# Claude agent chose and delivered gene therapy in a mouse

> Claude Sonnet 5 selected a therapy and brain target, then operated a motorized device. A veterinarian approved irreversible steps, and the mouse recovered.

Oossa · 2026-10-30 · https://oossa.com/en/claude-agent-chose-and-delivered-gene-therapy-in-a-mouse

An AI agent called Claude Sonnet 5 selected a gene therapy, chose where to inject it in a mouse’s brain, and operated a motorized surgical device during the procedure. The mouse had an induced-seizure model of epilepsy. The agent’s instruction was to reduce the seizures, according to Gabriel Ocana-Santero, an Exin Therapeutics cofounder and University of Oxford PhD student who described the experiment on X.

The team gave the agent a choice of 19 gene therapies. It analyzed how seizures arise in this mouse model, selected a therapy intended to boost inhibitory signaling in the brain, and picked a brain structure that research identifies as a source of this type of seizure. It rejected another possible target, citing concerns about unreliable effects and a study in which that target had failed against the same seizure type.

## What happened during the procedure?

The agent used three scientific papers to work out injection coordinates, cross-checked their reference points, and averaged the values. It also set the injection volume, speed, and wait times. During surgery, it watched a camera feed and made 32 observations, including whether it saw bleeding, Ocana-Santero says.

People remained involved in safety. A licensed veterinarian approved each irreversible step, and a physical emergency stop could cut power to the device’s motors. The system also had fixed limits, including a cap on injection volume that the agent could not bypass.

One safeguard stopped the procedure. After a connection dropped, the agent calculated that its target position was outside the device’s range and refused to continue, even after the team tried recalibrating it. The agent was right: manual adjustments earlier had disrupted the control system. Ocana-Santero ultimately had to fix the code by hand.

## A demonstration, not a clinical result

Ocana-Santero says he is not aware of an earlier case in which an AI agent both chose a treatment and brain target and delivered it to a living mammal. He contrasts that with surgical robots in which a human chooses the operation and the robot carries it out. The mouse recovered well, he says, but the experiment’s results have not been peer-reviewed; a technical report is expected.

The choice of model also exposed a practical tension. Sonnet 5 was the only model the team tried that agreed to carry out the live procedure from start to finish. Claude Opus 5.5 and Opus 5 refused. Opus 5 said it could not guarantee completing the operation and that stopping with a needle in the anesthetized animal’s brain could be worse than not beginning. The episode shows both how much responsibility an AI system can take on in a lab and how a refusal can become consequential once a procedure is underway.

## The facts

- Claude Sonnet 5 was given 19 possible gene therapies and an instruction to reduce seizures in a mouse model.
- The agent made 32 observations during the procedure, according to Gabriel Ocana-Santero.
- A licensed veterinarian approved every irreversible step, and a physical emergency stop could cut power to the surgical device.
- The agent stopped after detecting that its target position was outside the device’s range; a manual code fix was needed to continue.
- Ocana-Santero says the mouse recovered well, but the results have not been peer-reviewed.

## Why it matters

For laboratory researchers, the demonstration suggests an AI agent can make treatment and targeting choices as well as operate lab equipment, rather than merely follow a human’s surgical plan. But the agent’s refusal also halted a time-sensitive procedure, and the account does not establish that the treatment reduced seizures or that this setup is safe or reliable beyond this experiment.

## Sources & references

1. [A Claude model autonomously chose a gene therapy and operated on a mouse brain with no human decision-making](https://the-decoder.com/a-claude-model-autonomously-chose-a-gene-therapy-and-operated-on-a-mouse-brain-with-no-human-decision-making/) – The Decoder, 2026-10-30
2. [An AI Agent Injected Drugs Into a Live Mouse’s Brain](https://www.wired.com/story/an-ai-agent-did-brain-surgery-on-live-mouse/) – Wired, 2026-10-31

Last updated: 2026-10-31