Inhibitory Synaptic Transmission Governs Inspiratory Motoneuron Synchronization

Neurons within the intact respiratory network produce bursts of action potentials that cause inspiration or expiration. Within inspiratory bursts, activity is synchronized on a shorter timescale to generate clusters of action potentials that occur in a set frequency range and are called synchronous oscillations. We investigated how GABA and glycine modulate synchronous oscillations and respiratory rhythm during postnatal development. We recorded inspiratory activity from hypoglossal nerves using the in vitro rhythmically active mouse medullary slice preparation from P0–P11 mice. Average oscillation frequency increased with postnatal development, from 17 ± 12 Hz in P0–P6 mice (n = 15) to 38 ± 7 Hz in P7–P11 mice (n = 37) (P < 0.0001). Bath application of GABAA and GlyR antagonists significantly reduced oscillation power in neonates (P0–P6) and juveniles (P7–P10) and increased peak integrated activity in both age groups. To test whether elevating slice excitability is sufficient to reduce oscillation power,...