It's the mystery of the brain: How do billions of cells conspire to create memory, reason and desire? To pick apart how a network of neurons functions, researchers at the California Institute of Technology have created a hybrid of living cells and silicon they call the "neurochip."

The device consists of 16 wells etched from silicon. Each contains an electrode and is just big enough to hold a single neuron from a rat brain. Axons can grow out and establish connections to the other cells in the array. To study the neurons' complex group behavior, researchers can stimulate any cell and then monitor the electrical responses of the rest of the network. Physicist Jerome Pine, who created the neurochip with postdoc Michael Maher, says that such a neurochip-type device could ultimately serve as a hi-fi interface to a living nervous system; a chip implanted in the brain would replace electrodes taped to the scalp as a way to send and receive signals.