the precuneus, medial anterior cingulate cortex, temporo-parietal junction, or superior frontal cortex produced widespread and pronounced changes in functional connectivity with intra-hemispheric and contralateral regions. Conversely, lesions to the visual or motor cortex had limited effects on global connectivity.49 Neurodegenerative processes, characterised by gradual and selective spreading of pathology across brain regions, might cause a progressive targeted network injury, leading to specific “disconnection syndromes” and progressive cognitive dysfunction.50,51 The difference between neurological disorders due to focal lesions and most neurodegenerative diseases is that in the former case networks are affected at random, with no specific topographic and chronological pattern, whereas in the latter case networks are affected with a relatively stereotyped sequence. Network analysis may therefore help to explain the link between local damage, long-range disconnection, and more widespread physiological and clinical dysfunction. Literature in this emerging field is still scarce but already points to intriguing new hypotheses, as described in this section.
