Topographic amnesia: spatial memory disorder, perceptual dysfunction, or category specific semantic memory impairment?

A 60 year old patient, SE, who presented with a severe difficulty in finding his way around previously familiar environments and a mild prosopagnosia is described. SE had herpes simplex encephalitis resulting in selective right temporal lobe damage. He showed normal spatial learning, but was severely imparied in his ability to recognise pictures of buildings and landmarks. The disorder was not confined to the visual modality, but rather involved a loss of knowledge about famous buildings and landmarks when tested from their spoken name. SE was contrasted with a more severely prosopagnosic patient, PHD, who showed normal ability to recognise buildings and landmarks, indicating that recognition of people dissociates from recognition of buildings/landmarks. It is concluded that SE's failure of place knowledge represents a category specific supramodal semantic memory impairment.