As far as I can tell, this is just a clever trick. The cultured neurons aren't really learning anything. The researchers are stimulating one side of the array (top or bottom), to indicate if the ball is above or below the paddle, and based on the ensuing response the computer moves the paddle up or down.
Here's the trick - if you stimulate a group of neurons, their spontaneous activity will be (briefly) different from an unstimulated group. You can use this fact to make it seem like the NN is learning to play pong.
It would be like claiming a network of cats can learn to play pong. I put cats in two different boxes. To tell the cats whether the ball is above or below the paddle I will spray water into one of the boxes. Then I will listen for hissing from both boxes. Based on where I hear the most hissing is the direction i move the paddle.
Here's the trick - if you stimulate a group of neurons, their spontaneous activity will be (briefly) different from an unstimulated group. You can use this fact to make it seem like the NN is learning to play pong.
It would be like claiming a network of cats can learn to play pong. I put cats in two different boxes. To tell the cats whether the ball is above or below the paddle I will spray water into one of the boxes. Then I will listen for hissing from both boxes. Based on where I hear the most hissing is the direction i move the paddle.