Pacemaker neurons and neuronal networks: an integrative view

Ramirez, Jan‐Marino; Tryba, Andrew K.; Peña, Fernando

doi:10.1016/j.conb.2004.10.011

Cited by 209 publications

(219 citation statements)

References 59 publications

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“…Moreover, instead of changing the set of CPG neurons as occurred in our experiments, modulation of the pyloric network in the STG produces multiple outputs by changing the cellular and synaptic properties of a conserved set of CPG neurons (Hooper and Marder, 1987;Ayali and HarrisWarrick, 1999;Marder et al, 2005;Thirumalai et al, 2006). Although the identity of all network neurons has yet to be accomplished for most rhythmic motor circuits, previous studies of the mammalian respiratory CPG support the possibility that the core CPG neurons are distinct during different forms of respiration (Ramirez et al, 2004;Ramirez and Viemari, 2005).…”

Section: Discussionmentioning

confidence: 89%

Convergent Motor Patterns from Divergent Circuits

Saideman¹,

Blitz²,

Nusbaum³

2007

Journal of Neuroscience

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Neuromodulation changes the cellular and synaptic properties of neurons, thereby enabling individual neuronal circuits to generate multiple activity patterns. However, distinct modulatory inputs could conceivably also configure different motor circuits to generate similar activity patterns. Using the isolated stomatogastric ganglion (STG) of the crab Cancer borealis, we showed previously that pyrokinin (PK) peptides activate the gastric mill (chewing) rhythm without the participation of the projection neuron modulatory commissural neuron 1 (MCN1). MCN1, which does not contain the PK peptide, also activates the gastric mill rhythm and, at these times, is a gastric mill central pattern generator (CPG) neuron. Here, we show that the gastric mill rhythms elicited by PK superfusion and MCN1 stimulation in the isolated STG are comparable, in contrast to the distinct gastric mill rhythms elicited by other input pathways. We also identified several cellular and synaptic mechanisms underlying the PK-and MCN1-elicited gastric mill rhythms that are distinct, including additional differences in their core CPG neurons. For example, the presence of the inhibitory synapse from the pyloric pacemaker neuron anterior burster onto the gastric mill CPG was necessary only for generation of the PK-elicited gastric mill rhythm. Similarly, the dorsal gastric motor neuron regulated only the PK rhythm, apparently because of PK-mediated enhancement of its synaptic actions. Thus, we demonstrate that different modulatory inputs can elicit comparable, as well as distinct activity patterns from the same neuronal ensemble. Moreover, these comparable rhythms can result from distinct CPGs using overlapping, but distinct sets of cellular and synaptic mechanisms.

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Section: Discussionmentioning

confidence: 89%

Convergent Motor Patterns from Divergent Circuits

Saideman¹,

Blitz²,

Nusbaum³

2007

Journal of Neuroscience

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“…CPGs are highly modulated neural circuits that rely on GPCRs to produce a rhythmic output (Ramirez et al, 2004;Marder and Bucher, 2001). The effects of DA on a model CPG, the pyloric network, have been extremely well characterized (Harris-Warrick et al, 1998;Gruhn et al, 2005;Johnson et al, 2003;Kloppenburg et al, 2000;Kloppenburg et al, 1999;Peck et al, 2001); however, the molecular mechanisms by which DA exerts its effects are completely unknown.…”

Section: Discussionmentioning

confidence: 99%

Arthropod D2 receptors positively couple with cAMP through the Gi/o protein family

Clark

Baro

2007

Comparative Biochemistry and Physiology Part B: Biochemistry an

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The pyloric network is an important model system for understanding neuromodulation of rhythmic motor behaviors like breathing or walking. Dopamine (DA) differentially modulates neurons within the pyloric network. However, while the electrophysiological actions of DA have been well characterized, nothing is known about the signaling events that mediate its effects. We have begun a molecular characterization of DA receptors (DARs) in this invertebrate system. Here, we describe the cloning and characterization of the lobster D 2 receptor, D 2αPan . We found that when expressed in HEK cells, the D 2αPan receptor is activated by DA, but not other monoamines endogenous to the lobster nervous system. This receptor positively couples with cAMP through multiple Gi/o proteins via two discrete pathways: 1) a Gα mediated inhibition of adenylyl cyclase (AC), leading to a decrease in cAMP and 2) a Gβγ mediated activation of Phospholipase Cβ (PLCβ), leading to an increase in cAMP. Alternate splicing alters the potency and efficacy of the receptor, but does not affect monoamine specificity. Finally, we show that arthropod D 2 receptor coupling with cAMP varies with the cellular milieu.

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“…Membrane properties have been shown to contribute in various ways to rhythmicity in many rhythmic motor systems (Marder and Calabrese, 1996;Kiehn et al, 2000;Harris-Warrick, 2002;Grillner, 2003;Ramirez et al, 2004). We, therefore, characterized the membrane and firing properties of Chx10 cells as well as a number of active membrane properties that have been directly involved in promoting rhythmicity.…”

Section: Membrane Properties Of Chx10 Neurons Are Heterogeneousmentioning

confidence: 99%