Human senses are fascinating. The sense of sight, sound, touch, taste, smell, and how the body receives and translates the sensory information gives people a unique way to perceive the environment surrounding them.
Of the five senses, our sense of smell is undoubtedly one of the most powerful and absorbing senses that draws a strong connection with memory. The sense of smell is so closely associated with memory compared to the other senses because of the brain’s anatomy.
For some people, the smell of freshly baked cookies or baked bread can bring childhood memories flooding back. Similarly, the smell of a specific perfume scent can remind one of a particular person who used to wear it. This sensory experience causes a person to pick up “involuntary memory” or the recollection of hidden or long-gone memories through smell.
Why and how smell triggers strong memories? Keep reading to learn more about what goes on in the brain when the sense of smell is activated and its ability to trigger memory information vividly.
How Smell Works
Research shows that 75% of all emotions processed daily are due to smell. Because of this, people are 100 times more likely to recall something due to their sense of smell over their sight, hearing, and touch. Additional research reveals that there can be a 40% improvement in mood after getting exposed to pleasing scents.
Smells are chemical particles that travel through the nose. The scent then flows into and is handled by the olfactory bulb, located in the front region of the brain and right above the nasal cavity. The olfactory bulb receives and processes the information about the sensation and sends the information to the other parts of the central command for further processing.
A human nose has roughly 400 olfactory receptors, also known as smell or odor receptors, which are the neurons responsible for detecting odors. Each of these receptors can be activated by numerous different odor molecules, and every odor molecule can activate several different types of receptors.
The Odors in the Brain
The relationship between olfactory receptors and odor molecules and how they interact enables people to identify a wide range of smells. What people assume of one smell is, in reality, a combination of several odor molecules activated on different receptors, making some interactions better “matches” than others. This creates a particular sensory pattern that allows people to detect the smell of freshly baked bread or the salty beach air.
What makes the olfaction (the technical name of sense of smell) unique and stronger among other senses is its receptor cells, as these cells are neurons. Every olfactory receptor cell has hair-like filaments called cilia, carrying receptors structured to bind to specific molecules. Together with a fiber called the axon, they all come together in the olfactory nerve and travel to the brain.
Simply put, the olfactory nerve has neurons with direct contact (through airborne molecules or odorants) to the outside world and the other in direct contact with the brain. When an odor links to an olfactory receptor, it produces a tiny electrical signal that quickly detects the smell.
That smell information bypasses the thalamus, a structure in the brain that serves as a sensory relay station, where it is merged with taste information. What people ascribe to taste sensation is a result of sensory integration, so what people identify as flavor is essentially smell.
The scents flow through routes in the limbic system, encompassing the amygdala and the hippocampus, the region of the brain deep within the temporal lobe. The tiny part of the brain, the amygdala, is where the emotions are processed. Meanwhile, the adjoining hippocampus is where learning and memory are deep within.
How many odors can humans identify? Research shows that people’s sense of smell can discriminate at least one trillion different odors—far more than the previous estimate of only 10,000 scents. The impressive number gives all the more reasons why people should pay more attention and recognition to their sense of smell.
How Memory Works
From the very moment humans are born into the world, they are exposed to a multitude of sensations and reactive experiences. So, how do humans retain all that information accumulated from their young years up to the present—everything they have learned and experienced? The answer is through human storage called memories.
Memory pertains to the ongoing processes used to obtain, store, retain, and recover information. The three primary stages involved in memory include encoding, storage, and retrieval. The human memory can preserve and recollect information one has learned or experienced over time. Creating and recover memories is an essential part of the human experience.
There are three different types of memory: short-term memory, which stores information for a brief time and can only hold on to 7 +/- 2 pieces of information at once; long-term memory, which can store a large amount of information for a more extended period; and sensory memory, which allows people to retain sensory input, but cannot be consciously controlled.
The Formation of Memories
Paul Reber, Professor of Psychology at Northwestern University, says the brain’s memory storage capacity can hold up to 2.5 petabytes (a million gigabytes) of data or about three million hours of TV shows.
Information should be changed and registered in a usable form through the process called encoding. Encoding is the process of receiving, combining, and processing information from the outside world to the senses in the form of chemical and physical stimuli.
Once the memory has been encoded, it proceeds to the storage process. This is where the brain creates a permanent record of the encoded information and is recovered for later use. Finally, the retrieval process enables the recollection of the stored memory as a response to a trigger or some cue for use in an activity, leading the stored memories into conscious awareness.
The scent of a person’s perfume, the smell of the hair products they use, the odor of freshly cut grass—when certain smells are attached to specific events or associated with specific people, it becomes easier to remember the memory.
