Dissection of a sensorimotor circuit underlying pathogen aversion in C. elegans.

Area of Science:

• Neuroscience
• Behavioral Biology
• Computational Biology

Background:

• Altering animal behavior is crucial for defense against pathogen exposure.
• Pathogen colonization can alter intestinal physiology and trigger aversive behaviors in Caenorhabditis elegans.
• The neural pathways linking pathogen-sensing neurons to avoidance behaviors are largely unknown.

Purpose of the Study:

• To investigate the neural circuitry underlying learned pathogen avoidance in C. elegans.
• To identify the specific neurons and pathways involved in pathogen-averse locomotion.
• To understand the mechanisms of reflexive aversion to pathogenic bacteria.

Main Methods:

• Utilized C. elegans as a model organism.
• Performed functional assays and whole-brain simulations.
• Employed genetic analysis focusing on TRPM channels.
• Leveraged the C. elegans connectome for circuit discovery.

Main Results:

• Backward locomotion was identified as a component of learned pathogen avoidance.
• Chemosensory neurons, including AWB olfactory neurons, mediate reflexive aversion to bacteria like Pseudomonas aeruginosa and Enterococcus faecalis.
• A novel sensorimotor circuit involving olfactory neurons, interneurons, and motor neurons was uncovered, controlling backward locomotion for aversion.
• Intestinal distention and TRPM channel expression were implicated in the avoidance response.

Conclusions:

• A complete sensorimotor circuit for learned reflexive aversion has been identified.
• This research highlights the utility of computational modeling and connectomics in discovering neural regulators of behavior.
• The findings provide a foundation for understanding how neural circuits govern learned avoidance behaviors.