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Olfactory sensitivity for aliphatic esters in squirrel monkeys and pigtail macaques.
Matthias Laska1, Alexandra Seibt
1Department of Medical Psychology, University of Munich Medical School, Goethestrasse 31, D-80336 Munich, Germany. laska@imp.med.uni-muenchen.de
Behavioural Brain Research
|August 23, 2002
Summary
Squirrel monkeys and pigtail macaques possess high olfactory sensitivity to aliphatic esters, often exceeding that of rodents and dogs. Their detection ability decreases with longer carbon chains.
Area of Science:
- Olfactory Neuroscience
- Primate Sensory Perception
- Chemosensation
Background:
- Olfactory capabilities vary widely across species, often categorized by brain structure size (microsmatic vs. macrosmatic).
- Previous research has primarily focused on rodents and canids, with limited data on primate olfactory acuity for specific chemical compounds.
Purpose of the Study:
- To quantitatively assess olfactory sensitivity in two primate species (squirrel monkeys and pigtail macaques) to a series of aliphatic esters.
- To compare the olfactory performance of these primates with other mammalian species.
- To investigate the relationship between olfactory detection thresholds and the chemical structure of aliphatic esters.
Main Methods:
- A conditioning paradigm was employed to train and test four squirrel monkeys and three pigtail macaques.
- Olfactory detection thresholds were determined for a homologous series of aliphatic esters, from ethyl acetate to n-octyl acetate, including isomeric variations.
- Discrimination tasks were used to identify the lowest detectable concentrations (parts per million and parts per billion).
Main Results:
- Both primate species demonstrated high olfactory sensitivity, with detection thresholds below 1 part per million (ppm) for most esters.
- Several individuals exhibited detection thresholds below 1 part per billion (ppb), surpassing expectations.
- Squirrel monkeys generally outperformed pigtail macaques in detecting aliphatic esters.
- A significant negative correlation was observed between olfactory detection thresholds and the carbon chain length of n-aliphatic esters in both species.
Conclusions:
- Primate olfactory sensitivity for aliphatic esters is unexpectedly high, comparable to or better than that of rats, mice, and dogs.
- Neuroanatomical comparisons (e.g., brain size relative to body size) are poor predictors of olfactory performance.
- Broad classifications like 'microsmat' or 'macrosmat' are inadequate for describing the nuanced olfactory capabilities of different species.