Researchers at the Weizmann Institute of Science in Rehovot, Israel have built, using a system of neurons, a logical AND gate, a necessary component to build computational devices. The research may lead to computers that utilize computational properties found in the human brain.
From the New Scientist:
The gate is made from a network of neurons in a square shape approximately 900 micrometres on a side. Three of the sides form a "horseshoe" 150-micrometres wide, and packed with neurons. On the fourth side an isolated neuron island is linked to the other sides by two thinner bridges (see image, top right).
Neurons send their wire-like extensions that carry signals – axons – across those narrow bridges to the neuron island.
When stimulated with a small dose of a drug, the neurons send signals around the circuit. An ion blocker is used in the centre of the horseshoe to electrically isolate one side from the other.
By changing the width of the bridges, the researchers are able to control how many axons link to the neuron island, and tune their device to behave like an AND gate.
The neurons on the island only produce an output after receiving signals through both of the thin bridges. Like a natural system, the device transcends the performance of individual neurons – achieving 95% reliability from a collection of 40% reliable components.