Dyslexia, or reading disability, is a developmental disorder characterized by inaccurate and slow reading despite an averaged nonverbal intelligence and repeated exposure to written language.  Several theories were raised regarding the causes of dyslexia, such as an orthographic processing challenge, a deficit in executive functions and morphological abilities, and the leading theory- a phonological deficit. 

As reading is a new evolutionary human invention, the human brain had to utilize neural circuits that were not originally designated to read. This process is also referred to as a "neural recycling" and includes the utilization of brain regions and networks related to language processing, visual processing, cognitive control and more. Since the reading process is so complex, the neurobiological research on dyslexia focuses on different brain activity and connectivity related to changes in activation and functional connections of language, visual processing, and cognitive control abilities in these readers and whether different interventions help change these abilities and their related neural circuits.

These studies pointed to reduced brain activation of reading-related regions in those with dyslexia and increased right-lateralized activation in those readers. Reduced activation in visual, auditory/language-related regions as well as in cognitive control regions was reported, as well as the reduction between these networks, all related to lower reading skills. Interventions in the field of dyslexia focus on the attempts to improve reading skills in these readers, with neuroimaging studies suggesting greater reading gains associated with either increased engagement in orthographical-related regions (visual processing), language and phonological processing (auditory-related brain regions), executive functions-related regions and more.

Not every reader gains the same from a given intervention; the use of neuroimaging also allows us to determine the brain profiles of individuals with dyslexia responding to interventions vs non-responders in an attempt to get us closer to a “precision education” approach.  More information on such studies can be found here.