JournalPublicationResearch NewsSensory Systems

Aversive bimodal associations differently impact visual and olfactory memory performance in Drosophila

The photograph depicts an instant in the sensory scene of a representative vinegar fly while inside the training tube of the T-maze apparatus described in our study. The cylindrical copper-lined tube receives illumination from custom-made LED contraptions that emit lights of two different wavelengths – blue (452 nm) and green (520 nm). Upon contact with the positive and negative gridlines of the copper, the fly experiences an electric shock of 90V alongside the stimulus that is simultaneously presented. Once trained, flies are tested for their ability to remember the paired associations in a two-choice assay.

Animals form sensory associations and store them as memories to guide behavioral decisions. Although unimodal learning has been studied extensively in insects, it is important to explore sensory cues in combination because most behaviors require multimodal inputs. In our study, we optimized the T-maze to employ both visual and olfactory cues in a classical aversive learning paradigm in Drosophila melanogaster. In contrast to unimodal training, bimodal training evoked a significant short-term visual memory after a single training trial. Interestingly, the same protocol did not enhance short-term olfactory memory and even had a negative impact. However, compromised long-lasting olfactory memory significantly improved after bimodal training. Our study demonstrates that the effect of bimodal integration on learning is not always beneficial and is conditional upon the formed memory strengths. We postulate that flies utilize information on a need-to basis: bimodal training augments weakly formed memories while stronger associations are impacted differently.

Thiagarajan, D.; Eberl, F.; Veit, D.; Hansson, B. S.; Knaden, M.; Sachse, S.: Aversive bimodal associations differently impact visual and olfactory memory performance in Drosophila. iScience 25, 105485 (2022) Link