01519nas a2200301   4500008004100000022001400041245009500055210006900150260001200219300001400231490001700245520064100262653001300903653002400916653001500940653001500955653002400970653001900994653002301013100002101036700001301057700001301070700001901083700002301102700002301125700002101148856004801169       2010                        eng d  a1749-663200aReflex conditioning: a new strategy for improving motor function after spinal cord injury.0 aReflex conditioning a new strategy for improving motor function   c06/2010  aE12–E210 v1198 Suppl 13 aSpinal reflex conditioning changes reflex size, induces spinal cord plasticity, and modifies locomotion. Appropriate reflex conditioning can improve walking in rats after spinal cord injury (SCI). Reflex conditioning offers a new therapeutic strategy for restoring function in people with SCI. This approach can address the specific deficits of individuals with SCI by targeting specific reflex pathways for increased or decreased responsiveness. In addition, once clinically significant regeneration can be achieved, reflex conditioning could provide a means of reeducating the newly (and probably imperfectly) reconnected spinal cord.10aH-Reflex10alearning and memory10aLocomotion10aplasticity10areflex conditioning10aRehabilitation10aspinal cord injury1 aChen, Xiang Yang1 aChen, Yi1 aWang, Yu1 aThompson, Aiko1 aCarp, Jonathan, S.1 aSegal, Richard, L.1 aWolpaw, Jonathan  uhttp://www.ncbi.nlm.nih.gov/pubmed/2059053402917nas a2200265   4500008004100000022001400041245009700055210006900152260001200221300001000233490000800243520213200251653002202383653001202405653002102417653001302438653001802451653002102469653000902490653004102499100001902540700002302559700002102582856004802603       2002                        eng d  a0165-027000aTemporal transformation of multiunit activity improves identification of single motor units.0 aTemporal transformation of multiunit activity improves identific  c02/2002  a87-980 v1143 a<p><span style="font-family: arial, helvetica, clean, sans-serif; font-size: 13px; line-height: 17px;">This report describes a temporally based method for identifying repetitive firing of motor units. This&nbsp;</span><span class="highlight" style="font-family: arial, helvetica, clean, sans-serif; font-size: 13px; line-height: 17px;">approach</span><span style="font-family: arial, helvetica, clean, sans-serif; font-size: 13px; line-height: 17px;">&nbsp;is ideally suited to spike trains with negative serially correlated inter-spike intervals (ISIs). It can also be applied to spike trains in which ISIs exhibit little serial correlation if their coefficient of variation (COV) is sufficiently low. Using a novel application of the Hough transform, this method (i.e. the modified Hough transform (MHT)) maps motor unit action potential (MUAP) firing times into a feature space with ISI and offset (defined as the latency from an arbitrary starting time to the first MUAP in the train) as dimensions. Each MUAP firing time corresponds to a pattern in the feature space that represents all possible MUAP trains with a firing at that time. Trains with stable ISIs produce clusters in the feature space, whereas randomly firing trains do not. The MHT provides a direct estimate of mean firing rate and its variability for the entire data segment, even if several individual MUAPs are obscured by firings from other motor units. Addition of this method to a shape-based classification&nbsp;</span><span class="highlight" style="font-family: arial, helvetica, clean, sans-serif; font-size: 13px; line-height: 17px;">approach</span><span style="font-family: arial, helvetica, clean, sans-serif; font-size: 13px; line-height: 17px;">&nbsp;markedly improved rejection of false positives using simulated data and identified spike trains in whole muscle electromyographic recordings from rats. The relative independence of the MHT from the need to correctly classify individual firings permits a global description of stable repetitive firing behavior that is complementary to shape-based approaches to MUAP classification.</span></p>10aAction Potentials10aAnimals10aElectromyography10aH-Reflex10aMotor Neurons10aMuscle, Skeletal10aRats10aSignal Processing, Computer-Assisted1 aSchalk, Gerwin1 aCarp, Jonathan, S.1 aWolpaw, Jonathan  uhttp://www.ncbi.nlm.nih.gov/pubmed/1185004301678nas a2200277   4500008004100000022001400041245009700055210006900152260001200221300001000233490000800243520088300251653002201134653002101156653001301177653002501190653001601215653001501231653001801246653000801264100002301272700002101295700001501316700002101331856004801352       2001                        eng d  a0304-394000aEffects of chronic nerve cuff and intramuscular electrodes on rat triceps surae motor units.0 aEffects of chronic nerve cuff and intramuscular electrodes on ra  c10/2001  a1–40 v3123 aIn order to assess the long-term effects of implanted electrodes on motor unit properties, we studied triceps surae (TS) motor units in rats implanted for 3-10 months with a tibial nerve cuff electrode for H-reflex elicitation and intramuscular electrodes for recording TS electromyographic activity. Motor units with sag from implanted rats displayed greater tetanic force than those from unimplanted rats. Motor units without sag had shorter twitch contraction times. This disrupted the relationship between sag and contraction time that was always present in unimplanted rats. These differences were consistent with a small degree of muscle denervation and subsequent reinnervation. Further analyses