Graduate Program in Biomedical Engineering, University of Manitoba, Winnipeg, Manitoba, Canada.
Department of Psychology, University of Manitoba, Winnipeg, Manitoba, Canada.
Learn Behav. 2022 Mar;50(1):125-139. doi: 10.3758/s13420-021-00507-z. Epub 2022 Mar 25.
Pigeons are long-lived and slowly aging animals that present a distinct opportunity to further our understanding of age-related brain changes. Generally, for pigeons, the left hemisphere contributes to discrimination of local information, whereas the right contributes to processing of global information. The function of each hemisphere may be examined by covering one eye, as the optic nerves decussate almost completely in birds, directing the majority of visual information to the contralateral hemisphere. Using this eye-capping technique, we investigated pigeons' ability to select grains from among grit while under binocular and monocular viewing conditions, across three different age groups. Prior to the grit-grain discrimination task, pigeons were injected with a radioactive tracer, which was taken up by the brain as the pigeons performed the task. Upon completion of the discrimination task, the pigeons' brains were imaged via [18F] fluorodeoxyglucose positron emission tomography (FDG-PET) scans. This process allowed us to compare hemispheric activity during the discrimination task for each individual within each age group. The Very Old subjects showed significantly worse discrimination performance compared to the Adult and Old subjects, particularly when needing to search primarily with their right hemisphere. Furthermore, the Very Old subjects did not show differences in hemispheric activation when performing the task, whereas the left hemisphere was most active for the Adult and Old groups. To our knowledge, this is the first study to use FDG-PET imaging to evaluate whether the pigeon brain shows evidence of age-related reduction in hemispheric asymmetry during a visual discrimination task.
鸽子是长寿且衰老缓慢的动物，这为我们进一步了解与年龄相关的大脑变化提供了独特的机会。一般来说，对于鸽子而言，左半球有助于局部信息的辨别，而右半球则有助于整体信息的处理。通过遮盖一只眼睛，可以检查每只半球的功能，因为在鸟类中，视神经几乎完全交叉，将大部分视觉信息引导到对侧半球。使用这种眼罩技术，我们研究了鸽子在双眼和单眼观察条件下，从沙砾中选择颗粒的能力，跨越了三个不同的年龄组。在进行沙砾颗粒辨别任务之前，给鸽子注射放射性示踪剂，当鸽子完成任务时，示踪剂就会被大脑摄取。在辨别任务完成后，通过[18F]氟脱氧葡萄糖正电子发射断层扫描（FDG-PET）扫描对鸽子的大脑进行成像。这个过程允许我们在每个年龄组内的每个个体中比较辨别任务期间的半球活动。非常老的鸽子与成年和老年鸽子相比，辨别表现明显更差，尤其是当它们主要需要用右半球进行搜索时。此外，非常老的鸽子在执行任务时没有显示出半球激活的差异，而成年和老年组的左半球最为活跃。据我们所知，这是第一项使用 FDG-PET 成像来评估鸽子大脑在视觉辨别任务中是否存在与年龄相关的半球不对称性减少的研究。
