Visual and spatial discrimination behavior following hippocampal lesions in pigeons

Abstract

We investigated whether the avian hippocampus (Hp) was a functional homologue of the mammalian Hp. Nine pigeons with bilateral Hp and area parahippocampalis (APH) lesions and 10 sham-operated pigeons were tested on the postoperative retention of preoperatively acquired visual discriminations and the postoperative acquisition and retention of visual discriminations, as well as on the reversal of visual discriminations. In addition, the pigeons were trained on the acquisition and reversal of a position discrimination, both in an operant chamber and in a T-maze. Hp-APH pigeons showed no evidence of retrograde amnesia for visual information, nor were they impaired in the postoperative acquisition, reversal, or retention of visual discriminations. Although Hp-APH pigeons were not impaired in the acquisition and reversal of a position discrimination in the operant chamber, they were impaired in the acquisition and reversal of a position discrimination in a T-maze. We believe our findings support the notion that the avian Hp is a functional homologue of the mammalian Hp.