Developmental dyslexia, learning and the cerebellum.

Theoretical frameworks for dyslexia must explain how the well-established phonological deficits and the literacy deficits arise. Our longstanding research programme has led to a distinctive 'twin level' framework that proposes, first, that the core deficits are well described in terms of poor skill automaticity. Second, these 'cognitive level' symptoms are attributed to abnormal cerebellar function--a 'brain-level' analysis. The evidence includes data from behavioural, imaging, neuroanatomical and learning studies. The frame-work leads to an 'ontogenetic' analysis that links cerebellar deficit at birth, via problems in articulation and working memory, to the known phonological, speed and literacy difficulties. Differences in locus of cerebellar impairment, experience and/or links to other brain regions may account for subtypes of dyslexia and possibly other developmental disorders. The automaticity/ cerebellar deficit framework provides an explicit demonstration that it is possible to explain motor, speed and phonological deficits within a unified account, integrating previously opposed approaches.