Effects of odors on brain function

My colleagues and I have developed methods to assess the effects of odor on physiological function at the level of changes in brain function. We have found that electroencephalography (EEG) analysis provides us with a detailed picture of these changes. In this article we introduce findings from assessing the effects of coffee aroma. Coffee can have a relaxing effect while also restoring alertness, and it is widely understood that this effect comes from its aroma. We selected 6 types of typical coffee beans and used electroencephalographic analysis to study differences in effects according to bean type. In order to assess relaxation effects, we analyzed alpha waves. Significantly higher values for alpha waves were associated with exposure to Guatemala than to Mandheling or Hawaii Kona. These values also tended to be higher for Guatemala than for the control substance or for Mocha Mattari. Alpha waves tended to decrease with exposure to Mandheling in comparison to the control substance. We used P300 event related potential as a physiological indicator of cognitive function. P300 latency was significantly shorter for Brazil Santos than for no odor, Guatemala, or Mocha Mattari, and tended to be shorter than for Blue Mountain. These results suggest that, because the effects of coffee aroma can vary depending on the type of coffee beans used, it could be quite useful to categorize coffee beans according to desired objective. Recent rapid developments in brain imaging, including EEG, now make it possible to explore previously unknown relationships between odor and the human brain. These developments are opening the door to rapid advances in research in this field.