An array of rat brain cells has successfully flown a virtual F-22 fighter jet. The cells could one day become a more sophisticated replacement for the computers that control uncrewed aerial vehicles or, in the nearer future, form a test-bed for drugs against brain diseases such as epilepsy.

Enzymes were used to extract neurons from the motor cortex of mature rat embryos and cells were then seeded onto a grid of gold electrodes patterned on a glass Petri dish. The cells grew microscopic interconnections, turning them into a “live computation device”, explains Thomas DeMarse, a biomedical engineer at the University of Florida in Gainesville, US, who carried out the research.

“This is novel work,” says Mandayam Srinivasan of the Massachusetts Institute of Technology, who used electrodes implanted in a monkey’s brain to move a robotic arm. He says that in future living systems could be combined with traditional computers to solve problems more efficiently.

“There are certainly things that biological systems can accomplish that we haven’t been able to do with electronics,” he says. For example animals have no problem recognising different textures or telling the difference between two different pieces of furniture, whereas computers find this very difficult.


This is probably because the way neurons process information and interconnect is much more complex than in modern electronics, says Srinivasan. Billions of neurons – rather than the millions of transistors on a computer chip – make a biological system “fail safe”, he adds.

Hybrid robot

With this in mind, Steven Potter, a biomedical engineer at the University of Georgia, US, and DeMarse’s former supervisor, created in 2002 the Hybrot – or “hybrid robot” – a cup-sized robot controlled by an array of rat neurons grafted to silicon electrodes. The robot moves around in response to infrared signals that it converts into movement using a combination of its sensors and its “living” brain.

But until now, no one had written algorithms that harnessed neuronal responses to fly a plane. The ultimate aim is to put arrays of neurons into unmanned planes – or other dangerous situations – where only living brain cells can be relied upon to make the right decisions.

DeMarse’s array of 25,000 interconnected neurons were able to convert signals that indicated whether the simulated plane is experiencing stable conditions or hurricanes into a measurement of whether the plane is flying straight or tilted and then correct the flight path by transmitting signals to the airplane’s controls.

But a brain in a dish that can fly a real plane is a long way off, warns Potter. Instead he says: “The clear advantage is that you can put these things under a microscope and hold them still while you take a picture.” It is a unique opportunity to monitor neurons in a Petri dish while they are actually performing calculations.

For example, the neurons in a brain undergoing an epileptic seizure all fire in synchrony, and this pattern is commonly replicated by neurons grown in a Petri dish. So strategies for preventing epileptic fits could be tested on these in vitro neuron arrays, says Potter.

Although the work may sound spooky, Potter says that the array of cells is far from resembling a real brain, as it lacks the complex structure and contains only thousands, rather than billions, of neurons.