The Triune Brain

Before we can discuss retraining our brains to think differently in terms of recovering from something like PTSD or generalized anxiety or even transitioning from major life events like divorce, it’s important to step back for a moment and talk about the human brain.

Let’s talk for a moment about Dr. Paul MacLean and his triune brain model.  Dr. MacLean theorized that we humans didn’t have one brain; we, in fact, have three.


MacLean referred to the reptilian brain as the “R-Complex”.  “The reptilian brain, the oldest of the three, controls the body’s vital functions such as heart rate, breathing, body temperature and balance. Our reptilian brain includes the main structures found in a reptile’s brain: the brainstem and the cerebellum. The reptilian brain is reliable but tends to be somewhat rigid and compulsive.”(McGill)  The reptilian brain is not a learning center.  In other words, it doesn’t learn from mistakes.  It simply behaves instinctively.

I love how marital and sex therapist Dr. David Schnarch describes the reptilian brain in action in his book Passionate Marriage: Keeping Love and Intimacy Alive in Committed Relationships:

When prehistoric mammals’ lives were at stake, fast primitive responses served best. Unfortunately, threats to our identity and emotional security often trigger similar responses. When interpersonal pressure is high enough and we get anxious, survival reactions “hard-wired” into the reptilian and mammalian parts of your brain take control from your neocortex. Your anxiety increases your impulse to fight, submit, or run away. The more anxiety and pressure to adapt, the more this tends to occur. When this happens frequently we label it being “poorly adjusted.” Roughly speaking, the part of your brain that predominates determines the characteristics you display. When you’re severely anxious, as though your life is at stake, you behave like a reptile. Reptiles and badly frightened people have two characteristics: they have no sense of humor, and they eat their young. Relationships aren’t peaceful or stable. Although you’re responsible for what you do at such times, the notion of “choosing” is erroneous because the part of your brain that chooses (your neocortex) is no longer in control. Lessons in “fighting fair” are usually forgotten because reptiles don’t fight fair.

For learning and choosing, you need the emotional and analytical minds.  “The limbic brain emerged in the first mammals. It can record memories of behaviours that produced agreeable and disagreeable experiences, so it is responsible for what are called emotions in human beings. The main structures of the limbic brain are the hippocampus, the amygdala, and the hypothalamus. The limbic brain is the seat of the value judgments that we make, often unconsciously, that exert such a strong influence on our behaviour.” (McGill)

Schnarch goes on to explain, “When you have your anxiety under better control, you stop going for your partner’s jugular vein. You act like mammals do: you’re capable of mother-infant nurturance and pair-bonding (like geese who “imprint” on their partner)— but not intimacy or choosing someone and being chosen.”

For what differentiates humans from mammals, we need the neocortex.  “The neocortex first assumed importance in primates and culminated in the human brain with its two large cerebral hemispheres that play such a dominant role. These hemispheres have been responsible for the development of human language, abstract thought, imagination, and consciousness. The neocortex is flexible and has almost infinite l earning abilities. The neocortex is also what has enabled human cultures to develop.” (McGill)  Our ability to experience relational intimacy also resides in the neocortex. In other words, until the neocortex came on the scene, no being on the planet was capable of experiencing intimacy with another being.  Our neocortex makes it possible for us to experience intimacy.

Schnarch hits it out of the park with this:

“What we do know about intimacy is that it hinges on our capacity to make self-other distinctions. Self-disclosure involves a capacity for self-awareness, self-reflection, and complex language. In humans, all these processes are mediated by the neocortex. Intimacy is a relatively unique phenomenon within the animal kingdom— something we share with few other species (if any), and one that’s singularly sophisticated in humans. Until we evolved a neocortex, humans were not capable of intimacy.”

This is what our brain looks like.  What’s more, it is not siloed.  Our little lizard brain affects our mammalian brain, and, in turn, often determines what our very human neocortical brain will do.

Believe it or not, we have a much bigger say in how that whole song and dance goes down.

One Comment on “The Triune Brain

  1. Pingback: I’m so f*cking male – 03 – noahsmindfuck

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