Inhibitory representations: their formation, modulation and function in memory circuits

Feelings, images, ideas and events are stored in our brains to be retrieved at appropriate times. The proposed research seeks to explain how this occurs. Percepts are represented in the brain by the positive activity of assemblies of excitatory neurons. We have recently proposed that the brain creates negative representations of these perceptual assemblies to prevent inappropriate activation. When appropriate, context-specific neuronal pathways may turn off the negative representations to reveal latent perceptions or memories.

This project builds on our observation that olfactory habituation in fruit flies, a process in which they learn to ignore a familiar inconsequential odour, arises from the formation of negative images of odour-evoked excitatory patterns. We will study how these negative representations are constructed in the simple fruit fly brain and how these representations and their effects are regulated by environmental or behavioural context. Additional studies will ask whether and how negative representations promote suppression of predator-presence memory in fruit flies.

The findings are relevant to humans, whose brain circuits share key features with the fly brain. The work is clinically relevant because defects in habituation, memory encoding and recall are associated with conditions including autism, schizophrenia and post-traumatic stress disorder.