| The sense of smell is part of our chemical sensing system. It not only has a role in helping to interpret smells, but also taste flavors. The olfactory system is the first sensory system to develop in a fetus. However, it is one of the most neglected sensory systems in human research compared to visual and auditory sensory systems. It is difficult to objectively quantify exploration of the olfactory system. Different adequate methods to produce a selective and controlled stimulation of the olfactory system are lacking.;Recently, more studies have used functional imaging techniques to investigate the olfactory system in humans. Functional magnetic resonance imaging (fMRI) is the main technique used in recent studies. fMRI is a non-invasive method which allows researchers to study the functions of the human olfactory system without any contrast agent. However, there are a few commercial olfactometers in the field that are compatible to MR imaging. The cost of commercial olfactometers is not always affordable for most research institutes. Therefore, most of the olfactory system studies require a specifically-built olfactometer for their particular needs.;The purpose of this study is to build a cost effective olfactometer, which can be used not only in a research, but also in a clinical environment. Its main feature is MR compatible, so that studies with functional imaging will be easily adapted to this olfactometer. Different tests have been applied to determine the characteristics of the olfactometer and its delay time, sometimes called the "rise time" or "fall time". A mask and cannula were also tested to determine which would be best for olfactory stimulation. The results showed that the custom-built olfactometer has less than 1 second delay time. For human subjects testing with fMRI showed positive results. Brain activations were recorded from olfactory stimulation by using this olfactometer to deliver the odorant stimuli. It is now being used with a new research project that involves obsessive-compulsive disorder patients with the use of pleasant and unpleasant odorant stimuli. Some test subjects showed activations in the orbitofrontal cortex. |
