title: The connections from botzinger expiratory neurons to upper cervical inspiratory neurons in the cat.
abstract: These experiments examined possible inhibitory inputs to upper cervical inspiratory neurons from the expiratory neurons of the Botzinger complex. Eighty-one Botzinger neurons were tested with antidromic mapping for a projection to the C1 segment of the spinal cord; 44/81 (54%) were found to project, 27/79 (34%) contralaterally, 17/68 (25%) ipsilaterally, and 1/66 (2%) both contralaterally and ipsilaterally. Antidromic mapping in contralateral C1 demonstrated the presence of a collateral in 3/15 (20%) of the Botzinger neurons tested, while 3/9 (33%) had collateral arborizations in ipsilateral C1. The collaterals mapped were not localized to the region of the upper cervical inspiratory neurons. Microstimulation in C3 (12-17 microA, 0.2-ms duration) at locations which produced short-latency (2.7-3.5 ms) inhibition of phrenic nerve discharge resulted in the short latency (3.0 ms) inhibition of 1/27 (3.7%) upper cervical inspiratory neurons as demonstrated by cross-correlation. It was concluded that while some upper cervical inspiratory neurons may be inhibited during expiration by the Botzinger expiratory neurons, this connection is not a strong one.
authors.affiliation: Department of Anaesthesia, University of Toronto, Ontario, Canada.
authors.forename: J H
authors.initials: JH
authors.lastname: Mateika
authors.forename: J
authors.initials: J
authors.lastname: Duffin
mesh_terms: D000818:Animals; D002415:Cats; D004558:Electric Stimulation; D005071:Evoked Potentials; D008526:Medulla Oblongata / Q000032:analysis / Q000166:cytology* / Q000502:physiology; D013116:Spinal Cord / Q000032:analysis / Q000166:cytology* / Q000502:physiology; D013569:Synapses / Q000032:analysis