Timing of medullary late-inspiratory neuron discharges: vagal afferent effects indicate possible off-switch function

J Neurophysiol. 1993 May;69(5):1784-7. doi: 10.1152/jn.1993.69.5.1784.


1. In decerebrate paralyzed cats, we observed the responses of ventral and dorsal medullary inspiratory (I) neurons to two types of vagal afferent input that shorten neural I: lung inflation and vagal electrical stimulation. 2. A study population of 15 I neurons whose firing patterns suggested involvement in the inspiratory OFF-switch (IOS) was selected on the basis of two criteria: late onset of firing and excitation by vagal inputs. 3. Firing in relation to the end of I showed two types of response to vagal inputs. The pre-expiratory onset time (time from initial spike to end of I) was either unchanged (type 1 response in 5/15 neurons) or significantly changed (type 2 response in 10/15 neurons). 4. It is suggested that type 1 neurons, whose firing patterns remain closely locked to the end of I despite considerable changes of I duration, are involved in promoting the IOS, whereas type 2 neurons are either not involved (e.g., late-onset premotor neurons) or are involved at an earlier temporal processing stage.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Afferent Pathways / physiology
  • Animals
  • Brain Mapping
  • Cats
  • Electric Stimulation
  • Evoked Potentials / physiology
  • Inhalation / physiology*
  • Lung / innervation*
  • Medulla Oblongata / physiology*
  • Motor Neurons / physiology
  • Neural Inhibition / physiology
  • Neurons / physiology
  • Phrenic Nerve / physiology
  • Respiratory Center / physiology
  • Synaptic Transmission / physiology*
  • Vagus Nerve / physiology*