Most studies of human brain development rely on animals or on brain slices taken after death; both are useful but have limits. Brain models have been mostly two-dimensional or made with a three-dimensional gel, said Rosemarie Hunziker, program director of tissue engineering and biomaterial at the National Institute of Biomedical Imaging and Bioengineering, which funded Dr. Kaplan’s research. None of those systems replicate the brain’s gray or white matter, or how neurons communicate, Dr. Hunziker said. “Even if you get cells to live in there, they don’t do much,” she said. Dr.

Mind-controlled computing is a new field. So new, that in 2009, Emotiv Systems open-sourced their brainwave-reading headset to developers and researchers to help drive innovation. Musician Richard Warp responded to the challenge. Warp is a composer, married to a neuroscientist, who believes in creating music with your mind. Using a neuroheadset (his is an Emotiv EPOC, but there are plenty of brain-computer interfaces (BCI) on the market these days for under $100), he built a generative music system that responds to the brain signal.

Coleman and his team are developing wireless flexible electronics one can apply on the forehead just like temporary tattoos to read brain activity. "We want something we can use in the coffee shop to have fun," Coleman says. The devices are less than 100 microns thick, the average diameter of a human hair. They consist of circuitry embedded in a layer or rubbery polyester that allow them to stretch, bend and wrinkle. They are barely visible when placed on skin, making them easy to conceal from others.