Evidence for multiple rhythmogenic networks in the rat en bloc preparation

The pre-Botzinger Complex is coextensive with a population of SP and DAMGO-sensitive inspiratory neurons, retained in the transverse slice preparation, which has been extensively used to study mechanisms for respiratory rhythm generation. Here, qualitatively different effects of peptidergic modulation were observed in two preparations reduced, and complete. The reduced preparation was either the standard transverse slice, or an en bloc preparation whose rostral margin corresponded with the rostral margin of the transverse slice. The complete preparation was an en bloc preparation whose rostral margin extended just past the vagus rootlets, approximately 600 μm past the rostral margin of the reduced preparation. In the reduced preparation, periods following peptider-gic modulation were distributed continuously, while in the complete preparation, periods were distributed multimodally. These observations suggest that additional rhythmogenic circuitry is retained in the complete preparation.