Fruit flies can learn non-elemental olfactory discriminations

Proc Biol Sci. 2020 Nov 11;287(1938):20201234. doi: 10.1098/rspb.2020.1234. Epub 2020 Nov 11.


Associative learning allows animals to establish links between stimuli based on their concomitance. In the case of Pavlovian conditioning, a single stimulus A (the conditional stimulus, CS) is reinforced unambiguously with an unconditional stimulus (US) eliciting an innate response. This conditioning constitutes an 'elemental' association to elicit a learnt response from A+ without US presentation after learning. However, associative learning may involve a 'complex' CS composed of several components. In that case, the compound may predict a different outcome than the components taken separately, leading to ambiguity and requiring the animal to perform so-called non-elemental discrimination. Here, we focus on such a non-elemental task, the negative patterning (NP) problem, and provide the first evidence of NP solving in Drosophila. We show that Drosophila learn to discriminate a simple component (A or B) associated with electric shocks (+) from an odour mixture composed either partly (called 'feature-negative discrimination' A+ versus AB-) or entirely (called 'NP' A+B+ versus AB-) of the shock-associated components. Furthermore, we show that conditioning repetition results in a transition from an elemental to a configural representation of the mixture required to solve the NP task, highlighting the cognitive flexibility of Drosophila.

Keywords: Drosophila melanogaster; Pavlovian conditioning; associative learning; feature-negative discrimination; insect; negative patterning.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Discrimination Learning / physiology*
  • Drosophila / physiology*
  • Female
  • Male
  • Odorants
  • Smell / physiology*

Associated data

  • Dryad/10.5061/dryad.v9s4mw6t1
  • figshare/10.6084/m9.figshare.c.5189374