[
International Worm Meeting,
2021]
A neural circuit in the brain processes sensory stimuli such as an odor to elicit a motor command. To understand the mechanism of such a sensory processing, a number of studies have sought to identify a neural circuit which processes a specific sensory stimulus (functional neural circuit). For identification of a functional neural circuit, it is required to conduct two types of experiments throughout the brain: 1) locating neurons that respond to the stimulus, and 2) identifying their cell types (cell-IDs) to estimate their connectivity based on anatomical connections. Locating stimulus-responsive neurons can be achieved by whole-brain calcium imaging, which record all neuronal activities throughout the brain. However, due to the lack of way to efficiently identifying cell-IDs, it has been difficult to identify a complete functional neural circuit with whole-brain imaging and cell identification. To overcome the limitation, the method for cell identification of all neurons, called NeuroPAL, was developed in C. elegans (Yemini et al., Cell, 2020). Together with the connectome information as well as the records of all neuronal activities, we are now able to estimate a functional neural circuit based on cell-IDs of stimulus-responsive neurons. To identify a complete functional neural circuit by integrating those techniques, we established a whole-brain imaging system combined with efficient cell identification system using NeuroPAL. This system consists of a 3D confocal microscopy, a multi-color imaging system, a microfluidic device, and a pipeline of an image analysis (Chronis et al., Nat. Meth., 2007; Wen et al., eLife, 2021). By using this system, we successfully recorded activities of most head neurons simultaneously with an information of each cell-ID. Now we are identifying a set of odor-responsive neurons using this system with stimulation by a repellent odor 2-nonanone (Kimura et al., J. Neurosci., 2010). This study aims to identify a complete functional neural circuit for specific sensory processing pathways and it may provide clues for how a sensory stimulus is processed in the whole of a neural circuit. We thank Ev Yemini and Oliver Hobert for the help on NeuroPAL.