A memristor is a device that, like a resistor, opposes the passage of current. But memristors also have a memory. The resistance of a memristor at any moment depends on the last voltage it experienced, so its behaviour can be used to recall past voltages.

Now memristors are being used in a US military-funded project trying to make brain-like computers, says Wei Lu, who led the team at the University of Michigan in Ann Arbor that demonstrated the new behaviour

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Memristors lend themselves to the task because the way that their resistance gives a glimpse of an earlier voltage is analogous to the way that a synapse’s electrical behaviour is dependent on its past activity.

Lu and colleagues have now provided the first demonstration that the analogy stands up. What’s more, their memristors were built with materials already used in the manufacture of computer chips.

Lu’s team used a mixture of silicon and silver to join two metal electrodes where they cross. The junction mimics a particular behaviour of synapses that allows neurons to learn new firing patterns, and is believed to allow memories to be stored.

In the brain the timing of electrical signals in two neurons affects the ease with which later messages can jump across the synapse between them. If the pair fire in close succession, the synapse becomes more likely to pass subsequent messages between the two.

Read more at New Scientist

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