Progress in brain neural connectomics

Abstract

As the most complex system in the universe, the brain is the nature’s ultimate territory of human exploration. The vast number of neurons of various cell types and functions, together with their intricate structural and functional connections, pose substantial challenges for understanding the way the brain works. Thus comes the need to map the neuronal “wiring diagrams”, i.e. connectomics-exploring the neural connections between brain areas, nuclei, and neurons on the whole-brain scale in a high-throughput manner, which is more and more recognized as the roadmap to understanding the mechanisms of brain functions. Over recent years, advances of multiple-level imaging, neural circuit tracing and activity manipulation, and image processing techniques have greatly propelled the development of neural connectomics, enabling neuroscientists to observe the fine structures, connectivity and functions of neurons on the level of specific brain areas or the entire brain. Here we summarize recent technical advances in macro-, meso-, and micro-connectomics, along with recent work on neural circuit structures and functions. We also discuss the difficulties, challenges and future directions of connectomics studies, and propose that the zebrafish is currently an ideal model for mapping structural and functional neural connectivity on the whole brain scale.