Why are some people smart, but others aren’t (brain chemistry-wise)?

Brain speed, if reduced to its physical mechanisms, is how fast an action potential (an impulse of electric charge) travels through and from neuron to neuron.

This is how neurons talk to each other; and neurons need to talk to each other, for example, when your eye needs to tell your brain what it is seeing, and then your brain needs to tell your hands what to do.

It all takes time.

As we know, our brain is based on electricity and chemicals, but the main form of base communication between neurons is indeed these electric impulses.

It is well accepted that the main modulator of the speed of these impulses is what we call a myelin sheath (a kinda fatty, rolled-up blanket around the neuron’s neck). It’s sort of like how your laptop charger cable has a layer of plastic or rubber around it to insulate it.

Neurons are often slender and also benefit from insulation. What actually happens is that the charge, when along a properly insulated neuron, jumps along the neuron faster (the term for this is “saltatory conduction”, where “saltatory” is based on the Latin for “leap” in English).

Neuroscientists often see it via a hose analogy — if you have more layers of protection around a water hose, the water can travel faster without much loss.

The caveat, or complexity, with neurons, is that you need to leave some unprotected spaces just in case you need to use that space as a place to send an initial message to the neuron.

As I see it, the spaces also are the places where the charges subsequently domino and correspond (they’re used as stepping stones to leap across a river, for example).

So myelin sheaths benefit the neuron the thicker and more plentiful they are. Although, there must remain places open at intervals. These open places are called Nodes of Ranvier, a really sexy name. On the whole though, more myelin means more speed.

Now we’ve been talking on the singular neuron level. We must not forget that neurons operate in vast networks of millions. Let’s say you need to get from one end of a city to another. You should just take a straight road plus little a shortcut for the quickest path.

But if you haven’t trained a lot to know about this shortcut, you may meander and take a longer time, make some errors and wrong turns. Similarly, in terms of networks, speed can also be greater affected by how reinforced and trained the network is.

More practice and more data will naturally lead to a greater repository of approaches to choose from, and logically the brain would follow the most energy-efficient one.


So, is the brain speed difference between people?

Yes, different by nature marginally and all else environmentally.

On the myelin level, small increases can add up. Some people say you should eat fish, or nuts, or whatever, to increase myelin coating. Only a rigorous scientific study can say for sure.

But on the network level, we can see these differences on greater timescales. Give a child who has been consistently practicing addition and multiplication problems a list of these sorts of problems. Their network for solving these types of problems is optimized.

We will almost surely see that the speed of their completion, on average, would be faster than a child that isn’t dealing with these sorts of situations.

But clearly, on average, this is a matter of training your neural pathways, not anything largely innate. There may be a few genetic differences in the ability for myelination or perhaps the step size for neuron-weight updating, sure; however, we can see that brain speed is highly susceptible to practice in specific domains.

A person who quickly can think of a sentence in English may not be able to read emotions as quickly — it just depends on what they’ve trained in the years and in their recent memory until that moment.

So, people definitely aren’t constitutionally equal in brain speed. Although, we could dispel a notion of intelligence as a static speed constant. Oftentimes, all it takes is practice (sometimes a lot of practice), and the results can be surprising.

One example: learning Chinese was eternally hard for me. Recently, I had less than 2 weeks to learn what most people would spend 30 weeks on during the school year (two levels of Chinese).

I spent most of my waking time training on these words and recognizing subtle differences in the Chinese characters. There were diminishing returns that farther I got (burnout), but my ability to quickly recognize characters generally increased to a level never had before.

Now I’m super amazed with how my brain automatically recognizes characters with greater ease.

I don’t credit myself because I’m just so surprised. We credit the wiring up there in my head (also maybe my parents, my childhood teachers for fostering that?).

I wish I could just communicate the feeling I had to people: that if something seems too impossibly hard, it often won’t after a while. In fact, because it seemed so hard before makes it all the much more rewarding.

Now, we didn’t need a neuroscience degree to feel this, but since we can explain it, we can more confidently generalize it to other parts of life.

  • therefore


Tips for speed differentiation:

  1. Build more myelin and speed increases.
  2. Optimize task pathways through practice and speed increases more significantly.


Thanks for reading

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