Sexual dimorphism in the complete connectome of the Drosophila male central nervous system

Stuart Berg
Isabella R Beckett
Marta Costa
Philipp Schlegel
Elizabeth C Marin
Aljoscha Nern
Stephan Preibisch
Wei Qiu
Shin-ya Takemura
Andrew Champion
Reed A. George
Gary Huang
William Katz
Christopher Ordish
Ken Hayworth
Eric Trautman
Vivek Jayaraman
Wyatt Korff
Geoffrey W Meissner
Sandro Romani
Jan Funke
Christopher Knecht
Stephan Saalfeld
Louis Scheffer
Scott Waddell
Gwyneth Card
Carlos Ribeiro
Michael B. Reiser
Harald Hess
Gerry Rubin
Gregory S.X.E. Jefferis
bioRxiv (2026)

Abstract

Sex differences in behaviour exist across all animals, typically under strong genetic regulation. In Drosophila, fruitless/doublesex transcription factors can identify dimorphic neurons but their organisation into functional circuits remains unclear.

We present the connectome of the entire Drosophila male central nervous system. This contains 166,691 neurons spanning the brain and nerve cord, fully proofread and annotated including fruitless/doublesex expression and 11,691 types. We provide the first comprehensive comparison between male and female brain connectomes to synaptic resolution, finding 7,205 isomorphic, 114 dimorphic, 262 male-specific and 69 female-specific types.

This resource enables analysis of full sensory-to-motor circuits underlying complex behaviours and the impact of dimorphic elements. Sex-specific/dimorphic neurons are concentrated in higher brain centres while the sensory and motor periphery are largely isomorphic. Within higher centres, male-specific connections are organised into hotspots defined by male-specific neurons or arbours. Numerous circuit switches reroute sensory information to form antagonistic circuits controlling opposing behaviours.

(Full author list included with the paper.)
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