Connections of the piriform cortex of the homing pigeon Columba livia studied with fast blue and WGA-HRP

The piriform cortex in homing pigeons receives a projection from the olfactory bulb and is necessary for the operation of those aspects of the navigational map based on olfactory stimuli in these animals. The afferent and efferent projections of the piriform cortex were studied using retrograde migration of wheat-germ agglutinin horseradish peroxidase (WGA-HRP) and Fast Blue, and anterograde migration of WGA-HRP. The piriform cortex was found to receive projections from, and send projections to, numerous regions and nuclei in the telencephalon, diencephalon and lower brainstem. A reciprocal connection with the parahippocampal region suggests that the piriform cortex and hippocampal formation may be part of a neural system that regulates navigational map learning. The piriform cortex also connects reciprocally with a large portion of the anterior telencephalon, including the cortex prepiriformis and hyperstriatum dorsale. In general, the pathway connections of the piriform cortex in homing pigeons are similar to those of the piriform cortex in mammals.