Zoom 2 – The Limbic System, and where the Self might come from

You have definitely pored over the question (to differing extents) “Who am I?” Well, look no further than this over-simplified science post to find an answer to that question.

A vital part of you necessary to answer that question is the limbic system – a not really well-defined collection of different parts of your brain. It was first described in 1952.

The limbic system is the home to your memories (hippocampus), smell (piriform cortex), and emotions and motivation and learning (don’t make me choose a specific area, but do know the amygdala, nucleus accumbens, and orbitofrontal cortex (+more) are involved).

It’s been suggested to drop the term limbic system, because, well, it doesn’t do justice to what it truly is. “Limbic” is Medieval Latin for “border” – and the problem is, that it seems to really hard to pin down a border between the limbic system and the rest of the brain. At first, it was said that the limbic system is responsible for emotions, and the rest of the neocortex for cognition. But there can be no cognition without access to what we have learned – which is part of the limbic system. Furthermore, the areas included in the limbic system have often changed, due to advances in neuroscience. Why stick to a definition that obviously isn’t suited?

As I’ve already touched upon, the limbic system is responsible for emotions, memory, learning, motivation – so essentially collecting all the different life experience data points that are unique to YOUR life, and evaluates them. The way in which you’ve learned something therefore will ALWAYS be unique. And those past lessons learned determine, which new experiences you will collect and be able to evaluate in the future.

Your experiences make you even more “you” than before, a feedback loop that will continue for your entire life.

So, there it is! Finally, THE question has been answered, and all it took was a little more than 300 words. If only you’d known it would be this easy.

Commentary:

Paul MacLean first described the limbic system. He was also the man who brought us the “Triune” theory which describes the brain as a kind of Russian Matroschka doll: humans have a reptile brain, covered by a mammal brain, covered by a monkey-brain. You might have heard of the theory. Carl Sagan was so enamored with the idea, that he wrote an entire book about it (“The Dragons of Eden”). I beg you now, please forget this theory. (For a better explanation of “Why?” than I could ever give, stop by @thebrainscientist and read his blog post on why you don’t have a reptile brain. IT’S SO WELL-WRITTEN.)

 

Please keep in mind, I am a learning and memory researcher. Few things are more deeply engrained in my circuits and algorithms. So, if you ask me what makes you “YOU”, I will always say “what you have lived through, and what it has taught you”. Therefore, in my humble opinion, the limbic system has a lot to answer for when it comes to the self. It’s a personal theory I often touch upon, and probably will write about a lot more extensively in the future.

 

It’s divided into cortical (outer layer of the cerebrum (front part of brain), subcortical (below the cortex) and diencephalic (interbrain) areas.