title: Identification and functional characterization of the trigeminal ventral cervical reflex pathway in the swine.
abstract: OBJECTIVE
  Trigeminal motor reflexes are clinically useful for diagnosing brain stem lesions. We identified and functionally characterized the neuronal circuit of a new variant of the trigemino-cervical reflex involving the ventral cervical muscles in the swine.
  
  
  METHODS
  The distribution and functional properties of the field potentials of the trigeminal reflex elicited by electrical stimulations of the snout were determined with electrodes in different regions of the brain. The generator of the reflex was determined from scanning evoked magnetic fields over the brainstem. The neuronal circuit was determined with electrodes placed along the trigeminal reflex pathway.
  
  
  RESULTS
  The reflex produced a large positive potential in the brain (up to 200 microV in the primary somatosensory cortex) with a latency of about 14ms. Its amplitude declined rapidly with stimulation rate above 0.5Hz and was abolished by a muscle relaxant. The accompanying magnetic field was produced by a generator ventral to the pons. This generator was found to be the ventral cervical muscles that were activated by a circuit involving the brainstem trigeminal nuclei and cervical motor nuclei.
  
  
  CONCLUSIONS
  It is not known whether this new variant of the trigeminal cervical reflex is species-specific or it also exists in humans. It should be possible to test this possibility in humans, since it produces strong characteristic electrical potentials and magnetic fields in the swine. If it exists in humans, then it may be useful as a clinical tool for testing the integrity of the brainstem and C1 and C2 since the circuit is now identified and characterized in the animal model.
authors.affiliation: Department of Emergency and Critical Care Medicine, Jichi Medical School, Tochigi, Japan.
authors.forename: Seiya
authors.initials: S
authors.lastname: Kato
authors.forename: Nicholas
authors.initials: N
authors.lastname: Papuashvili
authors.forename: Yoshio C
authors.initials: YC
authors.lastname: Okada
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001933:Brain Stem / Q000166:cytology / Q000502:physiology; D004569:Electroencephalography; D004576:Electromyography; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects / Q000502:physiology; D015225:Magnetoencephalography; D009046:Motor Neurons / Q000502:physiology; D009334:Neck Muscles / Q000294:innervation*; D009475:Neurons, Afferent / Q000502:physiology; D018733:Nicotinic Antagonists / Q000494:pharmacology; D012018:Reflex / Q000502:physiology*; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology; D034421:Sus scrofa; D014276:Trigeminal Nerve / Q000166:cytology* / Q000502:physiology*; D014403:Tubocurarine / Q000494:pharmacology
chemical_list: D018733:Nicotinic Antagonists; D014403:Tubocurarine