<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Xiang Yang Chen</style></author><author><style face="normal" font="default" size="100%">Yi Chen</style></author><author><style face="normal" font="default" size="100%">Lu Chen</style></author><author><style face="normal" font="default" size="100%">Tennissen, Ann M.</style></author><author><style face="normal" font="default" size="100%">Jonathan Wolpaw</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Corticospinal tract transection permanently abolishes H-reflex down-conditioning in rats.</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of neurotrauma</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">corticospinal tract</style></keyword><keyword><style  face="normal" font="default" size="100%">H-reflex conditioning</style></keyword><keyword><style  face="normal" font="default" size="100%">plasticity</style></keyword><keyword><style  face="normal" font="default" size="100%">rat</style></keyword><keyword><style  face="normal" font="default" size="100%">spinal cord injury</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2006</style></year><pub-dates><date><style  face="normal" font="default" size="100%">11/2006</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/pubmed/17115915</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">23</style></volume><pages><style face="normal" font="default" size="100%">1705–1712</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Previous studies have shown that corticospinal tract (CST) transection, but not transection of other major spinal cord tracts, prevents down-conditioning of the H-reflex, the electrical analog of the spinal stretch reflex. This study set out to determine whether the loss of the capacity for H-reflex down-conditioning caused by CST transection is permanent. Female Sprague-Dawley rats received CST, lateral column (LC), or dorsal column ascending tract (DA) transection at T8-9; 9-10 months later, they were exposed to the H-reflex down-conditioning protocol for 50 days. In the LC and DA rats, H-reflex size fell to 60 (+/- 9 SEM)% and 60 (+/- 19)%, respectively, of its initial size. This down-conditioning was comparable to that of normal rats. In contrast, H-reflex size in the CST rats rose to 170 (+/- 42)% of its initial size. A similar rise does not occur in rats exposed to down-conditioning shortly after CST transection. These results indicate that CST transection permanently eliminates the capacity for H-reflex down-conditioning and has gradual long-term effects on sensorimotor cortex function. They imply that H-reflex down-conditioning can be a reliable measure of CST function for long-term studies of the effects of spinal cord injury and/or for evaluations of the efficacy of experimental therapeutic procedures, such as those intended to promote CST regeneration. The results also suggest that the role of sensorimotor cortex in down-conditioning extends beyond generation of the essential CST activity.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Xiang Yang Chen</style></author><author><style face="normal" font="default" size="100%">Lu Chen</style></author><author><style face="normal" font="default" size="100%">Jonathan Wolpaw</style></author><author><style face="normal" font="default" size="100%">Jakeman, Lyn B.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Corticospinal tract transection reduces H-reflex circadian rhythm in rats.</style></title><secondary-title><style face="normal" font="default" size="100%">Brain research</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">circadian rhythms</style></keyword><keyword><style  face="normal" font="default" size="100%">corticospinal tract</style></keyword><keyword><style  face="normal" font="default" size="100%">diurnal rhythm</style></keyword><keyword><style  face="normal" font="default" size="100%">H-Reflex</style></keyword><keyword><style  face="normal" font="default" size="100%">rat</style></keyword><keyword><style  face="normal" font="default" size="100%">spinal cord injury</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2002</style></year><pub-dates><date><style  face="normal" font="default" size="100%">06/2002</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/pubmed/12031858</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">942</style></volume><pages><style face="normal" font="default" size="100%">101–108</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">In freely moving rats and monkeys, H-reflex amplitude displays a marked circadian variation without change in background motoneuron tone. In rats, the H-reflex is largest around noon and smallest around midnight. The present study evaluated in rats the effects on this rhythm of calibrated contusions of mid-thoracic spinal cord and mid-thoracic transection of specific spinal cord pathways. In 33 control rats, rhythm amplitude averaged 29.0(+/-2.6 S.E.)% of H-reflex amplitude. Contusion injuries at T8-9 that destroyed 53-88% of the white matter significantly reduced the rhythm to 18.9(+/-2.4)% of H-reflex amplitude. Transection of the ipsilateral lateral column, which contains the rubrospinal, vestibulospinal, and reticulospinal tracts, or bilateral transection of the dorsal column ascending tract did not affect rhythm amplitude or phase. In contrast, bilateral transection of the main corticospinal tract significantly reduced the rhythm to 14.7(+/-6.6)%. These results indicate that the H-reflex circadian rhythm depends in part on descending influence from the brain and that this influence is conveyed by the main corticospinal tract.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Xiang Yang Chen</style></author><author><style face="normal" font="default" size="100%">Feng-Chen, K. C.</style></author><author><style face="normal" font="default" size="100%">Lu Chen</style></author><author><style face="normal" font="default" size="100%">Stark, D. M.