The role of nasal chemical senses in garter snake response to airborne odor cues from prey.

Garter snakes increase tongue-flick rates in the presence of airborne odorants (amyl acetate, limonene, earthworm wash vapor, fish water vapor, earthworms, goldfish) but not water vapor. Main olfactory (MO) nerve lesions result in loss of this tongue-flick rate elevation in the presence of airborne odorants. Vomeronasal (VN) nerve lesions result in a diminution of tongue-flick rate elevation. Garter snakes discriminate between the 2 arms of a maze containing airborne earthworm odor as compared with a blank control. Following MO nerve lesions, snakes fail to make this discrimination. Following VN nerve lesions or VN duct suture, snakes are initially able to make the discrimination but may eventually cease to prefer the prey-odor side of the maze and may stop eating prey rewards. These results support the idea that airborne odorants are detected by the main MO system and that such detection does not require a functional VN system.