Functional magnetic resonance imaging (fMRI) during mental writing with phonograms.

Functional magnetic resonance imaging (fMRI) at 1.5 T using a gradient echo echo-planar sequence was employed to identify brain regions activated during the performance of a mental writing task using phonograms. Four regions were activated in all six subjects; the region surrounding the left intraparietal sulcus, the region surrounding the middle part of the left precentral sulcus and the posterior part of the left superior frontal sulcus, the region surrounding the right intraparietal sulcus, and the region surrounding either or both of the left and right cingulate sulci. The left intraparietal region was usually the most extensively activated. The results suggest that these four regions particularly the left intraparietal region, are essential in writing with phonograms. Since the left hemisphere was more extensively activated than the right, fMRI during the mental writing task is a good candidate for determining non-invasively which hemisphere is dominant for language.