Recording the slow potentials evoked by odors in the olfactory mucosa of awake animals.

ABSTRACT

The aim of this report is to expose several improvements which are essential for obtaining good recordings from the basal side of the olfactory mucosa of awake rats with Ag-AgCl electrodes implanted through holes drilled in the roof of the nasal bone. In a first step, we present how this minimally invasive method was developed and validated in anesthetized rats. We insist particularly on several important points such as the size and form of the electrode tip, the careful deposit of silver chloride on this tip or the location of the implanting site. Then we demonstrate that the recorded signals have the characteristics of an electro-olfactogram (EOG), i.e that they have a local origin, that they change with odors and concentrations, and that they do not appear during pure air delivery, nor after ipsilateral nostril closure. Lastly we show that this method was successfully utilized in awake rats. In provided data demonstrating the rhythmicity of EOGs in freely-breathing animals and allowed us to study their relationships with respiration.