Primate Research Institute, Kyoto University, Inuyama, Aichi 484-8506, Japan.
Neuropsychologia. 2013 Nov;51(13):2856-62. doi: 10.1016/j.neuropsychologia.2013.09.011. Epub 2013 Sep 11.
Deficits in the occipital cortex have varying consequences among mammalian species. Such variations are indicative of evolutionary transitions in the striate cortical contribution to visually guided behavior. However, little is known about the role of the striate cortex in visually guided behavior in chimpanzees due to ethical concerns about invasive experiments and methodological limitations such as the inability to monitor gaze movements. We had the opportunity to study the behavioral consequences of a deficit in the occipital cortex in a chimpanzee with a naturally occurring arachnoid cyst in her right occipital lobe. We assessed the chimpanzee's ability to detect a small light probe (0.5 visual degree, Michelson contrast > 0.9) presented at several locations in the visual field while monitoring gaze direction using an infra-red remote eye-tracker recently introduced to studies of great apes. The results showed the chimpanzee was unable to detect the probe in the lower left quadrant of the visual field, suggesting severe loss of contrast sensitivity in a part of hemivisual field that is retinotopically corresponded to the hemisphere of the cyst. A chimpanzee with a naturally occurring deficit in the right striate cortex and the availability of remote eye-tracking technology presented a unique opportunity to compare the role of the occipital lobe in visually guided behavior among various primate species.
哺乳动物的枕叶皮层缺陷有不同的后果。这种变化表明，纹状皮层对视觉引导行为的贡献在进化上发生了转变。然而，由于对侵入性实验的伦理关注以及无法监测眼球运动等方法学限制，对于黑猩猩的视觉引导行为中纹状皮层的作用知之甚少。我们有机会研究一只黑猩猩右枕叶蛛网膜囊肿引起的枕叶皮层缺陷对其视觉引导行为的影响。我们评估了这只黑猩猩在使用最近引入的用于大猿研究的红外线远程眼动追踪器监测注视方向的情况下，在几个视野位置检测小光探针（0.5 视度，米歇尔逊对比度>0.9）的能力。结果表明，黑猩猩无法检测到视野左下角的探针，这表明其半视野的对比敏感度严重丧失，该区域与囊肿所在的大脑半球在视网膜上相对应。一只黑猩猩的右纹状皮层自然出现缺陷，并且具备远程眼动追踪技术，为比较不同灵长类物种的枕叶在视觉引导行为中的作用提供了独特的机会。
