Figure 2.

MEART's brain (above) and a MEA culture dish (below). A week-old culture of ∼50 000 neurons and glia from embryonic rat cortex, growing in a MEA and forming a dense network 1–2 mm across. Fifty-nine 30 μm electrodes spaced at 200 μm intervals connect a few hundred of the network's neurons to the outside world, by allowing their activity to be extracellularly recorded or evoked by electrical stimulation.