Translating Behavioral Neuroscience to Daily Life

Neuroscience of Smell

Human beings are bombarded in their daily lives with a variety of sensory data coming from a number of sensory systems in the human body. Many times the input of sensory data can cause a sensorimotor response, or an automatic action on the part of the human body in response to sensory input. In other words, the sight, smell, or sound of something can cause the body to automatically begin an action. For instance, the sight of the police can, in some people, cause an increase in heart rate or perspiration. This in turn can cause a person to undergo a psychological process such as stress, or fear. Certain smells can also elicit a physical response on the part of a person. Aromachology is the study of how certain smells can cause sensor motor responses which in turn stimulate emotional responses on the part of an individual. Researchers have studied the effects of specific odors in the hope that they can be used to increase the health of individuals. Recently I personally experienced a state of emotional happiness as a result of what I believe was the influence of the aroma of baked bread.

After a long and grueling day at work, and an equally long commute home I was in a very bad mood when I entered the grocery store. I didn't want to have to stop, especially after such a long day but I needed to do some shopping and didn't have much of a choice. It was my olfactory system that was most effected by my entering the store when the first thing I noticed was the smell of bread coming from the bakery department. The cilia located in my olfactory mucosa immediately came into contact with the odorant molecules from the baked bread. This contact activated adenylyl cyclase which led to the formation of cAMP (cyclic adenosine monophosphate) as well as the activation of calcium and sodium channels and the creation of a generator potential within the receptor cells. The generator potential then spread to axons which transmitted the potential to the synaptic endings in the olfactory bulb. The action potential, or signal strength of the sensory input, is directly related to the amount of odorant molecules; and since the smell of freshly baked bread permeated the store, there must have been a great amount of odorant molecules.

From the olfactory sensors in my nose the information was then transmitted to my brain through millions of axon fibers which converged on the glomeration located on the olfactory bulbs. This input was then transmitted to my mitral cells whose axons enter the olfactory tract and on to the olfactory cortex located in the limbic system of my brain. The direct connection between the amygdala, or the region of the limbic system where emotional responses are processed, and the olfactory cortex allowed for the sensory input from my nose, the smell of the freshly baked bread, to elicit a sensorimotor response. This response took the form of an emotional change in my body, my heart rate began to decrease, I was no longer agitated or angry, and my facial expressions changed from stern to happy. I was smiling and didn't even realize I was doing it. It was the sensory input from the baked bread that somehow instigated a number of physical changes in my body which resulted in a change in my emotional state.

As a result of my exposure to the smell of baked bread, my day, which had been miserable, no longer seemed so bad and, in fact, became better. Throughout the day I had been short-tempered, agitated, and in a generally bad mood and the commute home did little to temper my mood. But, since the 1980's aromachology has been demonstrated to have a measurable effect on people's moods, cognition, and behavior. (Goldstein 63) While there are many hypotheses as to why this may be so, it is generally believed that certain odors can influence the activity of cAMP which in turn influence the generator potential of olfactory receptor cells. Increases and decreases in cAMP have, in scientific studies, been linked to changes in the emotional state of subjects and I believe that my experience may be an example of this.