What went where? Impaired object-location learning in patients with right hippocampal lesions

The role of the right medial temporal-lobe structures in memory for object location was investigated in three studies. In the first two studies, 118 patients with selective amygdalo-hippocampectomy or with anterior temporal lobectomy (either invading or largely sparing the hippocampal region) and 33 healthy participants were tested on array learning. Groups with extensive right hippocampal lesions were impaired on immediate and delayed recall and on learning to criterion. In the third study, magnetic resonance imaging (MRI) was used in 75 of these patients to measure the extent of tissue remaining in the various medial temporal-lobe structures. The extent of right hippocampus remaining was found to be the best predictor of array-learning performance, underlining its critical role in building a representation of objects in space.