Our brains are pretty amazing, but the rest of our bodies have incredible intelligence as well. The heart is one organ that we normally relegate to simple, but important tasks like pumping blood to our organs and cells, but it has additional wisdom to offer.
Our heart and brain are constantly sending signals back and forth to one another to help communicate information about our environment and how to respond to it. Specifically, our hearts communicate to our entire nervous system to tell us how to feel. Our emotions are reflected then in our breath.
Feedback signals between the heart and brain create a level of coherence that can calm and center us, or add to a feeling of fear, chaos, and instability. Be learning how to center into our hearts and breathe deeply, we can teach ourselves how to stay connected to a center of compassion and openness.
In yogic traditions, the heart is called the Anahata chakra. This translates from the Sanskrit to mean “unstruck note” or “unplayed chord.” This is how the heart should operate when it is completely open and holds no trauma.
When the heart is not contracting we breathe deeply and fully. When the heart is on “lock-down” because of a perceived hurt or betrayal, the breath also contracts. You can see how intimately the heart and lungs are created, but this then also sends feedback signals to the brain. This results in feelings of euphoria, bliss, love, trust, and hope as opposed to fear and withdrawal, and profoundly directs our subsequent actions.
Research from the HeartMath Institute and other bodies have indicated that when we create rejuvenating emotions (and breathe accordingly) we send signals to the brain which harmonize our entire bodies. A completely different set of hormonal signals is set off via neurochemicals and neurotransmitters that helps us feel calm and confident. 
When the heart, brain, and breath are all synced, coherence is optimal. The frequency for this optimal state is approximately 0.10 Hertz. It is very low vibration, below the threshold of 20 Hertz, typically the lowest frequency that humans can detect with the unaided ear.
Some researchers even believe that this is the “vibe” that we pick up from other sentient creatures to detect if their hearts are open and loving, or contracted and traumatized.
If you want to create an open-hearted, full-breath, heart-brain connection and coherence, you can do it by your own conscious action.
Try the following exercise:
Sit in a quiet place with your spine erect and your hands resting comfortably in your lap or over your heart. Focus your energy on your heart chakra and imagine a small light starting to surround the heart organ. Feel and continue to imagine that light expanding into your lungs and filling your whole chest.
Begin to breathe deeply, taking your time, and continuing to focus on the heart center and filling it with light. Allow your belly to fill completely with an inhale, and draw the belly in toward your spine as you exhale. Don’t rush the breathe or force it, but do try to keep your awareness on your heart.
Now think of a time when you felt heartbroken or betrayed. Surround yourself and the person or persons involved in this heartache with the light that has been building in your chest. Continue to breathe deeply. Allow your exhalation to “breathe out” any pain that is associated with this event.
As you inhale, with the same event in mind, take in wholeness, love, joy, and a sense of happiness and comfort. If it helps, think of another event or person who has made you feel this way, and allow it to expand your heart, replacing the once-broken parts of your energy and experience.
Continue doing this until you observe the contraction in your heart lessen. As any contraction does lessen, you will notice that it also becomes easier to breathe deeply. Keep filling your heart with light, and if you need to, tell yourself you are safe, you can love, and you are loved. This active mental and physical process will start to change your heart-brain coherence, alter your neurochemical makeup, and make positive states easier to achieve.
You will also be training your heart to be open, and ready, eager to give and receive love in the world, without fear of being hurt.
If you practice this exercise, in time, you will build a brand new neural network in your mind which habituates feelings of love and openness. Try to do it for at least ten minutes for three months, as research indicates it takes approximately 66 days to form a new habit. 
As you develop heart-brain-breath coherence you will even notice that you begin to breathe this way, with an open heart without thinking about it. From there, your world experience will drastically change as you invite love, compassion and connection into your space.
 Heart-Brain Interactions – HeartMath Institute. (2015, March 2). Retrieved from https://www.heartmath.org/articles-of-the-heart/the-math-of-heartmath/heart-brain-interactions/
 How Long Does it Take to Form a Habit? Backed by Science. (2018, July 13). Retrieved from https://jamesclear.com/new-habit