Avian hippocampal role in space and content memory.

The present study examined whether the hippocampal formation of homing pigeons (Columba livia) was necessary for learning the contents of different goal locations in an open-field, laboratory environment. Results showed that, although control animals were able to distinguish between two goal locations that contained food items of different quality, pigeons with bilateral hippocampal lesions were impaired in goal-quality discrimination, even though non-spatial cues could have been used to distinguish between goal locations. Probe trials further revealed that the hippocampal formation-lesioned pigeons were impaired in the use of space to recognize goal locations as well as having a poorer capacity to integrate spatial information with the visual features of food bowls. These results promote a revised view of avian hippocampal memory function, one in which the avian hippocampal formation is critical not only for learning the spatial properties of goal locations but also for learning what happens at goal locations in an animal's environment.