Spatial orientation of the golden hamster in conditions of conflicting location-based and route-based information

Abstract

The orientation of golden hamsters during their return from a food source at the centre of an experimental arena to their nest at the arena's periphery was examined. The experiments took place under different visual conditions and involved conflicting spatial information, which the animal could collect either en route, during the outward journey to the food source, or on site, at the point of departure of the return trip. When the arena and nest box were rotated before the start of the trial (so that the hamsters started the outward journey from different points in absolute space), the animals returned directly to the point of departure of each particular hoarding trip when tested under infra-red light. Deprived of visual cues, they resorted to route-based information, i.e. they depended on the registration and computation of cues which had been generated during the outward journey. If tested under the ordinary room lights, the animals returned in a constant direction towards the usual location of the nest box, but with slight deviations towards the changing point in space where they had initiated each hoarding trip. They therefore relied mainly on stable location-based features from the distant visual background which they had associated with the standard location of the nest entrance; at the same time, however, they were also influenced by information derived from the outward journey. If exposed to a weak light source from outside the arena, the animals' homing behaviour reflected the simultaneous influence of three categories of information: (a) The light as a stable, location-based cue which the subjects had associated with the usual location of the nest; (b) the registration of the previous outward journey by means of internal (idiothetic) path-dependent variables; and (c) the registration of the previous outward journey using the light as visual reference. These results illustrate the interplay and functional hierarchy of various categories of spatial information which the hamster, active at dusk and at night, can use in laboratory conditions as well as in its natural habitat.