ascribed this effect to the nerve cuff rather than to the intramuscular electrodes. Comparable changes in motor unit properties may occur in humans with implanted nerve cuffs.10achronic recording10acontraction time10aH-Reflex10aimplanted electrodes10amotor units10anerve cuff10areinnervation10asag1 aCarp, Jonathan, S.1 aChen, Xiang Yang1 aSheikh, H.1 aWolpaw, Jonathan  uhttp://www.ncbi.nlm.nih.gov/pubmed/1157883102272nas a2200241   4500008004100000022001400041245007000055210006800125260001200193300001400205490000800219520158400227653001301811653002001824653002501844653001501869653001801884100002301902700002101925700001501946700002101961856004801982       2001                        eng d  a0014-481900aMotor unit properties after operant conditioning of rat H-reflex.0 aMotor unit properties after operant conditioning of rat Hreflex  c10/2001  a382–3860 v1403 aOperant conditioning of the H-reflex produces plasticity at several sites in the spinal cord, including the motoneuron. This study assessed whether this spinal cord plasticity is accompanied by changes in motor unit contractile properties. Thirty-one adult male Sprague-Dawley rats implanted for chronic recording of triceps surae electromyographic activity and H-reflex elicitation were exposed for at least 40 days to HRup or HRdown training, in which reward occurred when the H-reflex was greater than (12 HRup rats) or less than (12 HRdown rats) a criterion value, or continued under the control mode in which the H-reflex was simply measured (7 HRcon rats). At the end of H-reflex data collection, rats were anesthetized and the contractile properties of 797 single triceps surae motor units activated by intraaxonal (or intramyelin) current injection were determined. Motor units were classified as S, FR, Fint, or FF on the basis of sag and fatigue properties. Maximum tetanic force and twitch contraction time were also measured. HRdown rats exhibited a significant increase in the fatigue index of fast-twitch motor units. This resulted in a significant decrease in the percentage of Fint motor units and a significant increase in that of FR motor units. HRup conditioning had no effect on fatigue index. Neither HRup nor HRdown conditioning affected maximum tetanic force or twitch contraction time. These data are consistent with the hypothesis that conditioning mode-specific change in motoneuron firing patterns causes activity-dependent change in muscle properties.10aH-Reflex10amotor unit type10aoperant conditioning10aplasticity10atriceps surae1 aCarp, Jonathan, S.1 aChen, Xiang Yang1 aSheikh, H.1 aWolpaw, Jonathan  uhttp://www.ncbi.nlm.nih.gov/pubmed/1168131402242nas a2200241   4500008004100000022001400041245008800055210006900143260001200212300001400224490000800238520154300246653002401789653001301813653001501826653001501841653001601856100002301872700002101895700001501916700002101931856004801952       2001                        eng d  a0014-481900aOperant conditioning of rat H-reflex affects motoneuron axonal conduction velocity.0 aOperant conditioning of rat Hreflex affects motoneuron axonal co  c01/2001  a269–2730 v1363 aThis study assessed the effects of operant conditioning of the H-reflex on motoneuron axonal conduction velocity in the rat. After measurement of the control H-reflex size, rats were either exposed for at least 40 days to the HRup or HRdown conditioning mode, in which reward occurred only if the soleus H-reflex was greater than (HRup mode) or less than (HRdown mode) a criterion or continued under the control condition (HRcon mode) in which the H-reflex was simply measured. We then measured axonal conduction velocity of triceps surae motor units of HRup, HRdown, and HRcon rats by stimulating the axon in the ventral root and recording from the tibial nerve. Conduction velocity was 8% less in successful HRdown rats than in HRcon rats (P=0.02). Conduction velocity in HRup rats and unsuccessful HRdown rats was not significantly different from that in HRcon rats. Since recording bypassed the intra-spinal portion of the motoneuron, the change was clearly in the axon. This decrease was similar to the 6% decrease previously found in successful HRdown monkeys. Unsuccessful HRdown rats and monkeys did not show this decrease. This result suggests that the mechanism of HRdown conditioning is similar in rats and monkeys and provides further support for the hypothesis that HRdown conditioning decreases motoneuron excitability by producing a positive shift in firing threshold. While traditional theories of learning emphasize synaptic plasticity, neuronal plasticity may also contribute to operantly conditioned behavioral changes.10aconduction velocity10aH-Reflex10amotoneuron10aplasticity10aSpinal Cord1 aCarp, Jonathan, S.1 aChen, Xiang Yang1 aSheikh, H.1 aWolpaw, Jonathan  uhttp://www.ncbi.nlm.nih.gov/pubmed/1120629002325nas a2200229   4500008004100000022001400041245009300055210006900148260001200217300001200229490000700241520165100248653001301899653001101912653002501923653001501948653001601963100002101979700002502000700002302025856004702048       1993                        eng d  a0014-481900aOperant conditioning of the primate H-reflex: factors affecting the magnitude of change.0 aOperant conditioning of the primate Hreflex factors affecting th  c12/1993  a31–390 v973 aPrimates 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)10aH-Reflex10amonkey10aoperant conditioning10aplasticity10aSpinal Cord1 aWolpaw, Jonathan1 aHerchenroder, P., A.1 aCarp, Jonathan, S.  uhttp://www.ncbi.nlm.nih.gov/pubmed/8131830