They say their "mini-brain" can sense and respond to its environment.

Writing in the journal Neuron, Dr Brett Kagan, of the company Cortical Labs, claims to have created the first ''sentient'' lab-grown brain in a dish.

Other experts describe the work as ''exciting'' but say calling the brain cells sentient is going too far.

"We could find no better term to describe the device,'' Dr Kagan says. ''It is able to take in information from an external source, process it and then respond to it in real time."

Mini-brains were first produced in 2013, to study microcephaly, a genetic disorder where the brain is too small, and have since been used for research into brain development.

But this is the first time they have been plugged into, and interacted with, an external environment, in this case a video game.

The research team:

• grew human brain cells grown from stem cells and some from mouse embryos to a collection of 800,000
• connected this mini-brain to the video game via electrodes revealing which side the ball was on and how far from the paddle

In response, the cells produced electrical activity of their own.

They expended less energy as the game continued.

But when the ball passed a paddle and the game restarted with the ball at a random point, they expended more recalibrating to a new unpredictable situation.

The mini-brain learned to play in five minutes.

It often missed the ball - but its success rate was well above random chance.

Although, with no consciousness, it does not know it is playing Pong in the way a human player would, the researchers stress.

BBC