Sex-based differences in learning require the production of two male-specific neurons in the brain of the nematode Caenorhabditis elegans, reports a study published in this week’s Nature. In most organisms, sex-specific differences in behaviour extend to cognitive-like processes such as learning, which can aid reproductive success, but the underlying neural mechanisms have remained unclear.
The nervous system of C. elegans has been studied extensively, but Arantza Barrios and colleagues demonstrate the existence of a previously unknown pair of neurons, which they call MCMs (mystery cells of the male), in the head region of male C. elegans. These neurons arise upon sexual maturation from specialized cells called glia, and the authors use salt-avoidance experiments to show that they are essential for a male-specific form of learning that balances sensory behaviour with reproductive priorities. For instance, the authors find that in the presence of mates, MCM neurons in male worms condition them to prioritize sex over food.
These findings link developmental and anatomical sex differences in high-order processing areas of the brain to sex-specific behaviour during learning, thereby helping to shed light on the neural basis of sex differences in behaviour.