An AI Agent Injected Drugs Into a Live Mouse’s Brain

If you give an AI agent a robotic arm, an injector, and a live mouse, it might just perform brain surgery.

Biotech founder Gabriel Ocana Santero recently did that using an agent to successfully carry out a brain injection procedure on a living mouse. Though it required some extra steps, it offers a glimpse into how AI could eventually become an active participant in laboratory research.

Santero posted about the experiment on social media and tells WIRED he was interested in exploring what happens when AI agents are given direct access to lab equipment, rather than simply being asked to design experiments or analyze results.

“We’ve realized that we need to connect these agents to a lab to get the maximum value from them,” he says. Santero is the CEO and cofounder of Exin Therapeutics, a San Francisco–based startup using AI to analyze brain activity to develop drugs for epilepsy and neurodegenerative diseases.

AI models are trained primarily on published scientific literature. That means they may miss important information about the research process, including failed experiments, unexpected observations, and decisions scientists make in real time. Integrating AI models with real-world experiments can make the models more reliable, Santero says.

It’s why his team decided to connect an AI agent to a custom-built surgical setup used for performing brain injections on mice. The rig included a motorized device used to immobilize a mouse and a camera that allowed the agent to observe the procedure, move an injection needle, and control the delivery of a compound. For the experiment, his team was testing a gene therapy to see whether it could reduce seizures in a mouse with epilepsy.

They asked the AI model to choose a treatment from 19 options in a spreadsheet. A veterinary surgeon first performed a craniotomy on the mouse while the AI agent observed. The agent selected the therapy, brain region, and injection coordinates, then controlled the robotic arms and injector needle, as well as all the parameters, such as volume and speed.

The team initially tested Anthropic’s Claude Opus 5.5 model, but it refused to guide the needle into the mouse’s brain, suggesting it might stop midway through the surgery, which could endanger the animal.

“He did the experimental planning, but when it was time to inject, he said, ‘something on my output is telling me I shouldn't do this,’” Santero says, referring to the agent. “That was very interesting.”

The team switched to using Claude Sonnet 5, which agreed to proceed. Opus is a heavy-reasoning intelligence specialist best for complex multistep problem-solving, according to Anthropic, while Sonnet is better suited for everyday tasks, though it may be a stretch to call mouse brain surgery a common chore. (Anthropic did not respond to a request for comment.)

Frontier labs have been planning for more widespread physical manifestations of AI, and researchers have already begun enlisting agents to do other things in the physical world. In August, Anthropic put out a framework for how its models can interact with the real world. More recently, AI engineers put GPT, Claude, and Grok in charge of a car to pick up lunch at In-N-Out Burger. Only one of the models succeeded.

The brain injection procedure wasn’t without hiccups either. The researchers had established safeguards, including requiring the AI to propose an injection plan for human approval and installing an emergency button a human could hit that would disconnect the rig’s motors. They also restricted the agent's access to the underlying equipment code to prevent it from modifying its own operating rules.

However, a technical glitch disrupted the equipment's coordinate system. Although the agent correctly recognized that the calculated injection position was wrong, it refused to modify the code to correct the problem because its instructions explicitly prohibited doing so.

The team resolved the issue by using a separate AI agent on Opus 5 to make the necessary code changes, but they didn’t tell the agent that a live surgery was happening. The resulting back and forth delayed the procedure, Santero says: A typical brain injection surgery like this takes about 45 minutes, while this experiment lasted slightly longer than an hour. They’re now waiting for the therapy to take effect before assessing its impact on seizures.

Despite those glitches, Santero and his team were impressed by the agent’s performance. They’re testing Grok and other models next to figure out whether one model performs better. The company is also experimenting with agent-controlled craniotomies—a much more complicated task—but wants to be absolutely sure of their safety before moving to live surgeries.

“A mistake at that stage could seriously harm the mouse,” he says.

Santero thinks AI agents will increasingly work alongside human scientists, with direct access to lab equipment. For now, he says human oversight is key, particularly when experiments involve living animals. And it’s far too soon to unleash an AI agent on a human brain.

As for the mouse, Santero reports it’s recovering well.