A Tutorial in Connectome Analysis: Topological and Spatial Features of Brain Networks

High-throughput methods for yielding the set of connections in a neural system, the connectome, are now being developed. This tutorial describes ways to analyze the topological and spatial organization of the connectome at the macroscopic level of connectivity between brain regions as well as the microscopic level of connectivity between neurons. I will describe topological features at three different levels: the local scale of individual nodes, the regional scale of sets of nodes, and the global scale of the complete set of nodes in a network. Such features can be used to characterize components of a network and to compare different networks, e.g. the connectome of patients and control subjects for clinical studies. At the global scale, different types of networks can be distinguished and we will describe Erdoes-Renyi random, scale-free, small-world, modular, and hierarchical archetypes of networks. Finally, the connectome also has a spatial organization and we describe methods for analyzing wiring lengths of neural systems. As an introduction for new researchers in the field of connectome analysis, I will discuss the benefits and limitations of each analysis approach.

Timetable

The tutorial will be divided into three parts (about one hour each including discussion):

Part 1. Organization of neural systems

(Slides)

- Evolution of neuronal networks
- Clusters as a functional specialization
- Modular organization: ensembles, columns, areas, clusters

Part 2. Network analysis

(Slides)

- Random networks: an introduction to network theory
- It's a Small-world: neighbors are well-connected to each other
- Scale-free networks: the emergence of highly connected components
- Spatial organization: connections lengths and component placement

Part 3. Structure and function in neural systems

(Slides)

- Cluster and small-world organization of neural systems
- The spatial factor: why areas are localized at a defined position
- How the network structure helps the brain to adapt to and survive changes
- The future step: simulating functional dynamics on brain networks

Reading material

Kaiser M (2011). A Tutorial in Connectome Analysis: Topological and Spatial Features of Brain Networks. Neuroimage 57:892-907 [Article (PDF)]