Modulation of Circuit Feedback Specifies Motor Circuit Output

Blitz, Dawn M.; Nusbaum, Michael P.

doi:10.1523/jneurosci.1461-12.2012

Cited by 45 publications

(42 citation statements)

References 90 publications

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“…We would like to emphasize that the choice of the feeding circuit for the study of circuit function of DAACPs is not random, because the expression of specific feeding behavior, which is a motivated behavior, is modulated by many intrinsic and extrinsic factors (36,76) that are often mediated by actions of neuromodulators (36,(77)(78)(79). Consistent with this complexity, previous work has shown that the feeding circuit is extensively modulated by neuromodulators, including neuropeptides that have been discovered in Aplysia (41,42,48,49,66,67,69).…”

Section: Approaches For Identifying Daacps In Biological Tissuementioning

confidence: 99%

Characterization of GdFFD, a d-Amino Acid-containing Neuropeptide That Functions as an Extrinsic Modulator of the Aplysia Feeding Circuit

Bai

Livnat

Romanova

et al. 2013

Journal of Biological Chemistry

108

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Background: L-to-D conversion of an amino acid in a neuropeptide can be required for bioactivity. Results: A new D-amino acid-containing peptide (DAACP), GdFFD, shows stereospecific bioactivity in the feeding circuit. Conclusion: Our findings broaden the importance of this unusual post-translational modification, providing new methods to accelerate DAACP discovery. Significance: GdFFD is the first DAACP showing bioactivity in a well defined circuit.

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Section: Approaches For Identifying Daacps In Biological Tissuementioning

confidence: 99%

Characterization of GdFFD, a d-Amino Acid-containing Neuropeptide That Functions as an Extrinsic Modulator of the Aplysia Feeding Circuit

Bai

Livnat

Romanova

et al. 2013

Journal of Biological Chemistry

108

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“…The influence of projection pathways on neural networks is typically studied assuming a feed-forward architecture, in which descending projection neuron pathways initiate, terminate, or modify the activity of the target network [7, 21, 38, 15]. However, neural circuitry in biological systems is more complex, in that projection neurons receive feedback from their target networks [8, 37, 34, 44]. In rhythmically active oscillatory networks, such feedback can influence the pattern of descending inputs from projection neurons, and, in some cases, rhythmically patterned projection neuron input influences the motor pattern of the target network [41].…”

Section: Introductionmentioning

confidence: 99%

A Modeling Exploration of How Synaptic Feedback to Descending Projection Neurons Shapes the Activity of an Oscillatory Network

Kintos¹,

Nadim²

2014

SIAM J. Appl. Dyn. Syst.

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Rhythmic activity which underlies motor output is often initiated and controlled by descending modulatory projection pathways onto central pattern generator (CPG) networks. In turn, these descending pathways receive synaptic feedback from their target CPG network, which can influence the CPG output. However, the mechanisms underlying such bi-directional synaptic interactions are mostly unexplored. We develop a reduced mathematical model, including both feed-forward and feedback circuitry, to examine how the synaptic interactions involving two projection neurons, MCN1 and CPN2, can produce and shape the activity of the gastric mill CPG in the crab stomatogastric nervous system. We use simplifying assumptions that are based on the behavior of the biological system to reduce this model down to 2 dimensions, which allows for phase plane analysis of the model output. The model shows a distinct activity for the gastric mill rhythm that is elicited when MCN1 and CPN2 are co-active compared to the rhythm elicited by MCN1 activity alone. Furthermore, the presence of feedback to the projection neuron CPN2 provides a distinct locus of pattern generation in the model which does not require reciprocally inhibitory interactions between the gastric mill CPG neurons, but is instead based on a half-center oscillator that occurs through a tri-synaptic pathway that includes CPN2. Our modeling results show that feedback to projection pathways may provide additional mechanisms for the generation of motor activity. These mechanisms can have distinct dependence on network parameters and may therefore provide additional flexibility for the rhythmic motor output.

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“…An interesting aspect of the type 3 gastric mill rhythms was that short breaks were often visible within individual LG bursts. This is reminiscent of the POC-activated gastric mill rhythms observed in vitro (Blitz and Nusbaum, 2012).…”

Section: Multiple Gastric Mill Rhythms Exist In Vivomentioning

confidence: 63%

“…While the gastric mill rhythm is not always active in vitro (45% active; Stein et al, 2005), it is almost always active in vivo (82% active). Sensory pathways have been shown to activate the gastric mill rhythm (via the actions of descending modulatory projection neurons) both in vitro and in vivo (Blitz and Nusbaum, 2012;Blitz et al, 2004;Saideman et al, 2007;Hedrich et al, 2009Hedrich et al, , 2011Diehl et al, 2013). It is reasonable to assume that the increased amount of gastric mill activity in vivo is due to additionally activated sensory pathways, as most of them are inactive in vitro.…”

Section: Multiple Gastric Mill Rhythms Exist In Vivomentioning

confidence: 99%

Sources and range of long-term variability of rhythmic motor patternsin vivo.

Yarger

Stein

2015

Journal of Experimental Biology

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The mechanisms of rhythmic motor pattern generation have been studied in detail in vitro, but the long-term stability and sources of variability in vivo are often not well described. The crab stomatogastric ganglion contains the well-characterized gastric mill (chewing) and pyloric (filtering of food) central pattern generators. In vitro, the pyloric rhythm is stereotyped with little variation, but intercircuit interactions and neuromodulation can alter both rhythm cycle frequency and structure. The range of variation of activity in vivo is, with few exceptions, unknown. Curiously, although the patterngenerating circuits in vivo are constantly exposed to hormonal and neural modulation, the majority of published data show only the unperturbed canonical motor patterns typically observed in vitro. Using long-term extracellular recordings (N=27 animals), we identified the range and sources of variability of the pyloric and gastric mill rhythms recorded continuously over 4 days in freely behaving Jonah crabs (Cancer borealis). Although there was no evidence of innate daily rhythmicity, a 12 h light-driven cycle did manifest. The frequency of both rhythms increased modestly, albeit consistently, during the 3 h before and 3 h after the lights changed. This cycle was occluded by sensory stimulation (feeding), which significantly influenced both pyloric cycle frequency and structure. This was the only instance where the structure of the rhythm changed. In unfed animals the structure remained stable, even when the frequency varied substantially. So, although central pattern generating circuits are capable of producing many patterns, in vivo outputs typically remain stable in the absence of sensory stimulation.

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Modulation of Circuit Feedback Specifies Motor Circuit Output

Cited by 45 publications

References 90 publications

Characterization of GdFFD, a d-Amino Acid-containing Neuropeptide That Functions as an Extrinsic Modulator of the Aplysia Feeding Circuit

Characterization of GdFFD, a d-Amino Acid-containing Neuropeptide That Functions as an Extrinsic Modulator of the Aplysia Feeding Circuit

A Modeling Exploration of How Synaptic Feedback to Descending Projection Neurons Shapes the Activity of an Oscillatory Network

Sources and range of long-term variability of rhythmic motor patternsin vivo.

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