- Poster presentation
- Open Access
Cellular mechanisms of phase maintenance in the pyloric motif
© O'Brien et al; licensee BioMed Central Ltd. 2013
- Published: 8 July 2013
- Duty Cycle
- Phase Maintenance
- Central Pattern Generator
- Burst Duration
- Pacemaker Neuron
Many biological motor patterns such as leech and lamprey swimming, ventilation in crabs and food particle filtration in crustaceans are maintained in a range of frequencies. This phenomenon is well-studied in the crustacean pyloric network, a central pattern generator (CPG) which produces a distinct bursting pattern with three-to-fivefold changes in period [1–4]. The flexibility of the network output requires neurons to adjust their temporal characteristics, such as burst duration, interburst interval and time to firing from synaptic input, in order to maintain their phase in the network pattern as the period changes. Recently, it has been shown that the coordinated neuromodulation of currents in pyloric neurons is a cellular mechanism sufficient to support phase maintenance [3, 4].
In the model neuron reported here, coordinated variation of the voltages of half-activation for the potassium (θK2) and hyperpolarization-activated (θh) currents provides a family of dynamical mechanisms for fine control of burst duration, interburst interval and latency to spiking. The mechanisms are determined by a global codimension-2 bifurcation, the Cornerstone bifurcation with bifurcation parameters θK2 and θh.. In Mechanism 1, the burst duration of a bursting neuron grows arbitrarily large as θK2 approaches a blue sky catastrophe, and the interburst interval grows arbitrarily large as θh approaches a SNIC bifurcation. We found level sets of duty cycle using an analytical approximation imposed by the Cornerstone bifurcation. These level sets describe coordination of the parameters that could be realized through neuromodulation. In Mechanism 2, a silent neuron exhibits a single burst in response to synaptic inhibitory input; the duration of the burst is determined by θK2. In Mechanism 3, a spiking neuron exhibits a pause before firing in response to synaptic inhibitory input; the duration of the pause is determined by θh.
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