The idea that brains differ between people isn’t new. Neither is the fact that the brain’s answer to new experiences is to change the connections between its neurons. For two things that sound almost like common sense, there’s, however, an impressive amount of details to consider.
Just how different are brains really? They all have the same regions and the same cell types and the big picture scaffolding is remarkably similar, but the fine-grained structure is where the snowflakes emerge. Why though? Part of that might be because our experiences are so different.
Our central vision, for example, is exposed to a very rich and quite individualized stream of information. In other words, each of us sees lots of different things in everyday life. If experience shapes the brain, it’s only logical to assume that the neural systems responsible for central vision should also be quite individual.
To test that, a new study in the Journal of Neuroscience compared a group of healthy participants and one of people with macular degeneration (a condition that affects central vision while sparing most of the periphery). They asked whether people who lose the same type of visual input, but adapt to it in their own ways show more variability in their visual cortices too?
But first, the researchers needed a way of measuring how “individual” a person’s visual cortex actually is. Their solution was to use functional connectivity: the pattern of coordinated activity between the visual cortex and the rest of the brain. They then measured individuality by asking how similar that pattern was between people. If two people have very similar patterns, their brains are, in this particular sense, less idiosyncratic. If the patterns differ, they are more individual.
As a baseline, the scientists first looked at the healthy participants and compared the “individuality” of the cortex representing central vision (which is more often used for attention-demanding tasks) with that of the cortex representing peripheral vision (less attention-demanding). Individuality was higher in the central vision area.
In people with macular degeneration, they could extend the test one step further by comparing a random peripheral region with the peripheral region that had become a sort of replacement for the damaged central vision area. If experience does indeed drive variability, the latter should show higher “individuality”, just as the central region does normally. And that’s exactly what the researchers found.
Now, what exactly does that tell us? The findings are consistent with the idea that experience might indeed leave a personal mark on the way our brains are organized. But it doesn’t mean that experience directly caused these changes or that every brain responds to experience in a completely unique way. What it does suggest is that two people adapting to the same problem may arrive at slightly different neural solutions, different patterns of functional connectivity. And that could eventually matter for treatment: if brains adapt differently, perhaps rehabilitation should take those individual differences into account rather than assuming that one approach will work equally well for everyone.
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Further reading
Demirayak, P., Fleming, L. L., Stewart, P., Chua, R., & Visscher, K. M. (2026). Increased attentive use is linked to more idiosyncratic functional connections. Journal of Neuroscience, 46(36), e2178252026.