Reading Disorders and Cortical (Brain) Function

Beneath the cerebral lobes Are the most sensitive brain structures. Here lie areas responsible for moving short-term memory traces into long-term memory traces (the hypocampal area). Also housed in this region is the diencephalon which helps the body maintain homeostasis. Of critical import to learning is the reticular activating system which helps with attention and concentration.

Scientists are aware that difficulty with specific cortical regions influence learning. We learned on previous presentations that higher level functions or complex cognitive tasks are dependent on the cerebral lobes.

Let’s Look At Specific Differences In Brain Structure In Individuals With Reading Disorders. Research has focused on reading disabilities, since they represent the most common and frequently identified type of Learning Disability.

Both hemispheres are equal in size. Studies have shown that brains of subjects with reading disabilities have no asymmetry in brain structures. Both hemispheres are equal in size. When we looked at the normal functioning brain or cerebral cortex, we noticed that the left hemisphere which is responsible for verbal tasks is larger than the right hemisphere.

Asymmetry Means that the left and right hemispheres are different in size. Asymmetry is a normative finding.

The differences are specific to the temporal lobe. The temporal lobe or planum temporale area. in normal subjects the left hemisphere has been found to be typically larger than the temporal lobe in the right hemisphere In normal individuals there is asymmetry in the size of the temporal lobes.

In subjects with LD, the left hemisphere has been found to be the same size as the right hemisphere.

This is a logical finding since… It makes sense that when this area is diminished in size, skills housed in the region will be compromised. If you remember, the left hemisphere is the hemisphere primarily responsible for language.

The CT Scan One technique for studying the brain is the CT scan (computed tomography). With this technique, an x ray beam is shot through the brain, identifying bone, grey matter, and fluid. A computer then reconstructs an image of each slice or brain section allowing abnormalities in structure to be detected. There are many ways that scientists study brain anatomy and function.

The Occipital Lobe Is Located At The Back of the Cerebral Cortex CT scans of the occipital lobe have shown asymmetry of the occipital pole in subjects without LD, and symmetry in subjects with LD. Other differences in brain anatomy in subjects diagnosed with a reading disorder are found in the occipital lobe.

Scientists believe differences in the occipital lobe… Are related to how the individual sees words rather than how the individual processes words. Many individuals with reading disorders have difficulty with letter stabilization. Read at the END OF THE SLIDE Scientists believe these subjects present with dyslexia

Letter Stabilization Has To Do With The Orientation Of Letters. Individuals with difficulty in this area often confuse b with p or d or q. Sometimes the letters are reversed. This is especially problematic with shorter words so that “was” is often read as “saw.”

The MRI shows other important differences. Magnetic resonance imaging (MRI) involves recording the electromagnetic energy of brain protons and constructing an image by superimposing magnetic fields. Magnetic Resonance Imaging is another technique that helps us understand brain anatomy and function.

The MRI Allows The Practitioner To Gain A Valuable Perspective Of The Brain. You can see in this slide that the MRI is similar to an xray.

Subjects with Reading Disorders do not show the expected asymmetry. MRI’s indicate that subjects without LD showed leftward asymmetry in the angular gyrus of the parietal lobe, Subjects with Reading Disorders do not show the expected asymmetry. The MRI has allowed scientists to understand other aspects of brain anatomy and how they relate to learning and disabilities

These Individuals May have difficulty with sound/symbol relationships. A is for Apple These patients have a different symptom cluster.

Or they may have difficulty with movement stabilization Or they may have difficulty with movement stabilization. (Sometimes they hate amusement park rides.) Sometimes they have difficulty riding in a car

The MRI and Other Techniques are used to measure brain activity while subjects are engaged in a task such as reading. The MRI and other techniques

These Techniques Measure Various Aspects Of Cortical Physiology. An fMRI is a non-invasive method that measures blood flow. PET and SPECT scans involve the injection of radioactive materials and allow the metabolic activity of specific brain regions to be measured. There are techniques that measure various aspects of cortical physiology during an activity. They give us the most valuable information on brain activity.

SPECT scan results have indicated that subjects with LD show under-functioning in the occipital lobe when reading in comparison to subjects without LD. The functional MRI and Spect scans show blood flow during an activity.

These imaging devices… Show collaborative information that testify to cortical differences in LD individuals. These differences indicate brain size and shape differ in various aspects. The differences are specific to the disability.

This research adds significant support to the hypothesis that Learning Disorders are directly related to brain anatomy.

The individual’s low motivation and performance are a psychological response to organic differences in the brain.

These anatomical differences do not prohibit learning… Individuals with LD can learn; the process may be inefficient because of the differences in brain structure and function. Inefficiency presents as: low accuracy or slow speed in learning or performing a task. This is quite distinct from inability or incapacity. These anatomical differences do not prohibit learning Individuals with LD can learn

Information can be processed, But it’s processed at a slower rate and/or by different methods as compared to individuals without LD. Which is why giving the individual necessary and reasonable accommodations such more time to process information is so critical.

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Licensed Psychologist LaSalle College High School Prepared by: Jo Ann Curcio Cohen, Ph.D. Licensed Psychologist Learning Specialist LaSalle College High School