A Sniff to Remember
The most ancient part of your brain - sometimes called the reptilian brain - houses your most basic survival instincts - fight (rage) or flight (fear.) The next layer of your brain, called the limbic system, is where the really fun stuff lives. The limbic system is home to emotion, memory, pride, libido, sensual pleasure and addictions.
What interests us here at Limba Systems is that this area of your brain - unlike any other part - is directly accessible via your sense of smell.
The Science
Our bodies are comprised of a variety of different of systems:
•The endocrine system contains glands and controls hormones and whatnot.
•The excretory system takes care of all the stuff that needs to come out of us.
•The immune system fights invading diseases.
•The integumentary system is a fancy word for skin.
•The nervous system has the nerves.
•The reproductive system makes babies.
•The respiratory handles our oxygen.
•The skeletal system and muscular systems keep it all standing.
But the greatest of these – for our purposes here - is the Limbic System.
The limbic system is a part of the nervous system (that means the brain and spinal cord) that sits in the second deepest part of the brain, just outside the reptilian brain. It is very very old, as brain parts go.
One might assume that the limbic system is the reason we evolved at all. It is the system that gives us pleasure (not just us, but all animals) so that we know to keep on eating and reproducing. Sometimes referred to as the "emotional brain”, the limbic system is responsible for processing and storing memory, fear, sex drive and emotion . It is the processing center for addictions, including overeating, and is the part of the brain that reacts to a recently-discovered protein called leptin, which is released by fat cells when we overeat.
Key Parts of the Limbic System
The term "limbic" comes from the Latin limbus, meaning "border" or "belt." The most prominent parts of the limbic system are the amygdala, hypothalamus, and hippocampus.
Amygdala
The amygdalas are two almond-shaped masses of neurons which appears to control the sex drive, fear and aggression.
Hypothalamus
The hypothalamus is the biggie. It is responsible for regulating hunger, thirst, response to pain, anger and aggression, pulse, blood pressure, breathing, and sexual arousal.
Hippocampus
The hippocampus consists of two “horns” that curve back from the amygdala. It is responsible for processing memory and converting short term memories to long term.
“Limbic system” is an old term, and current science has been busy blurring the lines between “inside” and “outside” it. Some of its newest members are the cingulated gyrus, the septum, the ventral tegmental area, the prefrontal cortex and the basal ganglia. I include these here not only because I don’t want to leave anyone out, but because I actually hope some neuroscientists will read this page and call me up, exclaiming at my brilliant, though lay-friendly descriptions.
If you had to choose your favorite brain part, I would definitely suggest choosing the limbic system. It was there for us when we were apes – rewarding behavior that kept us alive. Our sense of smell, directly connected to the limbic system via the olfactory bulb, was probably the most important sense at one time. We smelled rotten food. We smelled enemy B.O. We smelled pheromones that led us to our true loves and the continuation of our species.
Over the millennia, however, we have gotten blasé about smell. Ask anyone which sense they’d rather give up: sight, hearing, or smell, and they will usually choose smell. I know this because I asked at least five people. But the truth is, if you REALLY lost your sense of smell, you would be very sad. There are stories all over the internet of people who cannot smell, and the havoc it causes in their day-to-day lives.
SMELL is the ONLY SENSE THAT IS
DIRECTLY CONNECTED TO OUR BRAINS.
So thank you, limbic system. Thank you, olfactory bulb. Thank you, LimbaSlim.
