Or is that unrelated ? I guess what I’m wondering is are we able to produce more and more complex reasoning as we age despite the fact that our prefrontal cortex only shrinks as time goes by ?
In: Biology
My understanding was that most of the *growth* happened as a child and teen years, and much of adolescence and young-adult hood (up to the age of ~25) is the *pruning* of the brain to make it more efficient.
I was told tat this pruning process mostly starts at the back of the brain, and works it’s way forward, so your prefrontal cortex is the last part to be adjusted in this manner.
We could presume from this that your innate potential for complex reasoning and planning grows more advanced until the age of ~25, and then plateus.
However, your actually ability to plan will still depend on other mental factors, like the knowledge and skills you have.
Your ability to conduct complex reasoning and plans depends on both the state of your prefrontal cortext, and things you have learnt, and improving either has the potential to improve your complex reaosning.
Alright, imagine your brain is like a construction site. The prefrontal cortex is the boss overseeing rational thinking. Now, at around age 25, the boss stops expanding the site, but that doesn’t mean the workers (your brain) can’t keep building and improving. While the boss doesn’t grow, the workers can still get better at complex tasks, so you can continue to develop more complex reasoning skills even if the boss isn’t expanding anymore.
In simple terms:
The brain is like a building that is already being used while it’s still being built. At some point, the walls and roofs are finished, so the construction workers can leave, but you still can spend years furnishing the place. Later in life, the walls begin to crumble, the roofs leak, your furniture becomes unusable from water damage, and then you have to close off whole rooms.
In the very beginning, the space for rational thinking is just an area marked off on the foundation plate. Within the first 5 years, walls and a temporary roof are added quickly, so you get a small corner to use for rational thinking. This then grows over the next 20 years, making space for some furniture until the walls and roof are finally finished, and you have your first complete set of cheap IKEA furniture. If all goes well, at that age you don’t act childish and rash anymore. You now have all the facilities to act like a rational adult. After that, just like in life, you work on your furniture. Rearranging it with experience, buying nicer pieces, hanging some pictures of events you learned from, and so on.
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BTW, this is the reason that in many countries, you’re not a full adult at 18 in the eyes of the law, but can be judged as a teen. Your brain isn’t yet that of a fully formed adult, expecting you to act like one would be foolish. Usually, the end of that phase is at 21, when you are expected to have a brain that’s developed enough to at least follow the law and suppress your intrinsic behaviour.
It not growing doesn’t mean it starts shrinking, though as a commenter below shows, there is a loss with age. The PFC isn’t fully formed until our 20’s, so younger people have a more difficult time weighing pros and cons and seeing the potential consequences of their behaviour.
Edit: being better
The prefrontal cortex is the last part of the brain that becomes white matter instead of just grey matter. It is the last part of the brain that gets upgraded by becoming myelinated.
The idea that the brain is ‘done’ developing at 25 is largely a pop culture misunderstanding of the science. Your brain never stops developing and adapting (a concept known as ‘neuroplasticity’) throughout your life. Granted, not at the same speed as when you are younger.
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