HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Services Email this article to a friend Similar articles in this journal 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 Google Scholar Google Scholar Articles by Kudo, N Articles by Yamada, T Search for Related Content PubMed PubMed Citation Articles by Kudo, N Articles by Yamada, T

The properties and development of the stretch reflex pathway were investigated in new-born and fetal rats using the isolated spinal cord-hind limb preparation. Muscle afferent discharge was elicited by small stretch of the triceps surae muscle in the new-born rat and in the fetus. It appeared as early as embryonic day 18.5. Ramp-and-hold stretch elicited only phasic discharges in most afferent fibres. A phasic reflex response was evoked in the triceps surae muscle by brief or ramp-and-hold stretch of the muscle in the new-born rat. The threshold stretch required for evoking the reflex response was close to that for eliciting the afferent discharge. A reflex response in the triceps surae muscle was also evoked by electrical stimulation of the triceps surae muscle nerve or the sciatic nerve in the new-born rat. Excitatory post-synaptic potentials (e.p.s.p.s) in the triceps surae motoneurones were evoked by stimulation of the muscle nerve in the new-born rat. The amplitude of the e.p.s.p.s was large enough to generate spike potentials. Homonymous e.p.s.p.s were significantly larger than heteronymous e.p.s.p.s. The amplitudes of the e.p.s.p.s were very susceptible to the rate of stimulus repetition. At a stimulus frequency of 10 Hz they were depressed to less than 10% of the control value. Presynaptic impulses evoked by stimulation of afferents in the muscle nerve appear in the motor nucleus less than 1.0 ms before the onset of synaptically evoked field potentials. The interval between the arrival of impulses evoked by dorsal root stimulation and the onset of e.p.s.p.s in motoneurones was 0.56 +/- 0.16 ms, indicating monosynaptic transmission from the primary afferents to the motoneurones. In the fetus, a reflex response in the triceps surae muscle was observed following a small stretch of the muscle (or electrical stimulation of the sciatic nerve) in all preparations at embryonic day 20.5 and in about half of those examined at embryonic day 19.5. Neither stimulation evoked a reflex response at embryonic day 18.5. Latencies of the reflex responses evoked by muscle stretch or by nerve stimulation were similar to those in the new-born rat. It is concluded that the monosynaptically evoked stretch reflex response in the triceps surae muscle first appear at embryonic day 19.5. Natural and electrical stimulation of the plantar skin evoked a reflex response with long latencies in flexor muscles. Such a cutaneous reflex was first present at embryonic day 17.5, two days earlier than the onset of the stretch reflex.

This article has been cited by other articles:

				Z. Wang, L. Li, M. Goulding, and E. Frank Early Postnatal Development of Reciprocal Ia Inhibition in the Murine Spinal Cord J Neurophysiol, July 1, 2008; 100(1): 185 - 196. [Abstract] [Full Text] [PDF]

				H. Xu, A. Clement, T. M. Wright, and P. Wenner Developmental Reorganization of the Output of a GABAergic Interneuronal Circuit J Neurophysiol, April 1, 2007; 97(4): 2769 - 2779. [Abstract] [Full Text] [PDF]

				L. B. Silverman-Gavrila, P. M. R. Orth, and M. P. Charlton Phosphorylation-Dependent Low-Frequency Depression at Phasic Synapses of a Crayfish Motoneuron J. Neurosci., March 23, 2005; 25(12): 3168 - 3180. [Abstract] [Full Text] [PDF]

				D. Morin and D. Viala Coordinations of Locomotor and Respiratory Rhythms In Vitro Are Critically Dependent on Hindlimb Sensory Inputs J. Neurosci., June 1, 2002; 22(11): 4756 - 4765. [Abstract] [Full Text] [PDF]

				Y. Li and R. E. Burke Short-Term Synaptic Depression in the Neonatal Mouse Spinal Cord: Effects of Calcium and Temperature J Neurophysiol, May 1, 2001; 85(5): 2047 - 2062. [Abstract] [Full Text] [PDF]

				B.-X. Gao and L. Ziskind-Conhaim Development of Ionic Currents Underlying Changes in Action Potential Waveforms in Rat Spinal Motoneurons J Neurophysiol, December 1, 1998; 80(6): 3047 - 3061. [Abstract] [Full Text] [PDF]

				X. Ai, S. E. MacPhedran, and A. K. Hall Depolarization Stimulates Initial Calcitonin Gene-Related Peptide Expression by Embryonic Sensory Neurons In Vitro J. Neurosci., November 15, 1998; 18(22): 9294 - 9302. [Abstract] [Full Text] [PDF]

				B.-X. Gao, G. Cheng, and L. Ziskind-Conhaim Development of Spontaneous Synaptic Transmission in the Rat Spinal Cord J Neurophysiol, May 1, 1998; 79(5): 2277 - 2287. [Abstract] [Full Text] [PDF]

				A. K. Hall, X. Ai, G. E. Hickman, S. E. MacPhedran, C. O. Nduaguba, and C. P. Robertson The Generation of Neuronal Heterogeneity in a Rat Sensory Ganglion J. Neurosci., April 15, 1997; 17(8): 2775 - 2784. [Abstract] [Full Text] [PDF]