Triune Brain Theory and Addiction

Triune Brain Theory, Trauma and Addictions

Triune Brain Theory, Trauma and Addictions

Triune Brain Theory

The triune brain theory maps our brain's evolution and was developed by Paul D. MacLean beginning in the 60's and fully developed by his 1990 book, The Triune Brain in Evolution (Newman & Harris, 2009). Maclean was an American physician and neuroscientist who made significant contributions in the fields of physiology, psychiatry, and brain research through his work at Yale Medical School and the National Institute Mental Health (MacLean, 1998).

The triune brain theory suggests that the human brain is actually three brains in one: the reptilian brain, the mammalian brain, and the neocortex (Lambert, 2003; MacLean, 1998; Newman & Harris, 2009). The Greek term triune was chosen by Maclean for his evolutionary brain theory because it literally meant three-in-one (Lambert, 2003; Maclean, 1998). In the triune brain model, each of these three brains developed over time as the human species evolved, and each brain serves a distinct purpose in total brain and human functioning. The triune brain theory proposes that the three brains live together in the same skull and take turns dominating the others while the others serve as backup support (Newman & Harris; 2009). Each brain competes for control, and will manipulate and interfere with each other in order to achieve it. Each brain thinks it is the most important part (Lambert, 2003).

Reptilian Brain

The earliest and most primitive component is the reptilian brain, also referred to as the reptilian complex or R-complex (Lambert, 2003; Maclean, 1998; Newman & Harris; 2009). The reptilian brain is made up of the brainstem and the cerebellum, and its job is to help the body survive and maintain itself (Maclean, 1998). This is done by the cerebellum taking charge of autonomic body functions, including digestion, breathing, heartbeat, reproduction, and etc, while the brainstem handles response to stress, including a 'fight or flight' reaction. Reptilian brain behavior is automatic in nature and is very difficult to change. The reptilian brain does not reason and cannot look into the future. This is the oldest brain in terms of evolution of the three brains (Maclean, 1998).

Mammalian Brain

The next part of the brain to appear is the mammalian brain, also referred to as the limbic system or the mid brain (Lambert, 2003; Maclean, 1998; Newman & Harris; 2009). The mammalian brain consists of the septum, amygdala, hypothalamus, hippocampal complex, and cingulate cortex. According to the triune brain theory, the mammalian brain evolved after the reptilian brain and is in charge of human emotion as well as memory and other aspects of learning (Lambert, 2003; Maclean, 1998). This brain component appeared with the development of mammals and allowed attachment and emotions. If a reptile comes across its young after their birth, it may eat them. The mammalian brain allows parents to become attached to their young and helps ensure their survival into adulthood. We share this part of the brain with cats and dogs which is why they make such good pets. In short, the mammalian brain links emotions with behavior, which inhibits the reptilian brain, whose behavior is instinctual in nature (Maclean, 1998).

Neocortex

The last part of the brain to evolve was the neocortex, also referred to as the cerebral cortex or human brain (Lambert, 2003; Maclean, 1998; Newman & Harris; 2009). The neocortex takes up the most room in the skull and is found only in certain higher mammals including humans, dolphins and apes. The neocortex is responsible for higher brain functions such as reason, judgment, language, writing, abstraction and planning (Lambert, 2003; Maclean, 1998). This brain component is the newest and very human part of the brain that has allowed us to make spaceships and atom bombs, design the internet, as well as day-dream about other things while texting friends and loved ones on our smartphones. There are two areas within the neocortex, each with its own role: one area is in charge of voluntary movement, and the other processes sensory information. The neocortex is slower under pressure than other parts of the brain and when stressed can be effectively turned off leaving other more primitive parts to take over (Levine, 1997). In short, if you've ever said or done something in the heat of the moment this is what most likely happened (Lambert, 2003; Maclean, 1998).

Due to the triad nature of the brain, and the primary task of survival, a hierarchy of control exists within the structure (Maclean, 1998). The reptilian brain is the most important part of the brain, due to its primary responsibility for the continued survival of the physical body (Levine, 1997). It has the ability to override the mammalian brain and the neocortex. In situations that involve survival, the reptilian brain jumps in and reacts to the situation immediately. Left to its own devices, the neocortex would spend too much precious time thinking about the situation until it was too late. The mammalian brain also essentially overrides the neocortex. This is why, when a person is feeling an intense emotion, they will say and do extremely irrational things (Lambert, 2003; Maclean, 1998).

According to trauma and addiction specialists (Fox, 2002; Levine, 1997), the neocortex, can regain control over its more primitive parts through sustained and continuous breathing exercises. This technique provides oxygen to the three brains and delivers a message that there is no longer any danger to the reptilian brain. When this message is delivered, control can be relinquished back to the neocortex. Even so, because the neocortex is not in charge at the time of the heightened problem, experts agree this task can be extremely difficult to achieve. Deep breathing exercises are often part of contemporary trauma and addictions approaches to help the neocortex regain control by calming the instinctive driven reptilian brain (Fox, 2002; Levine, 1997).

Trauma

Although the triune brain theory is still quite controversial, it is fairly well accepted by the trauma and addictions treatment community (Fox, 2002; Levine, 1997). From of perspective of trauma, Levine (1997) suggests that the key to healing traumatic symptoms in humans is in the physiology of our triune brain. Levine (1997) proposes that the involuntary and instinctual portions of the human brain and nervous system are virtually identical to those of other mammals and even reptiles. Therefore, when faced with what