On the central generation of locomotion in the low spinal cat

Grillner, Sten; Zangger, P.

doi:10.1007/bf00235671

Cited by 757 publications

(388 citation statements)

References 30 publications

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“…Systemic administration of the noradrenergic precursor, L-DOPA, evokes spontaneous alternating activity of flexors and extensors (see Grillner 1969;Grillner and Zangger 1979). Intracellular motoneuron recordings during L-DOPA induced locomotion revealed strong mutual inhibitory interactions between interneuronal pathways to flexors and extensors (Jankowska et al, 1967a).…”

Section: Nih-pa Author Manuscriptmentioning

confidence: 99%

“…During fictive locomotion (e.g., Grillner and Zangger 1979;Jordan, 1991;Turkin and Hamm, 2004;Lafreniere-Roula and McCrea 2005) and treadmill locomotion (Duysens, 1977) in the cat and during the scratch reflex in the turtle (Stein 2005) and the cat (Lafreniere-Roula and McCrea 2005), rhythmic bursts of motoneuron activity can be absent (deleted) for a few cycles. During these deletions activity fails simultaneously in multiple synergist motoneuron pools and becomes tonic in multiple antagonists.…”

Section: Single Level Half-center Models Of the Cpgmentioning

confidence: 99%

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Organization of mammalian locomotor rhythm and pattern generation

McCrea

Rybak

2008

Brain Research Reviews

596

506

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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...

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Section: Nih-pa Author Manuscriptmentioning

confidence: 99%

Section: Single Level Half-center Models Of the Cpgmentioning

confidence: 99%

Organization of mammalian locomotor rhythm and pattern generation

McCrea

Rybak

2008

Brain Research Reviews

596

506

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“…Furthermore, we suggest that stimulation of trigeminal afferents is analogous to stimulation of segmental afferent pathways in the production of locomotion (Sherrington, 1910;Jankowska et al, 1987;Afelt, 1970;Budakova, 1972;Grillner and Zangger, 1979).…”

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confidence: 98%

Locomotion produced in mesencephalic cats by injections of putative transmitter substances and antagonists into the medial reticular formation and the pontomedullary locomotor strip

1988

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The purpose of this study was to determine the distribution of cells in the medial reticular formation (MRF) and the pontomedullary locomotor strip (PLS), which can induce locomotion when activated. Controlled microinjections of neuroactive substances (Goodchild et al., 1982) into the MRF or PLS were made in order to activate cell bodies in those areas. The ability of trigeminal receptive field stimulation to induce locomotion before and after drug infusion into the PLS was also assessed since the PLS and the spinal nucleus of the trigeminal nerve are similar in their anatomical distribution. Experiments were performed on precollicular-postmamillary decerebrate cats walking on a treadmill. Injections of glutamic acid (GA; 500 nmol) into the MRF produced locomotion that was antagonized by infusion of glutamic acid diethyl ester into the same spot. Decreases in the current threshold for locomotion produced by electrical stimulation of the MRF were observed when the MRF was infused with either GA (40–80 nmol), DL- homocysteic acid (DL-HCA; 200 nmol), or picrotoxin (PIC; 15 nmol). Injections of GA (100 nmol), DL-HCA (700 nmol), PIC (10–50 nmol), and substance P (2 nmol) into the PLS also produced locomotion. Locomotion produced by injections of PIC into the PLS was blocked by infusion of equal amounts of muscimol or GABA. Effective PLS injection sites were all confined to the trigeminal spinal nucleus or immediately ventral and medial to this in the adjacent lateral reticular formation. Trigeminal nerve peripheral field stimulation evoked locomotion after microinjection of PIC into the PLS, although this same facial stimulus was not effective prior to drug injection. We conclude that the MRF and PLS regions of the cat brain stem contain cells that produce locomotion when chemically stimulated, and we suggest that the PLS is closely related to or synonymous with the spinal nucleus of the trigeminal nerve. Furthermore, we suggest that stimulation of trigeminal afferents is analogous to stimulation of segmental afferent pathways in the production of locomotion (Sherrington, 1910; Jankowska et al., 1967; Afelt, 1970; Budakova, 1972; Grillner and Zangger, 1979).

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“…Although locomotion can be induced without any sensory input from the periphery (Grillner and Zangger, 1979), extensive studies in lower vertebrates and humans have demonstrated that sensory signals associated with afferents that register hip position, muscle loading, and cutaneous sensation from the foot sole have specific regulatory effects on locomotion (Whelan, 1996;Rossignol et al, 2006). An improved understanding of the physiologic processing of these sensory signals in human spinal cord injury (SCI) is important to the design and implementation of therapeutic interventions for locomotor rehabilitation.…”

Section: Introductionmentioning

confidence: 99%

Parallel facilitatory reflex pathways from the foot and hip to flexors and extensors in the injured human spinal cord

Knikou

Kay

Schmit

2007

Experimental Neurology

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Spinal integration of sensory signals associated with hip position, muscle loading, and cutaneous sensation of the foot contributes to movement regulation. The exact interactive effects of these sensory signals under controlled dynamic conditions are unknown. The purpose of the present study was to establish the effects of combined plantar cutaneous afferent excitation and hip movement on the Hoffmann (H) and flexion reflexes in people with a spinal cord injury (SCI). The flexion and Hreflexes were elicited through stimulation of the right sural (at non-nociceptive levels) and posterior tibial nerves respectively. Reflex responses were recorded from the ipsilateral tibialis anterior (TA) (flexion reflex) and soleus (H-reflex) muscles. The plantar cutaneous afferents were stimulated at three times the perceptual threshold (200 Hz, 24-ms pulse train) at conditioning-test intervals that ranged from 3 to 90 ms. Sinusoidal movements were imposed to the right hip joint at 0.2 Hz with subjects supine. Control and conditioned reflexes were recorded as the hip moved in flexion and extension. Leg muscle activity and sagittal-plane joint torques were recorded. We found that excitation of plantar cutaneous afferents facilitated the soleus H-reflex and the long latency flexion reflex during hip extension. In contrast, the short latency flexion reflex was depressed by plantar cutaneous stimulation during hip flexion. Oscillatory joint forces were present during the transition phase of the hip movement from flexion to extension when stimuli were delivered during hip flexion. Hip-mediated input interacts with feedback from the foot sole to facilitate extensor and flexor reflex activity during the extension phase of movement. The interactive effects of these sensory signals may be a feature of impaired gait, but when they are appropriately excited, they may contribute to locomotion recovery in these patients.

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On the central generation of locomotion in the low spinal cat

Cited by 757 publications

References 30 publications

Organization of mammalian locomotor rhythm and pattern generation

Organization of mammalian locomotor rhythm and pattern generation

Locomotion produced in mesencephalic cats by injections of putative transmitter substances and antagonists into the medial reticular formation and the pontomedullary locomotor strip

Parallel facilitatory reflex pathways from the foot and hip to flexors and extensors in the injured human spinal cord

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