Vertex analysis

Vertex Analysis is for morphometric features and non-normalized structures and describes the overall structure of a branched object based on topological and metrical properties. Use this analysis to compare the connectivity between trees and get some insight into the importance of random processes involved in the growth of a tree.

Select Vertex Analysis from the Structure drop-down menu on the Analyze ribbon. Neurolucida Explorer opens the Vertex Analysis window.

 

In this analysis, the ratio Va/Vb (primary bifurcation vertices to secondary bifurcation vertices) describes the connectivity.

Main types of vertices

  • Root (or origin) point: For neurons, the origin is the point at which the structure is attached to the soma.
  • Vd (bifurcation) or Vt (trifurcation): Nodal (or branching) points.
  • Vp: Terminal (or pendant) vertices.

Types of bifurcation points (Vd)

  • Va: primary vertices connecting 2 pendant vertices (Vp).
  • Vb: secondary vertices connecting 1 pendant vertex (Vp) to 1 bifurcation (Vd) or 1 trifurcation (Vt).
  • Vc: tertiary vertices connecting either 2 bifurcations (Vd), 2 trifurcations (Vt), or 1 bifurcation (Vd) and 1 trifurcation (Vt).

Types of trifurcation points (Vt)

  • Va': primary vertices connecting 3 pendant vertices (Vp).
  • Vb': secondary vertices connecting 2 pendant vertices (Vp) to 1 bifurcation (Vd) or 1 trifurcation (Vt).
  • Vc': tertiary vertices connecting 1 pendant vertex (Vp) to 2 bifurcation (Vd), 2 trifurcations (Vt), or 1 bifurcation (Vd) and 1 trifurcation (Vt).
  • Vd': quaternary vertices connecting either 3 bifurcation (Vd), 3 trifurcations (Vt), 1 bifurcation (Vd) and 2 trifurcations (Vt), or 2 bifurcations (Vd) and 1 trifurcation (Vt).
  • Va/Vb>1 suggests that the tree is non-random and symmetrical.
  • Va/Vb ~ 1 suggests that terminal nodes grew in random processes.
  • Va/Vb~ 0.5 suggest that segment growth grew the tree.
  • Va/Vb< 0.5 suggests the tree is non-random and asymmetrical.

Reference

Sadler, M., Berry, M. (1983). Morphometric study of the development of Purkinje cell dendritic trees in the mouse using vertex analysis. Journal of Microscopy, Vol. 131, Pt 3, September 1983, pp. 341-354.