Cerebral laterality for the generation of silent and written language in male and female right- and left- handers: a functional transcranial doppler ultrasound study

Background: The cerebral lateralization of language has attracted great research interest. Nevertheless, the bulk of the work focuses on language production and comprehension; research on cerebral lateralization during writing is limited. Material/ Methods: The present study assessed cerebral lateralization in 60 participants (mean age = 26.65 years, SD = 6.05, range = 20-44), 30 right-handers (14 men) and 30 left-handers (16 men), during written language production by means of functional transcranial Doppler ultrasonography (fTCD) for the first time. Results: Findings show that left-hemispheric lateralization is observed during silent word production, for both left- and right-handers. However, during written word production, the degree of typical (left) hemispheric lateralization was significantly increased for right-handers, while left-handers presented atypical (right) hemispheric lateralization. Importantly, the difference between silent and written word generation was significantly higher in left- compared to right-handers. No main effect of sex or interactions with sex were observed. Conclusions: Findings suggest that a wider network of right-hemispheric areas is used during writing in left-handers. Thus, the known differen - ces in cerebral lateralization between right- and left-handers are stron ger during written language production. However, the rela - tive contribution of language and motor areas needs to be further elucidated.