Odor discrimination assessment with an automated olfactometric method in a prosimian primate, Microcebus murinus

The present study was aimed at adapting an automated olfactometer designed for use with rodents to a nocturnal lemur Microcebus murinus. This apparatus allows rigorous control of odor stimuli. We show that M. murinus could remain quiet and attentive for about 20 min in the test chamber, allowing daily sessions of 40 consecutive trials. This allowed us to train M. murinus subjects to learn a go/no-go discrimination procedure using fruity-odor cues. Each of seven subjects reached or exceeded a criterion of 33 correct responses in a block of 40 trials in a range of 4-14 training sessions. When trained on an odor reversal task, performance initially dropped sharply, followed by rapid acquisition of the new task. These outcomes demonstrate that, like rodents, M. murinus can be trained using operant conditioning in an automated olfactometer. This species should prove useful for investigating cognitive capacities and neurodegenerative disease in a primitive primate model.