Dissecting the ventral nervous system in Drosophila melanogaster
In order to understand biological intelligence I wanted to map the simplest example that could still demonstrate learning. Learning, or classical conditioning, has long been shown to occur in decapitated insects, hence this was a logical target, specifically the most studied insect, the fruit fly (Drosophila melanogaster). This learning occurs in the insect equivalent of the spinal cord, referred to as the ventral nervous system (VNS). The initial task was to resolve the gross neuroanatomy of the VNS. Standardising the neuroanatomical regional boundaries into 3D painted domains, clarifying textural descriptions, as well as matching the literature synonyms, were all combined into the Drosophila nomenclature. This enables existing knowledge, from the literature, to be easily queried as well as providing a basis for future additions. These clarified anatomical definitions were agreed by a workshop of researchers with experience in the VNS. Definitions will be published to form the basis for a more detailed nomenclature to be developed upon. In order to combine 3D images taken from different flies, a template was chosen, and an alignment pipeline tool devised. This alignment pipeline enabled samples of secondary lineages, that make up the bulk of the neurons in the VNS, to be aligned. This lineage atlas provided fixed internal boundary points for the neuroanatomy to be defined against. Previous work has provided detailed information on these lineages, as well as showing their likely homologous relationship as a gross functional unit within behavioural circuits. By constructing a spatial atlas of these lineages, a gross connection plan can be devised, targeting future research. This lineage atlas, in combination with NBLAST, enables the identification of single neurons to their developmental origin simply by using their morphology. The template with neuroanatomical definitions has been made publicly available via VirtualFlyBrain.org (VFB) and FlyBase.org. The alignment pipeline has been made available via a web interface for researchers to align their own data to the any of the VFB templates. This project provides an anatomical and developmental gross map of the VNS to enable greater development of the connectome.