The millions to billions of cells that comprise mammalian brains are organized into many highly specialized cell types. Previous studies have demonstrated that known and novel cell types can be identified by their single-cell gene expression profiles. However, the actual number of cell types in the brain and the degree of diversity among these cell types has been unknown. This webinar presents a new collection of studies from the BRAIN Initiative Cell Atlas Network (biccn.org) and published in Nature on Dec 14, 2023, that report the first complete cell type atlas of a mammalian brain, with over 30 million cells profiled from the adult mouse brain using a combination of single-cell transcriptomic, epigenomic, and spatial transcriptomic approaches, identifying over 5,300 cell types in the entire mouse brain. These studies uncover multitudes of organizing principles of the extraordinary cell type diversity across the brain. This collective body of work represents a landmark achievement that will have far-reaching impact on understanding cell type-based brain circuit function across the neuroscience field. More about the collection of studies, published in Nature on December 13, 2023: https://www.biccn.org/science/whole-mouse-brain Speakers: 1:21 Overview - Hongkui Zeng https://www.biccn.org/science/whole-mouse-brain 6:20 A high-resolution transcriptomic and spatial atlas of cell types in the whole mouse brain - Zizhen Yao https://www.nature.com/articles/s41586-023-06812-z 17:38 Molecularly defined and spatially resolved cell atlas of whole mouse brain - Xingjie Pan https://www.nature.com/articles/s41586-023-06808-9 28:52 The molecular cytoarchitecture of the adult mouse brain - Jonah Langlieb https://www.nature.com/articles/s41586-023-06818-7 38:40 Single-cell DNA methylome and 3D multi-omic atlas of the adult mouse brain - Hanqing Liu https://www.nature.com/articles/s41586-023-06805-y 51:59 Single-cell analysis of chromatin accessibility in adult mouse brain - Songpeng Zu https://www.nature.com/articles/s41586-023-06824-9 1:00:25 Brain-wide correspondence of neuronal epigenomics and distant projections - Jingtian Zhou https://www.nature.com/articles/s41586-023-06823-w 1:11:01 A transcriptomic taxonomy of mouse brain-wide spinal projecting neurons - Carla Winter https://www.nature.com/articles/s41586-023-06817-8 1:22:10 Spatial atlas of the mouse central nervous system at molecular resolution - Hailing Shi https://www.nature.com/articles/s41586-023-06569-5 1:32:49 Conserved and divergent gene regulatory programs of the mammalian neocortex - Ethan Armand https://www.nature.com/articles/s41586-023-06819-6 1:43:34 Evolution of neuronal cell classes and types in the vertebrate retina - Karthik Shekhar https://www.nature.com/articles/s41586-023-06638-9 1:54:21 Q&A. Moderator: Yasmeen Hussain, Allen Institute for Brain Science --- The research and webinar presented was funded by grants from the National Institutes of Health’s Brain Research Through Advancing Innovative Neurotechnologies® Initiative (The BRAIN Initiative). The publications were supported by and coordinated through the BICCN (biccn.org) and BICAN (brain-bican.org).

The human brain contains more than 100 billion cells, but exactly how these cells are organized into types and how these cell types differ between brain regions and species is an open question. This webinar presents a new collection of studies focused on defining and characterizing the underlying gene expression, gene regulatory, and morphoelectric features of cell types in the human and non-human primate (NHP) brain. These studies employ a range of cellular resolution methods (most notably single cell genomics) for this purpose, marking the beginning of an exciting new era of high-resolution human and NHP analyses. The implications for understanding of human brain function, disease and disease modeling are profound. More about the collection of studies: https://www.biccn.org/science/human-and-nhp-cell-atlas Speakers: Ed Lein, Allen Institute for Brain Science​ 1:18 Kimberly Siletti, University Medical Center Utrecht, Netherlands​, 5:12 "Transcriptomic diversity of cell types in the adult human brain" http://www.science.org/doi/10.1126/science.add7046 Trygve Bakken, Allen Institute for Brain Science​, 13:45 "Comparative transcriptomics reveals human-specific cortical features" http://www.science.org/doi/10.1126/science.ade9516 Lijuan Liu, Southeast University, China​, 22:40 "Whole Human-Brain Mapping of Single Cortical Neurons for Profiling Morphological Diversity and Stereotypy" https://www.science.org/doi/10.1126/sciadv.adf3771 Wei Tian, Salk Institute​, 32:17 " Epigenomic complexity of the human brain revealed by single-cell DNA methylomes and 3D genome structures" http://www.science.org/doi/10.1126/science.adf5357 Chang Kim, University of California, San Francisco​, 41:42 "Spatiotemporal molecular dynamics of the developing human thalamus" http://www.science.org/doi/10.1126/science.adf9941 Q&A: 51:32 Moderator:​ Yasmeen Hussain, Allen Institute for Brain Science --- The research and webinar presented was funded by grants from the National Institutes of Health’s Brain Research Through Advancing Innovative Neurotechnologies® Initiative (The BRAIN Initiative). The publications were supported by and coordinated through the BICCN (biccn.org) and BICAN (brain-bican.org).

Learn about the Cell Types Knowledge Explorer (CTKE), a web tool that supports exploring individual cell types in M1. See the tool at https://knowledge.brain-map.org/celltypes.

The Brain Initiative Cell Census Network (BICCN) is a collaborative consortium of many labs interested in the cellular composition of the mammalian brain. BICCN has recently published a flagship publication describing the overall project, along with a companion package of papers describing the cell types, connectivity, anatomy and other properties of the mammalian primary motor cortex (MOp or M1). At this webinar, learn about this multimodal research from leaders of some of the research teams involved. Learn more: https://alleninstitute.org/what-we-do/brain-science/events-training/biccn-flagship-release To read Q&A and ask follow-up questions, please visit our forum: https://community.brain-map.org/t/decoding-the-mammalian-motor-cortex-biccn-flagship-release-webinar-q-a/1316