Some tiny clusters of brain cells grown in a lab dish are making big news at this week's Society for Neuroscience meeting in San Diego.

Known as "minibrains," these rudimentary networks of cells are small enough to fit on the head of a pin, but already are providing researchers with insights into everything from early brain development to Down syndrome, Alzheimer's and Zika.

At a Sunday press conference at the neuroscience meeting, researchers said minibrains are helping them figure out how the Zika virus can disrupt human brain formation in the early stages of fetal development.