Electroolfactrograms (EOG)

Mice aged 2–4 months were sacrificed by anesthesia followed by rapid decapitation. After removing the skin, the skull was hemisected along the midline with a razor blade, exposing the turbinates. Hemisections were stabilized with pins in a custom Sylgard chamber for recording. Electroolfactograms were measured using glass pipettes filled with ACSF (tip size15–20µm, resistance ~0.5 MΩ). For some recordings, electrode tips were filled with 0.5% agarose. Electrodes were placed on the anterior surface of turbinate II and referenced to an Ag/AgCl wire placed on the surrounding bone. Signals were filtered (0.1Hz - 100 Hz) and amplified (1000X) using a differential amplifier (DAM-80, WPI). High-pass filtering introduced a slight rebound above baseline for strong responses. Odors were delivered using a custom olfactometer at a final dilution of 0.01% (1:1000 vol/vol in mineral oil, and a further 1:10 via airflow by combining flow from odorant headspace with a moisturized deodorized airstream) and a total flow rate of 100 ml/min. Odorants were obtained from Sigma at the highest purity available and diluted in mineral oil. Epithelia were kept moisturized at all times. The blanks are an average of multiple interleaved trials interspersed within the series. This averaged blank is re-displayed for each different odorant for comparison.