Inferior parietal lobule contributions to visual word recognition.

This study investigated how the left inferior parietal lobule (IPL) contributes to visual word recognition. We used repetitive TMS to temporarily disrupt neural information processing in two anatomical fields of the IPL, namely, the angular (ANG) and supramarginal (SMG) gyri, and observed the effects on reading tasks that focused attention on either the meaning or sounds of written words. Relative to no TMS, stimulation of the left ANG selectively slowed responses in the meaning, but not sound, task, whereas stimulation of the left SMG affected responses in the sound, but not meaning, task. These results demonstrate that ANG and SMG doubly dissociate in their contributions to visual word recognition. We suggest that this functional division of labor may be understood in terms of the distinct patterns of cortico-cortical connectivity resulting in separable functional circuits.