An investigation into the brain networks involved in rehabilitation of reading ability after stroke using magnetoencephalography (MEG)

Language impairments after stroke are common, and can affect any combination of reading, writing, speaking and understanding. Patients with a stroke affecting a particular area of the brain, known as the left ventral visual stream, often have problems with reading but other language functions are relatively spared. This disorder is known as 'pure alexia'. Patients with this disorder read slowly and laboriously, and find daily tasks such as reading the mail or following written instructions to be tiring and frustrating. Most sufferers are forced to retire or to find alternative jobs that do not involve much reading. There is no reliable method of rehabilitation for this disorder.

The proposed study aims to extend an existing project that tested whether a new form of reading rehabilitation for pure alexia was effective at improving these patients' reading speeds. The rehabilitation programme led to significant improvements in reading ability in some patients, but not all. Variables such as the amount of training, age and the size of damage caused by the patient's stroke could not explain why some patients benefited but others did not.

After completion of the rehabilitation programme, the patients were scanned using magnetoencephalography (MEG) - a type of functional brain imaging technique that provides accurate timing information about when brain regions involved in reading respond to a word. . Analysis of this data can also provide good evidence for how these brain regions are connected to form functional networks. Using MEG, it is thus possible to test how focal brain damage (in this case, to the left ventral visual stream) disrupts the functions of more widespread brain networks. As functional connectivity analysis using MEG is a relatively new technique, this would be the first analysis of this type in this patient group, and one of only a handful of studies in healthy volunteers.

I aim to test whether differences in functional connectivity could explain why some patients benefit from rehabilitation while others do not. I also aim to improve the understanding of the causes of acquired reading disorders by comparing functional connectivity in the patient group with the group of healthy control participants. It is anticipated that the information gained from this study will lead to recommendations for future approaches to the rehabilitation of reading disorders caused by stroke and other common causes of brain injury.