Convex Hull analysis

Use this analysis to measure the size of a neuronal dendritic field.

The program measures the size of the dendritic field by interpreting a branched structure as a solid object controlling a given amount of physical space. The amount of physical space is defined in terms of volume, surface area, area, and/or perimeter.

Cells with larger dendritic fields can potentially receive input from more cells of other types. When cells of the same type have overlapping dendritic fields, more than one of them can receive from the same pre-synaptic field.

There are two options:

A convex polygon is generated by connecting the tips of the distal branches. The volume and surface area of the polygon are reported.

Another way to think about the analysis is to imagine a plastic sheet wrapped around the entire neuron, with the plastic stretched tightly between the most distal points of adjacent processes. The volume encased by this plastic sheet is the volume calculated, with the surface area reported as well.

This analysis treats cells as planar shapes and calculates the area enclosed by the "rubber band" around the cell. It is performed on a projection of the data.

Area: Bounding area; Z information is not used.

perimeter: Distance around the most distal points that form the convex hull (length of the "rubber band")

Procedure

  1. Open the data file.
  2. Select the structures to analyze (see Selecting structures).
  3. Select Analyze>Convex Hull to display the Convex Hull Analysis window.
  4. Select the desired metrics. Check Visualize surfaceto view the hull in the graphical window.

 

To analyze individual trees, select the trees individually and perform a separate Convex Hull analysis for each tree.

References

Rodieck, R. W. (1973). The vertebrate retina: Principles of structure and function. Oxford, England: W. H. Freeman.