Reversible inactivation of monkey superior colliculus. II. Maps of saccadic deficits
Reversible inactivation of monkey superior colliculus. II. Maps of saccadic deficits
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DOI：
10.1152/jn.1998.79.4.2097
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发表时间：
1998-04-01
影响因子：
2.5
通讯作者：
Wurtz, RH
中科院分区：
文献类型：
--
作者：
Quaia, C;Aizawa, H;Wurtz, RH
上级丘（SC）的神经元被组织为视觉和运动空间的地图。配套论文表明，蝇蕈醇注射到SC的中间层改变了运动的轨迹，并证实了先前报道的对潜伏期，幅度和扫视速度的影响。在本文中，我们分析了这些赤字在整个视野的模式，通过系统地比较每个赤字的大小，在整个网格的目标覆盖了大部分的视野。我们还翻译这些赤字的视觉/运动领域的SC地图，以获得在SC的赤字的程度的定性估计。我们发现了一个一致的模式，大幅增加扫视潜伏期的目标在对侧的视觉hemifield，伴随着轻微的和不一致的增加和减少扫视同侧hemifield。眼跳的起始速度和峰值速度在注射后降低。注射后的眼跳幅度要么hypometric或normometric，但很少hypometric。虽然在注射后扫视的初始方向的错误是小的，他们始终形成了一个简单的模式：一个初始方向与最小的错误（零方向）分离区域的顺时针和逆时针旋转的初始方向。然而，零方向没有穿过未激活区域的中心，如如果SC单独确定扫视方向所预期的，例如，一个人口代码。可以解释零方向与病变部位的未对准的一个假设是，与SC并行作用的另一系统有助于确定扫视轨迹。
Neurons in the superior colliculus (SC) are organized as maps of visual and motor space. The companion paper showed that muscimol injections into intermediate layers of the SC alter the trajectory of the movement and confirmed previously reported effects on latency, amplitude, and speed of saccades. In this paper we analyze the pattern of these deficits across the visual field by systematically comparing the magnitude of each deficit throughout a grid of targets covering a large fraction of the visual field. We also translate these deficits onto the SC map of the visual/movement fields to obtain a qualitative estimate of the extent of the deficit in the SC. We found a consistent pattern of substantially increased saccadic latency to targets in the contralateral visual hemifield, accompanied by slight and inconsistent increases and decreases for saccades to the ipsilateral hemifield. The initial and peak speed of saccades was reduced after the injection. The postinjection amplitude of the saccades were either hypometric or normometric, but rarely hypermetric. Although errors in the initial direction of the postinjection saccades were small, they consistently formed a simple pattern: an initial direction with minimal errors (a null direction) separating regions with clockwise and counterclockwise rotations of the initial direction. However, the null direction did not go through the center of the inactivated zone, as would be expected if the SC alone were determining saccade direction, e.g., with a population code. One hypothesis that can explain the misalignment of the null direction with the lesion site is that another system, acting in parallel with the SC, contributes to the determination of saccadic trajectory.