"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. Kaplan?s team found that a spongy silk material coated with a positively charged polymer could culture rat neurons, a stand-in for gray matter. By itself, silk did not encourage neurons to produce axons, branches that transmit electrical pulses to other neurons."

http://www.nytimes.com/2014/08/12/he...tion.html?_r=0

Spinal Cord next?
It would be nice to speed up the research we need.

Paolo