Properties of external plexiform layer interneurons in mouse olfactory bulb slices

K. A. Hamilton, T. Heinbockel, M. Ennis, G. Szabó, F. Erdélyi, A. Hayar

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

In the external plexiform layer (EPL) of the main olfactory bulb, apical dendrites of inhibitory granule cells form large numbers of synapses with mitral and tufted (M/T) cells, which regulate the spread of activity along the M/T cell dendrites. The EPL also contains intrinsic interneurons, the functions of which are unknown. In the present study, recordings were obtained from cell bodies in the EPL of mouse olfactory bulb slices. Biocytin-filling confirmed that the recorded cells included interneurons, tufted cells, and astrocytes. The interneurons had fine, varicose dendrites, and those located superficially bridged the EPL space below several adjacent glomeruli. Interneuron activity was characterized by high frequency spontaneous excitatory postsynaptic potential/currents that were blocked by the α-amino-3-hydroxy-5- methylisoxazole-4-propionic acid (AMPA)/kainate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione and largely eliminated by the voltage-sensitive Na+ channel blocker, tetrodotoxin. Interneuron activity differed markedly from that of tufted cells, which usually exhibited spontaneous action potential bursts. The interneurons produced few action potentials spontaneously, but often produced them in response to depolarization and/or olfactory nerve (ON) stimulation. The responses to depolarization resembled responses of late- and fast-spiking interneurons found in other cortical regions. The latency and variability of the ON-evoked responses were indicative of polysynaptic input. Interneurons expressing green fluorescent protein under control of the mouse glutamic acid decarboxylase 65 promoter exhibited identical properties, providing evidence that the EPL interneurons are GABAergic. Together, these results suggest that EPL interneurons are excited by M/T cells via AMPA/kainate receptors and may in turn inhibit M/T cells within spatial domains that are topographically related to several adjacent glomeruli.

Original languageEnglish
Pages (from-to)819-829
Number of pages11
JournalNeuroscience
Volume133
Issue number3
DOIs
Publication statusPublished - 2005

Fingerprint

Olfactory Bulb
Interneurons
Dendrites
Olfactory Nerve
Kainic Acid Receptors
Excitatory Postsynaptic Potentials
Action Potentials
Miniature Postsynaptic Potentials
6-Cyano-7-nitroquinoxaline-2,3-dione
Glutamate Decarboxylase
Tetrodotoxin
Green Fluorescent Proteins
Astrocytes
Synapses

Keywords

  • AMPA
  • Autocorrelation
  • Fast-spiking interneurons
  • GABAergic inhibition
  • Glomerular coding
  • High-frequency EPSP/EPSCs

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Properties of external plexiform layer interneurons in mouse olfactory bulb slices. / Hamilton, K. A.; Heinbockel, T.; Ennis, M.; Szabó, G.; Erdélyi, F.; Hayar, A.

In: Neuroscience, Vol. 133, No. 3, 2005, p. 819-829.

Research output: Contribution to journalArticle

Hamilton, K. A. ; Heinbockel, T. ; Ennis, M. ; Szabó, G. ; Erdélyi, F. ; Hayar, A. / Properties of external plexiform layer interneurons in mouse olfactory bulb slices. In: Neuroscience. 2005 ; Vol. 133, No. 3. pp. 819-829.
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