Brain electrochemistry data does not describe actual thoughts; it certainly can’t trace thoughts to origins outside of the brain itself:
Yet thought determinism says that every aspect of the pretty lady’s perceptions and thoughts in the infinite mirror results from cause-effect physics that can be traced to yesterday, last week, last year, and ultimately to the Big Bang. Such a causal chain, however, has never been shown to exist.
Richard W. Stevens, “The Infinity Mirror Trap: Part 2: The Thought Determinism Paradox” at Mind Matters News
Here’s the first part: Why the idea that the human mind is an illusion doesn’t work. There is a simple way to test whether our thoughts are all illusions. A fatal paradox, the infinity mirror, shows that they can’t just be illusions. What causes these experiences?