Commissural neuron

from Wikipedia, the free encyclopedia

Commissural neurons are neurons that, with their axons, connect the two halves of the nervous system in both the brain and the spinal cord , i.e. they form the commissures . There are numerous different populations (neuronal subtypes).

The dorsal commissural axons grow along a characteristic path: from the dorsal position of their cell bodies towards the midline, cross this and then grow towards the head. Because of this stereotypical growth, they are often used as models in neuroscientific research to study axonal pathfinding . After crossing the midline, they make different synaptic contacts with neurons on the contralateral hemisphere (i.e. those on the opposite side). Sometimes the axons also grow laterally away from the midline after crossing it. But they never cross back. This lateral (lateral) growth on the contralateral side is not understood down to the last detail.

The commissural axons change their readiness to react to the midline: the latter initially has an attractive effect before the axons cross, but then (after the axons cross) has an abruptly repulsive effect on the axons. The commissural axons change their sensitivity to the midline. Before crossing, they “see” the center line as attractive, after crossing it as repulsive. The signpost molecules that are generally responsible for this change and the correct outgrowth of the commissural axons are very diverse. Signal proteins from the class of netrins and morphogens, which belong to the Wnt signal path and the Hedgehog signal path , play a role, for example .

Individual evidence

  1. ↑ Anna I. Lyuksyutova, Chin-Chun Lu, Nancy Milanesio, Leslie A. King, Nini Guo, Yanshu Wang, Jeremy Nathans , Marc Tessier-Lavigne, Yimin Zou: Anterior-Posterior Guidance of Commissural Axons by Wnt-Frizzled Signaling . In: Science . tape 302 , no. 5652 , December 12, 2003, p. 1984–1988 , doi : 10.1126 / science.1089610 , PMID 14671310 .
  2. ↑ Dimitris Bourikas, Vladimir Pekarik, Thomas Baeriswyl, Åsa Grunditz, Rejina Sadhu, Michele Nardó, Esther T. Stoeckli: Sonic hedgehog guides commissural axons along the longitudinal axis of the spinal cord . In: Nature Neuroscience . tape 8 , no. 3 , March 2005, p. 297-304 , doi : 10.1038 / nn1396 .
  3. ↑ Alain Chédotal: Further tales of the midline . In: Current Opinion in Neurobiology . tape 21 , no. 1 , February 2011, p. 68-75 , doi : 10.1016 / j.conb.2010.07.008 .
  4. ^ TS Tran, E. Carlin, R. Lin, E. Martinez, JE Johnson, Z. Kaprielian: Neuropilin2 regulates the guidance of post-crossing spinal commissural axons in a subtype-specific manner. In: Neural development . tape 8 , December 2012, p. 15-15 , doi : 10.1186 / 1749-8104-8-15 .
  5. ↑ Homaira Nawabi, Valérie Castellani: Axonal commissures in the central nervous system: how to cross the midline? In: Cellular and Molecular Life Sciences . tape 68 , no. 15 , May 3, 2011, pp. 2539-2553 , doi : 10.1007 / s00018-011-0691-9 .
  6. ↑ Alex L. Kolodkin, Marc Tessier-Lavigne: Mechanisms and Molecules of Neuronal Wiring: A Primer . In: Cold Spring Harbor Perspectives in Biology . tape 3 , no. 6 , January 6, 2011, p. a001727 , doi : 10.1101 / cshperspect.a001727 , PMID 21123392 (open access).