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Researching Dyslexia

The Brain and Functional Imaging Technology

Jun 28, 2008

Dyslexia research, most often with people suffering from alexia, studies the brain's processes while reading, through functional imaging tests (or PETs and fMRIs).

Patients with alexia are those who gained dyslexia after some sort of head trauma or other brain injury. Researchers interested in studying dyslexia through how it affects the brain choose alexic patients because they are neither learning to read (like dyslexic children), nor adults who have already gained compensation skills for dyslexia.

It is important to study how dyslexia affects brain patterns in humans because if we understand what is different in dyslexic patients vs. normal patients, it will be easier to find a solution to helping individuals with dyslexia.

How PET and fMRI Works

Studies of the brain processes of dyslexics, especially alexics, utilize a modern technology termed functional imaging technology. Two ways to study the brain by functional imaging are with PET and fMRI tests. Both of these tests work by measuring an individual’s brain activity on the basis of the change in cerebral blood (measured by rCBF) or blood oxygenation. These tests are accurate within three millimeters – and it is one of the most specific technologies available for brain scanning.

Functional Imaging and How the Brain Reads

Functional Imaging Technology (via PET and fMRI tests) inform researchers about how the brain works when reading, writing, or speaking in four main ways:

It provides a measure of brain activity that is not detectable in simply behavioral tests. For example, it is used in subliminal testing, since it can record activity in the brain that is not necessarily visible in physical behavior.
These tests can index, or “mark”, brain activity at each stage of a certain task. For example, they can record the brain registering a command, deciding to respond, then sending the directions to the mouth and vocal chords for response (and all the steps in between).
Functional Imaging provides an additional source for researchers studying dyslexia. Not only does it improve the researcher’s process of coming to conclusions, it also validates their conclusions to the academic world.
Most importantly, these tests compare the brain activation in dyslexics against normal readers – which can reveal how dyslexic readers’ brains compensate while reading.

Problems with Functional Imaging

The current results from neural, or brain, studies of dyslexic readers, however, can be very difficult to interpret. For one, there are few consistent results that can be compared with one another across various academic studies. This makes it difficult to offer a scholarly comparison and draw concrete conclusions when looking between several studies. It also calls into question the validity of each study’s conclusion on its own, since it is difficult to recreate and prove given conclusions.

Also, it is difficult to discern whether the results are a cause or an effect of the person’s dyslexia. In general, it is very difficult to differentiate between abnormal neuronal processing (the casual basis of dyslexia) from the effects due to the difference in performance levels that arise as a result of dyslexia.

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Sources:

Shin, Linda M, ed. Learning Disabilities Sourcebook. Vol. 33. Detroit, MI: Omnigraphics, 1998.

Price, Cathy J. and Eamon McCrory. “Functional Brain Imaging Studies of Skilled Reading and Developmental Dyslexia.” The Science of Reading: A Handbook. Ed. Margaret J. Snowling and Charles Hulme. Oxford: Blackwell, 2005. 454-473.

Obler, Loraine K. and Kris Gjerlow. Language and the Brain.

The copyright of the article Researching Dyslexia in Disabilities is owned by Valerie Suydam. Permission to republish Researching Dyslexia in print or online must be granted by the author in writing.