The purpose of this fMRI study was to investigate the neural substrates related to the working memory of orthography. The question may be asked as to whether handling orthographic information should be considered as to a verbal or a visuospatial stimulus, because this information can be employed as a shape or as a location for visuospatial stimuli, even though it falls within the category of verbal information. Ten Korean native speakers were imaged using a 1.5T MR scanner while performing a one-back working memory task in orthography (OTH), phonology (PHO) and figures (FIG). The brain areas commonly activated in OTH and PHO were found to be in the bilateral, frontal and parietal cortices, which is consistent with previous working memory studies. Among these areas, the regions where the MR signal was found to be higher in OTH than in PHO were located in the inferior frontal gyrus and superior parietal lobule. When the figure was subtracted from orthography, inferior frontal gyrus was activated as well. Therefore, dealing with orthographic information seemed to activate a similar network of brain areas as for spatial information. However, considering that the additional activation in the inferior frontal gyrus was observed only in OTH, we can also conclude that dealing with orthography differed somewhat from the process of handling figures. This observation confirms the unique property of dealing with orthography, distinct from the process of handling figures.

Keywords: functional magnetic resonance imaging, working memory, orthography, phonology, figure, inferior frontal gyrus