Muscimol-induced inactivation of monkey frontal eye field: Effects on visually and memory-guided saccades
Muscimol-induced inactivation of monkey frontal eye field: Effects on visually and memory-guided saccades
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DOI：
10.1152/jn.1999.81.5.2191
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发表时间：
1999-05-01
影响因子：
2.5
通讯作者：
Segraves, MA
中科院分区：
文献类型：
--
作者：
Dias, EC;Segraves, MA
虽然神经生理学，解剖学和成像证据表明，额眼场（FEF）参与的眼睛运动的产生，慢性病变的FEF在人类和猴子似乎只造成轻微的缺陷，在视觉引导的扫视一代。当受试者在具有更多认知要求的任务中进行测试时，观察到更强的效果。我们在急性失活FEF区域后测试了眼功能，以最大限度地减少FEF丧失后功能的可塑性和重新分配的影响，并更深入地了解FEF对完整大脑中眼球运动的指导作用。通过将蝇蕈醇直接微量注射到三只猴子的FEF中生理定义的位点中来诱导灭活。FEF失活严重损害了猴子的视觉引导和记忆引导的扫视。与视野中的任何其他位置相比，猴子对失活的FEF位点的视网膜定位表示发起的扫视较少。被启动的扫视具有较长的潜伏期，较慢的速度，和较大的目标误差比控制。这些效果都存在视觉引导和记忆引导的扫视，虽然记忆引导的扫视更中断。最初，这些效应在空间上受到限制，集中在失活位点中心的视网膜位置表征周围，但是，在几个小时的过程中，这些效应扩散到侧翼表征。目标位置的可预测性和猴子的动机也影响扫视性能。对于记忆引导的扫视，在此期间，猴子不得不记住目标的空间位置的时间的增加导致扫视的准确性和较小的峰值速度进一步降低，这表明在FEF失活后，保持目标位置相对于中央凹的代表性的能力逐渐丧失。此外，猴子经常过早扫视目标在同侧注射部位时，执行记忆任务，表明缺陷的控制固定，可能是注射后同侧和对侧FEF活动之间的不平衡的结果。也有一个渐进的固定准确性损失，猴子往往限制自发的视觉扫描同侧半野。这些结果强调了完整猴的FEF在产生所有自愿扫视眼球运动以及控制注视中的强大作用。
Although neurophysiological, anatomic, and imaging evidence suggest that the frontal eye field (FEF) participates in the generation of eye movements, chronic lesions of the FEF in both humans and monkeys appear to cause only minor deficits in visually guided saccade generation. Stronger effects are observed when subjects are tested in tasks with more cognitive requirements. We tested oculomotor function after acutely inactivating regions of the FEF to minimize the effects of plasticity and reallocation of function after the loss of the FEF and gain more insight into the FEF contribution to the guidance of eye movements in the intact brain. Inactivation was induced by microinjecting muscimol directly into physiologically defined sites in the FEF of three monkeys. FEF inactivation severely impaired the monkeys' performance of both visually guided and memory-guided saccades. The monkeys initiated fewer saccades to the retinotopic representation of the inactivated FEF site than to any other location in the visual field. The saccades that were initiated had longer latencies, slower velocities, and larger targeting errors than controls. These effects were present both for visually guided and for memory-guided saccades, although the memory-guided saccades were more disrupted. Initially, the effects were restricted spatially, concentrating around the retinotopic representation at the center of the inactivated site, but, during the course of several hours, these effects spread to flanking representations. Predictability of target location and motivation of the monkey also affected saccadic performance. For memory-guided saccades, increases in the time during which the monkey had to remember the spatial location of a target resulted in further decreases in the accuracy of the saccades and in smaller peak velocities, suggesting a progressive loss of the capacity to maintain a representation of target location in relation to the fovea after FEF inactivation. In addition, the monkeys frequently made premature saccades to targets in the hemifield ipsilateral to the injection site when performing the memory task, indicating a deficit in the control of fixation that could be a consequence of an imbalance between ipsilateral and contralateral FEF activity after the injection. There was also a progressive loss of fixation accuracy, and the monkeys tended to restrict spontaneous visual scanning to the ipsilateral hemifield. These results emphasize the strong role of the FEF in the intact monkey in the generation of all voluntary saccadic eye movements, as well as in the control of fixation.