ABSTRACT
A dynamic model of the Visual System is proposed that can explain typical symptoms of dyslexics during reading. In the model parameters are related to neurophysiological deficits which have been proposed as an underlying cause for developmental dyslexia. In a periodically forced version of the dynamic model for visual information processing, jump resonance occurs in the position feedback loop when the input frequency is in the neighborhood of the “eigen” frequency of the system. The “eigen” frequency of the system appears to be related to the synaptic throughput of a neural net: a reduced throughput leads to a lower “eigen” frequency, reflected in a lowered frequency of the alpha-rhythm in the EEG. During reading the input frequency into the cognitive system of dyslexics is supposed to be in the neighborhood of the “eigen” frequency, causing chaotic fluctuations in evoked potentials. These chaotic fluctuations in evoked potentials can explain the typical random omissions and insertions during the reading of dyslexics. Empirical evidence, supporting this point of view, is presented and some possible remedies for dyslexia are proposed.
