Sparse coding enables odour-specific memories

February 12th 2016
Versione stampabile

Venue: Edificio Povo 1, via Sommarive nr. 5, Povo (Tn) - Room A210
 At 2:00 p.m.

  • Andrew Lin -  Department of Biomedical Science, University of Sheffield, Sheffield, (UK)

How do we form stimulus-specific associative memories? Theoretical work suggests that stimulus-specificity is enabled by sparse coding, in which only a few neurons in a population respond to any given stimulus. However, it remains untested how sparse coding relates to behavioural performance. I addressed this question in Drosophila, where olfactory associative memories are stored by the Kenyon cells of the mushroom body, which encode odours sparsely. I showed that sparse coding in Kenyon cells is enforced by a negative feedback circuit between Kenyon cells and a single GABAergic neuron. Disrupting this negative feedback loop decreases the sparseness of Kenyon cell odour responses, increases inter-odour correlations, and prevents flies from learning to discriminate similar, but not dissimilar, odours. These results suggest that feedback inhibition suppresses Kenyon cell activity in order to maintain sparse, decorrelated coding and thus the odour-specificity of memories.