Brain Plasticity, Part One: Your Brain Keeps Changing

A writer named Anna Kucirkova came across something I'd posted a while back about getting older and the ways we adapt as we age. I'd mentioned neuroplasticity in passing. She reached out, and what follows are the opening sections of a longer piece she put together on the subject.

Neuroscientists use the word neuroplasticity, sometimes just brain plasticity, to describe one basic fact: the brain can change and keep growing no matter how old you are. That capacity to shift matters enormously while the brain is still developing, and it has a lot to do with the sort of person each of us becomes.

Go back before the 1960s and the accepted view was different. Scientists figured the brain did its real changing early, during infancy and the childhood years, and that by the time you reached adulthood its wiring had basically set. That turned out to be wrong. We now know the brain builds fresh neural pathways and reworks the ones already there, adapting to whatever is new, laying down memories, picking up information. It does this for as long as we're alive.

The first person to question the fixed-brain idea was the psychologist William James, back in 1890. In The Principles of Psychology he wrote that organic matter, and nervous tissue in particular, seemed to have a remarkable degree of plasticity. Nobody paid much attention. His suggestion sat more or less ignored for the next several decades.

Things started moving between the 1920s and the 1960s. Researchers took a serious look at whether new pathways could form, and they tracked older patients recovering from severe strokes. Some of those patients got lost functions back, which told scientists the brain was far more pliable than anyone had assumed. Later work nailed it down further: the brain can rewire itself after it's been injured.

A few features tend to define plasticity. One is that it shifts with age. It's with us our whole lives, but particular kinds of change come more readily at particular stages.

Another is that plasticity isn't a single process. It never shuts off, and it draws on more than just neurons. Glial cells and vascular cells are in the mix too.

It also happens for two separate reasons. Sometimes it's driven by learning, by lived experience, by the forming of memories. Other times it follows damage. When an area tied to some function gets hurt, intact regions can sometimes pick up the slack, and the lost ability comes back.

Both your surroundings and your genes feed into it. The input you get from your environment, everything you sense and take in, shapes how the brain develops. Genetics plays its own part: if you're wired to learn easily, information and skills tend to stick faster.

The researchers also split plasticity into two kinds. Functional plasticity is the brain shifting a job away from a damaged spot and handing it to healthy tissue. Structural plasticity is the brain physically remaking itself in response to learning. Both can be put to use to sharpen how we think.

So much for the assumption that brain power simply drains away with time, with injury, with illness, and that there's no getting it back. I have a piece coming soon called Aging Backwards Rather Than Aging Forwards. Oddly enough, I'd already been turning that idea over in my head right around the time Anna's email landed.

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