Here we describe and test a novel microfluidic local perfusion chamber for visualizing and manipulating synapses. Importantly, neurons can be cultured within microfluidic chambers for 3 weeks and longer. Both excitatory and inhibitory neurons inhabit the chamber (Figure S1). Furthermore, we demonstrate that we can organize neuronal connectivity between dissociated hippocampal neurons, resulting in the orderly organization of axons and dendrites in parallel rows distal from their cell bodies. The addition of a microperfusion channel that runs orthogonal to the dendrites and axons allows the spatially and temporally controlled addition of various drugs, transmitters etc. The dendrites present in the microgrooves can be readily imaged using Ca2+-indicators and presumably other dyes. As a proof of principle, we demonstrated that the μLP chambers can be used for synapse-to-nucleus signaling. We showed that local dendritic exposure caused increases in local as well as somatic calcium using live calcium imaging and that dendritic stimulation with spaced glutamate increased phospho-CREB in somata over massed stimulation. Lastly, we showed that DHPG applied to discrete (<50 μm) synaptic regions caused increases in Arc transcription within the nucleus and increased Arc mRNA targeted to the perfused dendrites.
