Pigment Dispersal Factor Signaling Regulates Threat-Reward Decision-Making In Caenorhabditis Elegans

Animals often encounter conflicting sensory information in complex and changeable natural environments.Taking risks,animals will get rewards,but get punishments.Avoiding risks,animals will avoid getting punishments,but lose the chance to get rewards.Therefore,in a conflict environment,animals are in a dilemma and need to weigh the advantages and disadvantages before making a decision,which is called threat-reward decision-making.Threat-reward decision-making is necessary for animals to survive and thrive,and to adapt to environmental changes.Studying the molecular and neural circuit mechanisms of threat-reward decision-making is helpful to understand how animals make decisions in a conflict environment.Caenorhabditis elegans(C.elegans)is a good model animal due to the simplicity of the nervous system and the amenability to genetic manipulations.Previous studies have shown that threat-reward decision-making is regulated by neuropeptide signaling in C.elegans.There are more than a hundred genes encoding neuropeptides in C.elegans,so it is worth investigating more extensively.By using behavioral analysis,gene rescuing,RNAi,calcium imaging,and neuronal manipulation,the molecular and neural circuit mechanisms of diacetyl-copper ions threat-reward decision-making regulated by pigment dispersion factor(PDF)signaling in C.elegans were studied.Pigment dispersal factor PDF-1 acted on pigment dispersion factor receptor PDFR-1 in RIM interneurons to regulate threat-reward decision-making.When C.elegans moved to the copper ring,diacetyl concentration was increased,which would inhibit RIM interneurons and decrease turning probability.When C.elegans moved away from the copper ring,diacetyl concentration was decreased,which would activate RIM interneurons and increase turning probability.PDF signaling may promote neurotransmission in the neural circuit of AWC^ON-AIB-RIM by enhancing the response of RIM interneurons to diacetyl stimuli,which would increase the probability of risk-taking decision.