Comparison of male and female fly brains is unlocking the secret workings of the mind by sex

Amazing stuff! This is huge! Mind boggling!

"An international team ... has mapped every neuron in the male Drosophila fly’s brain and nerve cord, to produce a wiring map of the 166,700 neurons and the millions of connections between them. ...

Since the female Drosophila fly brain has previously been mapped, involving the same group, this new work allowed the researchers to directly compare male and female connectomes and pinpoint differences between them.

This revealed that neurons can reroute sensory information into sex-specific behavioural circuits to drive different male and female responses to the same stimuli.

For example, male flies detect the smell of another male fly and respond with aggressive behaviour, whereas female flies respond to the same smell with courtship behaviour. ...

This is the first full-scale connectome of an adult animal’s brain and nerve cord ever produced. The entire dataset now exists as a public resource, openly available as a reference and tool for other researchers. ..."

From the highlights and abstract:

"Highlights

• Whole male Drosophila CNS connectome enables sensory-to-motor circuit analysis

• First synaptic-resolution comparison of male and female brains

• Sex-specific and dimorphic neurons concentrate in higher-order, integrative centers

• Analysis of visual, auditory, olfactory, and taste pathways reveals shared principles

Summary

Sex differences in behavior exist across all animals, typically under strong genetic regulation. In Drosophila, fruitless/doublesex transcription factors identify dimorphic neurons, but their organization into functional circuits remains unclear. We present the connectome of the entire Drosophila male central nervous system. This contains 166,700 neurons spanning the brain and nerve cord, fully proofread and annotated, including fruitless/doublesex expression and 11,710 neuron types.

We provide the first comprehensive comparison between male and female brain connectomes to synaptic resolution, finding 8,069 isomorphic, 138 dimorphic, 289 male-specific, and 71 female-specific types.

This resource enables analysis of full sensory-to-motor circuits underlying complex behaviors and the impact of dimorphic elements.

Sex-specific/dimorphic neurons are concentrated in higher brain centers, while the sensory and motor periphery is largely isomorphic.

Within higher centers, male-specific connections are organized into hotspots defined by male-specific neurons or arbors. Dimorphic neurons reroute information across sexes."

Comparison of male and female fly brains is unlocking the secret workings of the mind | University of Cambridge "Scientists have produced the first full scale wiring map of a male adult animal’s brain and nerve cord, enabling unprecedented insights into how the brain works and controls behaviour."

5 amazing visuals show how the male fruit fly’s brain map is advancing neuroscience "A years-long project by HHMI Janelia, Google Research, and collaborators has built the first complete brain map for a male fruit fly, a key model organism in science."

Sexual dimorphism in the complete Drosophila male central nervous system connectome (open access)

Graphical abstract

Figure 1 A densely annotated and cross-matched male CNS connectome

Figure 2 Information flow from sensory input to motor output organizes circuits spanning the brain and nerve cord

Figure 3 Sexual dimorphism in the fly brain