Long-lasting depolarizations in mitral cells of the rat olfactory bulb.
We investigated the mechanisms of long-lasting depolarizing potentials (LLDs) generated in mitral cells with whole-cell patch recordings in the rat olfactory bulb slice. LLDs occur spontaneously and are evoked by either orthodromic stimulation of the olfactory nerve or antidromic stimulation of mitral and tufted (M/T) cells. LLDs are followed by a long refractory period, limiting LLD generation to approximately 1 Hz. LLD production does not appear to involve either intrinsic voltage-activated or metabotropic mechanisms. The initiation of LLDs requires activation of non-NMDA but not NMDA receptors. Dual recordings from the apical dendrites and somata of mitral cells show that LLDs are generated in the distal portion of the apical dendrite, most likely in the glomerulus. The rising phase of LLDs shows characteristics of polyneuronal input, including a high variability and sensitivity to charge screening. Paired recordings from adjacent mitral cells suggest that LLDs occur synchronously only in cells whose apical dendrites ramify in the same glomerulus. These findings suggest that LLDs involve recurrent, intraglomerular dendrodendritic interactions among M/T cells.
Carlson
G C
GC
Department of Anatomy, Program in Neuroscience, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
Shipley
M T
MT
Keller
A
A
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D003712:Dendrites / Q000737:chemistry / Q000502:physiology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005260:Female; D018756:GABA Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D007608:Kainic Acid / Q000494:pharmacology; D008297:Male; D016202:N-Methylaspartate / Q000494:pharmacology; D009830:Olfactory Bulb / Q000166:cytology* / Q000502:physiology*; D018034:Olfactory Receptor Neurons / Q000502:physiology* / Q000648:ultrastructure; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D018091:Receptors, AMPA / Q000502:physiology; D018092:Kainic Acid Receptors / Q000502:physiology; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D015763:2-Amino-5-phosphonovalerate; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D001640:Bicuculline; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D007608:Kainic Acid; D016202:N-Methylaspartate; D018091:Receptors, AMPA; D018092:Kainic Acid Receptors; D016194:Receptors, N-Methyl-D-Aspartate; D005680:gamma-Aminobutyric Acid