Abstract Behavior varies even among genetically identical animals raised in the same environment. However, little is known about the circuit or anatomical origins of this individuality. We show individual Drosophila odor preferences (odor-vs-air and odor-vs-odor) are predicted by idiosyncratic calcium dynamics in olfactory receptor neurons (ORNs) and projection neurons (PNs), respectively. Variation in ORN presynaptic density also predicts odor-vs-odor preference. The ORN-PN synapse appears to be a locus of individuality where microscale variation gives rise to idiosyncratic behavior. Finally, simulating microscale stochasticity in ORN-PN synapses of a 3,062 neuron model of the antennal lobe recapitulates patterns of variation in PN calcium responses matching experiments. Our results demonstrate how physiological and microscale structural circuit variations can give rise to individual behavior, even when genetics and environment are held constant.

Neural correlates of individual odor preference inDrosophila