This is just amazing: Lab monkeys with chips implanted in their brains have been able to guide prosthetic arms to do what looks like fairly complicated activities--i.e., bringing food to their mouths and releasing it to eat. It's a crazy new step in the understanding of mind-body dualism (this illustration, from Descartes, represents an early stab at sorting it all out)--a physical object picking up what we think of as metaphysical impulses. Here's how it works:

[I]nside the monkeys’ skulls, the scientists implanted a small grid, about the size of a large freckle. The grid sat on the monkeys’ motor cortex, over a patch of cells known to signal arm and hand movements. It held 100 tiny electrodes, each connecting to a single neuron, its wires running out of the brain and to a computer.

The computer was programmed to analyze the collective firing of these 100 motor neurons, translate this sum into an electronic command and send it instantaneously to the arm, which was mounted flush with the monkeys’ left shoulder.

Really significant applications for paralysis victims, the incredibly lazy, and mad scientists.

--Britt Peterson