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Summer 2005 Table of Contents
Versión Español de este artículo (Spanish Version)

The Sense of Smell: A Powerful Sense

by Gloria Rodriguez-Gil, M.Ed.,
California Deaf-Blind Services Educational Specialist

Reprinted from reSources, Spring 2004, Volume 11, Number 2 with permission from California Deaf-Blind Services <http://www.sfsu.edu/~cadbs>

Abstract: This article is about how the sense of smell works and how this powerful sense may impact programming in the field of deafblindness.

Key Words: programming, deafblind, smell, senses

Several years ago I was shopping at Macy’s in New York when suddenly I smelled something familiar, and I immediately thought of my childhood doll Lucy. You see, I had not thought about Lucy for years, much less that Lucy had been my favorite doll back when I was growing up in Spain. Looking around, I realized that I was in the store’s toy section and that I was very close to a stand of dolls. Out of curiosity, I reached out for one of the dolls. On the doll’s box it said: “Made in Spain.”

This experience was incredible to me—that something so far back in my memory could be brought to the present by something so fleeting as one smell! Years later I recalled this incident when I learned that the part of the brain responsible for our sense of smell—the limbic system—is related to feelings and memory.

In order to make sense of what smell is and how we can think of using it in our work, let’s first explore how the sense of smell is put together.

How the sense of smell works

The sense of smell, just like the sense of taste, is a chemical sense. They are called chemical senses because they detect chemicals in the environment, with the difference being that smell works at dramatically larger distances than that of taste. The process of smelling goes more or less like this:

  1. Vaporized odor molecules (chemicals) floating in the air reach the nostrils and dissolve in the mucus (which is on the roof of each nostril).
  2. Underneath the mucus, in the olfactory epithelium, specialized receptor cells called olfactory receptor neurons detect the odor. These neurons are capable of detecting thousands of different odors.
  3. The olfactory receptor neurons transmit the information to the olfactory bulbs, which are located at the back of the nose.
  4. The olfactory bulbs has sensory receptors that are actually part of the brain which send messages directly to:
  5. These brain centers perceive odors and access memories to remind us about people, places, or events associated with these olfactory sensations.

Cross-section of head, through the nose.

It is important to add that “Our sense of smell is 10,000 times more sensitive than any other of our senses and recognition of smell is immediate. Other senses like touch and taste must travel through the body via neurons and the spinal cord before reaching the brain whereas the olfactory response is immediate, extending directly to the brain. This is the only place where our central nervous system is directly exposed to the environment.” (von Have, Serene Aromatherapy)

The Sense of Smell and the Limbic System

The olfactory bulb is one of the structures of the limbic system and a very ancient part of the brain. As mentioned in the previous description of the olfactory process, the information captured by the sense of smell goes from the olfactory bulb to other structures of the limbic system.

The limbic system is a network of connected structures near the middle of the brain linked within the central nervous system. These structures “work together to affect a wide range of behaviors including emotions, motivation, and memory” (Athabasca University-Advance Biological Psychology Tutorials). This system deals with instinctive or automatic behaviors, and has little, if anything, to do with conscious thought or will.

The limbic system is also concerned with translating sensory data from the neo-cortex (the thinking brain) into motivational forces for behavior. The limbic system is centrally involved in the mediation between a person’s recognition of an event, their perception of it as stressful, and the resulting physiological reaction to it, mediated via the endocrine system: Stimuli are processed conceptually in the cortex, and passed to the limbic system where they are evaluated and a motivational response is formulated.

Brain, showing location of major limbic system structures.

What does this has to do with our field?

In the field of deaf-blindness, we have always known that many children who are deaf-blind have a very sensitive sense of smell to compensate for their limited use of vision and hearing. Consequently, we have always said that the sense of smell plays a key role in this population for identifying people, places, objects and activities.

The following statements are heard frequently in this field: avoid wearing strong fragrances because they can elicit seizures in some children; use the sense of smell to provide additional information (olfactory cues) to the child about what is about to happen to the child, e.g., bringing a bar of soap close to the child’s nose before taking a bath to tell him that soon he will be taking a bath; or to wear the same soft scent every time you work with a particular child so he can recognize who you are by this smell. All of this is very valuable information. The sense of smell is a strong sense for identification purposes and can have a strong impact in your brain because it is such an integral part of it (to the point that strong chemical smells can definitely elicit seizures).

But what about the role the sense of smell plays in relation with children’s moods, levels of arousal, emotions, memories and physical reactions? Now we know that they are connected.

Many times we are with a child and we can’t understand what is going on with him. He can’t tell us in a formal way. Maybe he is fussy or crying or smiling and we don’t know why. Why is he having these behaviors? Could it be about something he smells? We don’t know. We definitely know we should be paying more attention to this environmental factor to see if and how this is affecting the child.

I still have some questions in relation to the impact of the sense of smell in children who are deaf-blind and whether we can use this sense for our advantage, e.g., the use of consistent olfactory cues that might provide information a child could use to better understand what is happening, or eliciting a specific response from a child using a specific scent.

Conclusions

Even though we don’t know exactly how children who are deaf-blind are impacted through their sense of smell, we know this sense is very strong and basic. When interacting with a child who is deaf-blind we should be aware of the environmental odors that might be affecting the child’s behavior. Ideally we should be pairing an odor with its source so the child can make the connection between what he is experiencing and its concrete referent.

As an educational specialist in the area of deaf-blindness, it would be interesting to work with a team that includes a neuroscientist and an aroma-therapist to find ways to use the sense of smell to the benefit of children who are deaf-blind.

The emotional connections and the memories attached to a smell seem to be very personal; it seems to be intrinsically enmeshed with the individual experience. I am certain that if another person had been walking with me that day several years ago at Macy’s, he or she would not have noticed the doll’s smell. And on perceiving the smell, he or she would not have thought of my doll Lucy or felt the same feelings I had with this experience. But strong memories can be encoded and be accessible through the natural workings of the sense of smell. It may be possible to create these links to help open another avenue for communication with children who are deaf-blind.

Related links

Utilizing the Sense of Smell in Children and Youth with Deaf-Blindness PDF document
http://www.sfsu.edu/~cadbs
California Deaf-Blind Services Fact Sheet by David Brown, CDBS Education Specialist
See CDBS list of Fact Sheets with some topics available in Chinese, Laotian, Spanish, and Vietnamese:
<http://www.sfsu.edu/~cadbs/factst.html>; email cadbs@ pacbell.net or call 800-822-7884

The Limbic System
http://www.driesen.com/the_limbic_system_-_2.htm
Driesen, Neuropsychology and Medical Psychology Resources

Smell and the Olfactory System)
http://web.sfn.org/content/Publications/BrainBriefings/smell.html
Society for Neuroscience - Brain Briefings, 1995.

Limbic System
http://psych.athabascau.ca/html/Psych402/Biotutorials/18/intro.shtml
Athabasca University-Advance Biological Psychology Tutorials

Olfaction
http://www.cf.ac.uk/biosi/staff/jacob/teaching/sensory/olfact1.html
Cardiff University-A Tutorial on the Sense of Smell

The Olfactory Response
http://www.serene-aromatherapy.de/aromaolfactory.html
von Have, Serene Aromatherapy

Our Chemical Senses: Olfaction
http://faculty.washington.edu/chudler/chems.html
Murray; Neuroscience for Kids Staff


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