A medullary inhibitory region for trigeminal motoneurons in the cat

Pablo Castillo, Cristina Pedroarena, Michael H. Chase, Francisco R. Morales

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


The present report describes the effects on trigeminal motoneurons of stimulation of a circumscribed site within the parvocellular region of the medullary reticular formation. This medullary site was selected because anatomical studies have shown that premotor interneurons project from this site to the trigeminal motorpool10,13. Electrical stimulation of this site induced IPSPs(PcRF-IPSPs) in jaw-closer motoneurons. A population of these IPSPs, recorded contralateral to the site of stimulation, exhibited latencies shorter than 1.5 ms (mean 1.16±0.08 SD). Their mean amplitude was 1.72 mV ± 1.13 SD and their mean duration was 3.52 ms ± 2.15 SD. We believe that these PcRF-IPSPs arose as the result of activation of a monosynaptic pathway. A comparable inhibitory input from this site to ipsilateral jaw-closer motoneurons and to both contra and ipsilateral digastric motoneurons was also observed. We therefore conclude that this medullary PcRF site contains premotor interneurons that are capable of postsynaptically inhibiting motoneurons that innervate antagonistic jaw muscles.

Original languageEnglish (US)
Pages (from-to)346-349
Number of pages4
JournalBrain research
Issue number2
StatePublished - May 24 1991
Externally publishedYes


  • Inhibition
  • Monosynaptic
  • Motoneuron
  • Parvocellularis
  • Reticular formation
  • Trigeminal

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology


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