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Pascual-García M, Unkel M, Slotman JA, Bolleboom A, Bouwen B, Houtsmuller AB, Dirven C, Gao Z, Hijazi S, Kushner SA. Morphological correlates of pyramidal cell axonal myelination in mouse and human neocortex. Cereb Cortex 2024; 34:bhae147. [PMID: 38610088 PMCID: PMC11014882 DOI: 10.1093/cercor/bhae147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 03/16/2024] [Accepted: 03/17/2024] [Indexed: 04/14/2024] Open
Abstract
The axons of neocortical pyramidal neurons are frequently myelinated. Heterogeneity in the topography of axonal myelination in the cerebral cortex has been attributed to a combination of electrophysiological activity, axonal morphology, and neuronal-glial interactions. Previously, we showed that axonal segment length and caliber are critical local determinants of fast-spiking interneuron myelination. However, the factors that determine the myelination of individual axonal segments along neocortical pyramidal neurons remain largely unexplored. Here, we used structured illumination microscopy to examine the extent to which axonal morphology is predictive of the topography of myelination along neocortical pyramidal neurons. We identified critical thresholds for axonal caliber and interbranch distance that are necessary, but not sufficient, for myelination of pyramidal cell axons in mouse primary somatosensory cortex (S1). Specifically, we found that pyramidal neuron axonal segments with a caliber < 0.24 μm or interbranch distance < 18.10 μm are rarely myelinated. Moreover, we further confirmed that these findings in mice are similar for human neocortical pyramidal cell myelination (caliber < 0.25 μm, interbranch distance < 19.00 μm), suggesting that this mechanism is evolutionarily conserved. Taken together, our findings suggest that axonal morphology is a critical correlate of the topography and cell-type specificity of neocortical myelination.
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Affiliation(s)
- Maria Pascual-García
- Department of Psychiatry, Erasmus MC, Doctor Molewaterplein 40, Rotterdam, 3015 GD, The Netherlands
| | - Maurits Unkel
- Department of Psychiatry, Erasmus MC, Doctor Molewaterplein 40, Rotterdam, 3015 GD, The Netherlands
| | - Johan A Slotman
- Erasmus Optical Imaging Centre, Department of Pathology, Erasmus MC, Doctor Molewaterplein 40, Rotterdam, 3015 GD, The Netherlands
| | - Anne Bolleboom
- Department of Neuroscience, Erasmus MC, Doctor Molewaterplein 40, Rotterdam, 3015 GD, The Netherlands
- Department of Neurosurgery, Erasmus MC, Doctor Molewaterplein 40, Rotterdam, 3015 GD, The Netherlands
| | - Bibi Bouwen
- Department of Neuroscience, Erasmus MC, Doctor Molewaterplein 40, Rotterdam, 3015 GD, The Netherlands
- Department of Neurosurgery, Erasmus MC, Doctor Molewaterplein 40, Rotterdam, 3015 GD, The Netherlands
| | - Adriaan B Houtsmuller
- Erasmus Optical Imaging Centre, Department of Pathology, Erasmus MC, Doctor Molewaterplein 40, Rotterdam, 3015 GD, The Netherlands
| | - Clemens Dirven
- Department of Neurosurgery, Erasmus MC, Doctor Molewaterplein 40, Rotterdam, 3015 GD, The Netherlands
| | - Zhenyu Gao
- Department of Neuroscience, Erasmus MC, Doctor Molewaterplein 40, Rotterdam, 3015 GD, The Netherlands
| | - Sara Hijazi
- Department of Psychiatry, Erasmus MC, Doctor Molewaterplein 40, Rotterdam, 3015 GD, The Netherlands
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, United Kingdom
| | - Steven A Kushner
- Department of Psychiatry, Erasmus MC, Doctor Molewaterplein 40, Rotterdam, 3015 GD, The Netherlands
- Department of Psychiatry, Columbia University, 1051 Riverside Drive, New York, NY 10032, United States
- SNF Center for Precision Psychiatry & Mental Health, Columbia University, 630 West 168th Street, New York, NY 10032, United States
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