This invention comprises a method for generating functional neural networks using neural progenitor cells on microelectrode arrays (MEAs). The method involves dissociating neural progenitor cells from an embryo, propagating the neural progenitor cells, passaging the neural progenitor cells and seeding the neural progenitor cells on MEAs to produce a functional neural network. The neural progenitor cells may be continuously passaged to propagate an endless supply of neural progenitor cells. The resultant passaged progenitor cell derived neural network MEA may be used to detect and/or quantify various biological or chemical toxins.