Spared Perception of the Structure of Scenes after Hippocampal Damage

To explore whether the hippocampus might be important for certain spatial operations in addition to its well-known role in memory, we administered two tasks in which participants judged whether objects embedded in scenes or whether scenes themselves could exist in 3-D space. Patients with damage limited to the hippocampus performed as well as controls in both tasks. A patient with large medial-temporal lobe lesions had a bias to judge objects in scenes and scenes themselves as possible, performing well with possible stimuli but poorly with impossible stimuli in both tasks. All patients were markedly impaired at remembering the tasks. The hippocampus appears not to be essential for judging the structural coherence of objects in scenes or the coherence of scenes. The findings conform to what is now a sizeable literature emphasizing the importance of the hippocampus for memory. We discuss our results in light of findings that other patients have sometimes been reported to be disadvantaged by spatial tasks like the ones studied here, despite less hippocampal damage and milder memory impairment.