“Learning from Connectomics on the Fly”, Philipp Schlegel, Marta Costa, Gregory S. X. E. Jefferis2017-12 (neuroscience)⁠:

• Whole brain EM connectomics will revolutionize neuroscience.

• Insects are at the forefront of this revolution.

• Mapping between light and EM image data can integrate anatomy and function.

• Quantitative definitions of cell type will promote experiments and communication.

• Tools and resources that integrate big neuroscience data are critical for neurobiologists.

Parallels between invertebrates and vertebrates in nervous system development, organization and circuits are powerful reasons to use insects to study the mechanistic basis of behavior.

The last few years have seen the generation in Drosophila melanogaster of very large light microscopy data sets, genetic driver lines and tools to report or manipulate neural activity. These resources in conjunction with computational tools are enabling large scale characterisation of neuronal types and their functional properties.

These are complemented by 3D electron microscopy, providing synaptic resolution data. A whole brain connectome of the fly larva is approaching completion based on manual reconstruction of electron-microscopy data. An adult whole brain dataset is already publicly available and focused reconstruction is under way, but its 40× greater volume would require ~500–5,000 person-years of manual labour. Nevertheless rapid technical improvements in imaging and especially automated segmentation will likely deliver a complete adult connectome in the next 5 years.

To enhance our understanding of the circuit basis of behavior, light and electron microscopy outputs must be integrated with functional and physiological information into comprehensive databases.

We review presently available data, tools and opportunities in Drosophila. We then consider the limits and potential of future progress and how this may impact neuroscience in rich model systems provided by larger insects and vertebrates.

See Also:

• A connectome of the Drosophila central complex reveals network motifs suitable for flexible navigation and context-dependent action selection

• Connectomic reconstruction of the inner plexiform layer in the mouse retina

• The Mind of a Mouse

• Large-scale neural recordings call for new insights to link brain and behavior

• All-optical visualization of specific molecules in the ultrastructural context of brain tissue

• High-throughput mapping of a whole rhesus monkey brain at micrometer resolution

• Deep learning models of cognitive processes constrained by human brain connectomes