Rotatable microfluidic device for simultaneous study of bilateral chemosensory neurons in Caenorhabditis elegans

The nematode Caenorhabditis elegans is a leading model system in genetics, development and neurobiology; its transparent body and small size make it particularly suitable for fluorescent imaging of cells and neurons within microfluidic setups. Simultaneously recording activity in bilaterally symmetric cells has proved difficult in C. elegans because the worm enters the chip and is then immobilised when it is lying on one side of the body. We developed a side-view rotatable microfluidic device that allows us to image a pair of bilateral neurons in a single focal plane of an epi-fluorescence microscope. We demonstrated the utility of the device by recording the responses of immobilised worms to controlled stimuli, focusing on the responses of two classes of head sensory neurons to changes in NaCl concentration. The results indicate that responses of ASE left and right and ASH left and right sensory neurons are stochastic. Simultaneous recordings of ASH left and right neurons tend to synchronise, pointing to a role of gap junctional connectivity. The anatomy of the C. elegans nerve ring makes this microfluidic approach ideally suited for the study of spatially extended pairs of neurons or larger neuronal circuits that lie within a limited depth of field.