Role of synaptic phosphatidylinositol 3-kinase in a behavioral learning response in C. elegans

How the worm changes its tastes In associative learning, you link potentially unrelated things because you are exposed to them at the same time. Ohno et al. studied a simple associative learning task in the nematode worm Caenorhabditis elegans. They presented the worms with a taste substance while withholding food. After starving in the presence of the taste substance, the animals switched their behavior from being attracted to the taste to finding it aversive. A specific isoform of the insulin receptor is critical for this type of associative learning—at least in worms. Science, this issue p. 313 Calsyntenin-dependent activation of insulin-PI3K signaling in the synaptic region governs associative learning. The phosphatidylinositol 3-kinase (PI3K) pathway regulates many cellular functions, but its roles in the nervous system are still poorly understood. We found that a newly discovered insulin receptor isoform, DAF-2c, is translocated from the cell body to the synaptic region of the chemosensory neuron in Caenorhabditis elegans by a conditioning stimulus that induces taste avoidance learning. This translocation is essential for learning and is dependent on the mitogen-activated protein kinase–regulated interaction of CASY-1 (the calsyntenin ortholog) and kinesin-1. The PI3K pathway is required downstream of the receptor. Light-regulated activation of PI3K in the synaptic region, but not in other parts of the cell, switched taste-attractive behavior to taste avoidance, mimicking the effect of conditioning. Thus, synaptic PI3K is crucial for the behavioral switch caused by learning.