When people drink too much alcohol, they may not have a full recollection of the night before because alcohol has a negative impact on a human’s memory, and it prevents the brain from processing and transferring information into long-term memories.
How Smell Affects Memory
Suppose a person passes by a coffee shop and inhales the aroma of freshly brewed coffee. Would they know what coffee smells like if they had never learned what coffee is? When a person smells something they know of and is associated with a significant event in their past, they initially have an emotional response, which is followed by a recollection of that specific experience.
The piriform cortex, the region on the brain that functions to the sense of smell, is the part responsible for the recollection of odor-triggered memories. The piriform cortex connects to all aspects of the brain, encompassing the orbitofrontal cortex. The orbitofrontal cortex makes judgments about sensory information (e.g., don’t eat food that smells off), and it triggers memory changes in the piriform cortex.
Essentially, the orbitofrontal cortex instructs the piriform cortex which events should be kept in the memory as long-term memory. The piriform cortex can serve as an archive for these memories.
Moreover, because smell inputs go through the thalamus and reach the amygdala and the hippocampus, it creates deep connections between scents, memories, and emotions. This is how memories prompted by smells are experienced more intimately compared to other senses.
It’s not uncommon for businesses and brands to use scents for marketing purposes. Real estate agents bring freshly baked goods to their open houses not only to offer them as appetizers to clients but also to touch on the potential clients’ sensory impressions with memories of comfort and home.
Just as how smells can help recall a memory, it can also draw out any memory association. If a person frequently smells a scent, that smell will lose its meaning and detach from a specific memory, losing the scent’s power to retrieve that memory. The interrelation between smell and memory also extends to memory-related health conditions. One of the common early symptoms of Alzheimer’s disease is increased confusion and memory loss.
The Stimulating Scent of Terpenes
This old adage of “use it or lose it” applies to smells and memories. Humans can strengthen their sense of smell by using it often, and engaging in mentally stimulating activities can improve memory functions. Inhaling pleasant aromas is a tried-and-true way to uplift one’s mood. This is why spa centers use aromatherapy to stimulate feelings of rejuvenation and relaxation.
One way people can take advantage of the powerful sense of smell is by using terpenes. Terpenes are the compounds found in plants, flowers, and trees; and are responsible for their scent. Hops, the cone-shaped flowers of the hop plant, are the primary bittering agent used to brew beer and contain terpenes. This is what gives beer its taste and tang.
Many types of terpenes and their key aromas are familiar to people. For instance, myrcene, the most common terpene. Its aromatic profile blends fruity and earthy scents that can be found in thyme, bay leaf, and parsley. Meanwhile, a terpene called limonene exudes a strong citrusy and bitter profile. This type can be spotted in citrus fruits, including lemons, limes, and oranges.
Because they produce vibrant fragrances and deliver respective effects—some terpenes contain properties that aid in pain relief, inflammation, relaxation, antibacterial, and soothing, among others—many people blend terpenes in essential oils, aromatherapy, and as a flavoring for products. Breathing the scents from essential oils and plants may alter a person’s mood and stress levels.
Incorporating terpenes in essential oil blends and other wellness practices is an excellent way to discern and gauge the different effects and therapeutic benefits of the better-known terpenes. Plus, it influences the mental and emotional state of a person. Of course, proper dilution and procedure should be followed for safe consumption.
For example, with its citrusy scent, limonene can help enhance one’s mood and suppress aggression, while myrcene can help with better sleep and serve as a muscle relaxant. There are other varieties that provide other benefits, such as improving memory and cognitive performance and alleviating anxiety.
Another thing, terpenes can be used for cooking—their natural capacity to elevate aromas and enrich the flavors of dishes. Terpenes exist in numerous raw foods, from vegetables and fruits to herbs and spices. Each type of terpene brings about a unique smell and flavor when it interacts with the elements released by other ingredients. Using terpenes for cooking can deliver a burst of flavor fitting for the palate and a satisfying aroma that can invigorate the mind and the body.
The Brain Reacts to What the Nose Knows
Every day, people learn new things and acquire new experiences. The brain cannot keep all this new information, so it decides what is worth remembering. The next time you suddenly feel an intense rush of emotions followed by a specific memory after getting a whiff of a particular perfume or a homemade pastry, know that that’s just how the brain processes smell information.
As people know, memory doesn’t always work flawlessly. But not to worry, you can always strengthen your memory through brain exercises and your sense of smell by consciously discriminating what you’re smelling.
Alternatively, you can enhance your sense of smell and memory by incorporating ready-to-use terpenes in your wellness practices or home cooking. By using different terpenes for your creative or experimental scent adventure, it can help stimulate your senses and memory experiences.
Head to Medical Terpenes for a variety of high-quality, food-grade terpenes!