Several approaches have taken advantage of neuronal morphology as a means of modelling synaptic connections. The Campenot chamber, formed with a plastic divider affixed to a glass slide by silicone grease, sections of areas of culture while allowing axons to project through a series of channels created in a collagen layer11,12. More recently, approaches using soft lithography have produced more precisely defined channels and compartment structures13,14. These microfluidic devices have enabled studies of axonal injury15–17, axon pathfinding18 and cellular migration19. They have also been utilized to investigate synaptogenesis20 and circuit connectivity21–24. A compartmentalized model of synaptic competition has been devised allowing the study of differences in individual neurons by chemically treating one chamber and performing synapse counting in another22. Axon diodes have also been created as a means of providing directionality in circuit models23. Renault et al. have demonstrated the use of optogenetics and calcium imaging as tools to evaluate neuronal communication in a compartmentalized device21. These approaches have provided a proof of concept for microfluidics as a strategy to compartmentalize culture in brain circuit studies, but thus far they
