Regional Distribution of the Locomotor Pattern-Generating Network in the Neonatal Rat Spinal Cord

Cowley, Kristine C.; Schmidt, Brian J.

doi:10.1152/jn.1997.77.1.247

Cited by 243 publications

(193 citation statements)

References 38 publications

Supporting

Mentioning

174

Contrasting

Order By: Relevance

“…The suggestion of a common RG is not in conflict with an extensive distribution of rhythmogenic capabilities (e.g., Kjaerulff and Kiehn 1996;Cowley and Schmidt 1997) providing that strong propriospinal connections create a single functional entity within the circuitry controlling motoneurons in the limb. In our terminology the CPG consists of a single, distributed, Central Rhythm Generator (CRG) network controlling several Unit Pattern Formation (UPF) modules (Lafreniere-Roula and McCrea 2005;Rybak et al, 2006a).…”

Section: Can the Two-level Cpg And Ubg Architectures Complement Each mentioning

confidence: 99%

Organization of mammalian locomotor rhythm and pattern generation

McCrea

Rybak

2008

Brain Research Reviews

586

506

View full text Add to dashboard Cite

Central pattern generators (CPGs) located in the spinal cord produce the coordinated activation of flexor and extensor motoneurons during locomotion. Previously proposed architectures for the spinal locomotor CPG have included the classical half-center oscillator and the unit burst generator (UBG) comprised of multiple coupled oscillators. We have recently proposed another organization in which a two-level CPG has a common rhythm generator (RG) that controls the operation of the pattern formation (PF) circuitry responsible for motoneuron activation. These architectures are discussed in relation to recent data obtained during fictive locomotion in the decerebrate cat. The data show that the CPG can maintain the period and phase of locomotor oscillations both during spontaneous deletions of motoneuron activity and during sensory stimulation affecting motoneuron activity throughout the limb. The proposed two-level CPG organization has been investigated with a computational model which incorporates interactions between the CPG, spinal circuits and afferent inputs. The model includes interacting populations of spinal interneurons and motoneurons modeled in the Hodgkin-Huxley style. Our simulations demonstrate that a relatively simple CPG with separate RG and PF networks can realistically reproduce many experimental phenomena including spontaneous deletions of motoneuron activity and a variety of effects of afferent stimulation. The model suggests plausible explanations for a number of features of real CPG operation that would be difficult to explain in the framework of the classical single-level CPG organization. Some modeling predictions and directions for further studies of locomotor CPG organization are discussed. KeywordsCPG; computational models; spinal cord; decerebrate; cat Half-center organization of the central pattern generatorMore than 90 years ago, T. Graham Brown (1911) demonstrated that the cat spinal cord can generate a locomotor rhythm in the absence of input from higher centers and afferent feedback. These and later investigations led to the widely accepted concept of central pattern generators Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Author ManuscriptBrain Res Rev. Author manuscript; available in PMC 2009 January 1. Published in final edited form as:Brain Res Rev. 2008 January ; 57(1): 134-146. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript (CPGs) which reside within the central nervous systems of invertebrates and vertebrates and control various rhythmic movements. Graham Brown (1914) also proposed...

show abstract

Section: Can the Two-level Cpg And Ubg Architectures Complement Each mentioning

confidence: 99%

Organization of mammalian locomotor rhythm and pattern generation

McCrea

Rybak

2008

Brain Research Reviews

586

506

View full text Add to dashboard Cite

show abstract

“…They are located in thoracolumbar spinal cord (Cazalets et al, 1995;Cowley and Schmidt, 1997;Kjaerulff and Kiehn, 1996;Marcoux and Rossignol, 2000) b.…”

Section: Amentioning

confidence: 99%

“…Given that Hb9 interneurones fulfill many of the criteria necessary for locomotor rhythmogenic neurones (see above), including that they are conditional endogenous bursters (see above, and Wilson et al, 2005), that during rhythmic activity they appear to burst in phase with ventral root activity (Hinckley et al, 2005), that locomotor rhythmogenesis seems to arise in large part from the part of the spinal cord which produces flexor-related bursting activity, L2 (Cazalets et al, 1995;Cowley and Schmidt, 1997;Kjaerulff and Kiehn, 1996;Marcoux and Rossignol, 2000), and that the rhythm generator may not be organised in a symmetric flexor-extensor half-centre network, we would propose the possibility that the locomotor network may be arranged as illustrated in Fig. 3.…”

