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Nonlinear behavior of sinusoidally forced pyloric pacemaker neurons.
A Szücs1, R C Elson, M I Rabinovich
1Institute for Nonlinear Science, Scripps Institution of Oceanography, University of California, San Diego, California 92093-0402, USA. aszucs@ucsd.edu
Journal of Neurophysiology
|April 5, 2001
Summary
Investigating lobster pyloric central pattern generator (CPG) neurons revealed that coupled pacemaker neurons exhibit complex nonlinear dynamics. Isolated neurons show simpler responses, suggesting cooperative behavior drives regular CPG oscillations.
Area of Science:
- Neuroscience
- Computational Neuroscience
- Systems Neuroscience
Background:
- The pyloric central pattern generator (CPG) in lobsters generates rhythmic motor patterns crucial for feeding behaviors.
- Understanding the intrinsic dynamics of CPG neuron ensembles is key to deciphering neural circuit function.
- Electrically coupled neurons within CPGs exhibit complex emergent properties.
Purpose of the Study:
- To investigate the intrinsic dynamics of electrically coupled pyloric neurons under periodic current forcing.
- To compare the dynamic responses of the intact pacemaker group, isolated PD motoneurons, and the isolated AB interneuron.
- To validate a modified Hindmarsh-Rose electronic model against biological experimental data.
Main Methods:
- Applied periodic current forcing (sinusoidal waveforms) to the pyloric pacemaker group (AB and two PD neurons) in different configurations.
- Recorded neuronal responses including synchronization, quasiperiodicity, and complex dynamics.
- Developed and tested a four-dimensional analog electronic circuit model simulating pyloric neuron activity.
Main Results:
- The intact pacemaker group displayed diverse nonlinear behaviors, including synchronization and complex dynamics, dependent on forcing parameters.
- Isolated pyloric dilator (PD) neurons showed a single, broad 1:1 entrainment zone.
- The isolated anterior burster (AB) neuron exhibited wider synchronization zones compared to the intact group, mimicking some complex dynamics.
- The electronic Hindmarsh-Rose model successfully reproduced biological firing patterns and nonlinear responses to forcing.
Conclusions:
- The pyloric pacemaker group functions as a uniform, low-dimensional deterministic nonlinear oscillator.
- Regular pyloric network oscillations arise from the cooperative behavior of strongly coupled neurons with distinct individual properties.
- The validated electronic model provides a reliable tool for further simulating pyloric CPG dynamics.