New Neurons Discovered in C. Elegans
Caenorhabditis elegans worms have two sexes: hermaphrodite and male. Hermaphrodites, the best studied, have just 302 neurons, but males have more — the MCMs raise their total to 385 neurons1.
NHGRIIn a species whose neural circuits have been comprehensively mapped, researchers at University College London and their colleagues have identified a new type of neuron. These glia-derived neurons, which researchers dubbed “mystery cells of the male,” or MCMs, are tied to sex-specific learning in the roundworm Caenorhabditis elegans. Researchers reported their finding in Nature last week (October 14).
Finding a new set of neurons in a well-studied system “is a bit of a shock,” study coauthor Richard Poole of University College London told Nature News, which noted that the team next plans to explore MCMs’ roles in brain sex differences and in learning. (See “Sex Differences in the Brain,” The Scientist, October 2015.)
Sex differences in behaviour extend to cognitive-like processes such as learning, but the underlying dimorphisms in neural circuit development and organization that generate these behavioural differences are largely unknown. Here we define at the single-cell level—from development, through neural circuit connectivity, to function—the neural basis of a sex-specific learning in the nematode Caenorhabditis elegans.
We show that sexual conditioning, a form of associative learning, requires a pair of male-specific interneurons whose progenitors are fully differentiated glia.
These neurons are generated during sexual maturation and incorporated into pre-exisiting sex-shared circuits to couple chemotactic responses to reproductive priorities.
Our findings reveal a general role for glia as neural progenitors across metazoan taxa and demonstrate that the addition of sex-specific neuron types to brain circuits during sexual maturation is an important mechanism for the generation of sexually dimorphic plasticity in learning.
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