What Is the Limbic System? (Plus How to Keep It Healthy & the Role of Essential Oils)

June 13, 2017
Limbic system - Dr. Axe

Although it’s only a small part of the brain in terms of volume, the limbic system has some of the most basic, life-sustaining and meaningful roles of all brain structure. The word limbic comes from the latin word limbus, meaning “border.” That’s because the limbic system forms a curved border around the subcortical parts of the brain called the cerebral cortex and the diencephalon.

Ever wonder what part of the brain controls emotions? While the entire central nervous system helps control our emotions, as you’ll learn, activities in the limbic system and autonomic nervous system are especially influential over our emotional health. The entire limbic system — including subparts like the hippocampus, hypothalamus and amygdala — helps control numerous emotional, voluntary, endocrine and visceral responses to our environments that we all experience daily. (1)


What Is the Limbic System?

Of all the areas of the brain, from an evolutionary perspective the limbic system is said to be one of the oldest and most primitive, having formed many hundreds of thousands of years ago. In fact, similar systems are also found in most other animals, even reptiles. In the past, the limbic system was sometimes even referred to as the “paleomammalian brain.” (2)

Although the limbic system works with other areas of the brain in complex ways, and therefore has far more than just one role, the word that best describes what the limbic system controls would be “emotions.” Secondly, a part of the limbic system called the hippocampus helps us form and retain memories, which is very important for learning and development.

At all stages of our life, the limbic system and hippocampus also help govern emotional behaviors. While it’s an oversimplification to say that someone’s emotions are only determined by limbic functions, it’s clear that this system plays a huge part in helping us do things like remember past events that were both pleasant and traumatic, perceive threats from our surroundings, make choices based on our experiences, control movements based on past learning, form sensory preferences/likes/dislikes, and much more.


Limbic System and Hippocampus Function and Structure 

The limbic system sits atop the brain stem, which is believed to be one of the first parts of the brain to develop, react to stimuli and the most basic in terms of sustaining life. It’s located on both sides of the thalamus and underneath the cerebrum.

There’s not total consensus among neuroscientists about which structures of the brain are technically part of the limbic system, considering it’s very hard to to neatly classify cortical areas given how much neural overlap there is. That being said, most consider the limbic system to be made up of cortical regions (structures), including:

  • Hippocampus: generally associated with memory and focus, but also helps with motor control (often learned through trial and error)
  • Amygdala: tied to fear and anxious emotions
  • Hypothalamus: primarily responsible for regulating hormones and maintaining “homeostasis” (more on this below)
  • Septal Nuclei: tied to pleasure and learning through reward and/or reinforcement
  • Cingulate Cortex: involved in many aspects of memory and emotion
  • Parahippocampal Gyrus: also helps with memory
  • Mammillary Bodies: connected to the amygdala and hippocampus
  • Fornix: connects other parts of the brain, including hippocampus and mammillary bodies

The limbic system is one hard-working region of the brain, as you can tell. Some specific limbic system functions include:

  • Controlling emotions like anger and fear
  • Regulating eating, hunger and thirst
  • Responding to pain and pleasure
  • Controlling functioning of the autonomic nervous system, including things like pulse, blood pressure, breathing and arousal
  • Sensing sexual satisfaction
  • Controlling aggressive or violent behavior
  • Responding to sensory information, especially sense of smell

The hippocampus is part of the entire limbic system, but it helps to understand how it contributes to memory to learning. Functions of the hippocampus include: (3)

  • Forming short-term and long-term memories through consolidating information
  • Learning new skills from reward, punishment, reinforcement and failure
  • Recognition of what’s familiar versus new
  • Navigation or sense of direction
  • Spacial memory
  • Involved in olfaction (smelling) and tying together smells with specific memories

Limbic System Disorders

Because subparts of the limbic system ultimately regulate important aspects of our conscious and unconscious patterns — including our emotions, perceptions, relationships, behaviors and motor control — it’s easy to see why damage to this region can cause serious problems. Disorders or behaviors that are related to limbic system dysfunction, or sometimes limbic system damage due to things like traumatic injuries or aging, include: (4)

