In this project we investigate which sensory stimuli Drosophila larvae can learn. By establishing extensive behavioural tests, we analyse the rewarding and punishing properties of these stimuli and the persistence of established memory forms.
Project
For more than 50 years, Drosophila melanogaster has been used as a model system to study associative odour learning and memory. Initially, Drosophila was used as an organism that allowed easy access to genes. In recent decades, however, more emphasis has been placed on the development of neurogenetic tools. As a result, Drosophila now offers the possibility of integrating molecular genetics with neuroscientific systems analysis.
Various factors have also made the Drosophila larva a suitable model organism for neuroscientific research:
- The larval brain consists of only about 10,000 nerve cells.
- Robust behavioural tests are available.
- Transgenic techniques have been established that allow the manipulation of individual nerve cells.
- A complete reconstruction of all nerve cells and synaptic connections is available in the near future.
Approach
In a standardised behavioural experiment, the larvae receive a two-part reciprocal training: A first group of larvae is exposed to odour A (conditioned stimulus 1 - CS1) together with a reward or punishment stimulus (unconditioned stimulus - US). The animals are then exposed to odour B (conditioned stimulus 2 - CS2) without a gustatory stimulus. In parallel, a second group of larvae receives reciprocal training: odour A without gustatory stimulus and then odour B with gustatory reward. Both groups are then tested for their preference for odour A and odour B. An increased preference for the rewarded odour means associative learning - represented as a performance index (PI). Current experiments will now analyse which stimuli the larva perceives as a reward (e.g. sugar, ethanol, amino acids) and as a punishment (e.g. salt, bitter substances, high temperatures).
Aim
The aim of this project is to test how large and what kind of learning capacity the Drosophila larva has by varying individual parameters: What can the larva learn with its simple brain? How long can the larva memorise things? Can a larva learn different things at the same time?
Publications
- Appetitive associative olfactory learning in Drosophila larvae
Apostolopoulou AA, Widmann A, Rohwedder A, Pfitzenmaier JE, Thum AS.
J Vis Exp. 2013 Feb 18;(72):4334.
DOI: 10.3791/4334 - Reversal learning in Drosophila larvae
Mancini N, Hranova S, Weber J, Weiglein A, Schleyer M, Weber D, Thum AS, Gerber B.
Learn Mem. 2019 Oct 15;26(11):424-435.
DOI: 10.1101/lm.049510.119 - Odor-taste learning in Drosophila larvae
Widmann A, Eichler K, Selcho M, Thum AS, Pauls D.
J Insect Physiol. 2018 Apr;106(Pt 1):47-54.
DOI: 10.1016/j.jinsphys.2017.08.004