Tree shrews (Tupaia belangeri) exhibit novelty preference in the novel location memory task with 24-h retention periods.
Novelty preference is pervasive in mammalian species, and describes an inherent tendency to preferentially explore novelty. The novel location memory task studied here assesses the ability of animals to form accurate memories of a spatial configuration, consisting of several identical objects placed within an arena. Tree shrews were first familiarized with a particular object configuration during several sessions, and then an object was displaced during a test session. Tree shrews exhibited enhanced exploration when confronted with this novel configuration. The most reliable indicator associated with novelty preference was an enhancement in directed exploration towards the novel object, although we also observed a non-specific overall increase in exploration in one experiment. During the test session, we also observed an exploration of the location, which had previously been occupied by the displaced object, an effect termed empty quadrant. Our behavioral findings suggest multiple stages of spatial memory formation in tree shrews that are associated with various forms of behavioral responses to novelty. Reduced novelty preference has been linked to major depressive disorder in human patients. Given the established social conflict depression model in tree shrews, we anticipate that the study of the neural circuits of novelty preference and their malfunction during depression may have implications for understanding or treating depression in humans.
Visual Cognition Laboratory, Department of Medicine, University of Fribourg Fribourg, Switzerland ; Fribourg Center for Cognition, University of Fribourg Fribourg, Switzerland.
Jayakrishnan
J
Nair
Visual Cognition Laboratory, Department of Medicine, University of Fribourg Fribourg, Switzerland.
Marlene
M
Topka
Visual Cognition Laboratory, Department of Medicine, University of Fribourg Fribourg, Switzerland ; Fribourg Center for Cognition, University of Fribourg Fribourg, Switzerland.
Abbas
A
Khani
Visual Cognition Laboratory, Department of Medicine, University of Fribourg Fribourg, Switzerland.
Manuela
M
Isenschmid
Visual Cognition Laboratory, Department of Medicine, University of Fribourg Fribourg, Switzerland ; Fribourg Center for Cognition, University of Fribourg Fribourg, Switzerland.
Gregor
G
Rainer
24 h retention period; animal models; depression; depressive disorder; habituation; major depressive disorder; spatial memory; spatial novelty