Rhythmic bursting in the pre-Bötzinger complex: mechanisms and models

Area of Science:

• Neuroscience
• Computational Biology
• Respiratory Physiology

Background:

• The pre-Bötzinger complex (pre-BötC) is crucial for respiratory rhythm generation.
• Persistent bursting activity in the pre-BötC can occur independently of synaptic inhibition.
• Potential ionic mechanisms include persistent sodium (INaP) and calcium (ICa)/calcium-activated nonspecific cation (ICAN) currents.

Purpose of the Study:

• To investigate the roles of INaP, ICa, Na+/K+ pump, synaptic mechanisms, and network interactions in pre-BötC rhythmic bursting.
• To explore how randomly distributed conductances influence bursting patterns in single neurons and neural populations.
• To understand the conditions under which different oscillatory regimes emerge in the pre-BötC.

Main Methods:

• Computational modeling of single neurons and excitatory neural populations.
• Simulation of bursting activity with randomly distributed INaP and ICa conductances.
• Analysis of ionic currents, Na+/K+ pump activity, synaptic interactions, and network dynamics.

Main Results:

• Synaptically coupled excitatory neurons with distributed INaP and/or ICAN currents can exhibit multiple oscillatory regimes.
• Bursting activity can be dependent on specific currents or independent of both INaP and ICAN.
• The Na+/K+ pump and network interactions modulate bursting patterns under various conditions.

Conclusions:

• The interplay of intrinsic ionic mechanisms (INaP, ICa/ICAN) and network properties generates diverse oscillatory states in the pre-BötC.
• Multiple oscillatory regimes and their state-dependent nature likely explain the observed rhythmic activities in the pre-BötC under different physiological conditions.
• This modeling study provides insights into the cellular and network mechanisms underlying respiratory rhythm generation.