Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America.
PLoS One. 2013;8(2):e56543. doi: 10.1371/journal.pone.0056543. Epub 2013 Feb 18.
The pigmented Long-Evans rat has proven to be an excellent subject for studying visually guided behavior including quantitative visual psychophysics. This observation, together with its experimental accessibility and its close homology to the mouse, has made it an attractive model system in which to dissect the thalamic and cortical circuits underlying visual perception. Given that visually guided behavior in the absence of primary visual cortex has been described in the literature, however, it is an empirical question whether specific visual behaviors will depend on primary visual cortex in the rat. Here we tested the effects of cortical lesions on performance of two-alternative forced-choice visual discriminations by Long-Evans rats. We present data from one highly informative subject that learned several visual tasks and then received a bilateral lesion ablating >90% of primary visual cortex. After the lesion, this subject had a profound and persistent deficit in complex image discrimination, orientation discrimination, and full-field optic flow motion discrimination, compared with both pre-lesion performance and sham-lesion controls. Performance was intact, however, on another visual two-alternative forced-choice task that required approaching a salient visual target. A second highly informative subject learned several visual tasks prior to receiving a lesion ablating >90% of medial extrastriate cortex. This subject showed no impairment on any of the four task categories. Taken together, our data provide evidence that these image, orientation, and motion discrimination tasks require primary visual cortex in the Long-Evans rat, whereas approaching a salient visual target does not.
色素性长耳豚鼠已被证明是研究视觉引导行为（包括定量视觉心理物理学）的极佳对象。这种观察结果，再加上其易于进行实验和与小鼠的密切同源性，使它成为一种有吸引力的模型系统，可以剖析视觉感知背后的丘脑和皮层回路。然而，鉴于文献中已经描述了在没有初级视觉皮层的情况下进行的视觉引导行为，因此，特定的视觉行为是否取决于大鼠的初级视觉皮层是一个经验问题。在这里，我们测试了皮质损伤对长耳豚鼠进行两种选择强制选择视觉辨别任务的影响。我们呈现了一个非常有信息量的主体的数据，该主体学习了几个视觉任务，然后接受了双侧损伤，导致超过 90%的初级视觉皮层被破坏。损伤后，与损伤前的表现和假手术对照组相比，该主体在复杂图像辨别、方向辨别和全场光流运动辨别方面存在严重且持久的缺陷。然而，在需要接近明显视觉目标的另一个视觉两种选择强制选择任务上，表现是完整的。第二个非常有信息量的主体在接受损伤超过 90%的内侧外纹状皮层之前学习了几个视觉任务。该主体在四个任务类别中均未表现出任何损伤。总之，我们的数据提供了证据表明，这些图像、方向和运动辨别任务需要长耳豚鼠的初级视觉皮层，而接近明显的视觉目标则不需要。
