Organic basis for dyslexia - Max Planck Leipzig Research Study

Severe and persistent reading and spelling impairment linked with difficulties in processing speech sounds (developmental dyslexia) may be associated with under-action of an area of the brain.

Establishing an underlying organic basis for dyslexia has been a controversial area in recent years, but a team based at the Max Planck Institute Leipzig has used functional MRI scanning on dyslexic adults.

They found that there was a dysfunction in the auditory sensory thalamus, the medial geniculate body (MGB), while all other structures in the auditory pathway behaved comparably with those in control patients without dyslexia.

Furthermore, MGB activity correlated with dyslexia diagnostic scores, indicating that the task modulation of the MGB is critical for performance in dyslexics.

The authors of the research, published this week in the online Proceedings of the National Academy of Sciences of the US, suggest that 'deficits in dyslexia are associated with a failure of the neural mechanism that dynamically tunes the MGB according to predictions from cortical areas to optimise speech processing.'

This research may go some way in establishing an underlying neural framework for the various presentations of some forms of dyslexia.

Read the Abstract and get access to the full paper here; PNAS online 

Authors: Begoña Díaz, Florian Hintz, Stefan J. Kiebel and Katharina von Kriegstein