Section: A Proposed Asymmetric Model Of Rhythm Generationmentioning

confidence: 99%

Strategies for delineating spinal locomotor rhythm-generating networks and the possible role of Hb9 interneurones in rhythmogenesis

Brownstone

Wilson

2008

Brain Research Reviews

135

122

View full text Add to dashboard Cite

Despite significant advances in our understanding of pattern generation in invertebrates and lower vertebrates, there have been barriers to the application of the principles learned to the definition of networks underlying mammalian locomotion. Major difficulties have arisen in identifying spinal interneurones in preparations which allow study of neuronal intrinsic properties and the role of identified interneurones in locomotor networks. Recent genetic technologies in which selective expression of fluorescent proteins in specific populations of mouse spinal neurones have provided new avenues of investigation. In this review, we focus on the generation of locomotor rhythm and outline criteria that rhythm-generating neurones might be expected to fulfill. We then examine the extent to which a recently identified population of spinal interneurones, Hb9 interneurones, fulfill these criteria. Finally, we suggest that Hb9 interneurones could be involved in an asymmetric model of locomotor rhythmogenesis through projections of electrotonically coupled rhythmgenerating modules to flexor pattern formation half-centres. The principles learned from studying this population of interneurones have led to strategies to systematically evaluate neurones that may be involved in locomotor rhythmogenesis.

show abstract

“…Although the neonatal rat shows activation of alternating cervical and lumbar patterns following drug application, (Ballion et al 2001;Juvin et al 2007), there is no a priori reason to suspect that monoaminergic receptor distributions are similar in both species. For example while rats appear to require thoracic segments to generate 5-HT-dependent rhythmic patterns in lumbar segments (Cowley and Schmidt 1997), the mouse at similar gestation ages does not (Nishimaru and Kudo 2000). This may point to differences in development between the mouse and rat in addition to differences in overall receptor distribution.…”

Section: Rhythmogenic Capability Of Cervicothoracic Regionsmentioning

confidence: 99%

Interaction Between Developing Spinal Locomotor Networks in the Neonatal Mouse

Gordon¹,

Dunbar²,

Vanneste³

et al. 2008

Journal of Neurophysiology

View full text Add to dashboard Cite

Gordon IT, Dunbar MJ, Vanneste KJ, Whelan PJ. Interaction between developing spinal locomotor networks in the neonatal mouse. J Neurophysiol 100: 117-128, 2008. First published April 24, 2008 doi:10.1152/jn.00829.2007. At birth, thoracosacral spinal cord networks in mouse can produce a coordinated locomotor-like pattern. In contrast, less is known about the cervicothoracic networks that generate forelimb locomotion. Here we show that cervical networks can produce coordinated rhythmic patterns in the brain stem-spinal cord preparation of the mouse. Segmentally the C 5 and C 8 neurograms were each found to be alternating left-right, and the ipsilateral C 5 and C 8 neurograms also alternated. Collectively these patterns were suggestive of locomotor-like activity. This pattern was not dependent on the presence of thoracosacral segments because they could be evoked following a complete transection of the spinal cord at T 5 . We next demonstrated that activation of thoracosacral networks either pharmacologically or by stimulation of sacrocaudal afferents could produce rhythmic activity within the C 5 and C 8 neurograms. On the other hand, pharmacological activation of cervical networks did not evoke alternating cervical rhythmic activity either in isolated cervicothoracic or -sacral preparations. Under these conditions, we found that activation of cervicothoracic networks could alter the timing of thoracosacral locomotor-like patterns. When thoracosacral networks were not activated pharmacologically but received rhythmic drive from cervicothoracic networks, a pattern of slow bursts with superimposed fast synchronous oscillations became the dominant lumbar neurogram pattern. Our data suggest that in neonatal mice the cervical CPG is capable of producing coordinated rhythmic patterns in the absence of input from lumbar segments, but caudorostral drive contributes to cervical patterns and rhythm stability.

show abstract

Regional Distribution of the Locomotor Pattern-Generating Network in the Neonatal Rat Spinal Cord

Cited by 243 publications

References 38 publications

Organization of mammalian locomotor rhythm and pattern generation

Organization of mammalian locomotor rhythm and pattern generation

Strategies for delineating spinal locomotor rhythm-generating networks and the possible role of Hb9 interneurones in rhythmogenesis

Interaction Between Developing Spinal Locomotor Networks in the Neonatal Mouse

Contact Info

Product

Resources

About