QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

HOME  |   SEARCH  |   ARCHIVE  |   SUBSCRIBE  |   CONTACT  |   HELP

This Article Full Text Full Text (PDF) Submit an eLetter Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (19) Citing Articles via Google Scholar Google Scholar Articles by Taylor, J. S. Articles by Vierck Jr, C. J. Search for Related Content PubMed PubMed Citation Articles by Taylor, J. S. Articles by Vierck Jr, C. J.

 Previous Article  |  Next Article 

Volume 17, Number 13, Issue of July 1, 1997 pp. 5004-5015
Copyright ©1997 Society for Neuroscience

Stretch Hyperreflexia of Triceps Surae Muscles in the Conscious Cat after Dorsolateral Spinal Lesions

Received Aug. 19, 1996; revised April 9, 1997; accepted April 21, 1997.

J. S. Taylor, R. F. Friedman, J. B. Munson, and C. J. Vierck Jr

Department of Neuroscience, University of Florida, Gainesville, Florida 32610-0244

Resistive force and electromyograms from triceps surae muscles were measured during dorsiflexion of both ankles of awake cats before and after interruption of one dorsolateral funiculus (DLF). DLF lesions produced ipsilateral increases in dynamic and static reflex force that persisted over 66 weeks. The increase in dynamic reflex force was velocity sensitive, as demonstrated by a greater effect for 60°/sec than for 10°/sec dorsiflexion. Also, the lesions increased dynamic force to a greater extent than static force (increased dynamic index). Background force (recorded immediately before each reflex response) was elevated ipsilaterally. However, increases in reflex force were observed when preoperative and postoperative background forces were matched within 10% and were associated with equivalent resting levels of electromyographic (EMG) activity. Resistive reflex force was significantly correlated with EMG responses to dorsiflexion and was not determined by nonreflexive mechanical stiffness of the muscles. Contralateral background and reflex force and associated EMG activity were decreased slightly, comparing preoperative and postoperative records.

Clinical testing revealed ipsilateral postoperative increases in extensor tone, increased resistance to hindlimb flexion, hypermetria during positive support responses, and appearance of the Babinski reflex. However, the most reliable tests of DLF lesion effects were the quantitative measures of dynamic and static reflex amplitude. The enhancement of stretch reflexes is suggestive of spasticity. However, hyperactive stretch reflexes, hypertonicity, and the Babinski reflex were observed soon after interruption of the ipsilateral DLF, in contrast to a gradual development of positive signs that is characteristic of a more broadly defined spastic syndrome from large spinal lesions. Also, other signs that often are included in the spastic syndrome, including clonus, increased flexor reflex activity, and flexor spasms, did not result from DLF lesions. Thus, unilateral DLF lesions provide a model of spasticity but produce only several components of a more inclusive spastic syndrome.

Key words: stretch reflex; spinal cord injury; cat; soleus; gastrocnemius; spasticity

This article has been cited by other articles:

				X. Li, K. Murray, P. J. Harvey, E. W. Ballou, and D. J. Bennett Serotonin Facilitates a Persistent Calcium Current in Motoneurons of Rats With and Without Chronic Spinal Cord Injury J Neurophysiol, February 1, 2007; 97(2): 1236 - 1246. [Abstract] [Full Text] [PDF]

				R. L. W. Harris, C. T. Putman, M. Rank, L. Sanelli, and D. J. Bennett Spastic Tail Muscles Recover From Myofiber Atrophy and Myosin Heavy Chain Transformations in Chronic Spinal Rats J Neurophysiol, February 1, 2007; 97(2): 1040 - 1051. [Abstract] [Full Text] [PDF]

				R. L. W. Harris, J. Bobet, L. Sanelli, and D. J. Bennett Tail Muscles Become Slow but Fatigable in Chronic Sacral Spinal Rats With Spasticity J Neurophysiol, February 1, 2006; 95(2): 1124 - 1133. [Abstract] [Full Text] [PDF]

				Y. Li, P. J. Harvey, X. Li, and D. J. Bennett Spastic Long-Lasting Reflexes of the Chronic Spinal Rat Studied In Vitro J Neurophysiol, May 1, 2004; 91(5): 2236 - 2246. [Abstract] [Full Text] [PDF]

				I. Hammar and E. Jankowska Modulatory Effects of alpha 1-,alpha 2-, and beta -Receptor Agonists on Feline Spinal Interneurons with Monosynaptic Input from Group I Muscle Afferents J. Neurosci., January 1, 2003; 23(1): 332 - 338. [Abstract] [Full Text] [PDF]

				D. J. Bennett, Y. Li, and M. Siu Plateau Potentials in Sacrocaudal Motoneurons of Chronic Spinal Rats, Recorded In Vitro J Neurophysiol, October 1, 2001; 86(4): 1955 - 1971. [Abstract] [Full Text] [PDF]

Home  |   Search  |   Archive  |   Subscribe  |   Contact  |   Help