Current Status of Treatments for Dyslexia: Critical Review

Ann W. Alexander, MD; Anne-Marie Slinger-Constant, MD


J Child Neurol. 2004;19(10):744-758. 

In This Article

What Can Be Learned From Studies Using Computer-Modeled Neural Networks?

The connectionist models are not related to any specific treatment approach but rather serve to elucidate some of the neurologic factors involved in learning to read. The connectionist model of orthography-phonology mapping developed by Harm and Seidenberg demonstrated that phonologic knowledge could be pretrained using phonologic forms of words.[62] Subsequent training to map orthography to the pretrained phonologic system changed its phonemic representations, making them more distinct. This change facilitated learning to read additional words, thus illustrating the reciprocity between the development of phonemic awareness and reading. They also found that if the model was made to have very subtle phonologic deficits, it had significant difficulty learning to read the word. Phonologic representations were ineffective, the neural maps were peculiar, and there was no evidence that the code for the alphabetic principle could be discerned. Rayner and colleagues suggested that these findings infer that constitutional differences in the capacity for encoding phonologic structure could result in the variable outcomes in learning to read, further supporting the phonologic deficit hypothesis for developmental dyslexia.[4]

Harm and Seidenberg also used a computer model to show that, when learning to read, the phonologic pathway predominates because orthographic-phonologic mapping is easier to learn.[62] The orthographic-semantic (sight word reading) mapping pathway takes longer to learn because the code is less explicit. These representations develop with the repetition of the exposure. Once developed, the orthographic-semantic pathway plays a greater role in word reading. Of note, the most efficient decoding occurred when both pathways worked together on almost all words, further illustrating the need for the optimal development of both to prevent reading disabilities.


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