Properties of external plexiform layer interneurons in mouse olfactory bulb slices

Area of Science:

• Neuroscience
• Olfactory System Research
• Cellular Electrophysiology

Background:

• The external plexiform layer (EPL) of the olfactory bulb contains mitral and tufted (M/T) cells and inhibitory granule cells.
• The function of intrinsic interneurons within the EPL remains largely unknown.

Purpose of the Study:

• To investigate the properties and function of interneurons located in the external plexiform layer of the mouse olfactory bulb.

Main Methods:

• Extracellular and whole-cell patch-clamp recordings from mouse olfactory bulb slices.
• Biocytin-filling for cell identification (interneurons, tufted cells, astrocytes).
• Pharmacological manipulation using AMPA/kainate receptor antagonists and tetrodotoxin.
• Analysis of spontaneous and evoked neuronal activity.
• Utilizing genetically modified mice expressing green fluorescent protein in GABAergic neurons.

Main Results:

• Identified interneurons with distinct electrophysiological properties compared to tufted cells.
• Interneuron activity characterized by high-frequency spontaneous excitatory postsynaptic currents, sensitive to AMPA/kainate receptor blockade.
• Interneurons exhibited low spontaneous action potential firing but responded to depolarization and olfactory nerve stimulation.
• Evidence suggests these interneurons are GABAergic, likely receiving excitatory input from M/T cells via AMPA/kainate receptors.

Conclusions:

• EPL interneurons are likely excited by M/T cells.
• These interneurons may provide inhibitory feedback to M/T cells.
• This circuitry could regulate activity spread within specific glomerular domains in the olfactory bulb.