In the cerebellar deficit hypothesis of dyslexia of Nicolson et al.

(2005), The cerebellar deficit hypothesis and dyslexic tendencies in a non-clinical sample

The cerebellar deficit hypothesis and dyslexic …

An independently validated study by Frank and Levinson in 1973 indicated that 97% of 115 dyslexics evidenced neurological and electronystagmographic signs of a dysfunction within the inner-ear and its supercomputer—the cerebellum. Dyslexia was postulated to occur when impaired ocular-motor fixation and sequential tracking due to a subclinical nystagmus of inner-ear and cerebellar origin scrambled the letter and word signals during reading and thus secondarily interfered with their cerebral cortical and related brain processing. A follow-up study of 4,000 learning disabled and dyslexics in 1988 further validated the hypotheses. Utilizing an optokinetic instrument, dyslexics were shown to have significantly reduced ocular-motor fixation, sequential tracking and visual span capacities as well as abnormal signal scrambling vs controls. Inner-ear-enhancing anti-motion sickness medications were clinically recognized to improve most all reading and non-reading dyslexic symptoms and mechanisms. Later research suggested that a majority of those with fears, phobias and related anxiety disorders have cerebellar-vestibular determinants and deficits as well as related abnormal optokinetic tracking, visual span and signal capacities vs controls.

Developmental dyslexia: the cerebellar deficit hypothesis.

Hypotheses Causes
Phonological Processing Magnocellular Deficit Cerebellar Deficit Temporal Processing Structural Brain Differences -suggests that dyslexia is due to a deficit in the ability to determine the constituent sounds that comprise spoken words (Kibby, 2008) Decreased ability to detect tone differences
Unable to categorize sounds
These differences lessen throughout life Magnocellular pathway: rapid visual processing
Contrast sensitivity: mixed results
Visual attention: key aspect of successful reading
Eye movement
(Schulte-Korne, 2010) Asymmetrical vs.

This chapter focuses on brain-based explanation of dyslexia in terms of abnormal cerebellar function. It begins with some details on the neuranatomy of the cerebellum and then considers the role of the cerebellum in cognition and skill automatization. The chapter proposes the cerebellar deficit hypothesis, which speculates that cerebellar abnormality at birth leads to the development of cognitive difficulties of dyslexic children.


Developmental dyslexia: the cerebellar deficit hypothesis ..

Barth, A.E., Denton, C.A., Stuebing, K.K., Fletcher, J.M., Cirino, P.T., Francis, D.J., & Vaughn, S. (2010). A test of the cerebellar hypothesis of dyslexia in adequate and inadequate responders to reading intervention. Journal of the International Neuropsychological Society, 16, 526-536. PMCID:

Developmental dyslexia - ScienceDirect

The cerebellar impairment hypothesis provides a causal explanation for developental dyslexia, subsuming the phonological deficit account within a broader framework.