Dyslexia and Related Disorders

Mapping the Brain

Introduction and Objectives

To understand learning disabilities, or as we refer to them at Shelton School, learning differences, it is important to understand how human beings learn.  Since learning takes place in the brain, an overview of the functions in the brain related to reading acquisition is included in this lesson.

By the end of this lesson, the student should be able to:

  •  Approximate the number of neurons and connections between neurons in the brain.
  • Describe the major functions of the left and right hemispheres, occipital lobes, temporal lobes, and corpus callosum.
  • List eight major causes for problems in school and identify the one describing learning differences.
  • State the normal mental ability range.

Circuits in the Brain

The brain is a complex network of neurons (nerve cells). There are at least a hundred billion neurons that make between five thousand and fifty thousand connections.  This adds up to one million billion, or one quadrillion, connections between the nerves in the cortex.  This information makes us realize how much in awe we should be of the human brain and our ability to do anything, especially our ability to do highly abstract tasks.

In the process of reading, writing and spelling, what would make anyone think that everything should work perfectly all of the time when we consider the number of connections in the central nervous system?  Well, it doesn’t work perfectly all of the time and no one has an absolutely perfect brain that never dysfunctions.

Once Too Often

Every one has probably had the experience of writing down a telephone number and getting some numbers wrong, leaving a number out, or reversing some of the numbers in the sequence.  Every one has probably had the experience of writing down a word, often while we were distracted, then, looking down at it to notice that we have spelled it wrong.

We have spelled it wrong because we did not process the information correctly. We all can experience processing difficulties.  But when you have a learning difference, these processing difficulties are so frequent that they become handicapping to your performance and especially to your performance in school.

True or False: Processing difficulties are only experienced by those who have learning differences.

  • True
  • False

Brain Architecture

At the back of the brain are the visual centers and on the left side of your brain is the area of the brain that interprets auditory signals.  This explanation makes it appear that the brain is divided up very specifically and neatly in a way that is easy for us to remember; however, it is not that easy.  Parts of the brain network, connect, and integrate with many other parts of the brain. It’s a very complex system.

The Left-Right Connection

Inside the brain is a part that looks almost snail-like.  If we cut our brain exactly in half, right in the center you’d find the corpus callosum.  That is the part of the brain that transfers information from the left hemisphere to the right hemisphere.  It is a very, very important network. An example of why that would be so important is:  In the left side of the brain we attach sounds to the symbols that we perceive as shapes, and we perceive the shapes on the right side of the brain.  So, information has to be sent from the right to the left side of the brain through the corpus callosum for us to be able to read and work.

Reading Skills

This is an illustration of the Posterior Reading System:  With the use of functional MRIs, the identification of the neural circuitry responsible for reading is possible.  As stated previously, the brain has four lobes, frontal, parietal, temporal, occipital. Depending on the level of reading skill, different areas of the brain are activated.

Beginning Readers

In beginning readers, the parieto-temporal area is more activated because of the dependency on analyzing the letters and sounds of the words. Another region that beginning readers depend on is the Broca’s area.

Skilled Readers

In more skilled readers, an exact neural model of a word is accessed in the occipito-temporal area. Good readers have a strong activation in the back of the brain.

Struggling Readers

In struggling readers, Broca’s area is often more strongly activated to sub-vocalize the sounds, which may give additional aid in the word analysis. Using this area compensates for the disruption in the back of the brain. Repetitions and many exposures to a word will hopefully help to form a neural model for the word, enhancing reading skills.

Matching: Here would be a drag and drop matching page (can't set up in trial mode)

Multiple Choice: What part of the brain transfers information from the left to the right of the hemisphere?

  • Amygdala
  • Corpus Callosum
  • Frontal Lobe
  • Occipital Lobe