aactivity-dependent10aJohn Eccles10aLearning10aMemory10amotor unit10amuscle10aplasticity10aSpinal Cord1 aWolpaw, Jonathan1 aCarp, Jonathan, S.  uhttp://www.ncbi.nlm.nih.gov/pubmed/1664718102878nas a2200241   4500008004100000022001400041245009400055210006900149260001200218300001200230490000800242520217200250653001802422653001902440653001302459653001502472653002302487100002102510700002302531700001302554700002102567856004802588       2002                        eng d  a0014-481900aCorticospinal tract transection prevents operantly conditioned H-reflex increase in rats.0 aCorticospinal tract transection prevents operantly conditioned H  c05/2002  a88–940 v1443 aOperant conditioning of the H-reflex, the electrical analog of the spinal stretch reflex, in freely moving rats is a relatively simple model for studying long-term supraspinal control over spinal cord function. Motivated by food reward, rats can gradually increase (i.e., up-condition) or decrease (i.e., down-condition) the soleus H-reflex. Earlier work showed that corticospinal tract transection prevents acquisition and maintenance of H-reflex down-conditioning while transection of other major spinal cord tracts does not. This study explores the effects on acquisition of up-conditioning of the right soleus H-reflex of mid-thoracic transection of: the right lateral column (LC, five rats) (containing the rubrospinal, vestibulospinal, and reticulospinal tracts); the entire dorsal column (DC, six rats) [containing the main corticospinal tract (CST) and the dorsal ascending tract (DA)]; the CST alone (five rats); or the DA alone (seven rats). After initial (i.e., control) H-reflex amplitude was determined, the rat was exposed for 50 days to the up-conditioning mode in which reward was given when the H-reflex was above a criterion value. H-reflex amplitude at the end of up-conditioning was compared to initial H-reflex amplitude. An increase > or =20% was defined as successful up-conditioning. In intact rats, H-reflex amplitude at the end of up-conditioning averaged 164% (+/-10%, SE), and 81% were successful. In the present study, LC and DA rats were similar to intact rats in final H-reflex amplitude and percent successful. In contrast, results for DC and CST rats were significantly different from those of intact rats. In the six DC rats, final H-reflex amplitude averaged 105% (+/-3)% of control and none was successful; and in the five CST rats, final H-reflex amplitude averaged 94% (+/-3)% and none was successful. The results indicate that the main CST, located in the dorsal column, is essential for H-reflex up-conditioning as it is for down-conditioning, while the dorsal column ascending tract and the ipsilateral lateral column (containing the main rubrospinal, vestibulospinal, and reticulospinal tracts) do not appear to be essential.10adorsal column10alateral column10aLearning10aplasticity10aspinal cord injury1 aChen, Xiang Yang1 aCarp, Jonathan, S.1 aChen, Lu1 aWolpaw, Jonathan  uhttp://www.ncbi.nlm.nih.gov/pubmed/1197676201213nas a2200313   4500008004100000022001400041245005000055210004500105300001400150490000700164520043400171653001300605653001000618653001700628653002100645653001300666653001100679653001500690653001100705653001200716653001100728653001600739653001600755653002200771653001500793100002100808700002300829856004700852       1993                        eng d  a0065-140000aThe volitional nature of the simplest reflex.0 avolitional nature of the simplest reflex  a103–1110 v533 aRecent 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.10abehavior10aBrain10aconditioning10ahuman physiology10aLearning10aMemory10amotoneuron10anature10aprimate10aReflex10aSpinal Cord10aspinal site10asupra spinal site10avertebrate1 aWolpaw, Jonathan1 aCarp, Jonathan, S.  uhttp://www.ncbi.nlm.nih.gov/pubmed/831723801769nas a2200253   4500008004100000022001400041245010600055210006900161260001200230300001400242490000800256520104100264653001701305653001301322653001101335653001501346653001701361653001201378653001801390100002101408700002301429700001601452856004701468       1989                        eng d  a0304-394000aMemory traces in spinal cord produced by H-reflex conditioning: effects of post-tetanic potentiation.0 aMemory traces in spinal cord produced by Hreflex conditioning ef  c08/1989  a113–1190 v1033 aOperant 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.10aconditioning10aLearning10aMemory10amotoneuron10apotentiation10aprimate10aspinal reflex1 aWolpaw, Jonathan1 aCarp, Jonathan, S.1 aLee, C., L.  uhttp://www.ncbi.nlm.nih.gov/pubmed/2779852