fMRI Scans Used to Improve Understanding of the Impact of Strokes

fMRI Scans Used to Improve Understanding of the Impact of Strokes

Psychologists at Rice University in Houston, Texas have developed a new method for analyzing brain activity that provides insight into the functioning of the brain following a stroke.

When part of the brain is damaged, the brain reorganizes itself and new neural connections form. This allows the brain to continue to function after part of the brain is damaged or diseased – That ability is termed neuroplasticity.

There are two ways the brain can achieve this reorganization. Compensatory masquerade is where the brain finds an alternative method to achieve the same result. Alternatively, there is functional takeover, when a function is completed by a part of the brain not normally associated with that function. Determining which of these two types of neuroplasticity occurs following a stroke could help scientists develop better tools and treatments for patients.

Simon Fischer-Baum, an assistant professor of psychology at Rice, and his team of researchers developed a new method of assessing brain activity, and determined that following a stroke, there is a functional takeover of certain tasks by other parts of the brain.

For the study, Fischer-Baum and his team conducted functional magnetic resonance imaging (fMRI) scans of 20 healthy patients and one patient that had suffered a stroke. fMRI detects brain activity from changes in blood flow, with the technique based on the fact that neuronal activation and cerebral blood flow are linked.

While undergoing the scans, patients were asked to read out words. Fischer-Baum and his team conducted a number of tests to determine which areas of the brain are associated with pronunciation, comprehension, and reading. Those tests involved patients reading out words with similar meanings, words with similar spelling but different pronunciation (tough and dough for instance) and words with similar pronunciation but different spelling (sew and dough for instance).

The team was able to compare blood flow – and brain activity – from the fMRI scans for each task in both the control group and the individual with brain damage. By comparing the fMRI scans, the team was able to assess whether stroke damage to the brain resulted in compensatory masquerade or functional takeover.

“If neuroplasticity results in compensatory masquerade, then we expected to find the same function in the same brain regions for the patient and the control group, but we did not,” explained Fischer-Baum. Orthographic processing, which is the knowledge of the spelling of words, was being performed by the left side of the brain in the patients from the control group. However, in the patient who had suffered a stroke and damage to the left side of the brain, the task was carried out in the right side of the brain, suggesting a functional takeover.

Fischer-Baum pointed out that the study is an important contribution to the field of neuroplasticity, helping scientists understand neural changes in terms of cognitive functioning.

The paper – The Cognitive Neuroplasticity of Reading Recovery Following Chronic Stroke: A Representational Similarity Analysis Approach – explaining the researchers’ techniques has been published in Neural Plasticity.

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