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Only a few odorant have had their detection thresholds determined in mice which is surprising due to the importance of basic data on olfactory sensitivity when working with mice as a model species. This is why I, in my study, determine the detection threshold values for bourgeonal, lyral, canthoxal, cyclamal, helional, lilial and 3-phenylpropanal (3-PPA). Working with analogue let me compare molecular structure and therefore I can see how different functional groups affect detectability.
Molecular structure for the seven aromatic aldehydes
The seven odorants were also chosen due to already established threshold values in humans and spider monkeys which let me compare olfactory sensitivity over species. Also I can see if the numbers of olfactory receptors have anything to do with olfactory sensitivity due to other studies that have determined the number of receptors in each species. In my study I worked with five mice from the strain CD-1, a strain close to wildtype. These animals were trained to work the apparatus used that is an automated olfactometer.
Automated olfactometer used in the study
A mouse puts it snout into a hole on the side of the plexiglasbox, breaking a photobeam when doing so, and is then presented either with an odorant or a blank. The blank consists of the odorless solvent used and the odorant is one of the aromatic aldehydes in increasing dilutions. By licking at the water spout when presented with the odorant the mouse performs correctly and is rewarded with a droplet of water. The mouse also performs correctly when pulling out it head instead of licking when presented with the blank, however, no reward is given.
Mouse operating the apparatus
A computer registers the correct and incorrect responses and calculates a percentage of correct choices. These results will determine if the mouse have reached its detection threshold or not. By getting a percentage of at least 75 in two on each other following sets of 20 trials the mouse is allowed to go down in concentration. On the other hand, when a mouse fails to reach 75% it is presented with an intermediate concentration, a concentration between the one failed and the last one the mouse succeeded with, giving a more accurate threshold value.


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Last updated: 05/07/10