Before the memristor, it would have been impossible to create something with the form factor of a brain, the low power requirements, and the instantaneous internal communications. Turns out that those three things are key to making anything that resembles the brain and thus can be trained and coaxed to behave like a brain. In this case, form is function, or more accurately, function is hopeless without form. [...]
A memristor is a two-terminal device whose resistance changes depending on the amount, direction, and duration of voltage that’s applied to it. But here’s the really interesting thing about a memristor: Whatever its past state, or resistance, it freezes that state until another voltage is applied to change it. Maintaining that state requires no power. That’s different from a dynamic RAM cell, which requires regular charge to maintain its state. The upshot is that thousands of memristors could substitute for massive banks of power-hogging memory. Just to be clear, the memristor is not magic—its memristive state does decay over time. That decay can take hours or centuries depending on the material, and stability must often be traded for energy requirements—which is one of the major research reasons memristors aren’t flooding the market yet. [...]
A biological brain is able to quickly execute this massive simultaneous information orgy—and do it in a small package—because it has evolved a number of stupendous shortcuts. Here’s what happens in a brain: Neuron 1 spits out an impulse, and the resultant information is sent down the axon to the synapse of its target, Neuron 2. The synapse of Neuron 2, having stored its own state locally, evaluates the importance of the information coming from Neuron 1 by integrating it with its own previous state and the strength of its connection to Neuron 1. Then, these two pieces of information—the information from Neuron 1 and the state of Neuron 2′s synapse—flow toward the body of Neuron 2 over the dendrites. And here is the important part: By the time that information reaches the body of Neuron 2, there is only a single value—all processing has already taken place during the information transfer. There is never any need for the brain to take information out of one neuron, spend time processing it, and then return it to a different set of neurons. Instead, in the mammalian brain, storage and processing happen at the same time and in the same place.
That difference is the main reason the human brain can run on the same power budget as a 20-watt lightbulb. [...]
To build a brain, you need to throw away the conceit of separate hardware and software because the brain doesn’t work that way. In the brain it’s all just wetware. If you really wanted to replicate a mammalian brain, software and hardware would need to be inextricable. We have no idea how to build such a system at the moment, but the memristor has allowed us to take a big step closer by approximating the biological form factor: hardware that can be both small and ultralow power. [...]
http://spectrum.ieee.org/robotics/artificial-intelligence/moneta-a-mind-made-from-memristors/0
