Short circuit : how brain connectivity and disconnectivity relate to brain function

The brain is like a super computer: it is a collection of interconnected computational units which work together to enable both basic functions, such as regulation of breathing, as well as higher functions, such as cognition, thought and emotion. The computational units, or regions, are located in the grey matter (i.e. the cortical surface and in the subcortex), whereas the connections between them, or tracts, are found in the white matter. The development and maintenance of both grey and white matter is essential to brain function. When either tissue type becomes compromised, so too does function.

Brain connectivity can non-invasively be derived from magnetic resonance images (MRI). Structural MRI can be used to examine the three-dimensional anatomy of the brain. This combined with either diffusion weighted images (DWI) or functional MRI (fMRI) can be used to estimate functional or structural connectivity, respectively.

Studying brain connectivity is crucial to learning about both brain function and dysfunction. However, in the case of pathology-related dysfunction, estimations of connectivity may not sufficiently represent underlying tissue damage. Pathologies, including white matter lesions, are involved in age-related neuro-degeneration as well as several neuro-psychiatric conditions. A data structure which takes pathology into account may provide additional insights into related loss of function.

The relationship between brain connectivity, disconnectivity and function is examined in this thesis.