Phonological grouping is specifically affected in cerebellar patients: a verbal fluency study

Objectives-Recent clinical and functional neuroimaging evidence points towa rds a cerebellar role in verbal production. At present it is not clear how the cerebellum participates in language production. The aim was to investig ate the influence of cerebellar lesions on verbal fluency abilities with sp ecific focus on the verbal searching strategies employed by patients with c erebellar damage. Methods-Twenty five patients with focal or degenerative cerebellar disease and 14 control subjects were tested in a timed verbal fluency task requirin g word production under forced (phonemic or semantic) conditions. To analys e the verbal searching strategy employed, semantic and phonemic cluster ana lyses were also performed. Results-Performances of cerebellar patients were comparable with those of c ontrols in the semantic task; conversely their performances were significan tly impaired when tested in the letter task. Cluster analysis results showe d that the verbal fluency impairment is linked to specific damage of phonem ically related retrieval strategies. Conclusion-Cerebella damage impairs verbal fluency by specifically affectin g phonemic rule performances while sparing semantic rule ones. These findin gs underline the importance of the cerebellar computing properties in strat egy development in the linguistic domain.