Short story about a teenager who has his brain replaced with a microchip (Psychological Horror)

There was a short story I read as a kid (between 2007 and 2009) about a world where people were raised from a young age with a microchip implanted in their skull which was trained over time to simulate the brain.

At some age, they would have their flesh brain tossed out in favor of the chip. But a month before the surgery, the chip would be set out of sync mode (so that it wasn't being corrected anymore based on how the flesh brain behaved).

Well, in this short story, the chip is set out of sync mode and this teenage kid then starts to realize that he can't control his actions. It starts with him disagreeing with his own choice of what fruit to buy at the supermarket.

So basically, the kid we listen to across the story is the consciousness that resides on the chip. He realizes this.

Then the surgery happens and the flesh brain is removed, and the chip is put in control.

Anyway, I don't remember the ending, but I remember I loved the story and it scared the hell out of me as a kid.

Existential, psychological terror is probably the best way to describe it.

Do you know what book has this story in it? Do you know what story this is?

Internet searches come up with nothing. I'm searching my house because I swear I don't remember tossing out this book.

Answer

I don't have my copy of Axiomatic on hand to verify, but this sounds a lot like "Learning to Be Me" by Greg Egan.

I was six years old when my parents told me that there was a small, dark jewel inside my skull, learning to me be.

_{Opening line of "Learning to Be Me"}

In the story, everyone has a neural implant called a "jewel" inserted into their brain at birth. The jewel trains itself to perfectly predict the actions of the human brain.

By the time one reaches adulthood, the jewel's simulation is a near-perfect predictor of the brain's activity, and the jewel is given control of the person's body while the redundant brain is discarded. In this way, people with the jewel can eliminate the cognitive decline associated with aging by implementing their minds on a machine. Also, by transplanting the jewels into cloned bodies genetically altered to develop without brains, they can live youthfully forever.

"Learning to Be Me" explores the consequences of a man's jewel failing to synchronize with his brain.

_{source: Axiomatic article on Wikipedia}