Central nervous mechanisms controlling rhythmic burst generation in the ventilatory motoneurones ofCarcinus maenas

Simmers, A. J.; Bush, Brian

doi:10.1007/bf00605283

Cited by 41 publications

(24 citation statements)

References 48 publications

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“…Motoneuronal contributions to pattern generation also have been reported in the crab ventilatory system (Simmers and Bush, 1983) and the crayfish swimmeret system (Heitler, 1978), in which motoneurons are thought to provide a positive feedback loop to sustain and reinforce an ongoing pattern. In the sea slugs Tritonia and Apl ysia, buccal and cerebral motoneurons can themselves drive repeating rhythms (Willows, 1980;Hurwitz et al, 1994;Perrins and Weiss, 1996), but these probably occur with the mediation of so-far unidentified C PG-type interneurons.…”

Section: Discussionmentioning

confidence: 89%

Pattern-Generating Role for Motoneurons in a Rhythmically Active Neuronal Network

1998

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The role of motoneurons in central motor pattern generation was investigated in the feeding system of the pond snail Lymnaea stagnalis, an important invertebrate model of behavioral rhythm generation. The neuronal network responsible for the three-phase feeding motor program (fictive feeding) has been characterized extensively and divided into populations of central pattern generator (CPG) interneurons, modulatory interneurons, and motoneurons. A previous model of the feeding system considered that the motoneurons were passive followers of CPG interneuronal activity. Here we present new, detailed physiological evidence that motoneurons that innervate the musculature of the feeding apparatus have significant electrotonic motoneuron3interneuron connections, mainly confined to cells active in the same phase of the feeding cycle (protraction, rasp, or swallow). This suggested that the motoneurons participate in rhythm generation. This was assessed by manipulating firing activity in the motoneurons during maintained fictive feeding rhythms. Experiments showed that motoneurons contribute to the maintenance and phase setting of the feeding rhythm and provide an efficient system for phase-locking muscle activity with central neural activity. These data indicate that the distinction between motoneurons and interneurons in a complex CNS network like that involved in snail feeding is no longer justified and that both cell types are important in motor pattern generation. This is a distributed type of organization likely to be a general characteristic of CNS circuitries that produce rhythmic motor behavior.

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Section: Discussionmentioning

confidence: 89%

Pattern-Generating Role for Motoneurons in a Rhythmically Active Neuronal Network

1998

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“…Grinnell, 1970;Shupliakov et al 1990) is unlikely in Xenopu.s embryos where motorneurones lack dorsally projecting axons. The possibility that vertebrate motoneurones could be integral members of a CPG, as is the case in many invertebrate systems (crayfish swimmerets: Heitler, 1978; crab gill chamber ventilation: Simmers & Bush, 1983) clearly requires further study. This possibility has only infrequently been suggested in vertebrate systems (e.g.…”

Section: Discussionmentioning

confidence: 99%

Cholinergic and electrical synapses between synergistic spinal motoneurones in the Xenopus laevis embryo.

Perrins

Roberts

1995

The Journal of Physiology

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connections were found which crossed the cord. The fast PSPs were blocked by 10 /M mecamylamine but not by 1 mm kynurenic acid, so were mediated by nicotinic acetylcholine receptors (nAChRs). These are the first unitary excitatory postsynaptic potentials (EPSPs) mediated by nAChRs recorded intracellularly within the vertebrate central nervous system. 4. Bidirectional electrical synapses were found between five pairs of motoneurones. All these pairs were on the same side of the spinal cord and less than 70 um apart. Each neurone responded in a graded manner to either hyperpolarizing or depolarizing current injected into the other. 5. Since motoneurones are rhythmically active during swimming, both chemical and electrical synapses will add to the fast on-cycle excitation underlying spiking activity in other motoneurones. This may increase the reliability and local synchrony of synergistic motoneurone firing during locomotion.

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“…Ventilatory motor neuron burst endings are therefore likely due to cyclic synaptic inhibition from the ventilatory CPG, as has been proposed previously [97], whereas burst beginnings are due to plateau potentials triggered either by postinhibitory rebound or excitatory input from the rest of the network. However, the presence of a plateau potential removes the need for the CPG to supply excitatory drive to the motor neurons throughout the burst duration.…”

Section: Motor Neuron Propertiesmentioning

confidence: 73%

“…3d, trace 2). Motor neuron bursting had initially been attributed to cyclic inhibition from the ventilatory CPG onto neurons that otherwise would fire tonically [97,98]. However, a subsequent study showed that the motor neurons possess plateau properties [99].…”

Section: Motor Neuron Propertiesmentioning

confidence: 99%

Crustacean Motor Pattern Generator Networks

Hooper

DiCaprio

2004

Neurosignals

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Crustacean motor pattern-generating networks have played central roles in understanding the cellular and network bases of rhythmic motor patterns for over half a century. We review here the four best investigated of these systems: the stomatogastric, ventilatory, cardiac, and swimmeret systems. Generally applicable observations arising from this work include (1) neurons with active, endogenous cell properties (endogenous bursting, postinhibitory rebound, plateau potentials), (2) nonhierarchical (distributed) network synaptic connectivity patterns characterized by high levels of inter-neuronal connections, (3) nonspiking neurons and graded transmitter release, (4) multiple modulatory inputs, (5) networks that produce multiple patterns and have flexible boundaries, and (6) peripheral properties (proprioceptive feedback loops, low-frequency muscle filtering) playing an important role in motor pattern generation or expression.

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Central nervous mechanisms controlling rhythmic burst generation in the ventilatory motoneurones ofCarcinus maenas

Cited by 41 publications

References 48 publications

Pattern-Generating Role for Motoneurons in a Rhythmically Active Neuronal Network

Pattern-Generating Role for Motoneurons in a Rhythmically Active Neuronal Network

Cholinergic and electrical synapses between synergistic spinal motoneurones in the Xenopus laevis embryo.

Crustacean Motor Pattern Generator Networks

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