Pursuit speed compensation in cortical area MSTd.
Pursuit speed compensation in cortical area MSTd.
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DOI：
10.1152/jn.00002.2001
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发表时间：
2002-11
影响因子：
2.5
通讯作者：
K. Shenoy;J. Crowell;R. Andersen
中科院分区：
文献类型：
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作者：
K. Shenoy;J. Crowell;R. Andersen
当我们向前移动时，视网膜上的视觉图像就会扩大。人类依靠这种扩展的焦点或中心来估计他们的自我运动或航向的方向，只要眼睛静止，视网膜焦点就对应于航向。然而，平滑的追踪眼球运动会增加扩张的视网膜图像的视觉运动，并取代扩张的焦点。尽管如此，即使视网膜焦点不再与航向相对应，人类在追踪眼球运动时仍能准确判断其航向。最近对猕猴的研究表明，追踪校正可能发生在内侧上颞区（MSTd）的背侧；该区域的神经元会调整到焦点的视网膜位置，并修改其调整以部分补偿由追踪引起的焦点偏移。然而，问题仍然是这些神经元是否会以更快的追踪速度进行更多的焦点调整，以补偿更快的追踪造成的更大的焦点偏移。为了研究这个问题，我们记录了猴子在模拟的自身或物体运动显示中以一定速度进行追踪眼球运动时的 40 个 MSTd 神经元。我们发现，大多数 MSTd 神经元在更快的追踪速度下会更多地调整它们的焦点调整，这与它们编码航向和其他运动参数而不管追踪速度如何的想法是一致的。在整个人群中，随着追求速度的增加，补偿的中位数增幅为完美补偿所需的 51%。我们在模拟追踪条件下从相同的神经元进行记录，其中凝视是固定的，但整个显示器反向旋转以产生与真实追踪期间相同的视网膜图像。这种情况产生的结果是视网膜线索有助于追踪补偿；补偿增幅为航向准确编码所需补偿增幅的30%。这两种情况之间的差异显着（P < 0.05），表明视网膜外线索也有显着贡献。我们发现首选追求和首选视觉运动方向之间存在系统性的反对。神经元可以利用这种抗对齐来结合视网膜和视网膜外的补偿信号。这些结果表明，许多 MSTd 神经元补偿了追踪速度、先前报道的追踪方向和追踪速度，并进一步表明 MSTd 是自我运动计算中的关键阶段。
When we move forward the visual images on our retinas expand. Humans rely on the focus, or center, of this expansion to estimate their direction of self-motion or heading and, as long as the eyes are still, the retinal focus corresponds to the heading. However, smooth pursuit eye movements add visual motion to the expanding retinal image and displace the focus of expansion. In spite of this, humans accurately judge their heading during pursuit eye movements even though the retinal focus no longer corresponds to the heading. Recent studies in macaque suggest that correction for pursuit may occur in the dorsal aspect of the medial superior temporal area (MSTd); neurons in this area are tuned to the retinal position of the focus and they modify their tuning to partially compensate for the focus shift caused by pursuit. However, the question remains whether these neurons shift focus tuning more at faster pursuit speeds, to compensate for the larger focus shifts created by faster pursuit. To investigate this question, we recorded from 40 MSTd neurons while monkeys made pursuit eye movements at a range of speeds across simulated self- or object motion displays. We found that most MSTd neurons modify their focus tuning more at faster pursuit speeds, consistent with the idea that they encode heading and other motion parameters regardless of pursuit speed. Across the population, the median rate of compensation increase with pursuit speed was 51% as great as required for perfect compensation. We recorded from the same neurons in a simulated pursuit condition, in which gaze was fixed but the entire display counter-rotated to produce the same retinal image as during real pursuit. This condition yielded the result that retinal cues contribute to pursuit compensation; the rate of compensation increase was 30% of that required for accurate encoding of heading. The difference between these two conditions was significant (P < 0.05), indicating that extraretinal cues also contribute significantly. We found a systematic antialignment between preferred pursuit and preferred visual motion directions. Neurons may use this antialignment to combine retinal and extraretinal compensatory cues. These results indicate that many MSTd neurons compensate for pursuit velocity, pursuit direction as previously reported and pursuit speed, and further implicate MSTd as a critical stage in the computation of egomotion.