  • Disinhibited behavior: This means someone doesn’t consider the risk of behaviors and ignores social conventions/rules.
  • Increased anger and violence: This is commonly tied to amygdala damage.
  • Hyperarousal: Amygdala damage, or damage to parts of the brain connected to the amygdala, can cause increased fear and anxiety. Anxiety disorders are sometimes treated with drugs that target areas of the amygdala to decrease fear-based emotions.
  • Hypoarousal: This can cause low energy or lack of drive and motivation.
  • Hyperorality/Kluver-Bucy Syndrome: This is characterized by amygdala damage that can lead to increased drive for pleasure, hypersexuality, disinhibited behavior and insertion of inappropriate objects in the mouth.
  • Appetite dysregulation: Destructive behaviors tied to hyperorality or thalamus dysfunction can include overeating, binge eating or emotional eating.
  • Trouble forming memories: Hippocampal damage can include short-term or long-term memory loss. Learning is often greatly impacted by hippocampal damage, since it depends on memory. Someone with the condition anterograde amnesia loses the ability to form and retain new memories. Interestingly, sometimes someone can hold on to older/long-term memories but lose the ability to form new short-term memories.
  • Cognitive disorders, such as Alzheimer’s disease: Research shows that people with Alzheimer’s and memory loss usually have experienced damage to the hippocampus. This causes not only memory loss, but also disorientation and changes in moods. Some of the ways that the hippocampus can become damaged include free radical damage/oxidative stress, oxygen starvation (hypoxia), strokes or seizures/epilepsy.

 

Limbic system structure and functions - Dr. Axe

 


Emotional and Psychological Link to the Limbic System

As you’ve probably gathered, the limbic system plays a powerful role in creating different emotions and feelings. In fact, some even call it “the emotional switchboard of the brain.” (5)

One important way that the limbic system impacts emotional health is through carrying sensory input from the environment to the hypothalamus and then from the hypothalamus to other parts of the body. The hypothalamus acts like the “regulator” of hormone control, helps the body maintain homeostasis and send signals to the pituitary/thyroid/adrenal glands. It receives information from many body parts, including the heart, vagus nerve, gut/digestive system and skin.

Because of the hypothalamus’s functions, the limbic system is directly in control of your “stress response” and these key functions:

  • Heart rate
  • Blood pressure
  • Breathing
  • Memory
  • Stress levels
  • Hormone balance
  • Moods

Interactions between the hypothalamus and the rest of the limbic system are responsible for controlling the autonomic nervous system — including the sympathetic nervous system (SNS) and parasympathetic nervous system (PNS). In other words, the SNS and PNS control our “fight or flight” response. Disorders like generalized anxiety, social anxiety, phobias, bipolar disorder, and even addictions and depression are tied to hyperarousal, high amounts of anxiety/fear and dysfunctions of the fight-flight-response.

Anxiety and high amounts of stress (including increased cortisol levels) also have an impact on inflammation levels, digestion and gut health, cardiovascular functions, your immune system, and the reproductive system — sometimes contributing to disorders like diabetes, insomnia, high blood pressure, higher susceptibility to infections and infertility.


Essential Oils and the Limbic System

The limbic system gathers information from the environment through sensory information. As you’ve experienced firsthand many times, your senses can alter your emotional state rapidly. For example, a pleasurable meal can make you feel comforted, and very loud noises can make you feel anxious.

Ever wonder why certain smells conjure up memories and even physical feelings so vividly? Our sense of smell is unique compared to our other senses (such as taste, sight and hearing) because it bypasses parts of the brain that other types of sensory information often cannot. Because of this, smells can often cause immediate and strong emotional reactions based on memories. Smells can bring us back to past events within milliseconds, making us feel a certain way based on past events, whether we realize why we’re suddenly feeling that way or not.

Essential oils, for example, can have dramatic effects on limbic function and how you feel. This is true because the strong fragrances they hold, which are found inside volatile molecules that can make their way into your bloodstream, travel directly through the blood/brain barrier very quickly.

  • As you’ll recall, the hippocampus is involved in olfaction (smelling). How so exactly? Aromatic molecules contained within essential oils interact with sensors in your nasal cavity, lungs, pores and more. Research shows that the olfactory bulb projects information into the ventral part of the hippocampus, and the hippocampus sends axons to the main olfactory bulb, (including the anterior olfactory nucleus and the primary olfactory cortex). This is how memories and smells become tied together. (6)
  • Once engaged, sensors emit strong emotional signals based on smells starting from your limbic system (hippocampus) and spreading throughout the rest of your body to places like your heart and digestive tract.
  • Because essential oils can impact memory, balance hormone levels and overall support healthy limbic system functions, much new scientific evidence shows that inhaling essential oils may be one of the fastest ways to create physiological or psychological benefits. These include decreasing anxiety, anger or even fatigue.

How to Keep the Limbic System Healthy

In order to maintain homeostasis and feel your best, the goal is to balance activities of the parasympathetic and sympathetic nervous systems. Too much activation of one causes high amounts of anxiety, but too much of the other causes low motivation and symptoms like fatigue. Here are ways to help keep your limbic system functioning smoothly.

