Unimpaired acquisition of spatial reference memory, but impaired homing performance in hippocampal-ablated pigeons.
Hippocampal ablated homing pigeons have been shown to suffer a retrograde spatial reference memory deficit involving a preoperatively acquired homeward orientation response based on local cues around a previously visited release site. Here we report that the postoperative acquisition of such a response is unimpaired. Initially, 25 hippocampal ablated and 11 sham-operated controls were given 5 training releases from each of two sites. In the subsequent experimental releases from the two training sites, the controls and half the hippocampal-ablated pigeons had their navigational maps rendered dysfunctional via an anosmic procedure. Nonetheless, both groups successfully oriented homeward, indicating that the hippocampal-ablated pigeons were unimpaired in the acquisition and implementation of directionally useful information around the training sites to direct a homeward orientation response. The remaining half of the hippocampal-ablated pigeons who were not rendered anosmic, and thus served as controls, also oriented homeward. The data indicate that, for hippocampal-ablated homing pigeons, postoperative acquisition is unimpaired in the same spatial reference memory task where a robust retrograde impairment was observed. However, the hippocampal-ablated pigeons were impaired in the time required to return home, indicating a deficit in homing performance beyond the initial orientation stage.
Bingman
V P
VP
Department of Physiology and Biochemistry, University of Pisa, Italy.
Ioalé
P
P
Casini
G
G
Bagnoli
P
P
D000818:Animals; D001931:Brain Mapping; D010856:Columbidae / Q000502:physiology*; D006624:Hippocampus / Q000502:physiology*; D006702:Homing Behavior; D008568:Memory / Q000502:physiology*; D009949:Orientation / Q000502:physiology*; D013037:Spatial Behavior / Q000502:physiology*