The representation of the horizontal meridian in the primary visual cortex

The authors report the findings of two patients that confirm the location o f the horizontal meridian in the human visual cortex. The first patient had an inferior quadrant defect with a band of horizontal meridian sparing. Ma gnetic resonance imaging showed a lesion concentrated along the medial stri ate cortex. The second patient had a homonymous horizontal defect that resu lted from removal of an arteriovenous malformation located in the lateral s triate cortex, The findings of these two patients demonstrate that the hori zontal meridian is represented at the calcarine fissure base in the primary visual cortex.