Synaptic Dynamics Do Not Determine Proper Phase of Activity in a Central Pattern Generator

Rabbah, Pascale; Nadim, Farzan

doi:10.1523/jneurosci.3284-05.2005

Cited by 36 publications

(40 citation statements)

References 87 publications

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“…It also revealed a number of interesting facts about how the dynamics of the network evolve. For example, it has traditionally been thought that the primary role of the PY to LP synapse is simply to return LP to its silent state [27]. Our analysis now demonstrates that an additional effect of this synapse is to strengthen the LP to PY synapse by causing LP to spend more time in its silent state, allowing for recovery from short-term depression.…”

Section: Discussionmentioning

confidence: 54%

“…The functions m ∞ , w ∞ , and τ ∞ are sigmoidal functions of voltage and are given in the Appendix. Recent experiments by Rabbah et al [27] showed that the delay in firing of PY relative to firing of LP is due to intrinsic properties of the neurons. Thus, in the silent state, we choose τ w,LP (v LP ) < τ w,PY (v PY ) so that PY has a a slower intrinsic decay rate than LP.…”

Section: Modelmentioning

confidence: 99%

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Maintaining phase of the crustacean tri-phasic pyloric rhythm

2007

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We construct and analyze a model network of the pyloric rhythm of the crustacean stomatogastric ganglion consisting of an oscillator neuron that inhibits two reciprocally inhibitory follower neurons. We derive analytic expressions that determine the phase of firing of the follower neurons with respect to the oscillator. An important aspect of the model is the inclusion of synapses that exhibit shortterm synaptic depression. We show that these type of synapses allow there to be a complicated relationship between the intrinsic properties of the neurons and the synapses between them in determining phase relationships. Our analysis reveals the circumstances and ranges of cycle periods under which these properties work in concert with or independently from one another. In particular, we show that phase maintenance over a range of oscillator periods can be enhanced through the interplay of the two follower neurons if the synapses between these neurons are depressing. Since our model represents the core of the oscillatory pyloric network, the results of our analysis can be compared to experimental data and used to make predictions about the biological network.

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Section: Discussionmentioning

confidence: 54%

Section: Modelmentioning

confidence: 99%

Maintaining phase of the crustacean tri-phasic pyloric rhythm

2007

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“…It is important to note that was is no a priori expectation for the phase lags to change with the synaptic modification (Eisen and Marder 1984;Rabbah and Nadim 2005). In our experiments, the rebound properties of the PD could keep the phase lag almost constant as the synaptic strength was changed, simply as a result of the PD rebounding faster when the inhibition is stronger, a normal feature observed in almost all neurons.…”

Section: Discussionmentioning

confidence: 63%

Artificial synaptic modification reveals a dynamical invariant in the pyloric CPG

et al. 2007

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The sequential firing of neurons in central pattern generators (CPGs) is generally thought to be a result of an interaction between intrinsic cellular and synaptic properties of the component neurons. Due to experimental limitations, it is usually difficult to address the role of each of these properties separately. We have done so by using the crustacean stomatogastric CPG and the dynamic clamp technique to measure how the network responds to the selective modification of an individual important synapse. Our results show that the burst periods and the phase lags between the constrictor (LP) and dilator (PD) neurons across preparations showed significant variability during equivalent experimental manipulations. Despite this variability, the ratio between the change in the burst period and the change in the phase lag between the same neurons was tightly preserved in all preparations, revealing a dynamical invariant in the system. This dynamical invariant was preserved despite the individual variability in the period and phase lag measurements, suggesting a tightly regulated constraint between the parameters of the network.

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“…Endogenous membrane currents strongly influence PIR (Rabbah and Nadim, 2005). I A and I h decrease and increase the rate of PIR, respectively (Tierney andHarris-Warrick, 1992, 1995a).…”

Section: Dopaminergic Systems Are Organized To Prevent Disruptions Inmentioning

confidence: 99%

Tonic Nanomolar Dopamine Enables an Activity-Dependent Phase Recovery Mechanism That Persistently Alters the Maximal Conductance of the Hyperpolarization-Activated Current in a Rhythmically Active Neuron

Rodgers

Fu²,

Krenz³

et al. 2011

J. Neurosci.

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The phases at which network neurons fire in rhythmic motor outputs are critically important for the proper generation of motor behaviors. The pyloric network in the crustacean stomatogastric ganglion generates a rhythmic motor output wherein neuronal phase relationships are remarkably invariant across individuals and throughout lifetimes. The mechanisms for maintaining these robust phase relationships over the long-term are not well described. Here we show that tonic nanomolar dopamine (DA) acts at type 1 DA receptors (D1Rs) to enable an activity-dependent mechanism that can contribute to phase maintenance in the lateral pyloric (LP) neuron. The LP displays continuous rhythmic bursting. The activity-dependent mechanism was triggered by a prolonged decrease in LP burst duration, and it generated a persistent increase in the maximal conductance (G max ) of the LP hyperpolarization-activated current (I h ), but only in the presence of steady-state DA. Interestingly, micromolar DA produces an LP phase advance accompanied by a decrease in LP burst duration that abolishes normal LP network function. During a 1 h application of micromolar DA, LP phase recovered over tens of minutes because, the activity-dependent mechanism enabled by steady-state DA was triggered by the micromolar DA-induced decrease in LP burst duration. Presumably, this mechanism restored normal LP network function. These data suggest steady-state DA may enable homeostatic mechanisms that maintain motor network output during protracted neuromodulation. This DA-enabled, activitydependent mechanism to preserve phase may be broadly relevant, as diminished dopaminergic tone has recently been shown to reduce I h in rhythmically active neurons in the mammalian brain.

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Synaptic Dynamics Do Not Determine Proper Phase of Activity in a Central Pattern Generator

Cited by 36 publications

References 87 publications

Maintaining phase of the crustacean tri-phasic pyloric rhythm

Maintaining phase of the crustacean tri-phasic pyloric rhythm

Artificial synaptic modification reveals a dynamical invariant in the pyloric CPG

Tonic Nanomolar Dopamine Enables an Activity-Dependent Phase Recovery Mechanism That Persistently Alters the Maximal Conductance of the Hyperpolarization-Activated Current in a Rhythmically Active Neuron

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