Extracellular recordings from rat olfactory epithelium slices using micro electrode arrays

In complex organisms chemical sensation at the olfactory epithelium in the nose is translated into electrical signals that propagate toward the brain for odor identification. In this study the olfactory epithelium was coupled to an 8 × 8 multi-electrode array (MEA) for spatial odor detection. Sagittal slices of rat olfactory epithelium with intact connections to the olfactory bulb were analyzed for their electrical responses to odorants and stimulants. In the absence of odorants or stimulants, spontaneous spiking activity could be observed at multiple sites (on average 15 out of 59) with a mean frequency of 22 ± 5 Hz. When perfusing the slices with 0.1 mM isoamyl acetate or l-carvone, the mean spike frequency increased to 41 ± 6 Hz and 44 ± 7 Hz respectively. Spike frequency was a function of isoamyl acetate concentration and increased from 38 ±6 Hz at 0.05 mM to 49 ±7 Hz at 0.5 mM. In the presence of FSK + IBMX the mean spike frequency increased to 94 ± 10 Hz. In addition, while FSK + IBMX increased the spike frequency at all sites displaying spontaneous activity, the induced responses to isoamyl acetate and l-carvone displayed a different but partially overlapping spatial distribution pattern. In conclusion, parallel multi-site extracellular recordings by MEA in olfactory slices potentially provide a powerful tool for odorant identification and quantification.