Cover: Multiregional Brain-on-a-Chip in vitro model. Neurons (green) from different brain regions (here prefrontal cortex, left, and amygdala, right) are restricted to distinct areas, but are connecting controllably to the other brain region through axons which are guided by microcontact printed lines. This is a zoom in image from the entire brain-on-a-chip model, which consists of three brain regions. This multiregional brain-on-a-chip is electrically active and reacts to drug applications in a brain region dependent way. Astrocytes are labelled in red. The smallest distance between the different brain areas is 1 mm. From Dauth S, Maoz BM, Sheehy SP, Hemphill MA, Murty T, Macedonia MK, Greer AM, Budnik B, Parker KK. Neurons derived from different brain regions are inherently different in vitro: a novel multiregional brain-on-a-chip. J Neurophysiol 117: 1320 –1341, 2017; doi:10.1152/jn.00575.2016.