Convex Hull analysis

Overview

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.

Analysis options

Neuron Structures

Each Neuron Set Individually: If the data include sets of modeled structures, check the box to report on each set individually.

Each Tree Individually: Check the box to report on each tree individually.

Cell Bodies: Check the box to include a report on selected cell bodies.

All Selected Objects

Choose the type of convex hull analysis to run on the selected objects:

Convex Hull 3D: 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 selected structure(s), with the plastic stretched tightly between the most distal points of adjacent processes. The volume encased by the sheet is calculated, and the surface area is reported as well.

XY Area Convex Hull: This 2D analysis treats selected tracings as planar shapes and calculates the area enclosed by a "rubber band" around the them. It is performed on a projection of the data.

  • Z information is not used in the Area reported.

  • The perimeter reported is the distance around the most distal points that form the convex hull (length of the "rubber band")

Visualize surface checkbox: Check the box to view the hull that is drawn in the graphical window.

Procedure

  1. Open the data file.
  2. Select the structures to analyze (see Selecting structures).
  3. Select Analyze > Spatial> Convex Hull to display the Convex Hull Analysis window.
  4. Select the desired parameters and click OK to run the convex hull analysis.

 

References

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