Clinical evidence of the role of the cerebellum in the suppression of overt articulatory movements during reading. A study of reading in children and adolescents treated for cerebellar pilocytic astrocytoma.

It has been suggested that the cerebellum is involved in reading acquisition and in particular in the progression from automatic grapheme-phoneme conversion to the internalization of speech required for silent reading. This idea is in line with clinical and neuroimaging data showing a cerebellar role in subvocal rehearsal for printed verbalizable material and with computational "internal models" of the cerebellum suggesting its role in inner speech (i.e. covert speech without mouthing the words). However, studies examining a possible cerebellar role in the suppression of articulatory movements during silent reading acquisition in children are lacking. Here, we report clinical evidence that the cerebellum plays a part in this transition. Reading performances were compared between a group of 17 paediatric patients treated for benign cerebellar tumours and a group of controls matched for age, gender, and parental socio-educational level. The patients scored significantly lower on all reading, but the most striking difference concerned silent reading, perfectly acquired by almost all controls, contrasting with 41 % of the patients who were unable to read any item silently. Silent reading was correlated with the Working Memory Index. The present findings converge with previous reports on an implication of the cerebellum in inner speech and in the automatization of reading. This cerebellar implication is probably not specific to reading, as it also seems to affect non-reading tasks such as counting.