A functional MRI study on the neural substrates for writing

Functional neuroanatomy of writing is relatively unknown compared to that of other linguistic processes. This study aimed at identifying brain regions crucial to the process of writing. Using functional magnetic resonance imaging (fMRI), brain hemodynamic activity was examined during three conditions that differentially engaged visual, linguistic, and/or motor functions: (1) writing names of pictures with the right index finger, (2) naming pictures silently, and (3) visually cued finger tapping. A writing minus naming comparison and a writing minus tapping comparison were performed, and brain regions commonly activated in these two contrasts were detected. Our main finding was that such common activation was observed in the anterior part of the left superior parietal lobule, the posterior part of the middle and superior frontal gyri, and the right cerebellum. The parietal and frontal regions were considered to subserve the process of writing as separated from that of naming and finger movements, which is consistent with the classical notion mainly proposed by studies of selective writing deficits called pure agraphia. The right cerebellar activation, on the other hand, was interpreted as the reflection of the execution of complex finger movements required for writing.