Understanding the mind-brain relationship through focal neurodegenerative pathology.

This paper considers the contribution that observations of neurodegenerative diseases can make to our understanding of the 'mind-brain' relationship. The theoretical context in which cognitive models have been implemented by evidence from brain-damaged patients and the contribution of neuroimaging are briefly described. Reasons why neurodegenerative pathologies, as 'systems' pathologies, are potentially useful in providing complementary information to that obtained in focal vascular pathologies are reported and two specific examples, semantic dementia and primary progressive apraxia of speech, are discussed. While recognising the role of functional neuroimaging, priority should be given to the study of patients with brain damage, especially of a neurodegenerative nature, to legitimise the relationship between specific functions and specific structures (systems).