Smell, Memory, and Emotion

May 2019 - Health & Wellness

More than any other, our sense of smell can trigger powerful memories and emotions, and immediately transport us to a time, a place, and a feeling—pleasant or traumatic: a whiff of apple pie to your grandmother’s kitchen, wood smoke to a camping trip, salty air to a childhood beach holiday, the smell of gas to a car accident.

This experience is known as “odour-evoked autobiographical memory” or the Proust phenomenon, after French writer Marcel Proust’s description, in his novel In Search of Lost Time, of a character’s childhood memory evoked by dipping a cookie into his cup of tea.

And how it works is all in your head. Our five senses are designed to ensure our survival as a species. The information they pick up is sent to our brains for processing, to inform what action we need to take in response. Our sense of smell gathers information about chemical molecules in our environment, both dangerous and beneficial, to detect danger, or to find food or a mate.

Unlike any other sense, smell is linked to our memories and emotions, which scientists believe are created because of how our brains are structured. Here’s how it works:

The Mechanics
Molecules from that tantalizing whiff of apple pie travel to receptors in neurons at the back of your nose, then to the olfactory bulb. Here, the information is analyzed then forwarded to the thalamus for processing with all other incoming sensory information.

Odour-cued memories, scientists believe, are more powerful, last longer, and evoke stronger feelings than those associated with any other sense, for two reasons:

  1. The olfactory bulb and thalamus are directly connected to the hippocampus and amygdala—areas of the brain that process learning, memory, and emotion. These are located in the limbic system, the most primitive area of the brain, which is linked to the central nervous system.
  2. We have over a thousand receptors for smell, which is many more than for sight and touch.
    In fact, an odour-evoked memory, formed in childhood, can be vividly recalled late in life.

The Power of Scent
Our brain’s response to smell can be harnessed as a powerful therapeutic tool with aromatherapy, which can be used to boost memory, ease pain and anxiety, and improve mood.

Lavender, for example, is often used in nursing homes and hospitals to calm anxiety; and lemon, used in work environments, can increase alertness and productivity.

Losing It
Our sense of smell, which peaks in our late teens, can also be an indicator of health and well-being.
• Loss of a sense of smell is a sign of chronic zinc deficiency. Good dietary sources include meats, oysters and wild fish, beans, raw milk, cheese, yogurt, and kefir.
• The production of new smell cells declines with age and is linked to a gradual reduction in the ability to detect and differentiate odours. The loss may indicate that the body is entering a state of disrepair and is no longer capable of repairing itself.
• A reduced sense of smell has been associated with brain cell function loss, and linked to both Alzheimer’s and Parkinson’s diseases.
• The olfactory nerve, the only part of the nervous system exposed to the open air, offers poisons and pathogens a quick route into the brain. 

Article was published in The Good Life magazine.

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