A two-choice discrimination method to assess olfactory performance in pigtailed macaques, Macaca nemestrina

Area of Science:

• Primate sensory neuroscience
• Olfactory perception research
• Animal behavior studies

Background:

• Assessing olfactory capabilities in non-human primates is crucial for understanding sensory processing.
• Previous methods for evaluating primate olfaction have limitations in sensitivity and efficiency.
• Pigtailed macaques (Macaca nemestrina) are suitable models for olfactory research due to their cognitive abilities.

Purpose of the Study:

• To establish and validate a new two-choice olfactory discrimination method for pigtailed macaques.
• To determine the olfactory detection thresholds for specific odorants in trained macaques.
• To compare the olfactory sensitivity of pigtailed macaques with other species.

Main Methods:

• Four pigtailed macaques were trained using a novel two-choice olfactory discrimination task.
• The training phase required a maximum of 900 trials over 3 months.
• Olfactory thresholds were investigated for peanut, iso-amyl acetate, and n-pentanoic acid in three macaques.

Main Results:

• Macaques successfully learned the olfactory discrimination task within 3 months.
• Detection thresholds varied by odorant: peanut (1:10000), iso-amyl acetate (up to 1:30000 or 1:30,000,000), and n-pentanoic acid (1:30000 to 1:300000).
• Olfactory sensitivity in pigtailed macaques is comparable to that of dogs and rats, suggesting high olfactory acuity.

Conclusions:

• The new two-choice olfactory discrimination method is effective for assessing primate olfactory abilities.
• Pigtailed macaques exhibit significant olfactory sensitivity, challenging previous assumptions about their sensory capabilities.
• Olfactory sensitivity appears linked to the biological relevance of odorants for the species.