The Role of the Avian Hippocampus in Sequence Learning and Visual Memory

Abstract

It has long been known that the hippocampus is important for spatial processing; however, more recently, questions have been asked about the hippocampus’ role in sequence learning and visual memory. Previous findings regarding the role of the hippocampus have provided some support for the avian hippocampus being a functional homologue of the mammalian hippocampus; however, with regard to sequence learning and visual memory, avian species have received less attention. This thesis aimed to determine whether damage to the hippocampus of pigeons resulted in impairments in sequence learning and visual memory. Control and hippocampal lesion pigeons were trained in standard operant chambers on 15 2-item lists, 30 3-item lists, and seven 4-item lists, consisting of a variety of visual stimuli. An external and constant sequence was used, as subjects were required to respond in a predetermined order, and were trained on the same stimuli until they met criterion. Hippocampal lesions had no effect on visual sequence learning with 2-, 3-, or 4-item lists. At the conclusion of training on the 3-item lists, subject’s retention of the lists was tested over a two day period in which they were presented with previously learnt lists. Again, hippocampal lesions had no effect on this visual memory task. These findings add to the growing evidence base from other species that suggests that damage restricted to the hippocampus does not impair sequence learning or visual memory.