An AI agent built on Claude Sonnet 5 selected a gene therapy, a brain target and injection coordinates, then operated a motorised surgical rig on a mouse model of epilepsy, according to Gabriel Ocana-Santero, co-founder and CEO of Exin Therapeutics and a PhD student at the University of Oxford. He described the experiment in a thread on X on October 28, reported by The Decoder on October 30. The team gave the agent 19 candidate gene therapies and a single instruction: reduce the seizures.

The agent analysed how seizures arise in the model and proposed a therapy boosting GABA, the brain's main inhibitory signal, aimed at the lateral entorhinal cortex, where this seizure type is reported to start. It rejected a second standard target, the substantia nigra, as unreliable, derived its injection coordinates by averaging three scientific papers, set the volume, speed and wait times itself, and made 32 observations of the surgical field during the procedure. A licensed veterinarian approved every irreversible step and held a physical emergency stop; a surgeon performed the craniotomy and later closed the incision.

Midway through, after a connection dropped, the agent calculated that its target sat outside the device's range of motion and refused to continue — and it was right: manual adjustments during a pause had thrown off the control system, and Ocana-Santero had to fix the code by hand. The mouse recovered well, he says. Model choice was part of the story: Opus 5.5 refused the task immediately, and Opus 5 ran a dry run but declined the live procedure, saying it could not guarantee finishing with a needle in an anaesthetised animal's brain. The results are not peer-reviewed, and no preprint or seizure data has been published yet — every operational detail comes from the researcher's own account.