How Fast Can a Rat Smell? (image) PLOS Caption Odor perception begins with an inhalation of odor molecules (odorants) to the olfactory receptor sheet within the nose. Increasing evidence is pointing towards the importance of sniffing behavior in olfactory coding. This image shows the respiratory trace (red) of a rat recorded during odor discriminations, overlaid on a main olfactory bulb calcium response map of the odorant eugenol. Credit Daniel Wesson et. al. Usage Restrictions Please attribute the image to: Daniel Wesson et. al. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.