We have developed tools to map transposon expression in single-cell transcriptomic data and revealed that transposon expression is highly stereotypical in the brain of fruit flies (Treiber and Waddell, 2020). We now use our tools to investigate transposon expression during complex brain functions, such as the formation of new memories.

We pioneered single-cell transcriptomics in the fly brain (Croset, Treiber and Waddell, 2018) and now combine this data with the complete connectome of the fly brain. This enables us to combine information about neuromodulation of individual neurons with their wiring patterns and provides fundamentally important data for models of complex brain processes.

We have a great understanding of the brain regions that are involved in the formation of associative memories in the fly brain, but the “engram”, the collection of individual cells that are recruited during the formation of a specific memory, remains elusive. Single-cell transcriptomics of carefully designed experimental groups have shed fascinating new insights into this process (manuscript in preparation). We continue to further sharpen our tools and believe that the engram is now within our reach.

Single-animal genotyping of transposon landscapes that we conducted revealed highly complex population frequencies of many transposon insertions inside neural genes (manuscript in preparation). Transposons could therefore contribute to behavioural variability between animals. We devised crossing schemes to generate isogenic fly strains and now phenotype these strains to establish associations between specific behaviours and transposon polymorphisms.