Glutamatergic mechanisms for speed control and network operation in the rodent locomotor CPG

Talpalar, Adolfo E.; Kiehn, Ole

doi:10.3389/fncir.2010.00019

Cited by 61 publications

(74 citation statements)

References 70 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Only recently have speed-dependent changes in network configuration been considered when studying the locomotor network in terrestrial [4, 6, 8, 35, 36] and aquatic animals [2, 3]. The present study stresses this point and provides benchmarks for further studies of neuronal networks underlying mammalian locomotion, as well as for locomotor deficits seen after spinal cord injury, stroke, Parkinson’s disease, or ALS.…”

Section: Discussionmentioning

confidence: 61%

Phenotypic Characterization of Speed-Associated Gait Changes in Mice Reveals Modular Organization of Locomotor Networks

2015

View full text Add to dashboard Cite

SUMMARY Studies of locomotion in mice suggest that circuits controlling the alternating between left and right limbs may have a modular organization with distinct locomotor circuits being recruited at different speeds. It is not clear, however, whether such a modular organization reflects specific behavioral outcomes expressed at different speeds of locomotion. Here, we use detailed kinematic analyses to search for signatures of a modular organization of locomotor circuits in intact and genetically modified mice moving at different speeds of locomotion. We show that wild-type mice display three distinct gaits: two alternating, walk and trot, and one synchronous, bound. Each gait is expressed in distinct ranges of speed with phenotypic inter-limb and intra-limb coordination. A fourth gait, gallop, closely resembled bound in most of the locomotor parameters but expressed diverse inter-limb coordination. Genetic ablation of commissural V0V neurons completely removed the expression of one alternating gait, trot, but left intact walk, gallop, and bound. Ablation of commissural V0V and V0D neurons led to a loss of walk, trot, and gallop, leaving bound as the default gait. Our study provides a benchmark for studies of the neuronal control of locomotion in the full range of speeds. It provides evidence that gait expression depends upon selection of different modules of neuronal ensembles.

show abstract

Section: Discussionmentioning

confidence: 61%

Phenotypic Characterization of Speed-Associated Gait Changes in Mice Reveals Modular Organization of Locomotor Networks

2015

View full text Add to dashboard Cite

show abstract

“…Like other vertebrate preparations, locomotor activity in zebrafish can be induced pharmacologically by activation of NMDA receptors (Cazalets et al, 1992;Zhang et al, 1996;Grillner, 2003;Cowley et al, 2005;Kiehn, 2006;McDearmid and Drapeau, 2006;Issberner and Sillar, 2007;Li et al, 2010;Talpalar and Kiehn, 2010). However, the NMDA-induced locomotor activity shows less frequency variation and therefore does not allow examining the activity of individual spinal network neurons over a large range of frequencies.…”

Section: Discussionmentioning

confidence: 99%

Initiation of Locomotion in Adult Zebrafish

Kyriakatos

Mahmood²,

Ausborn³

et al. 2011

Journal of Neuroscience

View full text Add to dashboard Cite

Motor behavior is generated by specific neural circuits. Those producing locomotion are located in the spinal cord, and their activation depends on descending inputs from the brain or on sensory inputs. In this study, we have used an in vitro brainstem-spinal cord preparation from adult zebrafish to localize a region where stimulation of descending inputs can induce sustained locomotor activity. We show that a brief stimulation of descending inputs at the junction between the brainstem and spinal cord induces long-lasting swimming activity. The swimming frequencies induced are remarkably similar to those observed in freely moving adult fish, arguing that the induced locomotor episode is highly physiological. The motor pattern is mediated by activation of ionotropic glutamate and glycine receptors in the spinal cord and is not the result of synaptic interactions between neurons at the site of the stimulation in the brainstem. We also compared the activity of motoneurons during locomotor activity induced by electrical stimulation of descending inputs and by exogenously applied NMDA. Prolonged NMDA application changes the shape of the synaptic drive and action potentials in motoneurons. When escape activity occurs, the swimming activity in the intact zebrafish was interrupted and some of the motoneurons involved became inhibited in vitro. Thus, the descending inputs seem to act as a switch to turn on the activity of the spinal locomotor network in the caudal spinal cord. We propose that recurrent synaptic activity within the spinal locomotor circuits can transform a brief input into a well coordinated and long-lasting swimming pattern.

show abstract

“…With the advent of genetic manipulations, studies have begun to elucidate the spinal neuronal circuitry involved in controlling the frequency of locomotor-like rhythmic bursts in terrestrial mammals, primarily by using in vitro neonatal mice preparations (Crone et al 2009;Gosgnach et al 2006;Talpalar and Kiehn 2010;Talpalar et al 2013). An emerging consensus is that the spinal mechanisms at slow frequencies are different from those at higher ones (Shevtsova et al 2015;Talpalar et al 2013).…”

Section: Possible Mechanisms Mediating Step-to-step Variability At Slmentioning

confidence: 99%

The spinal control of locomotion and step-to-step variability in left-right symmetry from slow to moderate speeds

Dambreville

Labarre

Thibaudier

et al. 2015

Journal of Neurophysiology

View full text Add to dashboard Cite

When speed changes during locomotion, both temporal and spatial parameters of the pattern must adjust. Moreover, at slow speeds the step-to-step pattern becomes increasingly variable. The objectives of the present study were to assess if the spinal locomotor network adjusts both temporal and spatial parameters from slow to moderate stepping speeds and to determine if it contributes to step-to-step variability in left-right symmetry observed at slow speeds. To determine the role of the spinal locomotor network, the spinal cord of 6 adult cats was transected (spinalized) at low thoracic levels and the cats were trained to recover hindlimb locomotion. Cats were implanted with electrodes to chronically record electromyography (EMG) in several hindlimb muscles. Experiments began once a stable hindlimb locomotor pattern emerged. During experiments, EMG and bilateral video recordings were made during treadmill locomotion from 0.1 to 0.4 m/s in 0.05 m/s increments. Cycle and stance durations significantly decreased with increasing speed, whereas swing duration remained unaffected. Extensor burst duration significantly decreased with increasing speed, whereas sartorius burst duration remained unchanged. Stride length, step length, and the relative distance of the paw at stance offset significantly increased with increasing speed, whereas the relative distance at stance onset and both the temporal and spatial phasing between hindlimbs were unaffected. Both temporal and spatial step-to-step left-right asymmetry decreased with increasing speed. Therefore, the spinal cord is capable of adjusting both temporal and spatial parameters during treadmill locomotion, and it is responsible, at least in part, for the step-to-step variability in left-right symmetry observed at slow speeds.

show abstract

Glutamatergic mechanisms for speed control and network operation in the rodent locomotor CPG

Cited by 61 publications

References 70 publications

Phenotypic Characterization of Speed-Associated Gait Changes in Mice Reveals Modular Organization of Locomotor Networks

Phenotypic Characterization of Speed-Associated Gait Changes in Mice Reveals Modular Organization of Locomotor Networks

Initiation of Locomotion in Adult Zebrafish

The spinal control of locomotion and step-to-step variability in left-right symmetry from slow to moderate speeds

Contact Info

Product

Resources

About