Collins Christine E, Lyon David C, Kaas Jon H
Department of Psychology, Vanderbilt University, Nashville, Tennessee 37203, USA.
J Neurosci. 2003 Mar 15;23(6):2251-64. doi: 10.1523/JNEUROSCI.23-06-02251.2003.
The retinotopic organization of the middle temporal visual area (MT) was determined in six adult owl monkeys and one adult marmoset 69 d to 10 months after lesions of the dorsolateral primary visual cortex (V1). The lesions removed were limited to extensive parts of the representation of the lower visual quadrant in V1. Microelectrodes were used to record from neurons at numerous sites in MT to determine whether parts of MT normally devoted to the lower visual quadrant (1) were unresponsive to visual stimuli, (2) acquired responsiveness to inputs from intact portions of V1, or (3) became responsive to some other visually driven input such as a relay from the superior colliculus via the pulvinar to MT. All monkeys (n = 6) with moderate to moderately large lesions had unresponsive portions of MT even after 10 months of recovery. These unresponsive regions were retinotopically equivalent to the removed parts of V1 in normal animals. Thus, there was no evidence for an alternative source of activation. In addition, these results indicate that any retinotopic reorganization of MT based on inputs from intact portions of V1 was not extensive, yet neurons near the margins of responsive cortex may have acquired new receptive fields, and the smallest 5 degrees lesion of V1 failed to produce an unresponsive zone. Deprived portions of MT were not remarkably changed in histological appearance in cytochrome oxidase, Nissl, and Wisteria floribunda agglutinin preparations. Nevertheless, some reduction in myelin staining and other histological changes were suggested. We conclude that MT is highly dependent on V1 for activation in these monkeys, and alternative sources do not become effective over months when normal activation is absent. Additionally, remaining V1 inputs have only a limited capacity to expand their activation territory into deprived portions of MT.
在6只成年猫头鹰猴和1只成年狨猴的背外侧初级视皮层（V1）受损69天至10个月后，确定了颞中视觉区（MT）的视网膜拓扑组织。切除的病变仅限于V1中下部视觉象限表征的广泛部分。使用微电极记录MT中多个部位的神经元活动，以确定MT中通常负责下部视觉象限的部分：（1）对视觉刺激无反应；（2）获得对V1完整部分输入的反应性；或（3）对其他视觉驱动输入有反应，例如通过丘脑枕从视上丘到MT的中继。所有有中度至中度大损伤的猴子（n = 6）即使在恢复10个月后，MT仍有无反应部分。这些无反应区域在视网膜拓扑上与正常动物中V1被切除的部分相对应。因此，没有证据表明存在替代激活源。此外，这些结果表明，基于V1完整部分输入的MT视网膜拓扑重组并不广泛，然而，反应性皮层边缘附近的神经元可能获得了新的感受野，V1最小5度的损伤未能产生无反应区。在细胞色素氧化酶、尼氏染色和紫藤凝集素制剂中，MT的剥夺部分在组织学外观上没有明显变化。尽管如此，还是提示有一些髓磷脂染色减少和其他组织学变化。我们得出结论，在这些猴子中，MT的激活高度依赖于V1，当正常激活缺失时，数月内替代源不会变得有效。此外，剩余的V1输入将其激活区域扩展到MT剥夺部分的能力有限。
