The synaptic basis for sexual dimorphism in the invertebrate nervous system

Abstract

Many animal behaviors are manifested differently in the two sexes of a given species, but how such sexual dimorphism is imprinted in the nervous system is not always clear. One mechanism involved is synaptic dimorphism, by which the same neurons exist in the two sexes, but form synapses that differ in features such as anatomy, molecular content or fate. While some evidence for synaptic dimorphism exists in humans and mammals, identifying these mechanisms in invertebrates has proven simpler, due to their smaller nervous systems and absence of external regulation by sex hormones. This review aims to present the current status of the field in invertebrates, the available toolkit for the study of synaptic dimorphism, and the standing questions that still remain incompletely answered.

Highlights

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  Genetic sex can govern neuronal wiring decisions in worms and flies.

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  Some behavioral differences between the sexes have a synaptic origin.

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  The molecular architecture of synapses can affect behavioral dimorphism.

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  The field will flourish when comparative connectomes for more species are completed.