Distinct Profiles of Myelin Distribution Along Single Axons of Pyramidal Neurons in the Neocortex

• Published in: Science (American Association for the Advancement of Science) Vol. 344; no. 6181; pp. 319 - 324
• Main Authors: Tomassy, Giulio Srubek, Berger, Daniel R., Chen, Hsu-Hsin, Kasthuri, Narayanan, Hayworth, Kenneth J., Vercelli, Alessandro, Seung, H. Sebastian, Lichtman, Jeff W., Arlotta, Paola
• Format: Journal Article
• Language: English
• Published: United States American Association for the Advancement of Science 18.04.2014; The American Association for the Advancement of Science
• Subjects: Anatomy; Animals; Axons; Axons - physiology; Behavioral neuroscience; Brain; Datasets; Image Processing, Computer-Assisted; Immunohistochemistry; Mice; Mice, Inbred C57BL; Microscopy, Electron; Myelin; Myelin Sheath - physiology; Myelination; Neocortex; Neocortex - cytology; Neocortex - physiology; Nervous system; Neurons; Oligodendroglia - cytology; Oligodendroglia - physiology; Population distributions; Pyramidal Cells - cytology; Pyramidal Cells - physiology; Somatosensory Cortex - cytology; Somatosensory Cortex - physiology; Vertebrates; Visual Cortex - cytology; Visual Cortex - physiology
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1249766

Myelin is a defining feature of the vertebrate nervous system. Variability in the thickness of the myelin envelope is a structural feature affecting the conduction of neuronal signals. Conversely, the distribution of myelinated tracts along the length of axons has been assumed to be uniform. Here, we traced high-throughput electron microscopy reconstructions of single axons of pyramidal neurons in the mouse neocortex and built high-resolution maps of myelination. We find that individual neurons have distinct longitudinal distribution of myelin. Neurons in the superficial layers displayed the most diversified profiles, including a new pattern where myelinated segments are interspersed with long, unmyelinated tracts. Our data indicate that the profile of longitudinal distribution of myelin is an integral feature of neuronal identity and may have evolved as a strategy to modulate long-distance communication in the neocortex.