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Synaptic output of dopaminergic neurons controls contextual learning by promoting antagonistic behaviors in Drosophila

Micaela Vicente Biscardi

  • CABA,
  • Argentina
  • Micaela Vicente Biscardi ¹
  • , Carolina D`Odorico ¹
  • , Melina Petrissans ¹
  • , Mario Rafael Pagani ¹
  • 1 Instituto de Fisiología y Biofísica (IFIBIO) Bernardo Houssay, Grupo de Neurociencia de Sistemas, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina.

Accumulated evidence supports an emerging model for the neuronal control of behavior in associative learning in Drosophila. In such model, dopaminergic neurons (DANs), which encode the unconditional stimuli, modulate the synaptic output of mushroom body neurons driving the appropriate behavior (approaching or avoidance). However, studies in vertebrates have shown that self-motivated contextual learning and other forms of learning depend on distinct molecular and cellular mechanisms. Here, we examined the role of dopaminergic neurons in contextual learning in freely behaving flies.

We blockade or enhanced neuronal activity of subset of DANs by using the several GAL4 lines to drive the expression of the thermosensitive allele Shits1 or TrpA1. We found that in contextual learning, flies showed habituation of the exploratory activity, which is controlled by DANs. Preliminary studies indicate that, habituation was promoted by two different clusters of DANs. Three neurons from the PAL cluster or one to four PPL2 neurons, or possibly both subsets contributed to promote habituation. Interestingly, habituation also was prevented by two different clusters of DANs. Neurons from the PAM cluster and one to two neurons from the PPM2 cluster were individually sufficient to prevent habituation. Taken together, habituation of a motivated behavior is under positive and negative control of DANs.