Data Blitz Talks
Mohamed Adel
(Griffith Lab)
Establishing an ex vivo model of the Drosophila associative learning circuit
Memories of association are one of the more powerful survival mechanisms: sweet smelling fruit is good, rotting meat is bad (for example). The ability to form associative memories based on odor is pervasive across species, including one as simple as the fruit fly. Mr. Adel presented his work developing a new method for observing and modifying the network responsible for developing these associations, to better understand the mechanics of how they form.
Fruit flies form associative memories, such as between an odor (conditioned stimulus; CS) and a reward or punishment (unconditioned stimulus; US). Olfactory associative memory formation requires the Mushroom Body, a higher brain structure, and the key players of the underlying circuit are well-defined. Dopamine is released by one of two clusters of dopaminergic neurons to depress the synapses between the mushroom body intrinsic neurons (Kenyon Cells), and their output, approach or avoidance mushroom body output neurons, to drive either avoidance or approach behavior, respectively. However, the mechanisms that govern dopamine release on the relevant synapses, and the precise mechanism by which dopamine encodes associative memory, among other questions, remain unclear. Similar to how hippocampal slice LTP has provided an important model for the investigation of mammalian memory mechanisms and recapitulates many of the cardinal features of behavioral memory, the establishment of an ex vivo model of Drosophila’s associative memory is needed to better understand the dynamics of this circuit. To establish this model, we artificially activate the CS and US pathways in dissected brains to mimic the aversive training paradigm. Then, we investigate whether this model recapitulates the hallmarks of associative learning; specificity to the trained CS, and whether it generates the physiological changes, “engrams,” observed in vivo. We provide evidence that the engrams observed in our ex vivo model resemble the in vivo engrams, and that they are indeed specific to the CS input. While our preliminary results appear informative, experiments are ongoing.