Sexual Dimorphisms in the Nervous System of the Nematode Caenorhabditis elegans

Throughout evolution, sensory information is processed by the opposing sexes into distinct sexually dimorphic behaviors. At the level of the nervous system, the cause of these dimorphic behaviors remains largely unknown. Dimorphism may result from differential structural or signaling properties of the neuronal network. The nematode Caenorhabditis elegans is an ideal model to explore the genetic control of neuronal sex differences and the sexual regulation of the nervous system and behavior. The male and hermaphroditic nervous systems of C. elegans contain the same set of 294 neurons, but each sex also has its own set of sex-specific neurons. Comparisons of the C. elegans connectome between both sexes have revealed a striking dimension of sexual identity: specific neurons have sexually dimorphic synaptic connectivity. Here we review studies that try to elucidate how shared neuronal circuits are modulated to process sensory information in a sex-specific manner.