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 Tunstall, M J Articles by Roberts, A Search for Related Content PubMed PubMed Citation Articles by Tunstall, M J Articles by Roberts, A

School of Biological Sciences, University of Bristol.

1. Intersegmental co-ordination in Xenopus embryos could be influenced by longitudinal gradients in neuronal properties or synaptic drive. To determine if such gradients exist intracellular recordings were made from putative motoneurones at different spinal levels. 2. No evidence was found of a longitudinal gradient in neuronal resting potentials. In a rostrocaudal direction the duration of current-evoked spikes increased and the amplitude of the spike after-hyperpolarization (AHP) decreased. 3. During fictive swimming the amplitude of the tonic excitatory synaptic input and the mid-cycle IPSPs declined in a rostrocaudal direction. The rise-time and fall-time of mid-cycle IPSPs increased in a rostrocaudal direction. 4. Rostral to the eighth post-otic segment mid-cycle IPSPs occurred on all cycles of fictive swimming episodes. More caudally IPSPs became irregular in occurrence and caudal to the twelfth post-otic segment no mid-cycle IPSPs could be detected, even during the injection of depolarizing current or when recording with KCl-filled electrodes. 5. The duration of spikes occurring during fictive swimming increased and the amplitude of spike AHP decreased in a rostrocaudal direction. A spike AHP was absent during fictive swimming activity in neurones caudal to the ninth post-otic segment even though it was present in current-evoked spikes in the same neurones. 6. On-cycle IPSPs (occurring shortly after the spike at phase values less than 0.4) were observed predominantly at the beginning of swimming episodes in neurones recorded rostral to the eighth segment, but were not detected at all in more caudal neurones. 7. If the rostrocaudal gradients in synaptic excitatory and inhibitory drive to putative motoneurones during fictive swimming are also present in premotor spinal interneurones they would be expected to have a strong influence on rostrocaudal delays. Such gradients could therefore be important components of the mechanism underlying intersegmental co-ordination.

This article has been cited by other articles:

				A. Beyeler, C. Metais, D. Combes, J. Simmers, and D. Le Ray Metamorphosis-Induced Changes in the Coupling of Spinal Thoraco-Lumbar Motor Outputs During Swimming in Xenopus laevis J Neurophysiol, September 1, 2008; 100(3): 1372 - 1383. [Abstract] [Full Text] [PDF]

				E. D. Tytell and A. H. Cohen Rostral Versus Caudal Differences in Mechanical Entrainment of the Lamprey Central Pattern Generator for Locomotion J Neurophysiol, May 1, 2008; 99(5): 2408 - 2419. [Abstract] [Full Text] [PDF]

				A. Borgmann, H. Scharstein, and A. Buschges Intersegmental Coordination: Influence of a Single Walking Leg on the Neighboring Segments in the Stick Insect Walking System J Neurophysiol, September 1, 2007; 98(3): 1685 - 1696. [Abstract] [Full Text] [PDF]

				A. J. Ijspeert, A. Crespi, D. Ryczko, and J.-M. Cabelguen From Swimming to Walking with a Salamander Robot Driven by a Spinal Cord Model Science, March 9, 2007; 315(5817): 1416 - 1420. [Abstract] [Full Text] [PDF]

				K. J. Christie and P. J. Whelan Monoaminergic Establishment of Rostrocaudal Gradients of Rhythmicity in the Neonatal Mouse Spinal Cord J Neurophysiol, August 1, 2005; 94(2): 1554 - 1564. [Abstract] [Full Text] [PDF]

				L. Juvin, J. Simmers, and D. Morin Propriospinal Circuitry Underlying Interlimb Coordination in Mammalian Quadrupedal Locomotion J. Neurosci., June 22, 2005; 25(25): 6025 - 6035. [Abstract] [Full Text] [PDF]

				W.-C. Li, S.-i. Higashijima, D. M. Parry, A. Roberts, and S. R. Soffe Primitive Roles for Inhibitory Interneurons in Developing Frog Spinal Cord J. Neurosci., June 23, 2004; 24(25): 5840 - 5848. [Abstract] [Full Text] [PDF]

				A. A.V. Hill, M. A. Masino, and R. L. Calabrese Intersegmental Coordination of Rhythmic Motor Patterns J Neurophysiol, August 1, 2003; 90(2): 531 - 538. [Full Text] [PDF]

				W.-C. Li, S. R. Soffe, and A. Roberts Spinal Inhibitory Neurons that Modulate Cutaneous Sensory Pathways during Locomotion in a Simple Vertebrate J. Neurosci., December 15, 2002; 22(24): 10924 - 10934. [Abstract] [Full Text] [PDF]

				M. R. Boyd and A. D. McClellan Changes in locomotor activity parameters with variations in cycle time in larval lamprey J. Exp. Biol., December 1, 2002; 205(23): 3707 - 3716. [Abstract] [Full Text] [PDF]

				H. Nakagawa and B. Mulloney Local Specification of Relative Strengths of Synapses between Different Abdominal Stretch-Receptor Axons and their Common Target Neurons J. Neurosci., March 1, 2001; 21(5): 1645 - 1655. [Abstract] [Full Text] [PDF]

				W. L. Miller and K. A. Sigvardt Extent and Role of Multisegmental Coupling in the Lamprey Spinal Locomotor Pattern Generator J Neurophysiol, January 1, 2000; 83(1): 465 - 476. [Abstract] [Full Text] [PDF]

				C. S. Green and S. R. Soffe Roles of Ascending Inhibition During Two Rhythmic Motor Patterns in Xenopus Tadpoles J Neurophysiol, May 1, 1998; 79(5): 2316 - 2328. [Abstract] [Full Text] [PDF]

				B. Mulloney A Test of the Excitability-Gradient Hypothesis in the Swimmeret System of Crayfish J. Neurosci., March 1, 1997; 17(5): 1860 - 1868. [Abstract] [Full Text] [PDF]