Remember to Stop and Smell the Roses
Olfaction and its Relationship to Memory
The following series of activities were designed and tested in conjunction with the National Association of Biology Teachers and the Society for Neuroscience joint Neurobiology Education Project.
TYPE OF ACTIVITY:
- Inquiry lab
- Involving experimental design
- First-Year High School Biology (Neuroscience: Sensory Reception or Memory;
Anatomy + Physiology of the Brain; Scientific Method/Experimental Design)
After completing these activities, students will be able to:
- Explain that olfaction elicits memory associations due, in part, to the
anatomical structure of the brain ("structure reflects function")
- Design and carry out experiments that investigate how olfaction
compares to other sensory modalities in the formation of memories
- Describe the major regions of the brain and their specialized functions
Designed based on Learning Cycle theory, students begin and end these activities in the laboratory, first in exploration and later in investigations designed by the students themselves.
Olfaction and memory seem to be integrally linked. In fact, there is a biological basis to this close association. Unlike other sensory neurons, which are routed first through the thalamus, olfactory neurons send information immediately into areas of the cerebrum, while other branches simultaneously travel directly into the portions of the limbic system associated with memory. In the initial activities that follow, students are given an opportunity to experience the association between olfaction and memory. Then they are introduced to some of the regional specialization of the brain. Using this information, students try to explain in anatomical terms why memory and olfaction are so closely related. Finally students design experiments to find out if other senses are as closely linked to memory.
During an Exploration activity, students smell several different odors. Each time, they are instructed to state the first thing that comes into their mind after sensing the odor, and then, if necessary to try to identify it. Using the written results of this activity, students are asked, "What do you notice about the comments you made after each odor?" The word "memory" should only be introduced by the students during this discussion. Students should be allowed to "uncover" this idea themselves. The instructor may need to point out that students find themselves saying things like, "It reminds me of..." or "It makes me think of ...." Students can later calculate what percentage of the time memories seem to be associated with odors.
Next, in the Concept/Term Introduction, students use models and reference materials to identify various parts of the brain (especially the olfactory nerve, the amygdala and the hippocampus, the regions of the cerebrum), and their particular areas of specialization. (The terms themselves are not particularly important in and of themselves. It is necessary that the regional specialization of the brain be conveyed, especially those areas that function in olfaction identification and memory storage/processing.) Then, students are asked to come up with a hypothesis that provides an anatomical justification for the close relationship between olfaction and memory. Most individual students, or at least one member in each working group (!) will notice that the olfactory nerve runs adjacent to the area of the brain thought to be responsible for long-term and short-term memory (the amygdala and the hippocampus).
Finally, students, working in their own lab groups, apply this information by choosing to explore one other sense and its relationship to memory. They will choose a hypothesis based on their newly acquired knowledge of brain anatomy and design an experimental set-up. Although they are free to employ any experimental technique, they are also able to follow the model demonstrated during the "Exploration" activity. (For example, the team that chooses to test the hypothesis stating that taste is not closely associated with memory, might ask their blindfolded "subjects" to indicate the first thing that comes into their mind when given various foods to taste. The researchers might decide to calculate the percentage of time that the responses show some association with a memory and compare this percentage to the data that were obtained during the olfaction tests.) When each lab group has concluded, they present their results and conclusions, including a discussion of their sources of error, to the rest of the class in an oral "Seminar" format. (If class time is not available for such a "Seminar," results may alternately be published/publicized in poster or lab report format.)
- Varies, depending upon availability of materials (refer to "Materials" section below)
- Exploration: 30 minutes
- Concept/Term Introduction:30-45 minutes (varies with number of
anatomical terms included)
- Application: 2 class periods (student planning + carrying out experimental
design); 1 additional "Seminar" class period if students present their results to the class orally
(The following materials will need to be made available to each lab group. However, if odor kits and reference materials for brain anatomy are limited, one group of students can use the odor kits while another group of students identify regions of the brain. The groups can switch stations before trying to draw any conclusions about the anatomical relationship between the sense of olfaction and memory. Of course, this is not ideal, but it does make the activities more amenable for use in the average classroom.)
- One(1) "odor" kit (ten unknown odors; although available from most
biological supply companies, "odor kits" can be made in the classroom
using black 35 mm film canisters that have been numbered and that
contain odors that would be familiar to the population of students in
- Brain model or other reference materials (texts, laser-disks
software, CD-rom, etc.) describing regions of the brain
- Several "blindfolds"
- Other materials as required by student experimental design (e.g., small
amounts foods and paper cups (TASTE); photographs or magazine
pictures (SIGHT); cassette player, tapes, other noisemakers (HEARING);
fabric swatches, felt, sandpaper, cotton balls, steel wool (TOUCH)