title: The source of spontaneous activity in the main olfactory bulb of the rat.
abstract: BACKGROUND
  In vivo, most neurons in the main olfactory bulb exhibit robust spontaneous activity. This paper tests the hypothesis that spontaneous activity in olfactory receptor neurons drives much of the spontaneous activity in mitral and tufted cells via excitatory synapses.
  
  
  METHODS
  Single units were recorded in vivo from the main olfactory bulb of a rat before, during, and after application of lidocaine to the olfactory nerve. The effect of lidocaine on the conduction of action potentials from the olfactory epithelium to the olfactory bulb was assessed by electrically stimulating the olfactory nerve rostral to the application site and monitoring the field potential evoked in the bulb.
  
  
  RESULTS
  Lidocaine caused a significant decrease in the amplitude of the olfactory nerve evoked field potential that was recorded in the olfactory bulb. By contrast, the lidocaine block did not significantly alter the spontaneous activity of single units in the bulb, nor did it alter the field potential evoked by electrical stimulation of the lateral olfactory tract. Lidocaine block also did not change the temporal patters of action potential or their synchronization with respiration.
  
  
  CONCLUSIONS
  Spontaneous activity in neurons of the main olfactory bulb is not driven mainly by activity in olfactory receptor neurons despite the extensive convergence onto mitral and tufted cells. These results suggest that spontaneous activity of mitral and tufted is either an inherent property of these cells or is driven by centrifugal inputs to the bulb.
authors.affiliation: Department of Biological Sciences, University of Cincinnati, Cincinnati, Ohio, United States of America.
authors.forename: Josif
authors.initials: J
authors.lastname: Stakic
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Suchanek
authors.forename: Geoffrey P
authors.initials: GP
authors.lastname: Ziegler
authors.forename: Edwin R
authors.initials: ER
authors.lastname: Griff
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D008012:Lidocaine / Q000494:pharmacology; D008297:Male; D009407:Nerve Block; D009830:Olfactory Bulb / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D009832:Olfactory Nerve / Q000187:drug effects / Q000502:physiology; D018034:Olfactory Receptor Neurons / Q000166:cytology* / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000187:drug effects
chemical_list: D008012:Lidocaine