Speaker
Description
Specific olfactory receptors tune the sensitivity of chemoreception, enabling olfactory sensory neurons (OSNs) to detect odours across a broad spectrum of intensities. In order to study additional mechanisms of odour-specific neuronal processing, we investigated OSN synapses in the Drosophila antennal lobe, the first relay station of the olfactory pathway. Here, we examined the structure and function of presynaptic active zones (AZs), where specialised molecular complexes control neurotransmission. Artificially reducing neurotransmitter release probability of OSN AZs disrupts both neural coding and behavioural reliability. Strikingly however, target-specific synaptic plasticity rescues these defects within a day. This homeostatic compensation is mediated by AZ biogenesis and requires the secretory pathway protein Sec31. Furthermore, our data show that highly sensitive OSNs expressing the alarm-odour receptor Or56a have a limited capacity for homeostatic plasticity and display a different layout of core AZ proteins compared to conventional food-odour detecting OSNs. We hypothesise that these features reflect the basal tuning of Or56a OSNs towards maximum levels of performance.
