A group of scientists at Reading University in the UK have developed a robot that is controlled by rat neurons. In case you're wondering why anyone would take rat brain cells and stuff them in a robot, the answer is simple: to learn more about the human brain, how it works and potentially make progress in the battle against degenerative diseases such as Alzheimer's.
In order to create the rat robot brain, scientists perform the following according to a New Scientist article:
the neural cortex from a rat fetus is surgically removed and disassociating enzymes applied to it to disconnect the neurons from each other. The researchers then deposit a slim layer of these isolated neurons into a nutrient-rich medium on a bank of electrodes, where they start reconnecting. They do this by growing projections that reach out to touch the neighbouring neurons.
Then, the neurons are controlled with electrical stimuli. How the neurons respond then tells the researchers which areas to stimulate to create a certain reaction, like avoiding an obstacle.