Different roles for inhibition in the rhythm-generating respiratory network

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• Rhythm-generating neural networks are crucial for various physiological functions.
• The pre-Bötzinger complex (preBötC) is a key inspiratory microcircuit for respiratory rhythm.
• The precise roles of local versus long-range inhibition in these networks are debated.

Purpose of the Study:

• To investigate the distinct roles of local and long-range inhibition in the respiratory network using a biophysical model.
• To understand how inhibition influences rhythmicity, synchrony, and stability within and between neural microcircuits.
• To validate computational findings with experimental data from the mouse preBötC.

Main Methods:

• Development of a biophysical model of the respiratory network, focusing on the preBötC.
• Simulations exploring the effects of varying local and long-range inhibition.
• In vitro electrophysiological recordings from mouse preBötC.
• Analysis of rhythmic variability, synchrony, and frequency under different inhibitory conditions.

Main Results:

• Increased local inhibition within the preBötC destabilized rhythmicity and synchrony.
• A two-phase rhythm required restructuring into coupled microcircuits with long-range inhibition for stability.
• Experimental data showed that blocking inhibition recovered rhythmic variability after excitation block.
• Local inhibition appears to control synchrony and robustness, while long-range inhibition aids rhythm generation.

Conclusions:

• The balance between excitation and inhibition dictates rhythmogenesis stability, with distinct roles for local and long-range inhibition.
• Local inhibition within the preBötC may serve descending control or robustness against insults like hypoxia.
• These findings on inhibitory roles in rhythmogenesis may generalize to other pattern-generating circuits in the nervous system.