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Unlearning the Triune (3-part) Model of the Brain - It's a Myth?!


Originally posted on Rise to Resilience.

"Change is the end result of all true learning." - Leo Buscaglia

I first learned of the triune, or three-part, model of the brain when researching Adverse Childhood Experiences and Resilience which became the original Rise to Resilience presentation.

Since then, I encountered the triune brain model regularly: Conscious Discipline uses it as a foundational concept. Dr. Dan Siegel's Hand Model of the Brain and the "flipping your lid" analogy. And in Community Resilience Initiative's training series, it was also a core component.

About two years ago, someone on a Facebook post attempted to correct my misbelief in the triune model. I dismissed it. Twice in the last year, a close friend shared with me evidence of the model being debunked, and I dismissed that too. It was when I received an email from Community Resilience Initiative (CRI) explaining their shift away from the triune brain model and towards the work of Dr. Lisa Feldman Barrett that I met my cognitive dissonance with curiosity. Dr. Feldman Barrett's work was that which my friend had tried to introduce me in recent months.

When I read CRI's email, I was ready to integrate this new (un)learning. Or at least start exploring more, anyway. Rather than allowing my confirmation bias to direct my exploration of the triune model being a myth, I led with my desire to learn. I am not writing this post to detail what several articles in the next paragraph do, but rather to model the learning process I have had over the last two months. I invite you to explore the coming links to inform your own learning, too.

I dove into Dr. Feldman Barrett's 7 and 1/2 Lessons About the Brain and really needed no more convincing. I didn't want to take "one" neuroscientist's word for it though, since I felt like that was what got me so attached to the triune brain model (it was initiated by just one person's theory, after all). So I looked some more and found reinforcement from sources such Your Brain is Not An Onion with a Tiny Lizard Inside and Rethinking the Reptilian Brain. As I reopened tabs and revisited search history to write this post, I also discovered an article from earlier this month by Dr. Feldman Barrett on Nautilus, unpacking three myths about the brain.

I had integrated the triune brain model into much of the work with caregivers and educators. It felt irresponsible to continue to perpetuate this myth once I learned that it had been long-debunked. So what to do instead? First, I sought advice on PACEs Connection. I considered what other aspects of neuroscience I could incorporate: NICABM's Window of Tolerance, infographics and media from the Center on the Developing Child at Harvard University, a variety of content from Trauma Geek and the Therapist Neurodiversity Collective, and finally a 3D Model of the Brain to support focusing on the functions of different parts of the brain.

While it's been uncomfortable to navigate the cognitive dissonance that (un)learning initiated, I am excited to be better informed than I was before and more prepared to navigate supporting children, their families, and educators.

Have you (un)learned something recently that challenged you?

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@Mike Ritter thank you for your thoughtful response; it has me reflecting more deeply both regarding what you said and Rick's response.

Personally, I believe that it is unethical for me to continue using the model knowing what I know now. This might be a stretch for some, and that's OK. One of my main concerns is that it is doing a disservice to myself and others (and potentially is harmful in ways I don't intend nor could measure) to continue to use the model, especially if I am not incorporating newer understandings and ensuring that updated information is being shared. There's a fine balance between ensuring that we create accessibility in content so that one need not be a neuroscientist to understand it and not doing so in an oversimplified way that perpetuates misinformation. This is speaking to how I felt when I started paying attention to the idea that the triune model was "wrong" or outdated - that I had been misinformed and perpetuating misinformation.

Some resources that I didn't directly link to but speak to epigenetics include https://developingchild.harvar...o-child-development/ , , and

Mike - Thank you for the kind and supportive approach to sharing your thoughts.  Your compassionate response was encouraging.

There are two quotes that come to mind. β€œAll models are wrong, but some are helpful” and β€œVariation is the norm!” So, I say this in the spirit of those two quotes.

The same events that are helpful for some, are harmful for others and vice versa. That is the reality of variation in the human experience. The triune brain model can be helpful to many, and it has been helpful.  However, when the model falls short, it has consequences.  Many times the consequences hit hardest on those that are outside the β€œnormal purview”.

I would love to have an extended conversation about the consequences in some educational messages surrounding the triune brain. Especially those messages regarding the interaction of the three parts of the brain to regulate emotions.  However, I will use this post to support your ideas regarding the helpfulness of understanding Epigenetics.  Science tells us that there are close to 20,000 protein coding genes and the few billion combinations that are represented in human variation.  This pales in comparison to the nearly 100 billion neurons in the brain and the 200 trillion connections they represent.  Yes! our DNA kicks off the show, but it is our experiences that are responsible for the change in gene expression.  They are also responsible for the vast other wiring changes that occurs from conception to death.

