| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Physiology, University of Wisconsin, Medical School, Madison, Wisconsin, USA
* To whom correspondence should be addressed. E-mail: lconhaim{at}physiology.wisc.edu.
Electrophysiological and morphological properties of genetically identified spinal interneurons were examined to elucidate their possible contribution to locomotor-like rhythmic activity in 1-to-4-day old mice. In the transgenic mice used in our study, the HB9 promotor controlled the expression of the reporter gene enhanced green fluorescent protein (eGFP), giving rise to GFP+ motoneurons and ventral interneurons. However, only motoneurons and a small group of bipolar, GFP+ interneurons expressed the HB9 protein. The HB9+/GFP+ interneurons were clustered close to the medial surface in lamina VIII along segments L1-L3. The correlation between activity pattern in these visually identified interneurons and motoneuron output was examined using simultaneous whole-cell and ventral root recordings. Neurochemically induced rhythmic membrane depolarizations in HB9/GFP interneurons were synchronous with ventral root rhythms, indicating that the interneurons received synaptic inputs from rhythm-generating networks. The frequency of excitatory postsynaptic currents significantly increased during ventral root bursts, but there was no change in the frequency of inhibitory postsynaptic currents during the cycle period. These data implied that HB9/GFP interneurons received primarily excitatory inputs from rhythmogenic interneurons. Neurobiotin-filled axon terminals were in close apposition to other neurons in the cluster and to motoneuron dendrites, raising the possibility that HB9/GFP interneurons formed synaptic connections with each other and with motoneurons. The expression of the vesicular glutamate transporter 2 in axon terminals of HB9/GFP interneurons indicated that these were glutamatergic interneurons. Our findings suggest that the visually identified HB9/GFP interneurons are premotor excitatory interneurons and putative constituents of networks generating locomotor rhythms in the mammalian spinal cord.
This article has been cited by other articles:
|
|
 |
|
  S. Tazerart, L. Vinay, and F. Brocard The Persistent Sodium Current Generates Pacemaker Activities in the Central Pattern Generator for Locomotion and Regulates the Locomotor Rhythm J. Neurosci., August 20, 2008; 28(34): 8577 - 8589. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. A. Gray Transcription factors and the genetic organization of brain stem respiratory neurons J Appl Physiol, May 1, 2008; 104(5): 1513 - 1521. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. C. Cowley, E. Zaporozhets, and B. J. Schmidt Propriospinal neurons are sufficient for bulbospinal transmission of the locomotor command signal in the neonatal rat spinal cord J. Physiol., March 15, 2008; 586(6): 1623 - 1635. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Ziskind-Conhaim and C. A. Hinckley Hb9 Versus Type 2 Interneurons J Neurophysiol, February 1, 2008; 99(2): 1044 - 1046. [Full Text] [PDF]
|
|
|
|
|
|
J. M. Wilson, A. I. Cowan, and R. M. Brownstone Hb9 Interneurons: Reply to Ziskind-Conhaim and Hinckley J Neurophysiol, February 1, 2008; 99(2): 1047 - 1049. [Full Text] [PDF]
|
|
|
|
|
|
P. Han, S. T. Nakanishi, M. A. Tran, and P. J. Whelan Dopaminergic Modulation of Spinal Neuronal Excitability J. Neurosci., November 28, 2007; 27(48): 13192 - 13204. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. M. Wilson, A. I. Cowan, and R. M. Brownstone Heterogeneous Electrotonic Coupling and Synchronization of Rhythmic Bursting Activity in Mouse Hb9 Interneurons J Neurophysiol, October 1, 2007; 98(4): 2370 - 2381. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Tazerart, J.-C. Viemari, P. Darbon, L. Vinay, and F. Brocard Contribution of Persistent Sodium Current to Locomotor Pattern Generation in Neonatal Rats J Neurophysiol, August 1, 2007; 98(2): 613 - 628. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. A. Deuchars Multi-tasking in the spinal cord - do 'sympathetic' interneurones work harder than we give them credit for? J. Physiol., May 1, 2007; 580(3): 723 - 729. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Zhong, M. A. Masino, and R. M. Harris-Warrick Persistent Sodium Currents Participate in Fictive Locomotion Generation in Neonatal Mouse Spinal Cord J. Neurosci., April 25, 2007; 27(17): 4507 - 4518. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. M. Wilson, D. A. Dombeck, M. Diaz-Rios, R. M. Harris-Warrick, and R. M. Brownstone Two-Photon Calcium Imaging of Network Activity in XFP-Expressing Neurons in the Mouse J Neurophysiol, April 1, 2007; 97(4): 3118 - 3125. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. A. Hinckley and L. Ziskind-Conhaim Electrical Coupling between Locomotor-Related Excitatory Interneurons in the Mammalian Spinal Cord. J. Neurosci., August 15, 2006; 26(33): 8477 - 8483. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 I. T. Gordon and P. J. Whelan Deciphering the organization and modulation of spinal locomotor central pattern generators J. Exp. Biol., June 1, 2006; 209(11): 2007 - 2014. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Nishimaru, C. E. Restrepo, and O. Kiehn Activity of Renshaw cells during locomotor-like rhythmic activity in the isolated spinal cord of neonatal mice. J. Neurosci., May 17, 2006; 26(20): 5320 - 5328. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Berkowitz, G. L. C. Yosten, and R. M. Ballard Somato-Dendritic Morphology Predicts Physiology for Neurons That Contribute to Several Kinds of Limb Movements J Neurophysiol, May 1, 2006; 95(5): 2821 - 2831. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Nistri, K. Ostroumov, E. Sharifullina, and G. Taccola Tuning and playing a motor rhythm: how metabotropic glutamate receptors orchestrate generation of motor patterns in the mammalian central nervous system J. Physiol., April 15, 2006; 572(2): 323 - 334. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. J. B. Butt, L. Lundfald, and O. Kiehn EphA4 defines a class of excitatory locomotor-related interneurons PNAS, September 27, 2005; 102(39): 14098 - 14103. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Ziskind-Conhaim and S. Redman Spatiotemporal Patterns of Dorsal Root-Evoked Network Activity in the Neonatal Rat Spinal Cord: Optical and Intracellular Recordings J Neurophysiol, September 1, 2005; 94(3): 1952 - 1961. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. M. Wilson, R. Hartley, D. J. Maxwell, A. J. Todd, I. Lieberam, J. A. Kaltschmidt, Y. Yoshida, T. M. Jessell, and R. M. Brownstone Conditional Rhythmicity of Ventral Spinal Interneurons Defined by Expression of the Hb9 Homeodomain Protein J. Neurosci., June 15, 2005; 25(24): 5710 - 5719. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
