Scientists in Cambridge have for the first time compared the detailed brain structures of male and female flies, identifying specific differences in nerve cell connections. This research has revealed distinctions that are believed to explain male aggression, courtship rituals, and the singing of 'love songs'.
The team mapped all 124 million nerve cell connections in a male fly's brain, building on similar work completed on a female fly two years ago. While approximately 95% of cells are shared between male and female fly brains, the remaining 5% are sufficient to drive distinct behaviours, according to Dr Isabella Beckett, a joint first author of the scientific paper published today in the Journal Cell.
These small differences in wiring can lead to significant behavioural changes. For instance, researchers identified brain circuits associated with male visual tracking during courtship, noting key differences in wiring that enhance this trait. There are also more extensive wiring differences linked to aggression, as males fight more frequently. Additionally, males possess unique wiring for producing a specific sound, or 'love song', to woo females.
The study's co-leader, Professor Gregory Jefferis of the Medical Research Council's Laboratory of Molecular Biology and University of Cambridge, described the breakthrough as "a really important new avenue in neuroscience." The research could help scientists better understand human behaviour and conditions where genetic differences affect brain wiring, such as autism and schizophrenia.