You raised a good question about the brain stem and the beating of the heart.  Your DNA may code the blood circulation system, yet our experiences impact that system tremendously.  I am not sure that science would say that only the neurons found in the brain stem are responsible for heart-rate variability. A complicated process of chemicals and sparks of energy between neurons sends the message to one another to regulate that process.  Variation would suggest that it is not the same subset of the 200 trillion connections that does it the same way for everyone.  It is certainly not met with the same outcome.  We know that our heart-rate increases when we are excited as well as when we are anxious.  That bears witness to variation in physical and emotional responses.  

In short, variation in physical, emotional, and cognitive responses are a part of the human experience. That variation causes some to be further helped by models like the triune brain and some to be further harmed. A recognition of this may not allow us to β€œdo no harm” but it can certainly assist with our ability to β€œhasten to help”.

It is important for folks engaging in this work to view themselves as students of trauma and that means being critical consumers of information. So I appreciate this conversation being put out here; as well as the various resources.

I have taken some time to review the links you provided Melissa. To me, overwhelmingly, it seems that what has been debunked about the triune model here is that it doesn't fit as an evolutionary theory of brain development. Sharks, mice, lizards, and humans all have brain stems, limbic systems, and cortices. There was no linear progression from one to the next over time. This conclusion appears overwhelming from what I can see.

But beyond that I wonder if other conclusions made are a bit overstated. For example, I understand that each brain part is responsible for many things.  That is, each neuron fires for multiple reasons, to serve multiple purposes. And this is (what I figure) creates neural networks. So perhaps something like the triune model simplifies the functions of each organ of the brain. In reality, each part is more robust. But does that mean the brain stem is suddenly not responsible for beating our hearts and regulating body temperature? Sure, maybe some part of the cortex is involved too - and that is important from a neuroscience perspective - but it doesn't negate the idea that perhaps the brain stem is a bit more specialized in this manner. Am I off here?

So I guess my overall conclusion is that maybe the triune model may still serve some purpose educationally, but not evolutionarily.  I suspect the people using it in training programs are not presenting on evolution.

Another thing I didn't see at all in these resources is any discussion of epigenetics. If the triune model doesn't work as a theory of evolution, it must, in part, be because of epigenetics. I might suggest to this crew The Epigenetics Revolution by Nessa Carey.

Finally, I am not sure any of this changes the overall approach. Does moving away from the triune model then also move us away from the notion that healing takes place in the context of healthy relationships over time? I should think not. Having safe therapeutic relationships, and creating safe, compassionate spaces and communities still seems like the end game to me, regardless of conclusions about the triune model of the brain.

@Rick Griffin - I am looking forward to the conference this year! I registered as soon as I learned of it (and was able to submit a request for Professional Learning funds...thank you Head Start!)

I am also hoping to loop into your and @Theresa Barila's CRI trainings again in the future to both refresh and learn from how these new insights are being incorporated.

Grateful for the work that each of you, and CRI as a whole, continue to do!

Hi Melissa,

Thank you for your efforts to raise awareness of this new material. Cognitive dissonance is the right terminology to use, indeed!! When Rick and I started working on this, my first reaction was, oh my gosh, we have to re-do our curriculum, our materials, our learning, oh my! It felt at first like an impossible goal to set our sights on, but we knew we had to, we owed it to ourselves and our commitment to science and practice-- and to those who entrusted us with their interest in our work. Kudos to you.  I love your challenge: unlearn something, it stretches your brain and soul! Thank you.

Melissa, thanks for your courage to post this information. I also wanted to thank you for acknowledging CRI's role in bringing this issue to you.  I am excited to see what type of response you receive from your post.  The response in our training programs has been fabulous.

My rallying cry has been The Science of Trauma: Know it before you blow it! While many think there is no harm in continuing with the triune brain theory, I counter that by stating. "without an accurate understanding of what the brain's job is and how the brain is doing its job, mistakes in strategy implementation will ensue. " Unfortunately, the consequences of those mistakes often impact marginalized populations.

Please keep up the good work.

PS - I hope you get the opportunity to attend CRI's annual conference.  It promises to be a great one!


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