Microfluidic worm-chip for in vivo analysis of neuronal activity upon dynamic chemical stimulations

Conventional neuronal analysis at the single neuron level usually involves culturing of neurons in vitro and analysis of neuronal activities by electrophysiological or pharmacological methods. However, the extracellular environments of in vitro neuronal analysis cannot mimic the exact surroundings of the neurons. Here, we report a microfluidic worm-chip for in vivo analysis of neuronal activities upon dynamic chemical stimulations. A comb-shaped microvalve was developed to immobilize whole animal for high-resolution imaging of neuronal activities. Using a sequential sample introduction system, multiple chemical stimuli were delivered to an individual Caenorhabditis elegans nose tip based on programmed interface shifting of laminar flows. ASH sensory neuron responses to various stimuli in individual C. elegans were quantitatively evaluated, and mutants were significantly defective in neuronal responses to certain stimulus in comparison to others. Sensory reduction in the magnitude of the response to repetitive chemical stimulation with different durations was also found. Our study explored the possibility of real-time detection of neuronal activities in individual animals upon multiple stimulations.