</style></author><author><style face="normal" font="default" size="100%">Jonathan Wolpaw</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Short-Term and medium-term effects of spinal cord tract transections on soleus H-reflex in freely moving rats.</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of neurotrauma</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">corticospinal tract</style></keyword><keyword><style  face="normal" font="default" size="100%">dorsal column</style></keyword><keyword><style  face="normal" font="default" size="100%">dorsal column ascending tract</style></keyword><keyword><style  face="normal" font="default" size="100%">lateral column</style></keyword><keyword><style  face="normal" font="default" size="100%">rat</style></keyword><keyword><style  face="normal" font="default" size="100%">soleus activity</style></keyword><keyword><style  face="normal" font="default" size="100%">spinal cord injury</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2001</style></year><pub-dates><date><style  face="normal" font="default" size="100%">03/2001</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/pubmed/11284551</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">18</style></volume><pages><style face="normal" font="default" size="100%">313–327</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Spinal cord function is normally influenced by descending activity from supraspinal structures. When injury removes or distorts this influence, function changes and spasticity and other disabling problems eventually appear. Understanding how descending activity affects spinal cord function could lead to new means for inducing, guiding, and assessing recovery after injury. In this study, we investigated the short-term and medium-term effects of spinal cord bilateral dorsal column (DC), unilateral (ipsilateral) lateral column (LC), bilateral dorsal column ascending tract (DA), or bilateral dorsal column corticospinal tract (CST) transection at vertebral level T8-T9 on the soleus H-reflex in freely moving rats. Data were collected continuously for 10-20 days before and for 20-155 days after bilateral DC (13 rats), DA (10 rats), CST (eight rats), or ipsilateral LC (seven rats) transection. Histological examination showed that transections were 98(+/- 3 SD)% complete for DC rats, 80(+/- 20)% complete for LC rats, 91(+/- 13 SD)% complete for DA rats, and 95(+/-13)% complete for CST rats. LC, CST, and DA transections produced an immediate (i.e., first-day) increase in H-reflex amplitude. LC transection also produced a small decrease in background activity in the first few posttransection days. Other than this small decrease, none of the transections produced evidence for the phenomenon of spinal shock. For all transections, all measures returned to or neared pretransection values within 2 weeks. DA and LC transections were associated with modest increase in H-reflex amplitude 1-3 months after transection. These medium-term effects must be taken into account when assessing transection effects on operant conditioning of the H-reflex. At the same time, the results are consistent with other evidence that, while H-reflex rate dependence and H-reflex operant conditioning are sensitive measures of spinal cord injury, the H-reflex itself is not.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Xiang Yang Chen</style></author><author><style face="normal" font="default" size="100%">Lu Chen</style></author><author><style face="normal" font="default" size="100%">Jonathan Wolpaw</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Time course of H-reflex conditioning in the rat.</style></title><secondary-title><style face="normal" font="default" size="100%">Neuroscience letters</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">conditioning</style></keyword><keyword><style  face="normal" font="default" size="100%">Learning</style></keyword><keyword><style  face="normal" font="default" size="100%">Memory</style></keyword><keyword><style  face="normal" font="default" size="100%">plasticity</style></keyword><keyword><style  face="normal" font="default" size="100%">rat</style></keyword><keyword><style  face="normal" font="default" size="100%">Reflex</style></keyword><keyword><style  face="normal" font="default" size="100%">Spinal Cord</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2001</style></year><pub-dates><date><style  face="normal" font="default" size="100%">04/2001</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/pubmed/11290393</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">302</style></volume><pages><style face="normal" font="default" size="100%">85–88</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">This study sought to define the course of operantly conditioned change in the rat soleus H-reflex and to determine whether, like H-reflex conditioning and spinal stretch reflex conditioning in the monkey, it develops in distinct phases. Data from 33 rats in which the right soleus H-reflex was trained up (i.e. HRup mode) and 38 in which it was trained down (i.e. HRdown mode) were averaged to define the courses of H-reflex increase and decrease. In HRup rats, the H-reflex showed a large phase I increase within the first 2 days followed by gradual phase II increase that continued for weeks. In HRdown rats, the H-reflex appeared to show a small phase I decrease and then showed a gradual phase II decrease over weeks. In combination with other recent work, the data suggest that H-reflex conditioning begins with a rapid mode-appropriate alteration in corticospinal tract influence over the spinal arc of the H-reflex, which causes phase I change, and that the continuation of this altered influence induces gradual spinal cord plasticity that is responsible for phase II change. The results further establish the similarity of H-reflex conditioning in primates and rats. Thus, they encourage efforts to produce a single coherent model of the phenomenon based on data from the two species and indicate the potential clinical relevance of the rat data.</style></abstract></record></records></xml>