Neurons in the supplementary eye field of rhesus monkeys code visual targets and saccadic eye movements in an oculocentric coordinate system.
Neurons in the supplementary eye field of rhesus monkeys code visual targets and saccadic eye movements in an oculocentric coordinate system.
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恒河猴辅助眼野中的神经元在眼中心坐标系中编码视觉目标和扫视眼球运动。
DOI：
10.1152/jn.1996.76.2.825
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Bruce,CJ
中科院分区：
文献类型：
--
作者：
Russo,GS;Bruce,CJ
1.我们研究了猕猴补充眼野（SEF）中的神经元是否在眼心坐标（相对于当前固定方向）或颅心坐标（相对于头部）中编码扫视眼球运动。SEF中的颅中心编码先前已被认为是源于不同轨道位置的电诱发扫视的会聚外观。2.我们主要研究了在扫视开始之前开始响应的SEF神经元，因为这种扫视前活动可能与扫视生成和度量有关。使用记忆眼跳任务，我们分类为纯粹的视觉相关，纯粹的运动相关，或视觉和运动相关的每个神经元的前accadic活动。3.然后，我们映射的SEF神经元的反应场（感受野和运动场）从不同的轨道位置。当相对于中央注视点映射时，给定SEF神经元的最强反应总是发生在特定的极性方向上，偏离该方向时会出现相当对称的下降。当使用其他固定点位置进行测试时，他们最强的反应几乎总是持续发生在相对于每个固定点具有相同极方向的刺激上，因此他们似乎在以眼为中心的坐标系中对刺激方向和扫视方向进行编码。4.通过计算每个神经元的“交叉距离”，即在两个偏心轨道位置处测量的神经元的最佳极方向的延伸收敛的点的偏心率，以及2）“轨道扰动指数”，使得指数0对应于神经元的最佳极方向在不同轨道位置上没有变化（也就是说，完全眼中心响应场）和指数1对应于收敛到相同颅中心目标的最佳极方向而不管初始眼睛位置（即，完美的颅心反应场）。对于同时具有视觉和运动反应的神经元，这些测量值分别针对每种类型的活动使用在时间上分离视觉提示呈现和对它的扫视的任务来计算。几乎所有的交叉距离都远远超出了猴子的视力范围（+/- 50度）（38/39的运动活动和62/66的视觉活动）。视觉活动的中值交叉距离非常大（274度），运动活动的中值略微发散（超过无穷大）。因此，SEF神经元很少表现出明显的反应场方向的收敛。6.同样地，平均轨道扰动指数非常小（对于运动活动为-0.04 +/-0.21，平均值+/- SD，对于视觉活动为0.09 +/-0.15），也表明SEF神经元以眼中心的方式编码刺激和扫视。7.对于具有视觉和运动活动的神经元，两种活动的轨道扰动指数没有显著相关性（r = 0.16），即使它们的特征方向（从屏幕中心估计的最佳极方向）几乎相同（圆相关，r+ = 0.97）。视觉和运动活动轨道摄动指数之间缺乏显着的相关性是一致的假设，该指数的变化代表统计独立的测量误差。相反，视觉和运动活动特征方向的强协变表明，方向偏好是SEF的preaccadic活动的一个基本功能特性。
1. We investigated whether neurons in the supplementary eye field (SEF) of macaque monkeys code saccadic eye movements in oculocentric coordinates (relative to the current direction of fixation) or in craniocentric coordinates (relative to the head). Craniocentric coding in SEF had been previously suggested by the convergent appearance of electrically elicited saccades originating at different orbital positions. 2. We primarily studied SEF neurons that started responding before the beginning of saccades because such presaccadic activity is likely related to saccade generation and metrics. Using a memory-saccade task, we classified the presaccadic activity of each neuron as either purely visual related, purely movement related, or both visual and movement related. 3. We then mapped the response fields (receptive fields and movement fields) of SEF neurons from different orbital positions. When mapped relative to a central fixation point, the strongest responses for a given SEF neuron invariably occurred for a particular polar direction with fairly symmetrical declines for departures from that direction. When tested using other fixation point locations, their strongest responses almost always continued to occur for stimuli having the same polar direction relative to each fixation point tested, and thus they appeared to code both stimulus direction and saccade direction in an oculocentric coordinate system. 4. The effect of eye position on SEF presaccadic activity was quantified in two ways by computing, for each neuron, 1) an "intersection distance," the eccentricity of the point where extensions of the neuron's optimal polar directions measured at two eccentric orbital positions converged, and 2) an "orbital perturbation index" such that an index of 0 corresponded to no change in the neuron's optimal polar direction across different orbital positions (i.e., perfectly oculocentric response fields) and an index of 1 corresponded to optimal polar directions that converged to the same craniocentric goal regardless of initial eye position (i.e., perfectly craniocentric response fields). For neurons with both visual and movement responses, these measures were calculated separately for each type of activity using tasks that temporally separated the visual cue presentation and the saccade to it. 5. Almost all of the intersection distances were well beyond the oculomotor range (+/- 50 degrees) of the monkey (38/39 for movement activity and 62/66 for visual activity). The median intersection distance for visual activity was very large (274 degrees), and the median for movement activity was slightly divergent (beyond infinity). Thus SEF neurons rarely showed a conspicuous convergence of response field direction. 6. Likewise, the mean orbital perturbation indexes were very small (-0.04 +/- 0.21, mean +/- SD, for movement activity and 0.09 +/- 0.15 for visual activity), also indicating that SEF neurons code stimuli and saccades in an oculocentric manner. 7. For neurons with both visual and movement activities, the orbital perturbation indexes of the two activities were not significantly correlated (r = 0.16), even though their characteristic directions (optimal polar direction estimated from the center of the screen) were almost the same (circular correlation, r+ = 0.97). The lack of a significant correlation between the visual and movement activity orbital perturbation indexes is consistent with the hypothesis that most of the variation in this index represents statistically independent errors of measurement. Conversely, the strong covariation of visual and movement activity characteristic directions indicates that directional preference is a fundamental functional property of SEF presaccadic activity …