Neural Underpinnings of the Decline of Topographical Memory in Mild Cognitive Impairment.

Spatial navigation is one of the cognitive functions known to decline in both normal and pathological aging. In the present study, we aimed to assess the neural correlates of the decline of topographical memory in patients with amnestic mild cognitive impairment (aMCI). Patients with aMCI and age-matched controls were engaged in an intensive learning paradigm, lasting for 5 days, during which they had to encode 1 path from an egocentric perspective and 1 path from an allocentric perspective. After the learning period, they were asked to retrieve each of these paths using an allocentric or egocentric frame of reference while undergoing a functional magnetic resonance imaging scan. We found that patients with aMCI showed a specific deficit in storing new topographical memories from an allocentric perspective and retrieving stored information to perform the egocentric task. Imaging data suggest that this general decline is correlated with hypoactivation of the brain areas generally involved in spatial navigation.