SHOW NOTES

The Rumor

The rumor starts with your audience and their shrinking attention spans.  The last thing they want is to hear is your message, and they’re going to defy you to entertain them.  The reptilian brain represents the most primitive region of your brain and (maybe) you’ve heard it acts as some kind of a filter for the decision making process.  I started hearing this idea pop up in interviews and in a book or two I’ve read over the years, and I started to wonder whether there’s really any truth to it.  And, you have to admit, whether you’ve heard this concept or not, it certainly conjures up a great mental image.

According to the original theory, the reptilian brain (or R-complex) is an evolutionarily conserved region of the brain that’s responsible for the most basic of functions and instincts.  It makes up the brain stem and basal ganglia and, according to some people, it’s the region of the brain you’re supposed to be targeting.

And, to be blunt, it wants to tune you out.

It’s looking for reasons to ignore you, and the only way to impress it is if you startle it.   But, take heart.  If you can get your message past it, you stand a fighting chance of having your ideas sent up to higher regions of the brain for processing.

Very well then.

Enter Dr. Paul D. MacLean.

 

 The Theory

The triune brain theory was proposed by MacLean (1913-2007) in the 60’s.  MacLean believed the brain essentially evolved in three layers – the so called reptilian brain, the paleomammalian brain (the emotional brain, sometimes still referred to as the limbic system) and the neo-mammalian brain (the neocortex, responsible for cognitive thought).  Despite its popularity with the general public, it’s not clear to me whether this model was ever really widely accepted by the scientific community, and that’s not a good sign.

 

Some Support

So, we’ll start with some good news.  There doesn’t seem to be much debate that the human brain evolved…from something.  At least I could find some amount of collective agreement on that.

Rather, the issue appears to be exactly when certain features of the brain evolved.  As it turns out, those reptiles (and mammals) may not have been quite as primitive as MacLean first thought.

I’ll get back to that in a moment.

 

Decisions Made Easy (Sort of)

So, how does the brain arrive at a decision?  After all, this is what this Vit Review is all about.  At the heart of the matter, we are talking about an audience making a decision to read, watch, listen to or buy something that you’ve produced.  Does that pesky reptilian brain force them to hit the “back” button before you’ve finished communicating your message?    What kinds of roles do the neocortex and emotions play?  Are these regions always in opposition?

These were some of the questions I had and, as it turns out, these are not easy questions to answer.

The concepts of either a top-down system (where cognitive thought overrides emotions to come to a rational decision) or a bottom-up system (where emotions show up to hi-jack that rational process) have both been heavily criticized for being too simplistic.  We now know that there are likely multiple systems and networks in place when your brain makes a decision.  These are tied to memories and experiences, which are tied to your body’s response when it experiences something (e.g. an increase in heart rate, the hairs on the back of your neck stand up, something brought you to tears, etc).  You experience something, your brain searches for some kind of memory of having experienced it in the past and the reaction you had to it and, voilia, a decision is made.

If that sounds easy, it isn’t.

And, the more I read, the more MacLean’s reptilian brain isn’t really factoring into the process… at least not the reptilian brain that MacLean envisioned.

Confused?

So was I.

As it turns out, some regions of the brain stem may indeed be involved in emotional processing and decision making.  What this means for MacLean is that his reptiles may not be so primitive after all.  In fact, they might just be capable of feeling many of the things higher mammals (including you and I) feel.  And, for me, this is where this little rumor starts to unravel.

The problem with figuring out exactly how other species feel is that feelings are generally subjective.  But, even though you can’t ask a crocodile how he’s feeling today, reptiles indeed have all the neural substrates (as humans) needed to feel…something.

There’s no reason to believe that croc wouldn’t tell you his day sucked if he could communicate that to you.

Even though I’m starting to have some problems associating MacLean’s theory with your audience’s reptilian brain,   I don’t want (for a second) to make it seem as though I’m belittling MacLean’s contribution to brain evolution.  It isn’t at all uncommon to see theories and models put through the paces by other scientists and updated (or rejected) as new information comes to light.

Today, there seems to be some relevance and use for MacLean’s model in addiction medicine, but criticisms of the model (by other scientists) aren’t hard to find.  What remains unclear to me is how this theory evolved (pardon the pun) from MacLean’s original triune model to a situation where the reptilian brain acts as some kind of filter for everyday decisions.  I was unable to find any clear source where MacLean himself suggests this, although I did come up with one reference where he seems dismayed that emotions are capable of hijacking logical thinking.  This isn’t proof (in my mind) that he ever suggested these three brains were always working independently and/or that they constantly opposed one another.

Maybe I’m missing something.

 

Other Criticisms

MacLean’s model suggests that the neocortex is responsible for language and, therefore, only primates (particularly humans) are capable of this kind of communication.  However, some creatures in the animal kingdom prove to be a little challenging. Birds, in particular, seem to reap havoc all over MacLean’s model.  Their brains, although looking very different from our own, possess regions that are believed to be responsible for the production and learning of song.  Apparently, song may be to birds what speech is to humans.  It’s passed down through generations and can be picked up by other birds of the same species.  Not unlike living in Paris so you can learn French.

Okey dokey.

 

Wrapping Up

The truth is that, the more I read, the further I ventured away from MacLean’s reptilian brain and the theory that you need to shock your audience into listening to you.  I was left with a brain that uses several regions to process emotions (regions that don’t necessarily jive with MacLean’s model) and a brain that uses multiple networks to arrive at decisions.  While it seems emotions can definitely factor heavily in decision making (particularly in addiction), I’m left with the feeling that the concept of a reptilian brain is best left in the past.    So, next time you have a message to get across, grab yourself a coffee, craft a great story and make your audience feel something.

Fear, in particular, will work quite nicely.

And, you might do yourself a favor and forget about trying to apply MacLean’s reptilian brain to your message.

I know I have.

 

REFERENCES:

Bechara, A.  (2004). The role of emotion in decision-making:  Evidence from neurological patients with orbitofrontal damage.  Brain and Cognition, 55, 30-40.

Damasio, A., & Carvalho, G.B.  (2013). The nature of feelings:  Evolutionary and neurobiological origins.  Nature Reviews (Neuroscience), 14, 143-152.

Duzel, E., & Guitart-Masip, M. (2013).  Not so uncertain at last:  Locus coeruleus and decision making.  Neuron, 79, 9-11.

Frank, M. J., Cohen, M. X., & Sanfey, A.G.  (2009). Multiple systems in decision making – A neurocomputational perspective.  Current Directions in Psychological Science, 18(2), 73-77.

Gupta, R., Koscik, T.R., Bechara, A., & Tranel, D.  (2011). The amygdala and decision-making.  Neuropsychologia, 49, 760-766.

Holden, C.  (1979).  Paul MacLean and the triune brain. Science, 204 (4397), 1066-1068.

Katahira, K., Suzuki, K., Kagawa, H., & Okanoya, K.  (2013).  A simple explanation for the evolution of complex song syntax in Bengalese finches.  Biology Letters, 9, 20130842.

Newman, J., & Harris, J.C. (2009).  The scientific contributions of Paul D. MacLean (1913-2007).  The Journal of Nervous and Mental Disease, 197 (1), 3-5.

Reiner, A.  (1990). The triune brain in evolution.  Role in Paleocerebral functions (by Paul D. MacLean).  Review by Anton Reiner.  Science, 250 (4978), 303-305.