Lesion-Network Mapping: From a Topologic to Hodologic Approach

Historically, topological lesion-based studies have provided a direct way to map brain regions to their corresponding functions; however, these approaches fail to consider the impact of the lesion on broader brain networks. Focus has shifted in the latter half of the nineteenth century from topological to hodological, or network-based, approaches that link networks of brain regions to function. More recent advances in neuroimaging, including diffusion and resting-state functional MRI, have begun to reveal network-behavior maps in both healthy and clinical populations. An understanding of these relationships is imperative if we are to improve diagnostics, prognostics, and treatments of neurological and neuropsychiatric disorders. In this chapter, we begin by introducing general concepts in connectomics, including graph theory and connectome imaging techniques. We then outline strategies for quantifying lesions' impact on the connectome and, finally, discuss clinical applications and possible avenues of future work.