PT  - JOURNAL ARTICLE
AU  - Paavo Huoviala
AU  - Michael-John Dolan
AU  - Fiona M. Love
AU  - Philip Myers
AU  - Shahar Frechter
AU  - Shigehiro Namiki
AU  - Lovisa Pettersson
AU  - Ruairí J.V. Roberts
AU  - Robert Turnbull
AU  - Zane Mitrevica
AU  - Patrick Breads
AU  - Philipp Schlegel
AU  - Alexander Shakeel Bates
AU  - Tiago Rodrigues
AU  - Yoshinori Aso
AU  - Davi Bock
AU  - Gerald M. Rubin
AU  - Marcus Stensmyr
AU  - Gwyneth Card
AU  - Marta Costa
AU  - Gregory S.X.E. Jefferis
TI  - Neural circuit basis of aversive odour processing in <em>Drosophila</em> from sensory input to descending output
AID  - 10.1101/394403
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 394403
4099  - http://biorxiv.org/content/early/2020/11/04/394403.short
4100  - http://biorxiv.org/content/early/2020/11/04/394403.full
AB  - Evolution has shaped nervous systems to produce stereotyped behavioural responses to ethologically relevant stimuli. For example when laying eggs, female Drosophila avoid geosmin, an odorant produced by toxic moulds. Here we identify second, third, and fourth order neurons required for this innate olfactory aversion. Connectomics data place these neurons in a complete synaptic circuit from sensory input to descending output. We find multiple levels of valence-specific convergence, including a novel form of axo-axonic input onto second order neurons conveying another danger signal, the pheromone of parasitoid wasps. However, we also observe extensive divergence: second order geosmin neurons connect with a diverse array of 80 third order cell types. We find a pattern of convergence of aversive odour channels at this level. Crossing one more synaptic layer, we identified descending neurons critical for egg-laying aversion. Our data suggest a transition from a labelled line organisation in the periphery to a highly distributed central brain representation that is then coupled to distinct descending pathways.Competing Interest StatementThe authors have declared no competing interest.