Changes in control of saccades during gain adaptation.
Changes in control of saccades during gain adaptation.
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DOI：
10.1523/jneurosci.3470-08.2008
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发表时间：
2008-12-17
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影响因子：
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通讯作者：
Shadmehr R
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文献类型：
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作者：
Ethier V;Zee DS;Shadmehr R
在典型的短期扫视自适应协议中，目标朝向（增益下降）或远离（增益上升）初始注视在扫视内移动，导致扫视以端点错误完成。一个核心问题是运动系统如何适应这种错误：运动指令是否改变以将眼睛带到不同的目标，类似于目标的重新映射，或者适应集中在监测正在进行的运动指令并在飞行中纠正它们的过程，类似于通过内部反馈进行的变化？在这里，我们发现，在增益下降范式中，大脑学会了通过改变扫视的轨迹来产生较小幅度的扫视。适应眼跳有降低的峰值速度，降低的加速度，较浅的减速，并增加持续时间相比，控制眼跳的幅度相等。这些变化与作为正向模型的内部反馈的变化一致。另一方面，在增益模式中，大脑学会了产生一个更大幅度的眼跳，其轨迹与等幅度的控制眼跳相同。因此，而增益下降的范例似乎通过内部反馈，控制眼跳飞行中诱导适应，增益上升诱导适应主要是通过目标重新映射。我们的模拟解释说，对于每种条件，特定的适应产生了一个眼跳，使眼睛以最小的运动成本的目标。
In a typical short-term saccadic adaptation protocol, the target moves intra-saccadically either toward (gain-down) or away (gain-up) from initial fixation, causing the saccade to complete with an endpoint error. A central question is how the motor system adapts in response to this error: are the motor commands changed to bring the eyes to a different goal, akin to a remapping of the target, or is adaptation focused on the processes that monitor the ongoing motor commands and correct them midflight, akin to changes that act via internal feedback? Here, we found that in the gain-down paradigm, the brain learned to produce a smaller amplitude saccade by altering the saccade's trajectory. The adapted saccades had reduced peak velocities, reduced accelerations, shallower decelerations, and increased durations compared to a control saccade of equal amplitude. These changes were consistent with a change in an internal feedback that acted as a forward model. On the other hand, in the gain-up paradigm the brain learned to produce a larger amplitude saccade with trajectories that were identical to those of control saccades of equal amplitude. Therefore, whereas the gain-down paradigm appeared to induce adaptation via an internal feedback that controlled saccades midflight, gain-up induced adaptation primarily via target remapping. Our simulations explained that for each condition, the specific adaptation produced a saccade that brought the eyes to the target with the smallest motor costs.