Sequential activity of simultaneously recorded neurons in the superior colliculus during curved saccades
Sequential activity of simultaneously recorded neurons in the superior colliculus during curved saccades
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DOI：
10.1152/jn.01151.2002
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发表时间：
2003-09-01
影响因子：
2.5
通讯作者：
Wurtz, RH
中科院分区：
文献类型：
--
作者：
Port, NL;Wurtz, RH
视觉世界呈现出多个潜在的目标，这些目标可以通过眼球跳跃性运动带到中央凹。这些目标在运动地图上的上丘（SC）的多个位置产生活动，上丘是大脑中与扫视产生有关的区域。眼跳的产生一定是代表这些眼跳目标的神经元群之间竞争的结果，在本实验中，我们使用了多个可移动的微电极来跟踪这种竞争。我们同时从SC地图上的两个地点进行记录，每个地点与不同的扫视目标相关。这两个目标以快速的顺序出现，猴子如果向第一个出现的目标扫视，就会得到奖励。我们的研究集中在实验中，猴子做强烈的弯曲扫视，首先指向一个目标，然后指向另一个目标。当他们从一个目标转向另一个目标时，这些弯曲的扫视激活了SC地图上的两个地点。主要的发现是，强烈弯曲的扫视发生在两个神经元的连续活动之前，这一点可以从三个观察结果中看出：与第一个目标相关的神经元的放电率比第二个目标相关的神经元的放电率达到峰值要早；两个神经元的活动峰值出现的时间与扫视曲率的开始和结束有关；基于两个神经元活动的加权向量平均模型预测了扫视曲率的时间。直接平均扫视在目标之间结束，这样它们就不会去到任何一个目标，并且伴随着两个神经元的同时而不是顺序激活。因此，当多个神经元群在SC运动图上活跃时，产生的扫视是由这些神经元群活动的相对时间以及它们的大小决定的。相比之下，这两个位置的SC活动并不能预测扫视的最终方向，而且几个对照实验发现SC地图上其他位置的活动不足，无法解释最终方向。我们的结论是，SC神经元的活动预测了扫视曲率的时间，但不是轨迹的最终方向。这些观察结果与SC活动在选择扫视目标时至关重要的观点是一致的，但在确定确切的轨迹时并不重要。
The visual world presents multiple potential targets that can be brought to the fovea by saccadic eye movements. These targets produce activity at multiple sites on a movement map in the superior colliculus (SC), an area of the brain related to saccade generation. The saccade made must result from competition between the populations of neurons representing these many saccadic goals, and in the present experiments we used multiple moveable microelectrodes to follow this competition. We recorded simultaneously from two sites on the SC map where each site was related to a different saccade target. The two targets appeared in rapid sequence, and the monkey was rewarded for making a saccade toward the one appearing first. Our study concentrated on trials in which the monkey made strongly curved saccades that were directed first toward one target and then toward the other. These curved saccades activated both sites on the SC map as they veered from one target to the other. The major finding was that the strongly curved saccades were preceded by sequential activity in the two neurons as indicated by three observations: the firing rate for the neuron related to the first target reached its peak earlier than did the rate of the neuron for the second target; the timing of the peak activity of the two neurons was related to the beginning and end of the saccade curvature; a weighted vector-average model based on the activity of the two neurons predicted the timing of saccade curvature. Straight averaging saccades ended between the targets so that they did not go to either target, and they were accompanied by simultaneous rather than sequential activation of the two neurons. Thus when multiple populations of neurons are active on the SC movement map, the resulting saccade is determined by the relative timing of the activity in the populations as well as their magnitude. In contrast, SC activity at the two sites did not predict the final direction of the saccade, and several control experiments found insufficient activity at other sites on the SC map to account for that final direction. We conclude that the SC neuronal activity predicts the timing of the saccade curvature, but not the final direction of the trajectory. These observations are consistent with SC activity being critical in selecting the goal of the saccade, but not in determining the exact trajectory.