Central Circuits Controlling Locomotion in Young Frog Tadpoles

Roberts, Alan; Soffe, SR; Wolf, Ervin; Yoshida, Mika; Zhao, Fengshu

doi:10.1111/j.1749-6632.1998.tb09036.x

Cited by 170 publications

(150 citation statements)

References 29 publications

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“…the half-centers increased. Alternating single spikes were considered half-center activity [consistent with the tradition in experimental studies of locomotion (31,32)], and many of the high-frequency points in Fig. 3A and the remaining figures consist of alternating single spikes.…”

Section: Resultsmentioning

confidence: 99%

Reliable neuromodulation from circuits with variable underlying structure

Grashow

Brookings

Marder

2009

Proc. Natl. Acad. Sci. U.S.A.

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Recent work argues that similar network performance can result from highly variable sets of network parameters, raising the question of whether neuromodulation can be reliable across individuals with networks with different sets of synaptic strengths and intrinsic membrane conductances. To address this question, we used the dynamic clamp to construct 2-cell reciprocally inhibitory networks from gastric mill (GM) neurons of the crab stomatogastric ganglion. When the strength of the artificial inhibitory synapses (gsyn) and the conductance of an artificial Ih (gh) were varied with the dynamic clamp, a variety of network behaviors resulted, including regions of stable alternating bursting. Maps of network output as a function of gsyn and gh were constructed in normal saline and again in the presence of serotonin or oxotremorine. Both serotonin and oxotremorine depolarize and excite isolated individual GM neurons, but by different cellular mechanisms. Serotonin and oxotremorine each increased the size of the parameter regions that supported alternating bursting, and, on average, increased burst frequency. Nonetheless, in both cases some parameter sets within the sample space deviated from the mean population response and decreased in frequency. These data provide insight into why pharmacological treatments that work in most individuals can generate anomalous actions in a few individuals, and they have implications for understanding the evolution of nervous systems. dynamic clamp ͉ evolution ͉ serotonin ͉ stomatogastric ganglion ͉ oscillator H ow different are the brains in a population of healthy individuals of the same species? Both modeling and experimental studies demonstrate that similar circuit function can result from a large variation in the synaptic and intrinsic conductances that contribute to circuit function (1-11). This finding suggests that each individual could, during development, build a brain that differs significantly from all others and poses the question of whether circuits with diverse underlying structure, yet similar behavior, can respond reliably (12, 13) to neuromodulatory substances that alter brain states (14-21). Therefore, we used the dynamic clamp (22, 23) to construct 2-cell circuits (24) from neurons of the crab stomatogastric ganglion (STG). The strength of the reciprocal inhibitory synapses (g syn ) and the conductance of an artificial I h (g h ) were varied (24), and the resulting activity patterns were recorded in control saline and in response to 2 neuromodulatory substances, serotonin and the muscarinic agonist, oxotremorine.In these hybrid experiments, the intrinsic properties of these 2 biological neurons vary between each other and across preparations while 2 of the important parameters for network performance are under experimental control. This method ensures that the variability intrinsic to biological systems is retained, while allowing access to some of the parameters controlling network performance. Results and DiscussionWe used gastric mill (GM) neurons of the STG of t...

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Section: Resultsmentioning

confidence: 99%

Reliable neuromodulation from circuits with variable underlying structure

Grashow

Brookings

Marder

2009

Proc. Natl. Acad. Sci. U.S.A.

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“…In lower vertebrates which locomote by undulation, it has become clear that the neurones responsible for rhythm and pattern are one and the same (Lansner et al, 1998;Roberts et al, 1998). These animals do not have the complexity of multiple flexor and extensor muscles within a limb; that is, limbed vertebrates must control both intralimb and interlimb coordination.…”

Section: Pattern Formation and Rhythm-generating Modulesmentioning

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

137

122

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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.

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“…The propulsive forces used in undulatory swimming are generated by an alternating rostral-caudal wave of myotomal muscle contraction, initiated by a synaptic drive originating from myotomal motoneurons, which interacts with the mechanical properties of body tissues (Blight 1977;Grillner and Kashin 1975;Grillner et al 1998;Hoff and Wassersug 2000;Lindsey 1978;Roberts 1981;Roberts et al 1998;Wardle et al 1995;Wassersug 1989). Therefore during a cycle of undulatory swimming, rostral myotomal muscle fibers receive synaptic drive prior to caudal fibers and within a segment the synaptic drive alternates between ipsilateral and contralateral sides of the musculature.…”

Section: Rostral-caudal Delay and Ipsilateral-contralateral Alternatimentioning

confidence: 99%

Activation of Embryonic Red and White Muscle Fibers During Fictive Swimming in the Developing Zebrafish

Buss

Drapeau

2002

Journal of Neurophysiology

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Buss, Robert R. and Pierre Drapeau. Activation of embryonic red and white muscle fibers during fictive swimming in the developing zebrafish. J Neurophysiol 87: 1244 -1251, 2002; 10.1152/jn.00659.2001. Sub-threshold, motoneuron-evoked synaptic activity was observed in zebrafish embryonic red (ER) and white (EW) muscle fibers paralyzed with a dose of D-tubocurarine insufficient to abolish synaptic activity to determine whether muscle activation was coordinated to produce the undulating body movements required for locomotion. Paired whole-cell recordings revealed a synaptic drive that alternated between ipsilateral and contralateral myotomes and exhibited a rostralcaudal delay in timing appropriate for swimming. Both ER and EW muscle were activated during fictive swimming. However, at the fastest fictive swimming rates, ER fibers were de-recruited, whereas they could be active in isolation of EW fibers at the slowest fictive swimming rates. Prior to hatching, fictive swimming was preceded by a lower frequency, more robust and rhythmic synaptic drive resembling the "coiling" behavior of fish embryos. The motor activity observed in paralyzed zebrafish closely resembled the swimming and coiling behaviors observed in these developing fishes. At the early developmental stages examined in this study, myotomal muscle recruitment and coordination were similar to that observed in adult fishes during swimming. Our results indicate that the patterned activation of myotomal muscle is set from the onset of development.

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Central Circuits Controlling Locomotion in Young Frog Tadpoles

Cited by 170 publications

References 29 publications

Reliable neuromodulation from circuits with variable underlying structure

Reliable neuromodulation from circuits with variable underlying structure

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

Activation of Embryonic Red and White Muscle Fibers During Fictive Swimming in the Developing Zebrafish

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