The primitive brain, also known as the reptilian brain was the first one to emerge in the evolutionary theory of human beings. It is the oldest part of the brain structure and is responsible for the basic survival functions, such as breathing, heart rate, body temperature, and spatial orientation. It is also known as the reptilian brain because it is similar in architecture to the brainstem of reptiles. Its goal is to make sure we stay alive and reproduce. Because it regulates the survival mode of the human species it cannot be reprogrammed and its survival functions will always take precedence over other brain activity. For instance, when you hold your breath (a prefrontal cortex activity), the primitive brain will take over to make you breathe again.

Through specific training we are able to increase our resistance to breathe, but inevitably we give in and take a breath. Such threats to our survival are first addressed by the primitive brain and take precedence over other brain functions:

The primitive brain consists of:

• Brain stem: The brain stem sits above the spinal cord and has many connections between them. The brain stem, the most primitive part of the brain, is made up of the medulla, pons, cerebellum, midbrain, hypothalamus, and thalamus. It is the body's autopilot that carries out vital functions of the body for maintenance and survival such as breathing, the heartbeat, and blood pressure. It also controls vomiting, coughing, sneezing, and swallowing.
• Cerebellum: The cerebellum, or little brain, is the second largest region of the brain and it is located behind and below the cerebrum and at the back of the brain stem, attached to the midbrain. The cerebellum is responsible for movement and coordination,walking, posture, reflexes, and eye and head movement. It coordinates subconscious movements such as balance and coordinated movement and is constantly receiving updates about the body's position and movement. It also sends instructions to our muscles that adjust our posture and keeps our body moving smoothly.

The primitive brain is the seat of the autonomic response, as well as the seat of habits. It connects us to our external world through our skin, our pores, and our nerves. It controls what impulses get recognized and passed along to the two higher levels. This brain learns through imitation, avoidance, and repetition until something becomes habitual. Information usually enters at this point without our conscious awareness. We can make much of this information conscious and use it to our benefit, as biofeedback and hypnosis have shown us.