# Plasticity in inhibitory networks improves pattern separation in early olfactory processing

## TL;DR

Honeybees use inhibitory plasticity in their early olfactory system to better distinguish between similar odors, improving learning and adaptation.

## Contribution

The study reveals how inhibitory plasticity in the honeybee antennal lobe enhances pattern separation through selective suppression and enhancement of odor compounds.

## Key findings

- Inhibitory networks in the antennal lobe suppress shared odor compounds while enhancing distinct ones.
- Calcium imaging and computational models confirm improved pattern separation and neural coding efficiency.
- Graph convolutional networks show similar contrast enhancement mechanisms for odor categorization.

## Abstract

Distinguishing between nectar and non-nectar odors is challenging for animals due to shared compounds and varying ratios in complex mixtures. Changes in nectar production throughout the day and over the animal’s lifetime add to the complexity. The honeybee olfactory system, containing fewer than 1000 principal neurons in the early olfactory relay, the antennal lobe (AL), must learn to associate diverse volatile blends with rewards. Previous studies identified plasticity in the AL circuits, but its role in odor learning remains poorly understood. Using a biophysical computational model, tuned by in vivo electrophysiological data, and live imaging of the honeybee’s AL, we explored the neural mechanisms of plasticity in the AL. Our findings revealed that when trained with a set of rewarded and unrewarded odors, the AL inhibitory network suppresses responses to shared chemical compounds while enhancing responses to distinct compounds. This results in improved pattern separation and a more concise neural code. Our calcium imaging data support these predictions. Analysis of a graph convolutional neural network performing an odor categorization task revealed a similar mechanism for contrast enhancement. Our study provides insights into how inhibitory plasticity in the early olfactory network reshapes the coding for efficient learning of complex odors.

Inhibitory plasticity in the honeybee antennal lobe selectively enhances distinct odor compounds and suppresses shared ones, enabling efficient learning and adaptation to new odor environments.