Science

Press release (italian)

Science, April 2014

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

Giulio Srubek Tomassy,¹ Daniel R. Berger,^2,3 Hsu-Hsin Chen,¹ Narayanan Kasthuri,²
Kenneth J. Hayworth,² Alessandro Vercelli,⁴ H. Sebastian Seung,³ Jeff W. Lichtman,² Paola Arlotta¹

Myelin is a defining feature of the vertebrate nervous system. Variability in the thickness of the myelin envelope is a structural feature affectingx 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. [read more]

¹ Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, USA.
² Department of Molecular and Cellular Biology, Harvard University, Cambridge, USA.
³ Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, USA.
 ⁴ Neuroscience Institute Cavalieri Ottolenghi, Neuroscience Institute of Turin, Turin, Italy.

Harvard Stem Cell Institute
Harvard researchers present new view of myelin

(A) High-resolution rendering of myelin distribution along single axons of 22 pyramidal neurons traced and reconstructed in layer II/III of the V1 data set.
(C) High-resolution rendering of three representative neurons displaying differentmyelinationmodes.