ABSTRACT
We can now sketch a fairly convincing ‘bottom up’ account of one important learning task of the brain – learning to read. Cognitive reading skills appear to depend on the quality of individuals’ low level auditory and visual sensory processing. These processes make use of the links between the visual and language areas of the cerebral cortex to piggyback on the neurological apparatus that evolved for speaking, in order to associate the visual form of words with their spoken counterparts for reading. The eyes and attention scan each word to identify its letters and their order. The visual control of these
attentional and eye movements is mainly mediated by the magnocellular subcomponent of the visual system that is specialised for timing visual events. Hence, this system can detect any unwanted motion of the eyes and thus enable the ocular motor system to correct them. Impaired development of the visual magnocellular system is associated with unsteady fixation on words during reading, hence visual confusion and slow reading progress. Analogous processes seem to be important for hearing. Unfamiliar words are read by translating the
letters into their sounds, then assembling them into the auditory form of the word which gives its meaning. The distinctions between different letter sounds are conveyed by changes in the frequency and amplitude of the acoustic speech signal. These are picked up by large auditory neurones specialised for sensing auditory transients. Hence, people with high auditory transient sensitivity find it easy to acquire phonological skill, whereas poor readers tend to have low sensitivity to these acoustic transients and end up with poor phonological skills. Thus, both visual and auditory transient sensitivity, and hence orthographic and phonological skills, are
mediated by magnocellular systems in the brain that are specialised for tracking temporal changes. Ultimately therefore, the acquisition of reading skills depends on genetic and environmental influences over the development of magnocellular neurones. Understanding the neurobiological basis of reading problems is enabling teachers to really help children
who are making slow reading progress. Armed with knowledge of how auditory and visual transient sensitivity determines the development of reading skills, and of the profile of a particular pupil in each of these areas, teachers can design programmes targeted to each individual’s strengths and weaknesses. Taking advantage of the incredible plasticity of the developing brain, we now know that cognitive weaknesses can be remediated and improved by appropriate training. Thus, our increasing understanding of the neuroscience behind cognitive processes is already beginning to benefit teachers in their classrooms, directly and practically, to help children acquire the literacy skills required in modern life. And this understanding can only accelerate in the future.
