Measuring Olfactometer Output in Odor Port

Odors are hard to measure and typical humans have little intuition for how they behave.  However, there are now ways to [relatively] easily measure the concentration of odors in clean air.  These devices are called photoionization detectors (PIDs) and they are used heavily in industry to detect specific volatiles.  Many of these devices are good at quantifying a stable odor source, but lack temporal resolution.  Some companies, however, have elected to make particularly fast PIDs.  One of these is the minPID from Aurora Scientific.  This device gives a measure of odor concentration in clean air with millisecond precision.

We use it routinely to calibrate our odor presentation and it is really the only reason we have solid idea about what odor concentration is being presented to the animal in our odor port.

Routine testing: miniPID (bottom) inserted into one of the odor ports.

Tubing and odors, a non-ideal combination

In olfactometry, one is constantly fighting to produce temporally precise and stable concentration outputs.  This is especially critical when you want to make detailed measurements of perception or neural activity.  Unfortunately, investigators are constantly confounded by artifacts that can distort the temporal properties and concentration profile of odor output.  On this blog, I hope to eventually cover several issues that typically come up in calibrating olfactometers.  In this first installment, I will deal with the issue of tubing after the jump.