The Limbic System: Our Emotional Antenna
I like the idea that our bodies are related to our consciousness like a TV set is related to its broadcast signal. In this analogy our bodies are like the TV, our nervous system the antennae, and our consciousness the signal being broadcast. That is to say that our brains and bodies do not produce consciousness but pick up on it and express it.
With that in mind, let’s talk about the limbic system! It is ONE of the primary antennas for our emotions. It’s at least the primary antennae for picking up the external cues that contribute to our emotional state. The body’s got a lot of fun tricks. We’ll get to them in due time. The limbic system picks up signals from the outside and translates them into body-speak: neurotransmitters and hormones and other molecules the body uses to communicate. The feeling that results from all of this molecular movement is emotion.
Let’s start with the basics. What’s the limbic system?
I’ve heard it called the primitive or ancient brain, our emotional switchboard, and the subconscious brain. Whatever nickname you give it, it’s a group of structures in the brain that mediates emotion, motivation, and instinct. It’s not agreed upon exactly which structures get to be members of the limbic system, but I consider these four essential: the thalamus, the hippocampus, the amygdala, and the hypothalamus.
In a simplified nutshell, the thalamus processes all the information collected from our senses. The hippocampus compares this assessment of what’s happening to all our past experiences. “Am I threatened or safe?” The amygdala then acts like the alarm bell, assigning salience to the appropriate emotion. Then the hypothalamus goes to town telling the body how to respond through three primary ways:
The limbic system and the nervous system
Nerves project from the hypothalamus through the brainstem and spinal cord. Once they leave the spinal cord, they split into two branches of interest to us here. One branch is the oft-loathed “fight-or-flight” (sympathetic nervous system) and the other more peaceful branch we call “rest-and-digest”(parasympathetic nervous system). Depending on the emotional state determined by the rest of limbic system, the hypothalamus can activate one or the other branch. (1, 2) If fight or flight is activated, your heart will race, your pupils will dilate, blood will be diverted away from you digestive tract and your blood sugar will spike in anticipation of the fight ahead. If rest and digest is activated you’ll experience quite the opposite, a relaxation state optimal for sitting down to a nice meal.
The limbic system and the immune system
A few structures of the limbic system are directly connected by nerves to our immune organs like the thymus, spleen, and lymph tissue in the lungs and intestines. (3) Unsurprisingly, changes in the limbic system structures have been shown in studies to affect the activity of these organs. (4) Likely more impactful is the communication between the limbic system and immune cells via the nervous systems preferred messenger, neurotransmitters. Immune cells are peppered with receptors for neurotransmitters, which makes them look like little brains! This has led scientists to nickname the immune system the “mobile” or “floating brain”. (5) This is one clear way in which our emotional state can change the way our immune system behaves.
The limbic system and the hormonal system
This is what the hypothalamus is most famous for actually. It releases many hormones that keep our bodies operating at a basic level. It controls our stress response through the adrenal glands, our metabolism through the thyroid gland, our reproductive functions through the testes and ovaries, and so much more. It’s the source of oxytocin, the love hormone. And also the source of VIP, which Candace Pert speculated in her book Molecules of Emotion was the self-love hormone. (6,7) If we just connect the dots here, we can see the deep impacts that our emotional state can have on our physiology.
And of course all of this is just communication one way. There’s just as much if not more communication coming the other way. But that my friends is a topic for another blog. I hope that this overview of the inner workings of your brain gives you the confidence to know that your emotional state can create health or disease in your body. Your body isn’t just a machine, your internal experience matters. I find this so empowering because that is one thing we have some control over in this wild world. Please let me know your thoughts and questions in the comments!