Homing pigeons experience age-related spatial-cognitive decline similar to that seen in mammals. In contrast to mammals, however, previous studies have shown the hippocampal formation (HF) of old, cognitively impaired pigeons to be greater in volume and neuron number compared with young pigeons. As a partial explanation of the cognitive decline in older birds, it was hypothesized that older pigeons have reduced HF activation during spatial learning. The present study compared HF activation (via the activity-dependent expression of the immediate early gene c-Fos) between younger and older pigeons during learning of a spatial, delayed nonmatch-to-sample task. On the last day of training, c-Fos activation significantly correlated with behavioral performance in the young, but not old, pigeons suggesting more HF engagement by the young pigeons in solving the task. The behavioral correlation was additionally associated with consistently higher, but insignificant c-Fos activation across practically every HF subdivision in the young compared with the old pigeons. In sum, the results of the present study are consistent with the hypothesis that age-related decline in the spatial cognitive ability of homing pigeons is in part a result of an older HF being less responsive to the processing of spatial information. However, alternative interpretations of the data are discussed.

中文翻译：

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c-fos 显示，在接受空间记忆任务挑战时，老年信鸽的海马参与度较低

信鸽经历了与哺乳动物类似的与年龄相关的空间认知衰退。然而，与哺乳动物相比，之前的研究表明，与幼鸽相比，老年、认知障碍鸽子的海马结构 (HF) 在体积和神经元数量上更大。作为对老鸽认知能力下降的部分解释，假设老鸽在空间学习期间减少了高频激活。本研究比较了年轻和年长鸽子在学习空间延迟非样本任务期间的 HF 激活（通过即时早期基因 c-Fos 的活动依赖性表达）。在训练的最后一天，c-Fos 激活与年轻人的行为表现显着相关，但与老年人无关，鸽子建议幼鸽在解决任务时更多地参与高频活动。与老鸽相比，行为相关性还与在幼鸽的几乎每个 HF 细分中始终较高但微不足道的 c-Fos 激活相关。总之，本研究的结果与信鸽空间认知能力与年龄相关的下降部分是由于年龄较大的 HF 对空间信息处理的反应较弱的假设一致。然而，讨论了数据的替代解释。本研究的结果与以下假设一致，即信鸽空间认知能力与年龄相关的下降部分是由于较老的 HF 对空间信息处理的反应较弱。然而，讨论了数据的替代解释。本研究的结果与以下假设一致，即信鸽空间认知能力与年龄相关的下降部分是由于较老的 HF 对空间信息处理的反应较弱。然而，讨论了数据的替代解释。