Brain Structure and Function

, Volume 221, Issue 9, pp 4353–4368 | Cite as

Dorsal and ventral aspects of the most caudal medullary reticular formation have differential roles in modulation and formation of the respiratory motor pattern in rat

  • Sarah E. Jones
  • Davor Stanić
  • Mathias DutschmannEmail author
Original Article


The respiratory pattern generator of mammals is anatomically organized in lateral respiratory columns (LRCs) within the brainstem. LRC compartments serve specific functions in respiratory pattern and rhythm generation. While the caudal medullary reticular formation (cMRF) has respiratory functions reportedly related to the mediation of expulsive respiratory reflexes, it remains unclear whether neurons of the cMRF functionally belong to the LRC. In the present study we specifically investigated the respiratory functions of the cMRF. Tract tracing shows that the cMRF has substantial connectivity with key compartments of the LRC, particularly the parafacial respiratory group and the Kölliker-Fuse nuclei. These neurons have a loose topography and are located in the ventral and dorsal cMRF. Systematic mapping of the cMRF with glutamate stimulation revealed potent respiratory modulation of the respiratory motor pattern from both dorsal and ventral injection sites. Pharmacological inhibition of the cMRF with the GABA-receptor agonist isoguvacine produced significant and robust changes to the baseline respiratory motor pattern (decreased laryngeal post-inspiratory and abdominal expiratory motor activity, delayed inspiratory off-switch and increased respiratory frequency) after dorsal cMRF injection, while ventral injections had no effect. The present data indicate that the ventral cMRF is not an integral part of the respiratory pattern generator and merely serves as a relay for sensory and/or higher command-related modulation of respiration. On the contrary, the dorsal aspect of the cMRF clearly has a functional role in respiratory pattern formation. These findings revive the largely abandoned concept of a dorsal respiratory group that contributes to the generation of the respiratory motor pattern.


Respiratory pattern generation Nucleus retroambiguus Modulation of breathing Cough Sneeze 



The authors’ work is funded by a start-up fund from the Florey Institute of Neuroscience and Mental Health. SJ is supported by a Melbourne University International Research Scholarship. MD is supported by an ARC Future Fellowship (FT120100953). We also acknowledge the support of the Victorian Government through the Operational Infrastructure Scheme.

Supplementary material

429_2015_1165_MOESM1_ESM.pdf (128 kb)
Supplementary Fig. 1 Schematic representation of the topographical distribution of tachypneic (blue dots) and bradypneic responses (green dots) to glutamate microinjections into the caudal medullary reticular formation (cMRF). Darker shading equates to higher numbers of response evoked from a specific injection locus. Empty circles depict ineffective injection sites (PDF 128 kb)


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Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  • Sarah E. Jones
    • 1
  • Davor Stanić
    • 1
  • Mathias Dutschmann
    • 1
    Email author
  1. 1.Howard Florey Laboratories, Systems Neurophysiology DivisionFlorey Institute of Neuroscience and Mental Health, Gate 11 Royal Parade, University of MelbourneParkvilleAustralia

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