Touch inhibits feeding via a neural bottleneck in C. elegans

A neural bottleneck is characterized by the projection of multiple neurons onto a smaller

number of neurons. This network architecture suggests that the information encoded in the incoming signals is compressed at the bottleneck. The nervous system of the nematode C. elegans features such a bottleneck motif. The 302 neurons that make the brain of this animal are separated into two sub-networks - the somatic and the pharyngeal networks - that are only connected by a pair of gap junctions. Sensory information, for instance mechanical stimulation, recorded at the somatic network travels through the bottleneck and suppresses the pumping motion of the pharynx. To investigate the role of this bottleneck in information coding, we supply controlled mechanical stimuli to C. elegans while observing changes in feeding behavior.

Estimating information compression requires a large amount of measurements of both the input

and output signals. Therefore, we implemented a high-throughput assay to supply substrate vibrations with tunable amplitude and frequency as mechanical stimulus while observing pumping in C. elegans populations. Using our custom image analysis pipeline ‘PharaGlow’, we can detect automatically pumping events in multiple animals moving on standard cultivation plates (Bonnard and Liu, eLife 2022). Consistent with previous studies, we find that vibrations inhibited pumping and that touch information flows through the bottleneck. We will discuss the utility of this model system to study sensory information encoding and compression.