DEFICITS IN EYE POSITION FOLLOWING ABLATION OF MONKEY SUPERIOR COLLICULUS, PRETECTUM, AND POSTERIOR-MEDIAL THALAMUS
DEFICITS IN EYE POSITION FOLLOWING ABLATION OF MONKEY SUPERIOR COLLICULUS, PRETECTUM, AND POSTERIOR-MEDIAL THALAMUS
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DOI：
10.1152/jn.1982.48.2.318
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发表时间：
1982-01-01
影响因子：
2.5
通讯作者：
WURTZ, RH
中科院分区：
文献类型：
--
作者：
ALBANO, JE;WURTZ, RH
以前的调查的灵长类动物上级丘消融的影响产生了相互矛盾的结果：一些研究报告赤字的视觉引导扫视的准确性，而其他主要赤字的视觉引导扫视的潜伏期。本实验试图通过研究上级丘的完全损伤对中央和周边视觉目标的扫视的启动和准确性的影响来解决这一冲突。四只恒河猴被训练对视觉刺激进行扫视，然后对上级丘进行大的单侧手术消融。脑干的组织学重建显示，所有4只猴的丘切除几乎完全，包括代表视野中心和周边部分的浅层和深层。然而，在3只猴子的病变还包括广泛的区域，在前顶盖和后内侧丘脑的丘前。消融后，3只病变更广泛的猴子表现出从中央注视点到消融对侧偏心视觉目标的准确扫视能力的长期缺陷。扫视目标>. apprx。20.degree.从中心注视点的视觉反馈持续地下降，并且没有被随后的扫视纠正。在第4只猴子中，消融几乎仅限于丘，对病变对侧视觉目标的初始扫视准确性的缺陷相对较小，并且容易通过第2次扫视进行纠正。然后对猴子进行测试，以确定扫视准确性的缺陷是否与扫视的幅度或扫视对周边眼睛位置的影响有关。猴子被要求从不同偏心率的注视点进行相同幅度的扫视。消融后，眼位置的错误扫视视觉目标的目标偏心增加。对侧外周靶点的固定也有错误。错误的固定和扫视成正比的偏心率的视觉目标。眼球运动缺陷与眼跳幅度无关，而是与眼球在眼眶中的位置有关。虽然4只猴子中只有3只表现出在实现偏心眼位置方面的缺陷，但所有4只猴子在消融对侧的整个视野中对目标的扫视都表现出增加的延迟。潜伏期缺陷与眼位无关，并在第1个月内基本恢复。测试。完全单侧消融上级丘的效果对扫视的起始和准确性仅产生最小的影响。当顶盖前区和后内侧丘脑受到额外的损伤时，就会产生严重而持久的准确性缺陷。缺陷似乎是无法准确地匹配眼睛的位置视觉目标。顶盖前和后内侧丘脑的核团可能是产生这种缺陷的关键结构，这可能是因为它们与上级丘和额叶眼野相互连接。这些观察结果与假设视觉引导的扫视是使用指定目标在空间中的位置的信号生成的眼动控制的模型一致。
Previous investigations of the effects of ablations of the primate superior colliculus have produced conflicting results: several studies reported deficits in the accuracy of visually guided saccades while others reported primarily deficits in the latency of visually guided saccades. The present experiments attempted to resolve this conflict by examining the effects of complete lesions of the superior colliculus on the initiation and accuracy of saccades to central and peripheral visual targets. Four rhesus monkeys were trained to make saccades to visual stimuli and were then given large unilateral surgical ablations of the superior colliculus. Histological reconstructions of the brain stems showed that colliculus removal in all 4 monkeys was nearly complete and included the superficial and deep layers, representing the central and peripheral portions of the visual field. However, in 3 monkeys the lesions also included extensive regions anterior to the colliculus in the pretectum and in the posterior-medial thalamus. After the ablations the 3 monkeys with more extensive lesions showed a long-lasting deficit in the ability to make accurate saccades from a central fixation point to eccentric visual targets on the side contralateral to the ablation. Saccades to targets > .apprx. 20.degree. from the central fixation point consistently fell short and were not corrected by subsequent saccades. In the 4th monkey, with the ablation nearly restricted to the colliculus, deficits in the accuracy of initial saccades to visual targets on the side contralateral to the lesion were relatively small and were readily corrected by 2nd saccades. Monkeys were then tested to determine whether the deficits in the accuracy of saccades were related to the amplitude of the saccades or to saccades make to peripheral eye positions. The monkeys were required to make the same-amplitude saccades but from fixation points of varying eccentricity. After the ablations, the error in eye position for saccades to visual targets increased with the eccentricity of the target. Fixations of peripheral targets on the contralateral side were also in error. Errors in fixation and saccades were proportional to the eccentricity of the visual target. The oculomotor deficit was not specifically related to the amplitude of the saccade but rather to the position of the eye in the orbit. While only 3 of the 4 monkeys demonstrated deficits in achieving eccentric eye positions, all 4 monkeys demonstrated increased latencies for saccades to targets throughout the visual field contralateral to the ablation. Latency deficits were not correlated with eye position and largely recovered during the 1st mo. of testing. The effect of complete unilateral ablation of the superior colliculus alone produces only minimal effects on the initiation and accuracy of saccades. When there is additional damage to the pretectum and posterior-medial thalamus, severe and long-lasting deficits in accuracy are produced. The deficit appears to be an inability to match accurately the position of the eye to visual targets. The nuclei in the pretectum and posterior-medial thalamus may be the critical structures in producing this deficit, possibly because of their interconnections with the superior colliculi and frontal eye fields. These observations are consistent with a model of oculomotor control that assumes that a visually guided saccade is generated using a signal specifying the position of the target in space.