Functional MRI (fMRI) is frequently used for measurement of neural activity of living human brain. Block design experiment in fMRI is basic and frequently used. In this design, some stimulation or psychological task is presented to participants (stim condition) and no stimulation is presented (rest condition) are repeated. In analyzing, we shall make assumptions that blood flow will increase in stim condition and turn to normal state in rest condition in some brain areas related to this stimulation or task. On the other hand, numerous studies related to neural activities related to olfactory function on human have reported, and neural anatomical areas related to olfactory function were sometimes not consistent among studies. We, therefore, hypothesized that the cause of this variation may be due to the different temporal patterns of blood flow of brain activity among olfactory-related neural regions.
We performed simple block design experiment with presentation of olfactory stimulation. A pair of twenty seconds stim condition and same duration rest one was repeated thirty times, using 3T MRI scanner. Time of repetition was 2 seconds. In analysis, we put several conditions (hemodynamics models), about duration or slices of activation and latency from stimulus onsets, and shall present results.