Structural descriptions of neuronal networks are important for understanding brain dysfunctions; which dysfunctions, in particular? In a recent paper, we find this quote:


  The brain contains vast numbers of interconnected neurons that constitute anatomical and functional networks. Structural descriptions of neuronal network elements and connections make up the “connectome” of the brain (Hagmann, 2005; Sporns et al., 2005; Sporns, 2011), and are important for understanding normal brain function and disease-related dysfunction.


This quote is from the first paragraph in: T. B. Leergaard, C. C. Hilgetag and O. Sporns, Mapping the connectome: multi-level analysis of brain connectivity, Front. Neuroinform., 2012.


  Question: Understanding which dysfunctions, in particular, is aided by structural descriptions of neuronal networks?
Stam et al. have carried out a functional connectivity study in patients with Alzheimer's Disease. I don't know if that answers your question at all. Connectomics is just starting to kick off. It's far from certain that they it will end up being a key player in functional neuropathology in the coming decades, but it's one out of many promising new avenues of research.