The olfactory bulb, responsible for processing smell, is located in the forebrain. However, it starts with odor molecules, from something like food, traveling through the air where they are taken in by the nostrils. The odor molecules first meet chemoreptors located behind the eyes, which detect the presence of external stimuli (1; for a brief crash course on taste and smell, see this video). Next, the signals are sent to multiple areas in the brain after interacting with the olfactory cortex. Some signals are sent to the frontal lobe where the odors are individually identified, while other signals are sent to the limbic system which includes the hippocampus and amygdala (2). Because of these anatomical connections, smell is able to trigger memories, and amazingly, the olfactory bulb is the only structure related to the five senses that is connected to these areas responsible for emotion and memory (2).

Lose your sense of smell, lose your memories?

The sense of smell can also have negative implications for memory and emotions. On a medical level, there are many cases, such as head trauma, sickness, diabetes, and vitamin deficiency that can lead to the development of anosmia. Anosmia is when one loses their sense of smell, and as a result one’s sense of taste as well (3). In very extreme cases called congenital ansomia a person can be born without a sense of smell. Some may think that not being able to smell certain things such as garbage and dirty diapers would be beneficial, but those who do lose their sense of smell may experience depression. Anosmics “are deprived of the pleasure of eating and drinking” (4) and this lack of sensory experience greatly decreases one’s life experience. When they walk into the coffee shop that I mentioned earlier, an anosmic individual wouldn’t be reminded of their experiences associated with the smell. The most depressing part may be that they cannot differentiate a freshly baked cookie from a brussel sprout.