There is poor correlation between different scans of even the same person’s brain, experienced researchers say:
At one time, we were told that, one day, machines will read our minds. But, now researchers say, the more we know about the brain (set aside the mind for a moment), the more reasons we have for doubt:. …
Our minds read things but it doesn’t follow that we can read our minds. We can’t even read brains. Which is not the same thing.
News, “Why brain activity doesn’t reveal our minds” at Mind Matters News
Further reading:
We will never “solve” the brain. A science historian offers a look at some of the difficulties we face in understanding the brain
How far has AI mindreading come? Further than we may think. And some trends are troubling
and
Elon Musk’s myths about the mind. According to Musk, everything in the brain is an electrical signal. That’s pretty naive