Adolescence: Mind Altering times

In short: Teen’s brains go through huge changes as the prune synapses through adolescence.

Around the 1990’s, the verdict was still out on whether your mind finishes fundamental changes after the age of 3. Since brain imaging has allowed amazing and interesting insight… and this.

A bulldogs brain scan. Source:

Why 3 years old?

Early brain research was focused entirely on monkeys. They established that as an infant you have a huge humber of synapses and their connections. Throughout early years there is consistent connections and pruning of connections (synaptogenesis). By around age 3 this behaviour stopped to occur at the same rate. As such, the assumption was that this would be similar in a human.

The problem was that most of the monkeys studied passed sexual maturity around age 3, do not have the same social structure and developmental stages that humans do.

An early studied sought to prove this by comparing postmortem brains across all ages of humans. This showed consistent structural and material differences across ages:

An example — not from the same study. Source:

Two things were different. The area of neurons themselves, Grey Matter, decreased in the prefrontal cortex. Regions that transfer electrical signals, White Matter, increased.

The implication here is that White Matter “speed up processing” in the brain and hence and adults brain has gone through optimisation, by reducing unnecessary connections of synapses and replacing them with fast lanes to the important stuff!

After the age of 20 there was no significant difference in healthy brains of adults.

Okay, cool. So what?

  1. “it casts doubt” that your babies’ brains need formal education, milestones and stimulation to grow good brains.
  2. Teens aren’t just hormonal
  3. Teen brains may be more susceptible to impact than adult brains — think drugs, social pressures, etc.

This was written from Sarah-Jayne Blakemore’s article “Development of the social brain in adolescence” from “What’s next? Dispatches on the future of science” - 2009.

Recently I began reading this book of science essays that were meant to assess the future. Seeming it is 10 years since the book was published, I thought it may be interesting to revisit these. Here the focus was on neurons and empathy.

Founder of and Product Owner @ dunnhumby; just genuinely interested in a lot of things. Built racecars, built electronics, now building software

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