Sensory pathways and their modulation in the control of locomotion

Büschges, Ansgar; Manira, Abdeljabbar El

doi:10.1016/s0959-4388(98)80115-3

Cited by 104 publications

(64 citation statements)

References 40 publications

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“…There are different possibilities for how this second depolarization is generated. Previous investigations show that sensory signals from strain and movement sensors reinforce flexor MN activation during voluntary and locomotor movements (Bässler 1986;Akay et al 2001;summary in Bässler & Büschges 1998), as has been shown in a variety of walking systems (for summary, see Pearson 1993;Büschges & El Manira 1998). At present, it is not known what other sources of synaptic inputs are contributing to the control of flexor MN activity.…”

Section: Discussionmentioning

confidence: 90%

Control of stepping velocity in a single insect leg during walking

Gabriel

Büschges

2006

Phil. Trans. R. Soc. A.

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In the single middle leg preparation of the stick insect walking on a treadmill, the activity of flexor and extensor tibiae motor neurons and muscles, which are responsible for the movement of the tibia in stance and swing phases, respectively, was investigated with respect to changes in stepping velocity. Changes in stepping velocity were correlated with cycle period. There was a close correlation of flexor motor neuron activity (stance phase) with stepping velocity, but the duration and activation of extensor motor neurons (swing phase) was not altered. The depolarization of flexor motor neurons showed two components. At all step velocities, a stereotypic initial depolarization was generated at the beginning of stance phase activity. A subsequent larger depolarization and activation was tightly linked to belt velocity, i.e. it occurred earlier and with larger amplitude during fast steps compared with slow steps. Alterations in a tonic background excitation appear not to play a role in controlling the motor neuron activity for changes in stepping velocity. Our results indicate that in the single insect leg during walking, mechanisms for altering stepping velocity become effective only during an already ongoing stance phase motor output. We discuss the putative mechanisms involved.

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Section: Discussionmentioning

confidence: 90%

Control of stepping velocity in a single insect leg during walking

Gabriel

Büschges

2006

Phil. Trans. R. Soc. A.

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“…Previous studies of such gating focused on mechanisms involving the inhibition or enhancement of afferent input directly onto CPG elements or motor neurons, often involving a phasic regulation of the incoming sensory information (El Manira et al, 1997a;Nusbaum et al, 1997;Buschges and El Manira, 1998;DiCaprio, 1999;Evans et al, 2003;Frost et al, 2003;Rossignol et al, 2006). Because the GPR excitation of the projection neurons was gated out when the gastric mill rhythm had recently been activated by a distinct sensory pathway, this gating event ensured that the elicited motor pattern was not altered by changing the firing rate and/or pattern of the activated projection neurons.…”

Section: Discussionmentioning

confidence: 99%

Mechanosensory Gating of Proprioceptor Input to Modulatory Projection Neurons

Beenhakker¹,

Kirby²,

Nusbaum³

2007

J. Neurosci.

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Sensorimotor gating commonly occurs at sensory neuron synapses onto motor circuit neurons and motor neurons. Here, using the crab stomatogastric nervous system, we show that sensorimotor gating also occurs at the level of the projection neurons that activate motor circuits. We compared the influence of the gastro-pyloric receptor (GPR) muscle stretch-sensitive neuron on two projection neurons, modulatory commissural neuron 1 (MCN1) and commissural projection neuron 2 (CPN2), with and without a preceding activation of the mechanosensory ventral cardiac neurons (VCNs). MCN1 and CPN2 project from the paired commissural ganglia (CoGs) to the stomatogastric ganglion (STG), where they activate the gastric mill (chewing) motor circuit. When stimulated separately, the GPR and VCN neurons each elicit the gastric mill rhythm by coactivating MCN1 and CPN2. When GPR is instead stimulated during the VCN-gastric mill rhythm, it slows this rhythm. This effect results from a second GPR synapse onto MCN1 that presynaptically inhibits its STG terminals. Here, we show that, during the VCN-triggered rhythm, the GPR excitation of MCN1 and CPN2 in the CoGs is gated out, leaving only its influence in the STG. This gating effect appears to occur within the CoG and does not result from a ceiling effect on projection neuron firing frequency. Additionally, this gating action enables GPR to either activate rhythmic motor activity or act as a phasic sensorimotor feedback system. These results also indicate that the site of sensorimotor gating can occur at the level of the projection neurons that activate a motor circuit.

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“…Control of neuronal central pattern generators (CPGs) by modulatory interneurons appears to be an important common requirement in both invertebrates and vertebrates for optimizing CPG output to meet specific behavioral demands (Katz, 1995;Grillner et al, 1997;Selverston et al, 1997;Büschges and Manira, 1998;Kupfermann, 1998). Although intracellular stimulation and suppression experiments in isolated neuronal circuits have been very successful in revealing how individual modulatory neurons can activate rhythmic motor patterns or reconfigure neuronal networks (Marder and Calabrese, 1996), the role such neurons play in the natural activation of behavior is still poorly understood.…”

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confidence: 99%

Multiple Types of Control by Identified Interneurons in a Sensory-Activated Rhythmic Motor Pattern

2001

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Modulatory interneurons that can drive central pattern generators (CPGs) are considered as good candidates for decisionmaking roles in rhythmic behaviors. Although the mechanisms by which such neurons activate their target CPGs are known in detail in many systems, their role in the sensory activation of CPG-driven behaviors is poorly understood. In the feeding system of the mollusc Lymnaea, one of the best-studied rhythmical networks, intracellular stimulation of either of two types of neuron, the cerebral ventral 1a (CV1a) and the slow oscillator (SO) cells, leads to robust CPG-driven fictive feeding patterns, suggesting that they might make an important contribution to natural food-activated behavior. In this paper we investigated this contribution using a lip-CNS preparation in which feeding was elicited with a natural chemostimulant rather than intracellular stimulation. We found that despite their CPG-driving capabilities, neither CV1a nor SO were involved in the initial activation of sucrose-evoked fictive feeding, whereas a CPG interneuron, N1M, was active first in almost all preparations. Instead, the two interneurons play important and distinct roles in determining the characteristics of the rhythmic motor output; CV1a by modulating motoneuron burst duration and SO by setting the frequency of the ongoing rhythm. This is an example of a distributed system in which (1) interneurons that drive similar motor patterns when activated artificially contribute differently to the shaping of the motor output when it is evoked by the relevant sensory input, and (2) a CPG rather than a modulatory interneuron type plays the most critical role in initiation of sensory-evoked rhythmic activity.

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Sensory pathways and their modulation in the control of locomotion

Cited by 104 publications

References 40 publications

Control of stepping velocity in a single insect leg during walking

Control of stepping velocity in a single insect leg during walking

Mechanosensory Gating of Proprioceptor Input to Modulatory Projection Neurons

Multiple Types of Control by Identified Interneurons in a Sensory-Activated Rhythmic Motor Pattern

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