Respiratory neural activity during long-term facilitation.
Intermittent hypoxia results in a long-term facilitation (LTF) of respiratory efferent activity. The studies reviewed here presented data from both anesthetized and decerebrate, paralyzed, vagotomized, artificially ventilated adult cats. Multiple arrays of tungsten microelectrodes were used to record the concurrent responses of brain stem neurons that contribute to respiratory motor pattern generation. Spike trains were analyzed with firing rate histograms, peristimulus time histograms, cycle triggered histograms, spike triggered averages with multiunit phrenic efferent activity, cross correlation histograms, joint peristimulus time histograms and the gravity method. These studies addressed several hypotheses. (1) There is parallel processing of input from carotid chemoreceptors to the brain stem. (2) Respiratory related midline neurons are involved in the induction and maintenance of LTF. (3) There is a change in effective connectivity of brain stem neurons with LTF. (4) Neural networks involved in the induction and maintenance of LTF have patterns of synchrony that recur with a frequency greater than expected by chance.
Morris
K F
KF
Department of Physiology, University of South Florida Medical Center, 12901 Bruce B. Downs Blvd., Tampa, FL 33612-4799, USA. kmorris@hsc.usf.edu
Baekey
D M
DM
Shannon
R
R
Lindsey
B G
BG
D000818:Animals; D001933:Brain Stem / Q000503:physiopathology; D002344:Carotid Body / Q000503:physiopathology; D002415:Cats; D002628:Chemoreceptor Cells / Q000503:physiopathology; D004525:Efferent Pathways / Q000503:physiopathology; D000860:Hypoxia / Q000503:physiopathology*; D008954:Models, Biological; D009046:Motor Neurons / Q000502:physiology; D009415:Nerve Net / Q000503:physiopathology; D015656:Respiratory Mechanics; D012143:Respiratory Physiological Phenomena