Department of Optometry and Vision Science, University of Auckland, Private Bag 92019, Auckland, New Zealand.
Neuroimage. 2012 Apr 2;60(2):1307-15. doi: 10.1016/j.neuroimage.2012.01.078. Epub 2012 Jan 24.
Converging evidence from human psychophysics and animal neurophysiology indicates that amblyopia is associated with abnormal function of area MT, a motion sensitive region of the extrastriate visual cortex. In this context, the recent finding that amblyopic eyes mediate normal perception of dynamic plaid stimuli was surprising, as neural processing and perception of plaids has been closely linked to MT function. One intriguing potential explanation for this discrepancy is that the amblyopic eye recruits alternative visual brain areas to support plaid perception. This is the hypothesis that we tested. We used functional magnetic resonance imaging (fMRI) to measure the response of the amblyopic visual cortex and thalamus to incoherent and coherent motion of plaid stimuli that were perceived normally by the amblyopic eye. We found a different pattern of responses within the visual cortex when plaids were viewed by amblyopic as opposed to non-amblyopic eyes. The non-amblyopic eyes of amblyopes and control eyes differentially activated the hMT+ complex when viewing incoherent vs. coherent plaid motion, consistent with the notion that this region is centrally involved in plaid perception. However, for amblyopic eye viewing, hMT+ activation did not vary reliably with motion type. In a sub-set of our participants with amblyopia we were able to localize MT and MST within the larger hMT+ complex and found a lack of plaid motion selectivity in both sub-regions. The response of the pulvinar and ventral V3 to plaid stimuli also differed under amblyopic vs. non-amblyopic eye viewing conditions, however the response of these areas did vary according to motion type. These results indicate that while the perception of the plaid stimuli was constant for both amblyopic and non-amblyopic viewing, the network of neural areas that supported this perception was different.
来自人类心理物理学和动物神经生理学的综合证据表明，弱视与大脑外侧枕叶的运动敏感区域 MT 区的功能异常有关。在这种情况下，最近发现弱视眼能够正常感知动态条纹刺激，这令人惊讶，因为条纹的神经处理和感知与 MT 功能密切相关。对于这种差异的一个有趣的潜在解释是，弱视眼会招募替代的视觉大脑区域来支持条纹感知。这就是我们要测试的假设。我们使用功能磁共振成像（fMRI）来测量弱视视觉皮层和丘脑对条纹刺激的非相干和相干运动的反应，这些刺激被弱视眼正常感知。当用弱视眼和非弱视眼观察条纹时，我们在视觉皮层内发现了不同的反应模式。当观察非相干和相干条纹运动时，弱视眼的非弱视眼和对照组的眼睛会对 hMT+ 复合体产生不同的激活，这与该区域在条纹感知中起核心作用的观点一致。然而，对于弱视眼观察，hMT+ 的激活与运动类型之间没有可靠地变化。在我们的一部分弱视参与者中，我们能够在更大的 hMT+复合体中定位 MT 和 MST，并发现这两个子区域都缺乏条纹运动选择性。在条纹刺激下，丘脑枕和腹侧 V3 的反应也因弱视眼和非弱视眼的观察条件而异，但是这些区域的反应确实根据运动类型而变化。这些结果表明，尽管条纹刺激的感知对弱视眼和非弱视眼观察都是恒定的，但支持这种感知的神经区域网络是不同的。
