A mechanical device as small as a grain of rice is about to replace the mice. Instead of using laboratory mice to test new drug therapies, scientists will put human cells into microfabricated bioreactors that mimic how organs respond to experimental medicines. This new technology could speed up drug development, cut costs and curb false hopes. Vanderbilt University has a $2.1 million grant to develop a “microbrain” as part of a $70 million initiative by the National Institutes of Health. The overarching goal is to solve brain function mysteries related to obesity, Alzheimer’s, epilepsy and viral infections.