Visual-spatial localization by patients with frontal-lobe lesions invading or sparing area 46

Monkeys with unilateral principal sulcus (PS) lesions show a contralateral deficit in localizing remembered targets, especially as the recall interval is lengthened. We tested 20 patients with unilateral frontal-lobe excisions that invaded (FI) or spared (FS) area 46 (putative homologue of PS) and 32 normal controls (NC) on a task where subjects had to indicate the location of a light dot either immediately, or after 30 s, with or without interference. The FI group was worse than the NC group following both delay conditions. NC and FS groups differed only after interference. We concluded that area 46 is involved in recalling the location of visual targets, but unlike the monkey, the deficit is not restricted to a particular part of the visual field.