The Chemistry Underlying Learning In Worms

Using a simple behavioral test, scientists found two neuromodulatory signaling molecules underlying non-associative learning in C. elegans.

AsianScientist (Aug. 20, 2015) – Two neurotransmitters—neuropeptide and dopamine—play distinct roles in odor learning in the nematode worm, Caenorhabditis elegans. These findings, published in Neuroscience Research, reveal the signaling pathways involved in non-associative learning.

C. elegans display non-associative learning, the simplest type of learning which does not require associating two different events together. For example, after exposure to a repulsive odor, the worms learn to ‘run’ away from the source of the odor. This can be quantified by the straight trajectory of the animal getting away from the source of the odor after an initial exposure.

To uncover the molecular signal underlying this learning process, the authors studied different signaling mutants. Neuropeptides and dopamine are chemical signals that modulate excitatory and inhibitory signalling in the neural networks of the brain.

A group of researchers from Osaka University, the University of Tokyo, and Ibaraki University found that neuropeptide mutants do not display the learned behavior of running away from the repulsive odor. Thus, the authors hypothesized that neuropeptide signaling is crucial for the learned behavior.

Furthermore, they observed that dopamine mutants display the running behavior, but execute it in an aberrant manner. After running away from the repulsive odor, the animals do an unexpected turning behavior back toward the source again. The authors hypothesized that dopamine signaling have a role in the execution of the appropriate avoidance behavior after exposure to the repulsive odor.

This research advances our understanding of non-associative learning in the model organism, C. elegans. This group’s results are expected to lead to the understanding of mechanisms for learning and memory in higher animals.

The article can be found at: Yamazoe-Umemoto et al. (2015) Modulation of Different Behavioral Components by Neuropeptide and Dopamine Signalings in Non-Associative Odor Learning of Caenorhabditis elegans.


Source: Osaka University.
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