1 Introduction

1.1 Goal

The purpose of the plugin, is to provide an extra layer in the analysis of brain connectivity, through a graph theoretical approach. It is comprised of two distinct entities, one is the brainnets, and the other, the plugin itself. brainnets is the custom, in-house library for dealing with networks. The backbone network algorithms and features are implemented and stored within this library. The plugin acts as GUI and glue between BrainVoyager 21.x and brainnets. It helps the user load the requested data, configure the environment and perform any vizualizations.

1.2 Basic concepts of Graph Theory

Here shortly, we will give the basic concepts and notations for graph theoery as usually used. For more comprehensive materials on the topic, the interested readers are encouraged to consult (Sporns, 2010).

A set of vertices (or nodes) \(V\) and their associated edges (or connections) \(E\), make up a graph structure \(G = (V, E)\). The edges \(E\) can be either weighted (\(W\)) or binary (\(B\)) in which case they just indicate the presence of a connection between the nodes. Moreover, we can further distinguish the types edges based on the directionality of the connections, directed (\(D\)) or undirected(\(U\)).

Below is a sample connectivity matrix (weighted) and its representation as a graph structure. For the adjacency matrix, notice the symmetricity,which also implies undirectionality. For the graph, notice that the lines’ weights are relative to the connections’ weights as well as their color.

2 Usage

First things first. The minimum required version, is BrainVoyager 21.x. Make sure you have the plugin installed into the proper directory and it’s visible and accessible in the Plugins menu. Also, you have to have currently opened a VMR file.

2.1 Basic example

  1. Data

    Below, is the main window you will be prompted with, when you execute the plugin. You will have to load a pair of VTC / VOI files and provide a sample name for the current analysis. It is recommended to fill in a short, meaningful name.