Use Soothing or Uplifting Essential Oils

When used in aromatherapy (inhaled), there is evidence that essential oils are absorbed into the bloodstream and then trigger the hippocampus. This is mostly due to the amount of blood vessels in the lungs that take up the oils and then circulate them throughout the body, including to the brain.

Using a diffuser can help you experience the benefits of essential oils, or you can directly inhale them from the bottle or a cotton swab. You can diffuse lavender to reduce stress, melaleuca to cleanse the air, wild orange to improve your overall mood, frankincense for spiritual enlightenment, and peppermint essential oil to improve focus and energy.

Practice Deep Breathing

Deep breathing exercises coupled with intentional relaxation of muscles engages the circuitry of the PNS and strengthens it for future use. Relaxing/deep breathing also quiets the fight-or-flight SNS, since relaxed muscles send feedback to the alarm centers in the brain that there are no threats present. (7)

A simple way to practice deep breathing is to lay on your back and try taking slow, steady breaths from your diaphragm (near your belly, as opposed to from your chest). You can also try inhaling for four seconds, holding your breath for seven seconds and exhaling slowly for eight seconds, repeating this for five to 10 minutes.

Try Visualizations or Guided Imagery

Visual stimuli have important influences on emotional health, socialization and well-being. They can even be used to reduce anxiety disorders or symptoms of autism. (8)

To practice, bring to mind in detail a place that makes you feel happy and relaxed (a vacation, being in nature or time spent with family, for example). Imagine or feel that the experience is entering deeply into your mind and body, keeping your muscles relaxed and absorbing positive emotions, sensations and thoughts of the experience.

Exercise

Exercise helps control stress, balance hormones (such as cortisol), raise immune function and lower inflammation. One of the ways it does this is by training your autonomic nervous system/fight-flight-response to return to normal more quickly following periods of stress/arousal.

Make a Habit of Being Mindful, Still and Silent

You can try things guided meditation or regular healing prayer to achieve this. These can help you cultivate gratitude, reduce stress, make you feel more connected to others, become more mindful/aware of good things in your life, and increase feelings of compassion, kindness and well-being.


Interesting Facts and History of the Limbic System

The functions that different regions of the brain are responsible for have been debated since the time of Aristotle thousands of years ago. Neuroscience has come a long way since then, especially recently thanks to imaging studies like MRIs, and it’s now widely accepted that the prefrontal cortex, amygdala, anterior cingulate cortex, hippocampus and insula participate to control the majority of human emotional processes.(9)

Today, teaching people who struggle with anxiety or depression to intentionally learn to calm their autonomic nervous systems is a major focus in psychology, therapy and neuroscience research.

In recent decades, scientists have come to understand that our brains are always adapting to our environments throughout our entire life spans. The brain’s capacity to learn — and change itself depending on its environment — is called neuroplasticity, which when used to our advantage helps us become happier in addition to more knowledgeable.

The limbic system is responsible for governing “avoidance” versus “approach” behaviors in most animals — in other words feelings of pleasure versus anxiety/pain. Approach and avoidance are exactly what help keep us alive and ensure survival. That’s why the limbic system is said to be so “primitive” and is found in all types of species.

Because of how quickly the limbic system works, your brain can register something as being dangerous (such as a car speeding by you) and trigger you to move out of the way/avoid it BEFORE you even consciously know what happened or have time to think it over.

When you come across something threatening, your hippocampus immediately compares the image to its stored list of dangers. The hippocampus then communicates to your amygdala by sending high-priority alerts (which is why the amygdala is often called your “alarm bell”) that fast-track actions of your fight-or-flight/hormonal systems.

The brain typically detects negative information faster than positive information in order to prioritize ensuring survival. This is often called our “negativity bias” and explains why it’s often easier to remember bad events more easily than positive ones. Because of this tendency, it can be easy for some people to become overly anxious or depressed if they don’t train themselves to focus on the good in their lives or practice calming activities and gratitude. (10)


Final Thoughts on the Limbic System

  • The limbic system is a connection of many brain structures that help control emotions, in addition to memory, learning, motivation, and bodily functions like appetite and sex drive.
  • Subparts of the limbic system include the hippocampus, amygdala and hypothalamus.
  • One of the most notable areas that essential oils impact is your emotions tied to memories, thanks to activation of your limbic system/hippocampus. Essential oils that can help improve your mood, energy and focus include peppermint, lavender, orange and frankincense.
  • To keep your limbic system healthy, use soothing or uplifting essential oils, practice deep breathing, try visualizations or guided imagery, exercise, and try things like guided meditation and healing prayer to make a habit of being mindful, still and silent.

Read Next: The Lymphatic System: How to Make It Strong & Effective


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