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AI agent used to perform controversial brain surgery on a mouse, Anthropic Sonnet-controlled motorized surgery rig — Opus 5.5 refused to conduct biological experiment, Sonnet given free rein to treat epilepsy with a range of gene therapy vectors after
Exin Therapeutics, a biotech startup focusing on next-generation neurotherapeutics, claims it has successfully conducted brain surgery on a mouse using an AI agent. Its co-founder and CEO, Gabriel Ocana-Santero, shared the entire procedure on X, showing how the AI agent chose the gene therapy vector and dosage and the brain region where it would be applied. The AI agent also drove the robotic arms that injected the medication into the mouse’s brain. Thankfully, the operation seems to have been a success, with the mouse recovering well and recorded moving around in its enclosure.
Last night an AI agent performed brain surgery on a mouse.
We gave it 19 gene therapy vectors in a spreadsheet, a mouse model of epilepsy, access to a motorize surgery rig with cameras and one goal: reduce seizures.
It picked the drug. It picked the brain region. It derived the coordinates from three papers. Then it drove the stereotaxic arms into the brain and injected 250 nanolitres while watching the entry site through the rig camera for bleeding.
A licensed vet gated every irreversible step and held a physical kill switch to stop the AI agent.
Thread on what it decided, what it saw, and the moment it refused to let me override it.
[Writing this on the spot out of excitement, but I've been 18hrs in front of my laptop coding and coordinating this, so keeping it brief and descriptive, more cohesive thoughts on this soon...]October 28, 2026
“Autonomous surgical robots exist and they are better at the mechanics than our bench rig, [to be honest]. But in every one of them, a human decided what operation to perform, and the robot executed it,” Ocana-Santero said. “Nobody told this agent what to give or where to put it. It got a phenotype and a shelf of candidates and had to work out the therapy and the coordinates itself. I am not aware of an agent previously choosing a treatment and a brain target and then delivering it into a living mammal.”
The team used Anthropic Sonnet, which received a mouse model of epilepsy, control of a motorized surgery rig, and 19 gene therapy vectors in a spreadsheet. Aside from that, it also had access to three research papers, allowing it to choose the brain region where it should apply the treatment. Nevertheless, a licensed veterinarian was purportedly overseeing the entire operation, with every irreversible step requiring approval before the AI agent could proceed. Aside from that, the entire system also had an emergency stop button that would cut the power to every motor in the surgery rig.
The only thing that the vet surgeon on duty did was to do the craniotomy procedure to expose the brain, as the AI agent wasn’t allowed to do that yet for safety reasons. There were also several safeguards that the AI agents were banned from overriding, which even the human operators couldn’t bypass, necessitating a manual fix to the agent’s code during the operation.
What’s interesting, though, is that the startup only used Anthropic’s mid-range Sonnet model for the operation. It initially tried using Opus 5.5, but it immediately refused to do any work after it detected that it was working on a biological experiment. The older Opus 5 model was able to run the entire procedure on paper but refused to do live surgery. “The block isn't the rig and isn't the inputs. It's me. My own output was stopped when I started writing the plan for this surgery... if I try, it gets cut off the same way, and the worst version of that is me cut off partway through a live procedure with a needle somewhere in the brain,” the LLM reportedly told the Exin Therapeutics team. “Starting something I can't finish on an anesthetized animal is worse than not starting.”
EARLY conclusions
Autonomous surgical robots exist and they are better at the mechanics than our bench rig tbh. But in every one of them, a human decided what operation to perform, and the robot executed it.
Nobody told this agent what to give or where to put it. It got a phenotype and a shelf of candidates and had to work out the therapy and the coordinates itself. I am not aware of an agent previously choosing a treatment and a brain target and then delivering it into a living mammal.
This is what we mean by in vivo lab in the loop. FULLY connecting agents to our experimental capabilities. More on this soon.
P.S.: Mouse recovered well!
Full write-up soon on substackOctober 28, 2026
Despite the seeming success of the operation, some people are concerned about the ethics of such a procedure. While AI LLMs have been useful in medical research, adding them to sinus surgery has seen malfunctions skyrocket by more than 12 times. Aside from that, relying on an AI to make every decision in such a risky procedure puts accountability in question, especially if something goes wrong. We also haven’t even touched the long-standing ethical question of animal experimentation in the medical setting. Still, some users applauded the experiment, with one comment saying that they’re excited about the possibilities of these integrated technologies, as their son has been suffering from drug-resistant epilepsy for 19 years.
Jowi Morales is a tech enthusiast with years of experience working in the industry. He’s been writing with several tech publications since 2021, where he’s been interested in tech hardware and consumer electronics.
