View Program - 63rd Annual Drosophila Research Conference

Nervous systems process sensory information to extract relevant features from complex environments. While sensory processing algorithms are well-studied, their underlying circuit and molecular implementations remain poorly understood. How do neurons shape signal processing as they transform information from neurotransmitter input, to membrane voltage, to calcium influx, and finally to neurotransmitter release? How do these processes differ among cell types, and what molecular mechanisms drive those differences?
The Drosophila visual system is a highly tractable model for dissecting neural circuits at a subcellular level. Interneurons in the early visual system are genetically accessible, and their synaptic wiring diagram and gene expression profiles are well-characterized. Additionally, many studies have characterized their visual responses and their impact on visually-evoked behavior.
We have assembled a panel of genetically-encoded indicators of voltage, calcium, and neurotransmitter release for in vivo two-photon imaging in order to trace how visual information is transformed as it passes through neurons and across synapses. We display light and dark flash stimuli at multiple contrasts to probe the linearity and kinetics of these subcellular neural responses. Our lab previously showed that voltage and calcium sensors can be used to study visual processing with subcellular resolution, and we have now added an ultrafast calcium sensor and neurotransmitter sensors to our imaging toolkit. We are using these indicators in conjunction with pharmacological and cell type-specific genetic manipulations of ion channels and of neurotransmission to investigate how visual interneurons relay and transform information, as well as what classes of genes regulate signal processing in different neural cell types. By diversifying the types of observations we can make within neurons and synapses, we will gain novel insight into not only how Drosophila visual interneurons participate in signal processing, but also how central nervous system interneurons of different cell types function more broadly.

Dissecting the subcellular mechanisms of signal processing in the Drosophila visual system