title: Three-dimensional volume imaging with electron microscopy toward connectome.
abstract: Ultrastructural analyses with electron microscopy have provided indispensable information to understand physiology and pathology of the nervous system. Recent advancement in imaging methodology paved the way for complete reconstruction of the neuronal connection map in the central nervous system, which is termed 'connectome' and would provide key insights to understand the functions of the brain. The critical advancement includes serial ultrastructural observation with scanning electron microscopy (SEM) instead of conventional serial sectioning transmission electron microscopy along with specific tissue preparation methods to increase heavy metal deposition for efficient SEM imaging. The advanced imaging methods using SEM have distinct advantages and disadvantages in multiple aspects, such as resolution and imaging speed, and should be selected depending on the observation conditions, such as target tissue sizes, required spatial resolution and necessity for re-observation. Dealing with the huge dataset remained to be a major obstacle, and automation in segmentation and 3D reconstruction would be critical to understand neuronal circuits in a larger volume of the brain. Future improvement in acquisition and analyses of the morphological data obtained with the advanced SEM imaging is awaited to elucidate the significance of whole connectome as the structural basis of the consciousness, intelligence and memory of a subject.
authors.affiliation: Department of Anatomy and Molecular Histology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 1110 Shimokato, Chuo city, Yamanashi 409-3898, Japan nohno@yamanashi.ac.jp.
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Ohno
authors.affiliation: Department of Anatomy and Molecular Histology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 1110 Shimokato, Chuo city, Yamanashi 409-3898, Japan.
authors.forename: Mitsuhiko
authors.initials: M
authors.lastname: Katoh
authors.affiliation: Department of Anatomy and Molecular Histology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 1110 Shimokato, Chuo city, Yamanashi 409-3898, Japan.
authors.forename: Yurika
authors.initials: Y
authors.lastname: Saitoh
authors.affiliation: Department of Anatomy and Molecular Histology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 1110 Shimokato, Chuo city, Yamanashi 409-3898, Japan.
authors.forename: Sei
authors.initials: S
authors.lastname: Saitoh
authors.affiliation: Department of Anatomy and Molecular Histology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 1110 Shimokato, Chuo city, Yamanashi 409-3898, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Ohno
mesh_terms: D000818:Animals; D001921:Brain / Q000648:ultrastructure*; D063132:Connectome / Q000379:methods*; D016591:Histocytological Preparation Techniques; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008855:Microscopy, Electron, Scanning / Q000379:methods*; D046529:Microscopy, Electron, Transmission / Q000379:methods*
keywords: connectome; neuron; scanning electron microscopy; serial sectioning; synapse; three-dimensional reconstruction